[PATCH] D135822: [clang-tidy] Add option `IgnoreVoidReturnType` to `modernize-use-trailing-return-type`

[Bernhard Manfred Gruber via Phabricator via cfe-commits]

bernhardmgruber added a comment.

Hi! I am the original author of this check. I very much welcome your 
contribution! Thank you for the effort!

I am not a clang tools maintainer though, so you will need someone else to 
review and approve this change set.




Comment at: 
clang-tools-extra/clang-tidy/modernize/UseTrailingReturnTypeCheck.cpp:420-421
 
+  if (F->getReturnType()->isVoidType() && IgnoreVoidReturnType)
+return;
+

I would intuitively check the cheaper condition first to benefit form 
short-circuit evaluation.



Comment at: 
clang-tools-extra/docs/clang-tidy/checks/modernize/use-trailing-return-type.rst:73-76
+.. option:: IgnoreVoidReturnType
+
+   When `true`, the check will not rewrite function signature for functions
+   with void return type. Default is `true`.

I picked up the habit to word conditions/options in a positive manner. So I 
would rather name the option `RewriteVoidReturnType` instead of 
`IgnoreVoidReturnType` and use the inverted Booleans throughout the code. The 
reason is that my brain parses e.g. `if (!RewriteVoidReturnType)` easierly than 
`if(!IgnoreVoidReturnType)` because of the double negation.

Feel free to debate me here. This is not a strong opinion.


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[PATCH] D123065: [clang-tidy] support --load in clang-tidy-diff.py/run-clang-tidy.py

[Bernhard Manfred Gruber via Phabricator via cfe-commits]

bernhardmgruber added a comment.

> Yes, sure, just please specify what `user.name` and `user.email` would you 
> like to be associated with the commit's author?

`user.name`: Bernhard Manfred Gruber
`user.email`: bernhardmgru...@gmail.com

Thanks a lot!


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[PATCH] D123065: [clang-tidy] support --load in clang-tidy-diff.py/run-clang-tidy.py

[Bernhard Manfred Gruber via Phabricator via cfe-commits]

bernhardmgruber added a comment.

Ping.

Can someone merge this please for me? Thank you!


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[PATCH] D123065: [clang-tidy] support --load in clang-tidy-diff.py/run-clang-tidy.py

[Bernhard Manfred Gruber via Phabricator via cfe-commits]

bernhardmgruber updated this revision to Diff 421503.
bernhardmgruber added a comment.

Added missing '.' in helptext.


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Files:
  clang-tools-extra/clang-tidy/tool/clang-tidy-diff.py
  clang-tools-extra/clang-tidy/tool/run-clang-tidy.py


Index: clang-tools-extra/clang-tidy/tool/run-clang-tidy.py
===
--- clang-tools-extra/clang-tidy/tool/run-clang-tidy.py
+++ clang-tools-extra/clang-tidy/tool/run-clang-tidy.py
@@ -91,7 +91,7 @@
 def get_tidy_invocation(f, clang_tidy_binary, checks, tmpdir, build_path,
 header_filter, allow_enabling_alpha_checkers,
 extra_arg, extra_arg_before, quiet, config_file_path,
-config, line_filter, use_color):
+config, line_filter, use_color, plugins):
   """Gets a command line for clang-tidy."""
   start = [clang_tidy_binary]
   if allow_enabling_alpha_checkers:
@@ -125,6 +125,8 @@
   start.append('--config-file=' + config_file_path)
   elif config:
   start.append('-config=' + config)
+  for plugin in plugins:
+  start.append('-load=' + plugin)
   start.append(f)
   return start
 
@@ -195,7 +197,8 @@
  args.allow_enabling_alpha_checkers,
  args.extra_arg, args.extra_arg_before,
  args.quiet, args.config_file, args.config,
- args.line_filter, args.use_color)
+ args.line_filter, args.use_color,
+ args.plugins)
 
 proc = subprocess.Popen(invocation, stdout=subprocess.PIPE, 
stderr=subprocess.PIPE)
 output, err = proc.communicate()
@@ -279,6 +282,9 @@
   'command line.')
   parser.add_argument('-quiet', action='store_true',
   help='Run clang-tidy in quiet mode')
+  parser.add_argument('-load', dest='plugins',
+  action='append', default=[],
+  help='Load the specified plugin in clang-tidy.')
   args = parser.parse_args()
 
   db_path = 'compile_commands.json'
@@ -305,7 +311,8 @@
  args.allow_enabling_alpha_checkers,
  args.extra_arg, args.extra_arg_before,
  args.quiet, args.config_file, args.config,
- args.line_filter, args.use_color)
+ args.line_filter, args.use_color,
+ args.plugins)
 invocation.append('-list-checks')
 invocation.append('-')
 if args.quiet:
Index: clang-tools-extra/clang-tidy/tool/clang-tidy-diff.py
===
--- clang-tools-extra/clang-tidy/tool/clang-tidy-diff.py
+++ clang-tools-extra/clang-tidy/tool/clang-tidy-diff.py
@@ -160,6 +160,10 @@
   'command line.')
   parser.add_argument('-quiet', action='store_true', default=False,
   help='Run clang-tidy in quiet mode')
+  parser.add_argument('-load', dest='plugins',
+  action='append', default=[],
+  help='Load the specified plugin in clang-tidy.')
+
   clang_tidy_args = []
   argv = sys.argv[1:]
   if '--' in argv:
@@ -233,6 +237,8 @@
 common_clang_tidy_args.append('-extra-arg=%s' % arg)
   for arg in args.extra_arg_before:
 common_clang_tidy_args.append('-extra-arg-before=%s' % arg)
+  for plugin in args.plugins:
+common_clang_tidy_args.append('-load=%s' % plugin)
 
   for name in lines_by_file:
 line_filter_json = json.dumps(


Index: clang-tools-extra/clang-tidy/tool/run-clang-tidy.py
===
--- clang-tools-extra/clang-tidy/tool/run-clang-tidy.py
+++ clang-tools-extra/clang-tidy/tool/run-clang-tidy.py
@@ -91,7 +91,7 @@
 def get_tidy_invocation(f, clang_tidy_binary, checks, tmpdir, build_path,
 header_filter, allow_enabling_alpha_checkers,
 extra_arg, extra_arg_before, quiet, config_file_path,
-config, line_filter, use_color):
+config, line_filter, use_color, plugins):
   """Gets a command line for clang-tidy."""
   start = [clang_tidy_binary]
   if allow_enabling_alpha_checkers:
@@ -125,6 +125,8 @@
   start.append('--config-file=' + config_file_path)
   elif config:
   start.append('-config=' + config)
+  for plugin in plugins:
+  start.append('-load=' + plugin)
   start.append(f)
   return start
 
@@ -195,7 +197,8 @@
  args.allow_enabling_alpha_checkers,
  args.extra_arg, args.extra_arg_before,
  

[PATCH] D123065: [clang-tidy] support --load in clang-tidy-diff.py/run-clang-tidy.py

[Bernhard Manfred Gruber via Phabricator via cfe-commits]

bernhardmgruber updated this revision to Diff 421502.
bernhardmgruber added a comment.

Rebased on main and applied review comments.


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Files:
  clang-tools-extra/clang-tidy/tool/clang-tidy-diff.py
  clang-tools-extra/clang-tidy/tool/run-clang-tidy.py


Index: clang-tools-extra/clang-tidy/tool/run-clang-tidy.py
===
--- clang-tools-extra/clang-tidy/tool/run-clang-tidy.py
+++ clang-tools-extra/clang-tidy/tool/run-clang-tidy.py
@@ -91,7 +91,7 @@
 def get_tidy_invocation(f, clang_tidy_binary, checks, tmpdir, build_path,
 header_filter, allow_enabling_alpha_checkers,
 extra_arg, extra_arg_before, quiet, config_file_path,
-config, line_filter, use_color):
+config, line_filter, use_color, plugins):
   """Gets a command line for clang-tidy."""
   start = [clang_tidy_binary]
   if allow_enabling_alpha_checkers:
@@ -125,6 +125,8 @@
   start.append('--config-file=' + config_file_path)
   elif config:
   start.append('-config=' + config)
+  for plugin in plugins:
+  start.append('-load=' + plugin)
   start.append(f)
   return start
 
@@ -195,7 +197,8 @@
  args.allow_enabling_alpha_checkers,
  args.extra_arg, args.extra_arg_before,
  args.quiet, args.config_file, args.config,
- args.line_filter, args.use_color)
+ args.line_filter, args.use_color,
+ args.plugins)
 
 proc = subprocess.Popen(invocation, stdout=subprocess.PIPE, 
stderr=subprocess.PIPE)
 output, err = proc.communicate()
@@ -279,6 +282,9 @@
   'command line.')
   parser.add_argument('-quiet', action='store_true',
   help='Run clang-tidy in quiet mode')
+  parser.add_argument('-load', dest='plugins',
+  action='append', default=[],
+  help='Load the specified plugin in clang-tidy')
   args = parser.parse_args()
 
   db_path = 'compile_commands.json'
@@ -305,7 +311,8 @@
  args.allow_enabling_alpha_checkers,
  args.extra_arg, args.extra_arg_before,
  args.quiet, args.config_file, args.config,
- args.line_filter, args.use_color)
+ args.line_filter, args.use_color,
+ args.plugins)
 invocation.append('-list-checks')
 invocation.append('-')
 if args.quiet:
Index: clang-tools-extra/clang-tidy/tool/clang-tidy-diff.py
===
--- clang-tools-extra/clang-tidy/tool/clang-tidy-diff.py
+++ clang-tools-extra/clang-tidy/tool/clang-tidy-diff.py
@@ -160,6 +160,10 @@
   'command line.')
   parser.add_argument('-quiet', action='store_true', default=False,
   help='Run clang-tidy in quiet mode')
+  parser.add_argument('-load', dest='plugins',
+  action='append', default=[],
+  help='Load the specified plugin in clang-tidy')
+
   clang_tidy_args = []
   argv = sys.argv[1:]
   if '--' in argv:
@@ -233,6 +237,8 @@
 common_clang_tidy_args.append('-extra-arg=%s' % arg)
   for arg in args.extra_arg_before:
 common_clang_tidy_args.append('-extra-arg-before=%s' % arg)
+  for plugin in args.plugins:
+common_clang_tidy_args.append('-load=%s' % plugin)
 
   for name in lines_by_file:
 line_filter_json = json.dumps(


Index: clang-tools-extra/clang-tidy/tool/run-clang-tidy.py
===
--- clang-tools-extra/clang-tidy/tool/run-clang-tidy.py
+++ clang-tools-extra/clang-tidy/tool/run-clang-tidy.py
@@ -91,7 +91,7 @@
 def get_tidy_invocation(f, clang_tidy_binary, checks, tmpdir, build_path,
 header_filter, allow_enabling_alpha_checkers,
 extra_arg, extra_arg_before, quiet, config_file_path,
-config, line_filter, use_color):
+config, line_filter, use_color, plugins):
   """Gets a command line for clang-tidy."""
   start = [clang_tidy_binary]
   if allow_enabling_alpha_checkers:
@@ -125,6 +125,8 @@
   start.append('--config-file=' + config_file_path)
   elif config:
   start.append('-config=' + config)
+  for plugin in plugins:
+  start.append('-load=' + plugin)
   start.append(f)
   return start
 
@@ -195,7 +197,8 @@
  args.allow_enabling_alpha_checkers,
  args.extra_arg, args.extra_arg_before,
  

[PATCH] D123065: [clang-tidy] support --load in clang-tidy-diff.py/run-clang-tidy.py

[Bernhard Manfred Gruber via Phabricator via cfe-commits]

bernhardmgruber added a comment.

I did not base this revision on my latest main 
(422d05e792dbd6a97f5afd4cdd5e8aa677e97444 
) since I 
could not run the python scripts with the changes introduced in 
9e1f4f13984186984ba37513372c1b7e0c4ba4fd 
.


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[PATCH] D123065: [clang-tidy] support --load in clang-tidy-diff.py/run-clang-tidy.py

[Bernhard Manfred Gruber via Phabricator via cfe-commits]

bernhardmgruber created this revision.
bernhardmgruber added a reviewer: aaron.ballman.
Herald added subscribers: carlosgalvezp, mgehre, xazax.hun.
Herald added a project: All.
bernhardmgruber requested review of this revision.
Herald added a project: clang-tools-extra.
Herald added a subscriber: cfe-commits.

Support for loading shared objects as plugins into clang-tidy was added in 
https://reviews.llvm.org/D00. Unfortunately, the utility scripts 
`clang-tidy-diff.py` and `run-clang-tidy.py` did not receive corresponding 
arguments to forward such plugins to clang-tidy. This diff adds a 
`-load=plugin` option to both scripts.


Repository:
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https://reviews.llvm.org/D123065

Files:
  clang-tools-extra/clang-tidy/tool/clang-tidy-diff.py
  clang-tools-extra/clang-tidy/tool/run-clang-tidy.py


Index: clang-tools-extra/clang-tidy/tool/run-clang-tidy.py
===
--- clang-tools-extra/clang-tidy/tool/run-clang-tidy.py
+++ clang-tools-extra/clang-tidy/tool/run-clang-tidy.py
@@ -91,7 +91,7 @@
 def get_tidy_invocation(f, clang_tidy_binary, checks, tmpdir, build_path,
 header_filter, allow_enabling_alpha_checkers,
 extra_arg, extra_arg_before, quiet, config,
-line_filter, use_color):
+line_filter, use_color, plugins):
   """Gets a command line for clang-tidy."""
   start = [clang_tidy_binary]
   if allow_enabling_alpha_checkers:
@@ -123,6 +123,8 @@
   start.append('-quiet')
   if config:
   start.append('-config=' + config)
+  for plugin in plugins:
+  start.append('-load=' + plugin)
   start.append(f)
   return start
 
@@ -193,7 +195,7 @@
  args.allow_enabling_alpha_checkers,
  args.extra_arg, args.extra_arg_before,
  args.quiet, args.config, args.line_filter,
- args.use_color)
+ args.use_color, args.plugins)
 
 proc = subprocess.Popen(invocation, stdout=subprocess.PIPE, 
stderr=subprocess.PIPE)
 output, err = proc.communicate()
@@ -270,6 +272,9 @@
   'command line.')
   parser.add_argument('-quiet', action='store_true',
   help='Run clang-tidy in quiet mode')
+  parser.add_argument('-load', dest='plugins',
+  action='append', default=[],
+  help='Make clang-tidy load the specified plugin')
   args = parser.parse_args()
 
   db_path = 'compile_commands.json'
@@ -296,7 +301,7 @@
  args.allow_enabling_alpha_checkers,
  args.extra_arg, args.extra_arg_before,
  args.quiet, args.config, args.line_filter,
- args.use_color)
+ args.use_color, args.plugins)
 invocation.append('-list-checks')
 invocation.append('-')
 if args.quiet:
Index: clang-tools-extra/clang-tidy/tool/clang-tidy-diff.py
===
--- clang-tools-extra/clang-tidy/tool/clang-tidy-diff.py
+++ clang-tools-extra/clang-tidy/tool/clang-tidy-diff.py
@@ -160,6 +160,10 @@
   'command line.')
   parser.add_argument('-quiet', action='store_true', default=False,
   help='Run clang-tidy in quiet mode')
+  parser.add_argument('-load', dest='plugins',
+  action='append', default=[],
+  help='Make clang-tidy load the specified plugin')
+
   clang_tidy_args = []
   argv = sys.argv[1:]
   if '--' in argv:
@@ -233,6 +237,8 @@
 common_clang_tidy_args.append('-extra-arg=%s' % arg)
   for arg in args.extra_arg_before:
 common_clang_tidy_args.append('-extra-arg-before=%s' % arg)
+  for plugin in args.plugins:
+common_clang_tidy_args.append('-load=%s' % plugin)
 
   for name in lines_by_file:
 line_filter_json = json.dumps(


Index: clang-tools-extra/clang-tidy/tool/run-clang-tidy.py
===
--- clang-tools-extra/clang-tidy/tool/run-clang-tidy.py
+++ clang-tools-extra/clang-tidy/tool/run-clang-tidy.py
@@ -91,7 +91,7 @@
 def get_tidy_invocation(f, clang_tidy_binary, checks, tmpdir, build_path,
 header_filter, allow_enabling_alpha_checkers,
 extra_arg, extra_arg_before, quiet, config,
-line_filter, use_color):
+line_filter, use_color, plugins):
   """Gets a command line for clang-tidy."""
   start = [clang_tidy_binary]
   if allow_enabling_alpha_checkers:
@@ -123,6 +123,8 @@
   start.append('-quiet')
   if config:
   start.append('-config=' + config)
+  for plugin in plugins:
+  start.append('-load=' + plugin)
   start.a

[PATCH] D88700: [clang-tidy] modernize-use-trailing-return-type fix #44206

[Bernhard Manfred Gruber via Phabricator via cfe-commits]

bernhardmgruber marked an inline comment as done.
bernhardmgruber added inline comments.



Comment at: 
clang-tools-extra/clang-tidy/modernize/UseTrailingReturnTypeCheck.cpp:72
+TL.getAs().getTypePtr()->getDecl()->getName()))
+  return false;
   default:

aaron.ballman wrote:
> bernhardmgruber wrote:
> > There is a `break;` missing after this line. The build bot just told me. It 
> > should not change the meaning of the program though.
> > 
> > Can someone add that for me or do I need to upload another diff? Thank you!
> I'll take care of it, thanks for letting me know!
Great! Thank you for the help!


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[PATCH] D88700: [clang-tidy] modernize-use-trailing-return-type fix #44206

[Bernhard Manfred Gruber via Phabricator via cfe-commits]

bernhardmgruber added inline comments.



Comment at: 
clang-tools-extra/clang-tidy/modernize/UseTrailingReturnTypeCheck.cpp:72
+TL.getAs().getTypePtr()->getDecl()->getName()))
+  return false;
   default:

There is a `break;` missing after this line. The build bot just told me. It 
should not change the meaning of the program though.

Can someone add that for me or do I need to upload another diff? Thank you!


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[PATCH] D88700: [clang-tidy] modernize-use-trailing-return-type fix #44206

[Bernhard Manfred Gruber via Phabricator via cfe-commits]

bernhardmgruber added a comment.

Thank you for the quick review! Can you please commit it for me as well? Thank 
you!


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[PATCH] D80514: [clang-tidy] modernize-use-trailing-return-type support for C++20 concepts and decltype

[Bernhard Manfred Gruber via Phabricator via cfe-commits]

bernhardmgruber marked 12 inline comments as done.
bernhardmgruber added a comment.

Thank you for the time to review this!

Could you please also commit it for me? Thank you!




Comment at: 
clang-tools-extra/clang-tidy/modernize/UseTrailingReturnTypeCheck.cpp:430
+  AT->getKeyword() == AutoTypeKeyword::Auto &&
+  !hasAnyNestedLocalQualifiers(F->getDeclaredReturnType()))
+return;

aaron.ballman wrote:
> bernhardmgruber wrote:
> > aaron.ballman wrote:
> > > aaron.ballman wrote:
> > > > bernhardmgruber wrote:
> > > > > aaron.ballman wrote:
> > > > > > Why do we need to check that there aren't any nested local 
> > > > > > qualifiers?
> > > > > Because I would like the check to rewrite e.g. `const auto f();` into 
> > > > > `auto f() -> const auto;`. If I omit the check for nested local 
> > > > > qualifiers, then those kind of declarations would be skipped.
> > > > I'm still wondering about this.
> > > > Because I would like the check to rewrite e.g. const auto f(); into 
> > > > auto f() -> const auto;. If I omit the check for nested local 
> > > > qualifiers, then those kind of declarations would be skipped.
> > > 
> > > I don't think I understand why that's desirable though? What is it about 
> > > the qualifier that makes it worthwhile to repeat the type like that?
> > Thank you for insisting on that peculiarity! The choice is stylistically 
> > motivated to align function names:
> > 
> > ```
> > auto f() -> int;
> > auto g() -> std::vector;
> > auto& h();
> > const auto k();
> > decltype(auto) l();
> > ```
> > vs.
> > ```
> > auto f() -> int;
> > auto g() -> std::vector;
> > auto h() -> auto&;
> > auto k() -> const auto; 
> > auto l() -> decltype(auto);
> > ```
> > 
> > But judging from your response, this might be a surprise to users. Would 
> > you prefer having an option to enable/disable this behavior?
> > But judging from your response, this might be a surprise to users. Would 
> > you prefer having an option to enable/disable this behavior?
> 
> Maybe it will be, maybe it won't. :-D The reason I was surprised was because 
> it feels like a formatting related choice rather than a modernization related 
> choice. However, I've always struggled to understand the utility of this 
> check (it's one I  disable in every .clang-tidy configuration file I can), so 
> my reasoning may be flawed. I feel like the goal of this check isn't to 
> format code nicely, it's to modernize to using a trailing return type where 
> that adds clarity. But I don't think `auto& func()` changing into `auto 
> func() -> auto&` adds clarity (I think it removes clarity because the second 
> signature is strictly more complex than the first), and similar for 
> qualifiers. However, I think the exact same thing about `int func()` changing 
> into `auto func() -> int`.
> 
> Given that we document this function to rewrite all functions to a trailing 
> return type signature, I guess the behavior you've proposed here is 
> consistent with that goal and so I'm fine with it.
> However, I've always struggled to understand the utility of this check (it's 
> one I disable in every .clang-tidy configuration file I can)

I am sorry to hear that, but I have heard this from many other people as well. 
I am sometimes questioning myself whether it was a mistake to put this check 
into clang-tidy and annoy a lot of people. It might have been better as a 
standalone tool.

> I feel like the goal of this check isn't to format code nicely, it's to 
> modernize to using a trailing return type where that adds clarity.

I like that thinking! I started with trailing return types as a stylistic 
choice, but I soon realized that it indeed can add clarity by shifting away 
complicated return types to the end of a line where they bother me less.

> But I don't think `auto& func()` changing into `auto func() -> auto&` adds 
> clarity (I think it removes clarity because the second signature is strictly 
> more complex than the first).

With regard to clarity, you are right. And I noted down now that I shall add an 
option to prevent some of these rewrites. Thank you for the feedback!



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[PATCH] D80514: [clang-tidy] modernize-use-trailing-return-type support for C++20 concepts and decltype

[Bernhard Manfred Gruber via Phabricator via cfe-commits]

bernhardmgruber added a comment.

Btw: what is the general rule for Phabricator reviews here when to tick the 
`Done` checkbox of a comment? What is the semantic of this checkbox? Is the 
ticked state the same for everyone?

Thank you for the help!




Comment at: 
clang-tools-extra/clang-tidy/modernize/UseTrailingReturnTypeCheck.cpp:430
+  AT->getKeyword() == AutoTypeKeyword::Auto &&
+  !hasAnyNestedLocalQualifiers(F->getDeclaredReturnType()))
+return;

aaron.ballman wrote:
> aaron.ballman wrote:
> > bernhardmgruber wrote:
> > > aaron.ballman wrote:
> > > > Why do we need to check that there aren't any nested local qualifiers?
> > > Because I would like the check to rewrite e.g. `const auto f();` into 
> > > `auto f() -> const auto;`. If I omit the check for nested local 
> > > qualifiers, then those kind of declarations would be skipped.
> > I'm still wondering about this.
> > Because I would like the check to rewrite e.g. const auto f(); into auto 
> > f() -> const auto;. If I omit the check for nested local qualifiers, then 
> > those kind of declarations would be skipped.
> 
> I don't think I understand why that's desirable though? What is it about the 
> qualifier that makes it worthwhile to repeat the type like that?
Thank you for insisting on that peculiarity! The choice is stylistically 
motivated to align function names:

```
auto f() -> int;
auto g() -> std::vector;
auto& h();
const auto k();
decltype(auto) l();
```
vs.
```
auto f() -> int;
auto g() -> std::vector;
auto h() -> auto&;
auto k() -> const auto; 
auto l() -> decltype(auto);
```

But judging from your response, this might be a surprise to users. Would you 
prefer having an option to enable/disable this behavior?



Comment at: 
clang-tools-extra/test/clang-tidy/checkers/modernize-use-trailing-return-type.cpp:1
-// RUN: %check_clang_tidy -std=c++14,c++17 %s 
modernize-use-trailing-return-type %t -- -- -fdeclspec -fexceptions
+// RUN: %check_clang_tidy -std=c++14-or-later %s 
modernize-use-trailing-return-type %t -- -- -fdeclspec -fexceptions 
-DCOMMAND_LINE_INT=int
 // FIXME: Fix the checker to work in C++20 mode, it is performing a

riccibruno wrote:
> riccibruno wrote:
> > aaron.ballman wrote:
> > > bernhardmgruber wrote:
> > > > aaron.ballman wrote:
> > > > > The change to the language standard line makes me wonder if the fixme 
> > > > > below it is now stale, or if the test will fail in C++20 mode.
> > > > I just ran the tests again using `python .\check_clang_tidy.py 
> > > > -std=c++20 .\checkers\modernize-use-trailing-return-type.cpp 
> > > > modernize-use-trailing-return-type aa -- -- -DCOMMAND_LINE_INT=int` and 
> > > > I did not see mentioning of the use of an uninitialized variable. But I 
> > > > run on Windows, maybe the issue just surfaces on another OS? Is there a 
> > > > way to trigger the CI again?
> > > > 
> > > > I removed the FIXME in question in the hope the issue resolved itself.
> > > > But I run on Windows, maybe the issue just surfaces on another OS? Is 
> > > > there a way to trigger the CI again?
> > > 
> > > I also run on Windows so I can't easily test the behavior elsewhere for 
> > > you. The CI will get triggered on new patch uploads, but I still don't 
> > > always trust it. The bots are usually a more reliable source of CI truth 
> > > but we have no way to speculatively trigger all the bots.
> > I can run it for you with asan/msan.
> No warning with either asan or msan on x86-64 linux with clang 10.
Thank you @riccibruno for verifying that for me!


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[Bernhard Manfred Gruber via Phabricator via cfe-commits]

bernhardmgruber added a comment.

Ping.


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[PATCH] D80514: [clang-tidy] modernize-use-trailing-return-type support for C++20 concepts and decltype

[Bernhard Manfred Gruber via Phabricator via cfe-commits]

bernhardmgruber added inline comments.



Comment at: 
clang-tools-extra/test/clang-tidy/checkers/modernize-use-trailing-return-type.cpp:1
-// RUN: %check_clang_tidy -std=c++14,c++17 %s 
modernize-use-trailing-return-type %t -- -- -fdeclspec -fexceptions
+// RUN: %check_clang_tidy -std=c++14-or-later %s 
modernize-use-trailing-return-type %t -- -- -fdeclspec -fexceptions 
-DCOMMAND_LINE_INT=int
 // FIXME: Fix the checker to work in C++20 mode, it is performing a

aaron.ballman wrote:
> The change to the language standard line makes me wonder if the fixme below 
> it is now stale, or if the test will fail in C++20 mode.
I just ran the tests again using `python .\check_clang_tidy.py -std=c++20 
.\checkers\modernize-use-trailing-return-type.cpp 
modernize-use-trailing-return-type aa -- -- -DCOMMAND_LINE_INT=int` and I did 
not see mentioning of the use of an uninitialized variable. But I run on 
Windows, maybe the issue just surfaces on another OS? Is there a way to trigger 
the CI again?

I removed the FIXME in question in the hope the issue resolved itself.


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[PATCH] D80514: [clang-tidy] modernize-use-trailing-return-type support for C++20 concepts and decltype

[Bernhard Manfred Gruber via Phabricator via cfe-commits]

bernhardmgruber updated this revision to Diff 279625.
bernhardmgruber marked an inline comment as done.
bernhardmgruber edited the summary of this revision.
bernhardmgruber added a comment.

Removed probably stale FIXME.


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Files:
  clang-tools-extra/clang-tidy/modernize/UseTrailingReturnTypeCheck.cpp
  clang-tools-extra/clang-tidy/modernize/UseTrailingReturnTypeCheck.h
  
clang-tools-extra/docs/clang-tidy/checks/modernize-use-trailing-return-type.rst
  
clang-tools-extra/test/clang-tidy/checkers/modernize-use-trailing-return-type-cxx20.cpp
  
clang-tools-extra/test/clang-tidy/checkers/modernize-use-trailing-return-type.cpp

Index: clang-tools-extra/test/clang-tidy/checkers/modernize-use-trailing-return-type.cpp
===
--- clang-tools-extra/test/clang-tidy/checkers/modernize-use-trailing-return-type.cpp
+++ clang-tools-extra/test/clang-tidy/checkers/modernize-use-trailing-return-type.cpp
@@ -1,6 +1,4 @@
-// RUN: %check_clang_tidy -std=c++14,c++17 %s modernize-use-trailing-return-type %t -- -- -fdeclspec -fexceptions
-// FIXME: Fix the checker to work in C++20 mode, it is performing a
-// use-of-uninitialized-value.
+// RUN: %check_clang_tidy -std=c++14-or-later %s modernize-use-trailing-return-type %t -- -- -fdeclspec -fexceptions -DCOMMAND_LINE_INT=int
 
 namespace std {
 template 
@@ -11,6 +9,8 @@
 
 class string;
 
+class ostream;
+
 template 
 auto declval() -> T;
 }
@@ -215,18 +215,28 @@
 // CHECK-FIXES: {{^}}auto e13() -> struct A;{{$}}
 
 //
-// decltype (unsupported if top level expression)
+// deduced return types
 //
 
+const auto ded1();
+// CHECK-MESSAGES: :[[@LINE-1]]:12: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto ded1() -> const auto;{{$}}
+const auto& ded2();
+// CHECK-MESSAGES: :[[@LINE-1]]:13: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto ded2() -> const auto&;{{$}}
+
+decltype(auto) ded3();
+// CHECK-MESSAGES: :[[@LINE-1]]:16: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto ded3() -> decltype(auto);{{$}}
+
+
 decltype(1 + 2) dec1() { return 1 + 2; }
 // CHECK-MESSAGES: :[[@LINE-1]]:17: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
-// TODO: source range of DecltypeTypeLoc not yet implemented
-// _HECK-FIXES: {{^}}auto dec1() -> decltype(1 + 2) { return 1 + 2; }{{$}}
+// CHECK-FIXES: {{^}}auto dec1() -> decltype(1 + 2) { return 1 + 2; }{{$}}
 template 
 decltype(std::declval(std::declval)) dec2(F f, T t) { return f(t); }
 // CHECK-MESSAGES: :[[@LINE-1]]:44: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
-// TODO: source range of DecltypeTypeLoc not yet implemented
-// _HECK-FIXES: {{^}}auto dec2(F f, T t) -> decltype(std::declval(std::declval)) { return f(t); }{{$}}
+// CHECK-FIXES: {{^}}auto dec2(F f, T t) -> decltype(std::declval(std::declval)) { return f(t); }{{$}}
 template 
 typename decltype(std::declval())::value_type dec3();
 // CHECK-MESSAGES: :[[@LINE-1]]:50: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
@@ -463,6 +473,13 @@
 CONST_F_MACRO int& h19();
 // CHECK-MESSAGES: :[[@LINE-1]]:20: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
 // CHECK-FIXES: {{^}}auto h19() -> CONST_F_MACRO int&;{{$}}
+// Macro COMMAND_LINE_INT is defined on the command line via: -DCOMMAND_LINE_INT=int
+const COMMAND_LINE_INT& h20();
+// CHECK-MESSAGES: :[[@LINE-1]]:25: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto h20() -> const COMMAND_LINE_INT&;{{$}}
+decltype(COMMAND_LINE_INT{}) h21();
+// CHECK-MESSAGES: :[[@LINE-1]]:30: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto h21() -> decltype(COMMAND_LINE_INT{});{{$}}
 
 //
 // Name collisions
@@ -531,6 +548,14 @@
 return {0};
 }
 
+//
+// bug 44206, no rewrite should happen due to collision with parameter name
+//
+
+using std::ostream;
+ostream& operator<<(ostream& ostream, int i);
+// CHECK-MESSAGES: :[[@LINE-1]]:10: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}ostream& operator<<(ostream& ostream, int i);{{$}}
 
 //
 // Samples which do not trigger the check
@@ -544,7 +569,6 @@
 template  auto f(T t) -> int;
 
 auto ff();
-decltype(auto) fff();
 
 void c();
 void c(int arg);
Index: clang-tools-extra/test/clang-tidy/checkers/modernize-use-trailing-return-type-cxx20.cpp
===
--- /dev/null
+++ clang-tools-extra/test/clan

[PATCH] D80514: [clang-tidy] modernize-use-trailing-return-type support for C++20 concepts and decltype

[Bernhard Manfred Gruber via Phabricator via cfe-commits]

bernhardmgruber added a comment.

Great, I seems I forgot to submit the inline comments. Sorry about that!




Comment at: 
clang-tools-extra/clang-tidy/modernize/UseTrailingReturnTypeCheck.cpp:293
+StringRef File = SM.getBufferData(Loc.first);
+const char *TokenBegin = File.data() + Loc.second;
+Lexer Lexer(SM.getLocForStartOfFile(Loc.first), LangOpts, File.begin(),

aaron.ballman wrote:
> Should we verify that `End` is valid before doing this pointer arithmetic 
> with a value derived from it? For instance, what if `End` points into the 
> scratch buffer because it relies on a macro defined on the command line -- 
> will the logic still work?
That sounded like a scary scenario! Fortunately, `expandIfMacroId` even expands 
source locations inside the scratch buffer correctly into a location in a real 
file. I added two tests for it and they seem to pass. Thank you for the hint!



Comment at: 
clang-tools-extra/clang-tidy/modernize/UseTrailingReturnTypeCheck.cpp:430
+  AT->getKeyword() == AutoTypeKeyword::Auto &&
+  !hasAnyNestedLocalQualifiers(F->getDeclaredReturnType()))
+return;

aaron.ballman wrote:
> Why do we need to check that there aren't any nested local qualifiers?
Because I would like the check to rewrite e.g. `const auto f();` into `auto f() 
-> const auto;`. If I omit the check for nested local qualifiers, then those 
kind of declarations would be skipped.



Comment at: 
clang-tools-extra/clang-tidy/modernize/UseTrailingReturnTypeCheck.cpp:285-302
+SourceLocation End =
+expandIfMacroId(ReturnLoc.getSourceRange().getEnd(), SM);
+SourceLocation BeginNameF = expandIfMacroId(F.getLocation(), SM);
+
+// Extend the ReturnTypeRange until the last token before the function
+// name.
+std::pair Loc = SM.getDecomposedLoc(End);

aaron.ballman wrote:
> bernhardmgruber wrote:
> > Is there an easier way to get the token previous to the function name?
> There isn't, but if you find you're missing source location information for 
> something, you can also consider modifying Clang to add that source location 
> information and mark this as a dependent patch. It's not clear to me whether 
> that would be worth the effort for this patch or not, but my preference is to 
> avoid these little hacks whenever possible.
Thank you for the hint! I considered this for the concept location in an 
`AutoReturnType` and the expression inside a `decltype` `AutoReturnType`. 
Unfortunately I could not wrap my head around what is going on in SemaType.cpp 
:/


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[PATCH] D80514: [clang-tidy] modernize-use-trailing-return-type support for C++20 concepts and decltype

[Bernhard Manfred Gruber via Phabricator via cfe-commits]

bernhardmgruber updated this revision to Diff 279088.
bernhardmgruber marked 3 inline comments as done.
bernhardmgruber added a comment.

- Added two more tests with a macro supplied on the command line
- Rebased onto master


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Files:
  clang-tools-extra/clang-tidy/modernize/UseTrailingReturnTypeCheck.cpp
  clang-tools-extra/clang-tidy/modernize/UseTrailingReturnTypeCheck.h
  
clang-tools-extra/docs/clang-tidy/checks/modernize-use-trailing-return-type.rst
  
clang-tools-extra/test/clang-tidy/checkers/modernize-use-trailing-return-type-cxx20.cpp
  
clang-tools-extra/test/clang-tidy/checkers/modernize-use-trailing-return-type.cpp

Index: clang-tools-extra/test/clang-tidy/checkers/modernize-use-trailing-return-type.cpp
===
--- clang-tools-extra/test/clang-tidy/checkers/modernize-use-trailing-return-type.cpp
+++ clang-tools-extra/test/clang-tidy/checkers/modernize-use-trailing-return-type.cpp
@@ -1,4 +1,4 @@
-// RUN: %check_clang_tidy -std=c++14,c++17 %s modernize-use-trailing-return-type %t -- -- -fdeclspec -fexceptions
+// RUN: %check_clang_tidy -std=c++14-or-later %s modernize-use-trailing-return-type %t -- -- -fdeclspec -fexceptions -DCOMMAND_LINE_INT=int
 // FIXME: Fix the checker to work in C++20 mode, it is performing a
 // use-of-uninitialized-value.
 
@@ -11,6 +11,8 @@
 
 class string;
 
+class ostream;
+
 template 
 auto declval() -> T;
 }
@@ -215,18 +217,28 @@
 // CHECK-FIXES: {{^}}auto e13() -> struct A;{{$}}
 
 //
-// decltype (unsupported if top level expression)
+// deduced return types
 //
 
+const auto ded1();
+// CHECK-MESSAGES: :[[@LINE-1]]:12: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto ded1() -> const auto;{{$}}
+const auto& ded2();
+// CHECK-MESSAGES: :[[@LINE-1]]:13: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto ded2() -> const auto&;{{$}}
+
+decltype(auto) ded3();
+// CHECK-MESSAGES: :[[@LINE-1]]:16: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto ded3() -> decltype(auto);{{$}}
+
+
 decltype(1 + 2) dec1() { return 1 + 2; }
 // CHECK-MESSAGES: :[[@LINE-1]]:17: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
-// TODO: source range of DecltypeTypeLoc not yet implemented
-// _HECK-FIXES: {{^}}auto dec1() -> decltype(1 + 2) { return 1 + 2; }{{$}}
+// CHECK-FIXES: {{^}}auto dec1() -> decltype(1 + 2) { return 1 + 2; }{{$}}
 template 
 decltype(std::declval(std::declval)) dec2(F f, T t) { return f(t); }
 // CHECK-MESSAGES: :[[@LINE-1]]:44: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
-// TODO: source range of DecltypeTypeLoc not yet implemented
-// _HECK-FIXES: {{^}}auto dec2(F f, T t) -> decltype(std::declval(std::declval)) { return f(t); }{{$}}
+// CHECK-FIXES: {{^}}auto dec2(F f, T t) -> decltype(std::declval(std::declval)) { return f(t); }{{$}}
 template 
 typename decltype(std::declval())::value_type dec3();
 // CHECK-MESSAGES: :[[@LINE-1]]:50: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
@@ -463,6 +475,13 @@
 CONST_F_MACRO int& h19();
 // CHECK-MESSAGES: :[[@LINE-1]]:20: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
 // CHECK-FIXES: {{^}}auto h19() -> CONST_F_MACRO int&;{{$}}
+// Macro COMMAND_LINE_INT is defined on the command line via: -DCOMMAND_LINE_INT=int
+const COMMAND_LINE_INT& h20();
+// CHECK-MESSAGES: :[[@LINE-1]]:25: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto h20() -> const COMMAND_LINE_INT&;{{$}}
+decltype(COMMAND_LINE_INT{}) h21();
+// CHECK-MESSAGES: :[[@LINE-1]]:30: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto h21() -> decltype(COMMAND_LINE_INT{});{{$}}
 
 //
 // Name collisions
@@ -531,6 +550,14 @@
 return {0};
 }
 
+//
+// bug 44206, no rewrite should happen due to collision with parameter name
+//
+
+using std::ostream;
+ostream& operator<<(ostream& ostream, int i);
+// CHECK-MESSAGES: :[[@LINE-1]]:10: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}ostream& operator<<(ostream& ostream, int i);{{$}}
 
 //
 // Samples which do not trigger the check
@@ -544,7 +571,6 @@
 template  auto f(T t) -> int;
 
 auto ff();
-decltype(auto) fff();
 
 void c();
 void c(int arg);
Index: clang-tools-extra/test/clang-tidy/checkers/modernize-use-trailing-return-type-cxx20.cpp
===
--- /dev/null
+++ clang-tools-extra/test/clang-tidy/checkers/modernize-u

[PATCH] D80514: [clang-tidy] modernize-use-trailing-return-type support for C++20 concepts and decltype

[Bernhard Manfred Gruber via Phabricator via cfe-commits]

bernhardmgruber added a comment.

Ping.

Is there anything I am not seeing here that you still would like me to do? I 
feel like you are waiting for something obvious from my side :S.


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[Bernhard Manfred Gruber via Phabricator via cfe-commits]

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Ping.


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[Bernhard Manfred Gruber via Phabricator via cfe-commits]

bernhardmgruber added a comment.

Ping.


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[PATCH] D80514: [clang-tidy] modernize-use-trailing-return-type support for C++20 concepts and decltype

[Bernhard Manfred Gruber via Phabricator via cfe-commits]

bernhardmgruber added a comment.

In D80514#2071202 , @njames93 wrote:

> In D80514#2071056 , @bernhardmgruber 
> wrote:
>
> > Reuploaded diff in an attempt to trigger a CI build.
>
>
> It's not working, Still no big issue, when its ready to land just the checks 
> locally


That's exactly the issue; the tests run fine on my local machine. I run 
check_clang_tidy.py manually, since I lack some Unix tools for the full test 
suite. And the CI build that failed seems to have used the first verison of my 
diff, which I updated in the meantime. From my point of few the diff is ready. 
I am just waiting for feedback, a LGTM and a nice person who can commit it for 
me :)


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[PATCH] D80514: [clang-tidy] modernize-use-trailing-return-type support for C++20 concepts and decltype

[Bernhard Manfred Gruber via Phabricator via cfe-commits]

bernhardmgruber updated this revision to Diff 268155.
bernhardmgruber added a comment.

Reuploaded diff in an attempt to trigger a CI build.


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  clang-tools-extra/clang-tidy/modernize/UseTrailingReturnTypeCheck.h
  
clang-tools-extra/docs/clang-tidy/checks/modernize-use-trailing-return-type.rst
  
clang-tools-extra/test/clang-tidy/checkers/modernize-use-trailing-return-type-cxx20.cpp
  
clang-tools-extra/test/clang-tidy/checkers/modernize-use-trailing-return-type.cpp

Index: clang-tools-extra/test/clang-tidy/checkers/modernize-use-trailing-return-type.cpp
===
--- clang-tools-extra/test/clang-tidy/checkers/modernize-use-trailing-return-type.cpp
+++ clang-tools-extra/test/clang-tidy/checkers/modernize-use-trailing-return-type.cpp
@@ -1,4 +1,4 @@
-// RUN: %check_clang_tidy -std=c++14,c++17 %s modernize-use-trailing-return-type %t -- -- -fdeclspec -fexceptions
+// RUN: %check_clang_tidy -std=c++14-or-later %s modernize-use-trailing-return-type %t -- -- -fdeclspec -fexceptions
 // FIXME: Fix the checker to work in C++2a mode, it is performing a
 // use-of-uninitialized-value.
 
@@ -11,6 +11,8 @@
 
 class string;
 
+class ostream;
+
 template 
 auto declval() -> T;
 }
@@ -215,18 +217,28 @@
 // CHECK-FIXES: {{^}}auto e13() -> struct A;{{$}}
 
 //
-// decltype (unsupported if top level expression)
+// deduced return types
 //
 
+const auto ded1();
+// CHECK-MESSAGES: :[[@LINE-1]]:12: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto ded1() -> const auto;{{$}}
+const auto& ded2();
+// CHECK-MESSAGES: :[[@LINE-1]]:13: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto ded2() -> const auto&;{{$}}
+
+decltype(auto) ded3();
+// CHECK-MESSAGES: :[[@LINE-1]]:16: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto ded3() -> decltype(auto);{{$}}
+
+
 decltype(1 + 2) dec1() { return 1 + 2; }
 // CHECK-MESSAGES: :[[@LINE-1]]:17: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
-// TODO: source range of DecltypeTypeLoc not yet implemented
-// _HECK-FIXES: {{^}}auto dec1() -> decltype(1 + 2) { return 1 + 2; }{{$}}
+// CHECK-FIXES: {{^}}auto dec1() -> decltype(1 + 2) { return 1 + 2; }{{$}}
 template 
 decltype(std::declval(std::declval)) dec2(F f, T t) { return f(t); }
 // CHECK-MESSAGES: :[[@LINE-1]]:44: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
-// TODO: source range of DecltypeTypeLoc not yet implemented
-// _HECK-FIXES: {{^}}auto dec2(F f, T t) -> decltype(std::declval(std::declval)) { return f(t); }{{$}}
+// CHECK-FIXES: {{^}}auto dec2(F f, T t) -> decltype(std::declval(std::declval)) { return f(t); }{{$}}
 template 
 typename decltype(std::declval())::value_type dec3();
 // CHECK-MESSAGES: :[[@LINE-1]]:50: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
@@ -531,6 +543,14 @@
 return {0};
 }
 
+//
+// bug 44206, no rewrite should happen due to collision with parameter name
+//
+
+using std::ostream;
+ostream& operator<<(ostream& ostream, int i);
+// CHECK-MESSAGES: :[[@LINE-1]]:10: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}ostream& operator<<(ostream& ostream, int i);{{$}}
 
 //
 // Samples which do not trigger the check
@@ -544,7 +564,6 @@
 template  auto f(T t) -> int;
 
 auto ff();
-decltype(auto) fff();
 
 void c();
 void c(int arg);
Index: clang-tools-extra/test/clang-tidy/checkers/modernize-use-trailing-return-type-cxx20.cpp
===
--- /dev/null
+++ clang-tools-extra/test/clang-tidy/checkers/modernize-use-trailing-return-type-cxx20.cpp
@@ -0,0 +1,54 @@
+// RUN: %check_clang_tidy -std=c++20 %s modernize-use-trailing-return-type %t
+
+namespace std {
+template 
+struct is_same { static constexpr auto value = false; };
+
+template 
+struct is_same { static constexpr auto value = true; };
+
+template 
+concept floating_point = std::is_same::value || std::is_same::value || std::is_same::value;
+}
+
+//
+// Concepts
+//
+
+std::floating_point auto con1();
+// CHECK-MESSAGES: :[[@LINE-1]]:26: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto con1() -> std::floating_point auto;{{$}}
+
+std::floating_point auto con1() { return 3.14f; }
+// CHECK-MESSAGES: :[[@LINE-1]]:26: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto con1() -> std::floating_point auto { return 3.14f; }{{$}}

[PATCH] D80514: [clang-tidy] modernize-use-trailing-return-type support for C++20 concepts and decltype

[Bernhard Manfred Gruber via Phabricator via cfe-commits]

bernhardmgruber added a comment.

Ping.

Furthermore: how can I schedule another CI build with the newest version of the 
diff? When I go to the failed build from Harbormaster and I click restart, it 
rebuilds an older version of the diff. Thanks for the info!


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[PATCH] D80514: [clang-tidy] modernize-use-trailing-return-type support for C++20 concepts and decltype

[Bernhard Manfred Gruber via Phabricator via cfe-commits]

bernhardmgruber updated this revision to Diff 266060.
bernhardmgruber added a comment.

moved C++20 tests to a new file


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Files:
  clang-tools-extra/clang-tidy/modernize/UseTrailingReturnTypeCheck.cpp
  clang-tools-extra/clang-tidy/modernize/UseTrailingReturnTypeCheck.h
  
clang-tools-extra/docs/clang-tidy/checks/modernize-use-trailing-return-type.rst
  
clang-tools-extra/test/clang-tidy/checkers/modernize-use-trailing-return-type-cxx20.cpp
  
clang-tools-extra/test/clang-tidy/checkers/modernize-use-trailing-return-type.cpp

Index: clang-tools-extra/test/clang-tidy/checkers/modernize-use-trailing-return-type.cpp
===
--- clang-tools-extra/test/clang-tidy/checkers/modernize-use-trailing-return-type.cpp
+++ clang-tools-extra/test/clang-tidy/checkers/modernize-use-trailing-return-type.cpp
@@ -1,4 +1,4 @@
-// RUN: %check_clang_tidy -std=c++14,c++17 %s modernize-use-trailing-return-type %t -- -- -fdeclspec -fexceptions
+// RUN: %check_clang_tidy -std=c++14-or-later %s modernize-use-trailing-return-type %t -- -- -fdeclspec -fexceptions
 // FIXME: Fix the checker to work in C++2a mode, it is performing a
 // use-of-uninitialized-value.
 
@@ -11,6 +11,8 @@
 
 class string;
 
+class ostream;
+
 template 
 auto declval() -> T;
 }
@@ -215,18 +217,28 @@
 // CHECK-FIXES: {{^}}auto e13() -> struct A;{{$}}
 
 //
-// decltype (unsupported if top level expression)
+// deduced return types
 //
 
+const auto ded1();
+// CHECK-MESSAGES: :[[@LINE-1]]:12: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto ded1() -> const auto;{{$}}
+const auto& ded2();
+// CHECK-MESSAGES: :[[@LINE-1]]:13: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto ded2() -> const auto&;{{$}}
+
+decltype(auto) ded3();
+// CHECK-MESSAGES: :[[@LINE-1]]:16: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto ded3() -> decltype(auto);{{$}}
+
+
 decltype(1 + 2) dec1() { return 1 + 2; }
 // CHECK-MESSAGES: :[[@LINE-1]]:17: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
-// TODO: source range of DecltypeTypeLoc not yet implemented
-// _HECK-FIXES: {{^}}auto dec1() -> decltype(1 + 2) { return 1 + 2; }{{$}}
+// CHECK-FIXES: {{^}}auto dec1() -> decltype(1 + 2) { return 1 + 2; }{{$}}
 template 
 decltype(std::declval(std::declval)) dec2(F f, T t) { return f(t); }
 // CHECK-MESSAGES: :[[@LINE-1]]:44: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
-// TODO: source range of DecltypeTypeLoc not yet implemented
-// _HECK-FIXES: {{^}}auto dec2(F f, T t) -> decltype(std::declval(std::declval)) { return f(t); }{{$}}
+// CHECK-FIXES: {{^}}auto dec2(F f, T t) -> decltype(std::declval(std::declval)) { return f(t); }{{$}}
 template 
 typename decltype(std::declval())::value_type dec3();
 // CHECK-MESSAGES: :[[@LINE-1]]:50: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
@@ -531,6 +543,14 @@
 return {0};
 }
 
+//
+// bug 44206, no rewrite should happen due to collision with parameter name
+//
+
+using std::ostream;
+ostream& operator<<(ostream& ostream, int i);
+// CHECK-MESSAGES: :[[@LINE-1]]:10: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}ostream& operator<<(ostream& ostream, int i);{{$}}
 
 //
 // Samples which do not trigger the check
@@ -544,7 +564,6 @@
 template  auto f(T t) -> int;
 
 auto ff();
-decltype(auto) fff();
 
 void c();
 void c(int arg);
Index: clang-tools-extra/test/clang-tidy/checkers/modernize-use-trailing-return-type-cxx20.cpp
===
--- /dev/null
+++ clang-tools-extra/test/clang-tidy/checkers/modernize-use-trailing-return-type-cxx20.cpp
@@ -0,0 +1,54 @@
+// RUN: %check_clang_tidy -std=c++20 %s modernize-use-trailing-return-type %t
+
+namespace std {
+template 
+struct is_same { static constexpr auto value = false; };
+
+template 
+struct is_same { static constexpr auto value = true; };
+
+template 
+concept floating_point = std::is_same::value || std::is_same::value || std::is_same::value;
+}
+
+//
+// Concepts
+//
+
+std::floating_point auto con1();
+// CHECK-MESSAGES: :[[@LINE-1]]:26: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto con1() -> std::floating_point auto;{{$}}
+
+std::floating_point auto con1() { return 3.14f; }
+// CHECK-MESSAGES: :[[@LINE-1]]:26: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto con1() -> std::floating_point auto { return 3.14f; }{{$}}
+
+namespace a {
+tem

[PATCH] D80514: [clang-tidy] modernize-use-trailing-return-type support for C++20 concepts and decltype

[Bernhard Manfred Gruber via Phabricator via cfe-commits]

bernhardmgruber marked 2 inline comments as done.
bernhardmgruber added inline comments.



Comment at: 
clang-tools-extra/test/clang-tidy/checkers/modernize-use-trailing-return-type.cpp:550
+
+#if __cplusplus > 201703L /* C++2a and later */
+

njames93 wrote:
> bernhardmgruber wrote:
> > How do you want to handle these tests which require C++20? I have seen 
> > other checks use a separate file for tests which require a different 
> > language version.
> Yes, move them into a seperate file and specify `-std=c++20` in the run line
Ok, done. Thx!


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[PATCH] D80514: [clang-tidy] modernize-use-trailing-return-type support for C++20 concepts and decltype

[Bernhard Manfred Gruber via Phabricator via cfe-commits]

bernhardmgruber added inline comments.



Comment at: 
clang-tools-extra/clang-tidy/modernize/UseTrailingReturnTypeCheck.cpp:399
 
-  return true;
+  return;
 }

Eugene.Zelenko wrote:
> Non needed. See readability-redundant-control-flow.
Thx!



Comment at: 
clang-tools-extra/docs/clang-tidy/checks/modernize-use-trailing-return-type.rst:22
+  virtual float f3() const && = delete;virtual auto f3() const && -> float 
= delete;
+ 
===
 

Eugene.Zelenko wrote:
> bernhardmgruber wrote:
> > I tried 2 online rst editors and they failed to format the code blocks 
> > inside the tables. Will this work with the clang documentation?
> In other documentation such examples are sequential. Same below.
Ok! I will separate the code blocks again.


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[PATCH] D80514: [clang-tidy] modernize-use-trailing-return-type support for C++20 concepts and decltype

[Bernhard Manfred Gruber via Phabricator via cfe-commits]

bernhardmgruber updated this revision to Diff 266034.
bernhardmgruber marked 2 inline comments as done and 2 inline comments as done.
bernhardmgruber added a comment.

- split code tables in documentation
- removed unnecessary return statement


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Files:
  clang-tools-extra/clang-tidy/modernize/UseTrailingReturnTypeCheck.cpp
  clang-tools-extra/clang-tidy/modernize/UseTrailingReturnTypeCheck.h
  
clang-tools-extra/docs/clang-tidy/checks/modernize-use-trailing-return-type.rst
  
clang-tools-extra/test/clang-tidy/checkers/modernize-use-trailing-return-type.cpp

Index: clang-tools-extra/test/clang-tidy/checkers/modernize-use-trailing-return-type.cpp
===
--- clang-tools-extra/test/clang-tidy/checkers/modernize-use-trailing-return-type.cpp
+++ clang-tools-extra/test/clang-tidy/checkers/modernize-use-trailing-return-type.cpp
@@ -1,4 +1,4 @@
-// RUN: %check_clang_tidy -std=c++14,c++17 %s modernize-use-trailing-return-type %t -- -- -fdeclspec -fexceptions
+// RUN: %check_clang_tidy -std=c++14-or-later %s modernize-use-trailing-return-type %t -- -- -fdeclspec -fexceptions
 // FIXME: Fix the checker to work in C++2a mode, it is performing a
 // use-of-uninitialized-value.
 
@@ -11,6 +11,8 @@
 
 class string;
 
+class ostream;
+
 template 
 auto declval() -> T;
 }
@@ -215,18 +217,28 @@
 // CHECK-FIXES: {{^}}auto e13() -> struct A;{{$}}
 
 //
-// decltype (unsupported if top level expression)
+// deduced return types
 //
 
+const auto ded1();
+// CHECK-MESSAGES: :[[@LINE-1]]:12: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto ded1() -> const auto;{{$}}
+const auto& ded2();
+// CHECK-MESSAGES: :[[@LINE-1]]:13: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto ded2() -> const auto&;{{$}}
+
+decltype(auto) ded3();
+// CHECK-MESSAGES: :[[@LINE-1]]:16: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto ded3() -> decltype(auto);{{$}}
+
+
 decltype(1 + 2) dec1() { return 1 + 2; }
 // CHECK-MESSAGES: :[[@LINE-1]]:17: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
-// TODO: source range of DecltypeTypeLoc not yet implemented
-// _HECK-FIXES: {{^}}auto dec1() -> decltype(1 + 2) { return 1 + 2; }{{$}}
+// CHECK-FIXES: {{^}}auto dec1() -> decltype(1 + 2) { return 1 + 2; }{{$}}
 template 
 decltype(std::declval(std::declval)) dec2(F f, T t) { return f(t); }
 // CHECK-MESSAGES: :[[@LINE-1]]:44: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
-// TODO: source range of DecltypeTypeLoc not yet implemented
-// _HECK-FIXES: {{^}}auto dec2(F f, T t) -> decltype(std::declval(std::declval)) { return f(t); }{{$}}
+// CHECK-FIXES: {{^}}auto dec2(F f, T t) -> decltype(std::declval(std::declval)) { return f(t); }{{$}}
 template 
 typename decltype(std::declval())::value_type dec3();
 // CHECK-MESSAGES: :[[@LINE-1]]:50: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
@@ -531,6 +543,71 @@
 return {0};
 }
 
+//
+// Concepts
+//
+
+#if __cplusplus > 201703L /* C++2a and later */
+
+namespace std {
+template 
+struct is_same { static constexpr auto value = false; };
+
+template 
+struct is_same { static constexpr auto value = true; };
+
+template 
+concept floating_point = std::is_same::value || std::is_same::value || std::is_same::value;
+}
+
+std::floating_point auto con1();
+// CHECK-MESSAGES: :[[@LINE-1]]:26: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto con1() -> std::floating_point auto;{{$}}
+
+std::floating_point auto con1() { return 3.14f; }
+// CHECK-MESSAGES: :[[@LINE-1]]:26: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto con1() -> std::floating_point auto { return 3.14f; }{{$}}
+
+namespace a {
+template 
+concept Concept = true;
+
+template 
+concept BinaryConcept = true;
+}
+
+a::Concept decltype(auto) con2();
+// CHECK-MESSAGES: :[[@LINE-1]]:27: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto con2() -> a::Concept decltype(auto);{{$}}
+
+a::BinaryConcept decltype(auto) con3();
+// CHECK-MESSAGES: :[[@LINE-1]]:38: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto con3() -> a::BinaryConcept decltype(auto);{{$}}
+
+const std::floating_point auto* volatile con4();
+// CHECK-MESSAGES: :[[@LINE-1]]:42: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto con4() -> const std::floating_point auto*

[PATCH] D80514: [clang-tidy] modernize-use-trailing-return-type support for C++20 concepts and decltype

[Bernhard Manfred Gruber via Phabricator via cfe-commits]

bernhardmgruber created this revision.
bernhardmgruber added reviewers: aaron.ballman, JonasToth, Eugene.Zelenko, 
lebedev.ri.
bernhardmgruber added a project: clang-tools-extra.
Herald added subscribers: cfe-commits, xazax.hun.
Herald added a project: clang.
bernhardmgruber updated this revision to Diff 265993.
bernhardmgruber edited the summary of this revision.
bernhardmgruber marked 3 inline comments as done.
bernhardmgruber added inline comments.



Comment at: 
clang-tools-extra/clang-tidy/modernize/UseTrailingReturnTypeCheck.cpp:285-302
+SourceLocation End =
+expandIfMacroId(ReturnLoc.getSourceRange().getEnd(), SM);
+SourceLocation BeginNameF = expandIfMacroId(F.getLocation(), SM);
+
+// Extend the ReturnTypeRange until the last token before the function
+// name.
+std::pair Loc = SM.getDecomposedLoc(End);

Is there an easier way to get the token previous to the function name?



Comment at: 
clang-tools-extra/docs/clang-tidy/checks/modernize-use-trailing-return-type.rst:22
+  virtual float f3() const && = delete;virtual auto f3() const && -> float 
= delete;
+ 
===
 

I tried 2 online rst editors and they failed to format the code blocks inside 
the tables. Will this work with the clang documentation?



Comment at: 
clang-tools-extra/test/clang-tidy/checkers/modernize-use-trailing-return-type.cpp:550
+
+#if __cplusplus > 201703L /* C++2a and later */
+

How do you want to handle these tests which require C++20? I have seen other 
checks use a separate file for tests which require a different language version.


- fixed flags in RUN declaration in lit test
- added tests for C++20 concepts and requires clause
- added manual tokenization for AutoType return types which are not plain 
'auto' to find source range
  - 'const auto'
  - 'Concept auto'
  - 'decltype(auto)'
- improved formatting of documentation
- support for 'decltype(...)'
- added test for bug 44206, which seems to be fixed


https://reviews.llvm.org/D80514

Files:
  clang-tools-extra/clang-tidy/modernize/UseTrailingReturnTypeCheck.cpp
  clang-tools-extra/clang-tidy/modernize/UseTrailingReturnTypeCheck.h
  
clang-tools-extra/docs/clang-tidy/checks/modernize-use-trailing-return-type.rst
  
clang-tools-extra/test/clang-tidy/checkers/modernize-use-trailing-return-type.cpp

Index: clang-tools-extra/test/clang-tidy/checkers/modernize-use-trailing-return-type.cpp
===
--- clang-tools-extra/test/clang-tidy/checkers/modernize-use-trailing-return-type.cpp
+++ clang-tools-extra/test/clang-tidy/checkers/modernize-use-trailing-return-type.cpp
@@ -1,4 +1,4 @@
-// RUN: %check_clang_tidy -std=c++14,c++17 %s modernize-use-trailing-return-type %t -- -- -fdeclspec -fexceptions
+// RUN: %check_clang_tidy -std=c++14-or-later %s modernize-use-trailing-return-type %t -- -- -fdeclspec -fexceptions
 // FIXME: Fix the checker to work in C++2a mode, it is performing a
 // use-of-uninitialized-value.
 
@@ -11,6 +11,8 @@
 
 class string;
 
+class ostream;
+
 template 
 auto declval() -> T;
 }
@@ -215,18 +217,28 @@
 // CHECK-FIXES: {{^}}auto e13() -> struct A;{{$}}
 
 //
-// decltype (unsupported if top level expression)
+// deduced return types
 //
 
+const auto ded1();
+// CHECK-MESSAGES: :[[@LINE-1]]:12: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto ded1() -> const auto;{{$}}
+const auto& ded2();
+// CHECK-MESSAGES: :[[@LINE-1]]:13: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto ded2() -> const auto&;{{$}}
+
+decltype(auto) ded3();
+// CHECK-MESSAGES: :[[@LINE-1]]:16: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto ded3() -> decltype(auto);{{$}}
+
+
 decltype(1 + 2) dec1() { return 1 + 2; }
 // CHECK-MESSAGES: :[[@LINE-1]]:17: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
-// TODO: source range of DecltypeTypeLoc not yet implemented
-// _HECK-FIXES: {{^}}auto dec1() -> decltype(1 + 2) { return 1 + 2; }{{$}}
+// CHECK-FIXES: {{^}}auto dec1() -> decltype(1 + 2) { return 1 + 2; }{{$}}
 template 
 decltype(std::declval(std::declval)) dec2(F f, T t) { return f(t); }
 // CHECK-MESSAGES: :[[@LINE-1]]:44: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
-// TODO: source range of DecltypeTypeLoc not yet implemented
-// _HECK-FIXES: {{^}}auto dec2(F f, T t) -> decltype(std::declval(std::declval)) { return f(t); }{{$}}
+// CHECK-FIXES: {{^}}auto dec2(F f, T t) -> decltype(std::declval(std::declval)) { return f(t); }{{$}}
 template 
 typename decltype(std::declval())::value_type dec3();
 // CHECK

[PATCH] D80514: [clang-tidy] modernize-use-trailing-return-type support for C++20 concepts and decltype

[Bernhard Manfred Gruber via Phabricator via cfe-commits]

bernhardmgruber updated this revision to Diff 265993.
bernhardmgruber edited the summary of this revision.

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Files:
  clang-tools-extra/clang-tidy/modernize/UseTrailingReturnTypeCheck.cpp
  clang-tools-extra/clang-tidy/modernize/UseTrailingReturnTypeCheck.h
  
clang-tools-extra/docs/clang-tidy/checks/modernize-use-trailing-return-type.rst
  
clang-tools-extra/test/clang-tidy/checkers/modernize-use-trailing-return-type.cpp

Index: clang-tools-extra/test/clang-tidy/checkers/modernize-use-trailing-return-type.cpp
===
--- clang-tools-extra/test/clang-tidy/checkers/modernize-use-trailing-return-type.cpp
+++ clang-tools-extra/test/clang-tidy/checkers/modernize-use-trailing-return-type.cpp
@@ -1,4 +1,4 @@
-// RUN: %check_clang_tidy -std=c++14,c++17 %s modernize-use-trailing-return-type %t -- -- -fdeclspec -fexceptions
+// RUN: %check_clang_tidy -std=c++14-or-later %s modernize-use-trailing-return-type %t -- -- -fdeclspec -fexceptions
 // FIXME: Fix the checker to work in C++2a mode, it is performing a
 // use-of-uninitialized-value.
 
@@ -11,6 +11,8 @@
 
 class string;
 
+class ostream;
+
 template 
 auto declval() -> T;
 }
@@ -215,18 +217,28 @@
 // CHECK-FIXES: {{^}}auto e13() -> struct A;{{$}}
 
 //
-// decltype (unsupported if top level expression)
+// deduced return types
 //
 
+const auto ded1();
+// CHECK-MESSAGES: :[[@LINE-1]]:12: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto ded1() -> const auto;{{$}}
+const auto& ded2();
+// CHECK-MESSAGES: :[[@LINE-1]]:13: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto ded2() -> const auto&;{{$}}
+
+decltype(auto) ded3();
+// CHECK-MESSAGES: :[[@LINE-1]]:16: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto ded3() -> decltype(auto);{{$}}
+
+
 decltype(1 + 2) dec1() { return 1 + 2; }
 // CHECK-MESSAGES: :[[@LINE-1]]:17: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
-// TODO: source range of DecltypeTypeLoc not yet implemented
-// _HECK-FIXES: {{^}}auto dec1() -> decltype(1 + 2) { return 1 + 2; }{{$}}
+// CHECK-FIXES: {{^}}auto dec1() -> decltype(1 + 2) { return 1 + 2; }{{$}}
 template 
 decltype(std::declval(std::declval)) dec2(F f, T t) { return f(t); }
 // CHECK-MESSAGES: :[[@LINE-1]]:44: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
-// TODO: source range of DecltypeTypeLoc not yet implemented
-// _HECK-FIXES: {{^}}auto dec2(F f, T t) -> decltype(std::declval(std::declval)) { return f(t); }{{$}}
+// CHECK-FIXES: {{^}}auto dec2(F f, T t) -> decltype(std::declval(std::declval)) { return f(t); }{{$}}
 template 
 typename decltype(std::declval())::value_type dec3();
 // CHECK-MESSAGES: :[[@LINE-1]]:50: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
@@ -531,6 +543,71 @@
 return {0};
 }
 
+//
+// Concepts
+//
+
+#if __cplusplus > 201703L /* C++2a and later */
+
+namespace std {
+template 
+struct is_same { static constexpr auto value = false; };
+
+template 
+struct is_same { static constexpr auto value = true; };
+
+template 
+concept floating_point = std::is_same::value || std::is_same::value || std::is_same::value;
+}
+
+std::floating_point auto con1();
+// CHECK-MESSAGES: :[[@LINE-1]]:26: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto con1() -> std::floating_point auto;{{$}}
+
+std::floating_point auto con1() { return 3.14f; }
+// CHECK-MESSAGES: :[[@LINE-1]]:26: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto con1() -> std::floating_point auto { return 3.14f; }{{$}}
+
+namespace a {
+template 
+concept Concept = true;
+
+template 
+concept BinaryConcept = true;
+}
+
+a::Concept decltype(auto) con2();
+// CHECK-MESSAGES: :[[@LINE-1]]:27: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto con2() -> a::Concept decltype(auto);{{$}}
+
+a::BinaryConcept decltype(auto) con3();
+// CHECK-MESSAGES: :[[@LINE-1]]:38: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto con3() -> a::BinaryConcept decltype(auto);{{$}}
+
+const std::floating_point auto* volatile con4();
+// CHECK-MESSAGES: :[[@LINE-1]]:42: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto con4() -> const std::floating_point auto* volatile;{{$}}
+
+template 
+int req1(T t) requires std::floating_point;
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing retu

[PATCH] D80514: [clang-tidy] modernize-use-trailing-return-type support for C++20 concepts and decltype

[Bernhard Manfred Gruber via Phabricator via cfe-commits]

bernhardmgruber marked 3 inline comments as done.
bernhardmgruber added inline comments.



Comment at: 
clang-tools-extra/clang-tidy/modernize/UseTrailingReturnTypeCheck.cpp:285-302
+SourceLocation End =
+expandIfMacroId(ReturnLoc.getSourceRange().getEnd(), SM);
+SourceLocation BeginNameF = expandIfMacroId(F.getLocation(), SM);
+
+// Extend the ReturnTypeRange until the last token before the function
+// name.
+std::pair Loc = SM.getDecomposedLoc(End);

Is there an easier way to get the token previous to the function name?



Comment at: 
clang-tools-extra/docs/clang-tidy/checks/modernize-use-trailing-return-type.rst:22
+  virtual float f3() const && = delete;virtual auto f3() const && -> float 
= delete;
+ 
===
 

I tried 2 online rst editors and they failed to format the code blocks inside 
the tables. Will this work with the clang documentation?



Comment at: 
clang-tools-extra/test/clang-tidy/checkers/modernize-use-trailing-return-type.cpp:550
+
+#if __cplusplus > 201703L /* C++2a and later */
+

How do you want to handle these tests which require C++20? I have seen other 
checks use a separate file for tests which require a different language version.


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[PATCH] D56160: [clang-tidy] modernize-use-trailing-return-type check

[Bernhard Manfred Gruber via Phabricator via cfe-commits]

bernhardmgruber added a comment.

@Eugene.Zelenko I tried to find what you refer to by PR44206, but I could not 
find anything :/ Can you please provide me with a link? Thank you!


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[PATCH] D56160: [clang-tidy] modernize-use-trailing-return-type check

[Bernhard Manfred Gruber via Phabricator via cfe-commits]

bernhardmgruber updated this revision to Diff 198937.
bernhardmgruber marked 3 inline comments as done.
bernhardmgruber added a comment.

- fixed formatting
- fixed function names in tests
- added `-fexceptions` to test arguments
- fixed type in release notes


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Files:
  clang-tidy/modernize/CMakeLists.txt
  clang-tidy/modernize/ModernizeTidyModule.cpp
  clang-tidy/modernize/UseTrailingReturnTypeCheck.cpp
  clang-tidy/modernize/UseTrailingReturnTypeCheck.h
  docs/ReleaseNotes.rst
  docs/clang-tidy/checks/list.rst
  docs/clang-tidy/checks/modernize-use-trailing-return-type.rst
  test/clang-tidy/modernize-use-trailing-return-type.cpp

Index: test/clang-tidy/modernize-use-trailing-return-type.cpp
===
--- /dev/null
+++ test/clang-tidy/modernize-use-trailing-return-type.cpp
@@ -0,0 +1,563 @@
+// RUN: %check_clang_tidy %s modernize-use-trailing-return-type %t -- -- --std=c++14 -fdeclspec -fexceptions
+
+namespace std {
+template 
+class vector;
+
+template 
+class array;
+
+class string;
+
+template 
+auto declval() -> T;
+}
+
+//
+// Functions
+//
+
+int f();
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto f() -> int;{{$}}
+int ((f))();
+// CHECK-MESSAGES: :[[@LINE-1]]:7: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto ((f))() -> int;{{$}}
+int f(int);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto f(int) -> int;{{$}}
+int f(int arg);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto f(int arg) -> int;{{$}}
+int f(int arg1, int arg2, int arg3);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto f(int arg1, int arg2, int arg3) -> int;{{$}}
+int f(int arg1, int arg2, int arg3, ...);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto f(int arg1, int arg2, int arg3, ...) -> int;{{$}}
+template  int f(T t);
+// CHECK-MESSAGES: :[[@LINE-1]]:27: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}template  auto f(T t) -> int;{{$}}
+
+//
+// Functions with formatting
+//
+
+int a1() { return 42; }
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto a1() -> int { return 42; }{{$}}
+int a2() {
+return 42;
+}
+// CHECK-MESSAGES: :[[@LINE-3]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto a2() -> int {{{$}}
+int a3()
+{
+return 42;
+}
+// CHECK-MESSAGES: :[[@LINE-4]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto a3() -> int{{$}}
+int a4(int   arg   )   ;
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto a4(int   arg   ) -> int   ;{{$}}
+int a5
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto a5{{$}}
+(int arg);
+// CHECK-FIXES: {{^}}(int arg) -> int;{{$}}
+const
+int
+*
+a7
+// CHECK-MESSAGES: :[[@LINE-1]]:1: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+()
+// CHECK-FIXES: {{^}}() -> const{{$}}
+// CHECK-FIXES: {{^}}int{{$}}
+// CHECK-FIXES: {{^}}*{{$}}
+;
+
+int*a7(int arg);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto a7(int arg) -> int*;{{$}}
+template class C>
+Ca8(int arg);
+// CHECK-MESSAGES: :[[@LINE-1]]:7: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto a8(int arg) -> C;{{$}}
+
+
+//
+// Functions with qualifiers and specifiers
+//
+
+inline int d1(int arg);
+// CHECK-MESSAGES: :[[@LINE-1]]:12: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}inline auto d1(int arg) -> int;{{$}}
+extern "C" int d2(int arg);
+// CHECK-MESSAGES: :[[@LINE-1]]:16: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}extern "C" auto d2(int arg) -> int;{{$}}
+inline int d3(int arg) noexcept(true);
+// CHECK-

[PATCH] D56160: [clang-tidy] modernize-use-trailing-return-type check

[Bernhard Manfred Gruber via Phabricator via cfe-commits]

bernhardmgruber marked 2 inline comments as done.
bernhardmgruber added a comment.

@aaron.ballman I do not have commit privileges and I would be very thankful, if 
you could commit this patch for me! Thank you!




Comment at: clang-tidy/modernize/UseTrailingReturnTypeCheck.cpp:203
+  if (ContainsQualifiers + ContainsSpecifiers + ContainsSomethingElse > 1)
+return {};
+

aaron.ballman wrote:
> bernhardmgruber wrote:
> > aaron.ballman wrote:
> > > This should return `llvm::None`
> > I always wondered what the point of `llvm::None`, `std::nullopt` or 
> > `boost::none` is. When I write `return {};` it looks like i return an empty 
> > shell, exactly how I picture an empty optional in my head. That is why I 
> > prefer it this way. I will change it of course for this patch, but would 
> > you mind giving me a short reason, why `llvm::None` is preferable here?
> AFAIK, there's no functional difference between the two and it's more a 
> matter of consistency. Multiple different types can have the notion of a null 
> state, and this allows you to consistently specify that null state across 
> types in an explicit way.
> 
> I suppose there might also be a very slight argument for clarity in that a 
> user reading the code with `{}` could be confused into thinking that is 
> default constructing the contained type rather than creating an empty 
> optional object.
Thank you for the explanation! I see the point of being more explicit.


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[PATCH] D56160: [clang-tidy] modernize-use-trailing-return-type check

[Bernhard Manfred Gruber via Phabricator via cfe-commits]

bernhardmgruber added a comment.

@aaron.ballman and @JonasToth: Thank you for the patience and all the feedback! 
It means a great deal to me to have a patch accepted here!




Comment at: clang-tidy/modernize/UseTrailingReturnTypeCheck.cpp:95-98
+if (!S->getQualifierLoc() && Name.isIdentifier() &&
+VisitUnqualName(Name.getAsIdentifierInfo()->getName()))
+  return false;
+return true;

aaron.ballman wrote:
> This can also be simplified into a single return statement rather than an 
> `if`, but it's less clear to me whether that's an improvement. WDYT?
Let's simplify it.



Comment at: clang-tidy/modernize/UseTrailingReturnTypeCheck.cpp:203
+  if (ContainsQualifiers + ContainsSpecifiers + ContainsSomethingElse > 1)
+return {};
+

aaron.ballman wrote:
> This should return `llvm::None`
I always wondered what the point of `llvm::None`, `std::nullopt` or 
`boost::none` is. When I write `return {};` it looks like i return an empty 
shell, exactly how I picture an empty optional in my head. That is why I prefer 
it this way. I will change it of course for this patch, but would you mind 
giving me a short reason, why `llvm::None` is preferable here?


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[PATCH] D56160: [clang-tidy] modernize-use-trailing-return-type check

[Bernhard Manfred Gruber via Phabricator via cfe-commits]

bernhardmgruber updated this revision to Diff 198531.
bernhardmgruber marked 8 inline comments as done.
bernhardmgruber added a comment.

Fixed small nits suggested by @aaron.ballman. Thanks!


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Files:
  clang-tidy/modernize/CMakeLists.txt
  clang-tidy/modernize/ModernizeTidyModule.cpp
  clang-tidy/modernize/UseTrailingReturnTypeCheck.cpp
  clang-tidy/modernize/UseTrailingReturnTypeCheck.h
  docs/ReleaseNotes.rst
  docs/clang-tidy/checks/list.rst
  docs/clang-tidy/checks/modernize-use-trailing-return-type.rst
  test/clang-tidy/modernize-use-trailing-return-type.cpp

Index: test/clang-tidy/modernize-use-trailing-return-type.cpp
===
--- /dev/null
+++ test/clang-tidy/modernize-use-trailing-return-type.cpp
@@ -0,0 +1,563 @@
+// RUN: %check_clang_tidy %s modernize-use-trailing-return-type %t -- -- --std=c++14 -fdeclspec
+
+namespace std {
+template 
+class vector;
+
+template 
+class array;
+
+class string;
+
+template 
+auto declval() -> T;
+}
+
+//
+// Functions
+//
+
+int f();
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto f() -> int;{{$}}
+int ((f))();
+// CHECK-MESSAGES: :[[@LINE-1]]:7: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto ((f))() -> int;{{$}}
+int f(int);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto f(int) -> int;{{$}}
+int f(int arg);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto f(int arg) -> int;{{$}}
+int f(int arg1, int arg2, int arg3);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto f(int arg1, int arg2, int arg3) -> int;{{$}}
+int f(int arg1, int arg2, int arg3, ...);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto f(int arg1, int arg2, int arg3, ...) -> int;{{$}}
+template  int f(T t);
+// CHECK-MESSAGES: :[[@LINE-1]]:27: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}template  auto f(T t) -> int;{{$}}
+
+//
+// Functions with formatting
+//
+
+int a1() { return 42; }
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto a1() -> int { return 42; }{{$}}
+int a2() {
+return 42;
+}
+// CHECK-MESSAGES: :[[@LINE-3]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto a2() -> int {{{$}}
+int a3()
+{
+return 42;
+}
+// CHECK-MESSAGES: :[[@LINE-4]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto a3() -> int{{$}}
+int a4(int   arg   )   ;
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto a4(int   arg   ) -> int   ;{{$}}
+int a5
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto a5{{$}}
+(int arg);
+// CHECK-FIXES: {{^}}(int arg) -> int;{{$}}
+const
+int
+*
+a7
+// CHECK-MESSAGES: :[[@LINE-1]]:1: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+()
+// CHECK-FIXES: {{^}}() -> const{{$}}
+// CHECK-FIXES: {{^}}int{{$}}
+// CHECK-FIXES: {{^}}*{{$}}
+;
+
+int*a7(int arg);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto a7(int arg) -> int*;{{$}}
+template class C>
+Ca8(int arg);
+// CHECK-MESSAGES: :[[@LINE-1]]:7: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto a8(int arg) -> C;{{$}}
+
+
+//
+// Functions with qualifiers and specifiers
+//
+
+inline int d1(int arg);
+// CHECK-MESSAGES: :[[@LINE-1]]:12: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}inline auto d1(int arg) -> int;{{$}}
+extern "C" int d2(int arg);
+// CHECK-MESSAGES: :[[@LINE-1]]:16: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}extern "C" auto d2(int arg) -> int;{{$}}
+inline int d3(int arg) noexcept(true);
+// CHECK-MESSAGES: :[[@LINE-1]]:12: warning: use a trailing return type for this function 

[PATCH] D56160: [clang-tidy] modernize-use-trailing-return-type check

[Bernhard Manfred Gruber via Phabricator via cfe-commits]

bernhardmgruber updated this revision to Diff 198143.
bernhardmgruber marked 9 inline comments as done.
bernhardmgruber added a comment.

It took a long while to figure out how to handle certain macro cases. Here is 
what I came up with:

When tokenizing the source code from the beginning of the function to the 
function name, I now use clang's `Preprocessor` to lex these tokens again and 
expand macros on the way. I analyse the top-level macros if they just contain 
specifiers or qualifiers and store this information in a `ClassifiedToken`. 
When I later try to expand the return type location to include qualifiers, or 
when I want to remove specifiers from the return type range, I can use this 
information to also include/reprosition macros which I can regard as qualifiers 
or specifiers. This currently solves a lot of cases where macros are part of 
the return type.

Function style macros as part of the return type are not supported, as they are 
harder to lex and expand. The check currently provides no fixit in these cases.

Other changes:

- `expandIfMacroId()` now expands recursively because the `SourceLocation` 
might be inside nested macros
- renamed `nonMacroTokensBeforeFunctionName()` into 
`classifyTokensBeforeFunctionName()`
- improved some comments
- overriding `registerPPCallbacks` to hijack a reference to the preprocessor
- expanding macro ids in the initial return type source range gotten from the 
`FunctionDecl`


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D56160/new/

https://reviews.llvm.org/D56160

Files:
  clang-tidy/modernize/CMakeLists.txt
  clang-tidy/modernize/ModernizeTidyModule.cpp
  clang-tidy/modernize/UseTrailingReturnTypeCheck.cpp
  clang-tidy/modernize/UseTrailingReturnTypeCheck.h
  docs/ReleaseNotes.rst
  docs/clang-tidy/checks/list.rst
  docs/clang-tidy/checks/modernize-use-trailing-return-type.rst
  test/clang-tidy/modernize-use-trailing-return-type.cpp

Index: test/clang-tidy/modernize-use-trailing-return-type.cpp
===
--- /dev/null
+++ test/clang-tidy/modernize-use-trailing-return-type.cpp
@@ -0,0 +1,563 @@
+// RUN: %check_clang_tidy %s modernize-use-trailing-return-type %t -- -- --std=c++14 -fdeclspec
+
+namespace std {
+template 
+class vector;
+
+template 
+class array;
+
+class string;
+
+template 
+auto declval() -> T;
+}
+
+//
+// Functions
+//
+
+int f();
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto f() -> int;{{$}}
+int ((f))();
+// CHECK-MESSAGES: :[[@LINE-1]]:7: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto ((f))() -> int;{{$}}
+int f(int);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto f(int) -> int;{{$}}
+int f(int arg);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto f(int arg) -> int;{{$}}
+int f(int arg1, int arg2, int arg3);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto f(int arg1, int arg2, int arg3) -> int;{{$}}
+int f(int arg1, int arg2, int arg3, ...);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto f(int arg1, int arg2, int arg3, ...) -> int;{{$}}
+template  int f(T t);
+// CHECK-MESSAGES: :[[@LINE-1]]:27: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}template  auto f(T t) -> int;{{$}}
+
+//
+// Functions with formatting
+//
+
+int a1() { return 42; }
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto a1() -> int { return 42; }{{$}}
+int a2() {
+return 42;
+}
+// CHECK-MESSAGES: :[[@LINE-3]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto a2() -> int {{{$}}
+int a3()
+{
+return 42;
+}
+// CHECK-MESSAGES: :[[@LINE-4]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto a3() -> int{{$}}
+int a4(int   arg   )   ;
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto a4(int   arg   ) -> int   ;{{$}}
+int a5
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto a5{{$}}
+(int arg);
+// CHECK-FIXES: {{^}}(int arg) -> int;{{$}}
+const
+int
+*
+a7
+// CH

[PATCH] D56160: [clang-tidy] modernize-use-trailing-return-type check

[Bernhard Manfred Gruber via Phabricator via cfe-commits]

bernhardmgruber added inline comments.



Comment at: clang-tidy/modernize/UseTrailingReturnTypeCheck.cpp:274
+
+  if (F->getLocation().isInvalid())
+return;

aaron.ballman wrote:
> bernhardmgruber wrote:
> > aaron.ballman wrote:
> > > bernhardmgruber wrote:
> > > > aaron.ballman wrote:
> > > > > Should this also bail out if the function is `main()`?
> > > > How strange does
> > > > 
> > > > ```
> > > > auto main(int argc, const char* argv[]) -> int {
> > > > return 0;
> > > > }
> > > > ```
> > > > look to you?
> > > > 
> > > > I think the transformation is valid here. But I can understand that 
> > > > people feel uneasy after typing `int main ...` for decades. Should we 
> > > > also create an option here to turn it off for main? Or just not 
> > > > transform it? I do not mind. If I want `main` to start with `auto` I 
> > > > could also do this transformation manually.
> > > This comment was marked as done, but I don't see any changes or mention 
> > > of what should happen. I suppose the more general question is: should 
> > > there be a list of functions that should not have this transformation 
> > > applied, like program entrypoints? Or do you want to see this check 
> > > diagnose those functions as well?
> > I am sorry for marking it as done. I do not know how people work here 
> > exactly and how phabricator behaves. I thought the check boxes are handled 
> > for everyone individually. Also, if I add a new comment, it is checked by 
> > default.
> > 
> > How are you/most people going to use clang-tidy? Do you run it regularly 
> > and automatic? Do you expect it to find zero issues once you applied the 
> > check?
> > In other words, if you do not want to transform some functions, do you need 
> > an option to disable the check for these, so it runs clean on the full 
> > source code?
> > 
> > Personally, I do not need this behavior, as I run clang-tidy manually once 
> > in a while and revert transformations I do not want before checking in the 
> > changes.
> > I am sorry for marking it as done. I do not know how people work here 
> > exactly and how phabricator behaves. I thought the check boxes are handled 
> > for everyone individually. Also, if I add a new comment, it is checked by 
> > default.
> 
> No worries -- that new comments are automatically marked done by default is 
> certainly a surprise to me!
> 
> > How are you/most people going to use clang-tidy? Do you run it regularly 
> > and automatic? Do you expect it to find zero issues once you applied the 
> > check? In other words, if you do not want to transform some functions, do 
> > you need an option to disable the check for these, so it runs clean on the 
> > full source code?
> 
> I think it's hard to gauge how most people do anything, really. However, I 
> think there are people who enable certain clang-tidy checks and have them run 
> automatically as part of CI, etc. Those kind of folks may need the ability to 
> silence the diagnostics. We could do this in a few ways (options to control 
> methods not to diagnose, NOLINT comments, etc).
> 
> I kind of think we don't need an option for the user to list functions not to 
> transform. They can use NOLINT to cover those situations as a one-off. The 
> only situation where I wonder if everyone is going to want to write NOLINT is 
> for `main()`. It might make sense to have an option to not check program 
> entrypoints, but there is technically nothing stopping someone from using a 
> trailing return type with a program entrypoint so maybe this option isn't 
> needed at all.
> 
> How about we not add any options and if someone files a bug report, we can 
> address it then?
> How about we not add any options and if someone files a bug report, we can 
> address it then?

Sounds good to me!



Comment at: clang-tidy/modernize/UseTrailingReturnTypeCheck.cpp:180-184
+  if (Info.hasMacroDefinition()) {
+// The CV qualifiers of the return type are inside macros.
+diag(F.getLocation(), Message);
+return {};
+  }

aaron.ballman wrote:
> bernhardmgruber wrote:
> > aaron.ballman wrote:
> > > Perhaps I'm a bit dense on a Monday morning, but why should this be a 
> > > diagnostic? I am worried this will diagnose situations like (untested 
> > > guesses):
> > > ```
> > > #define const const
> > > const int f(void); // Why no fixit?
> > > 
> > > #define attr __attribute__((frobble))
> > > attr void g(void); // Why diagnosed as needing a trailing return type?
> > > ```
> > Because I would also like to rewrite functions which contain macros in the 
> > return type. However, I cannot provide a fixit in all cases. Clang can give 
> > me a `SourceRange` without CV qualifiers which seems to work in all my 
> > tests so far. But to include CV qualifiers I have to do some manual lexing 
> > left and right of the return type `SourceRange`. If I encounter macros 
> > along this way, I bail out because 

[PATCH] D56160: [clang-tidy] modernize-use-trailing-return-type check

[Bernhard Manfred Gruber via Phabricator via cfe-commits]

bernhardmgruber marked an inline comment as not done.
bernhardmgruber added a comment.

Thank you for the rich feedback @aaron.ballman. I found a solution which seems 
to work for many of my test cases.




Comment at: clang-tidy/modernize/UseTrailingReturnTypeCheck.cpp:274
+
+  if (F->getLocation().isInvalid())
+return;

aaron.ballman wrote:
> Should this also bail out if the function is `main()`?
How strange does

```
auto main(int argc, const char* argv[]) -> int {
return 0;
}
```
look to you?

I think the transformation is valid here. But I can understand that people feel 
uneasy after typing `int main ...` for decades. Should we also create an option 
here to turn it off for main? Or just not transform it? I do not mind. If I 
want `main` to start with `auto` I could also do this transformation manually.



Comment at: clang-tidy/modernize/UseTrailingReturnTypeCheck.cpp:274
+
+  if (F->getLocation().isInvalid())
+return;

aaron.ballman wrote:
> bernhardmgruber wrote:
> > aaron.ballman wrote:
> > > Should this also bail out if the function is `main()`?
> > How strange does
> > 
> > ```
> > auto main(int argc, const char* argv[]) -> int {
> > return 0;
> > }
> > ```
> > look to you?
> > 
> > I think the transformation is valid here. But I can understand that people 
> > feel uneasy after typing `int main ...` for decades. Should we also create 
> > an option here to turn it off for main? Or just not transform it? I do not 
> > mind. If I want `main` to start with `auto` I could also do this 
> > transformation manually.
> This comment was marked as done, but I don't see any changes or mention of 
> what should happen. I suppose the more general question is: should there be a 
> list of functions that should not have this transformation applied, like 
> program entrypoints? Or do you want to see this check diagnose those 
> functions as well?
I am sorry for marking it as done. I do not know how people work here exactly 
and how phabricator behaves. I thought the check boxes are handled for everyone 
individually. Also, if I add a new comment, it is checked by default.

How are you/most people going to use clang-tidy? Do you run it regularly and 
automatic? Do you expect it to find zero issues once you applied the check?
In other words, if you do not want to transform some functions, do you need an 
option to disable the check for these, so it runs clean on the full source code?

Personally, I do not need this behavior, as I run clang-tidy manually once in a 
while and revert transformations I do not want before checking in the changes.



Comment at: clang-tidy/modernize/UseTrailingReturnTypeCheck.cpp:180-184
+  if (Info.hasMacroDefinition()) {
+// The CV qualifiers of the return type are inside macros.
+diag(F.getLocation(), Message);
+return {};
+  }

aaron.ballman wrote:
> Perhaps I'm a bit dense on a Monday morning, but why should this be a 
> diagnostic? I am worried this will diagnose situations like (untested 
> guesses):
> ```
> #define const const
> const int f(void); // Why no fixit?
> 
> #define attr __attribute__((frobble))
> attr void g(void); // Why diagnosed as needing a trailing return type?
> ```
Because I would also like to rewrite functions which contain macros in the 
return type. However, I cannot provide a fixit in all cases. Clang can give me 
a `SourceRange` without CV qualifiers which seems to work in all my tests so 
far. But to include CV qualifiers I have to do some manual lexing left and 
right of the return type `SourceRange`. If I encounter macros along this way, I 
bail out because handling these cases becomes compilated very easily.

Your second case does not give a diagnostic, as it is not matched by the check, 
because it returns `void`.



Comment at: clang-tidy/modernize/UseTrailingReturnTypeCheck.cpp:234
+  bool ExtendedLeft = false;
+  for (size_t I = 0; I < Tokens.size(); I++) {
+// If we found the beginning of the return type, include const and volatile

aaron.ballman wrote:
> As a torture test for this, how well does it handle a declaration like:
> ```
> const long static int volatile unsigned inline long foo();
> ```
> Does it get the fixit to spit out:
> ```
> static inline auto foo() -> const unsigned long long int;
> ```
I honestly did not believe this compiled until I put it into godbolt. And no, 
it is not handled.
I added your test as well as a few other ones of this kind. You could also add 
`constexpr` or inside classes `friend` anywhere.

I will try to come up with a solution. I guess the best would be to delete the 
specifiers from the extracted range type string and readd them in the order of 
appearance before auto.



Comment at: clang-tidy/modernize/UseTrailingReturnTypeCheck.cpp:298
+  TSI->getTypeLoc().IgnoreParens().getAs();
+  if (!FTL) {
+diag

[PATCH] D56160: [clang-tidy] modernize-use-trailing-return-type check

[Bernhard Manfred Gruber via Phabricator via cfe-commits]

bernhardmgruber updated this revision to Diff 191233.
bernhardmgruber marked 7 inline comments as done and 2 inline comments as done.
bernhardmgruber added a comment.

- extracting specifiers from the return type if it consists of a multitoken 
built-in type, and preprending it to 'auto'.
- extended matcher to include `friend` declarations of functions
- added many tests for return types which contain specifiers


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D56160/new/

https://reviews.llvm.org/D56160

Files:
  clang-tidy/modernize/CMakeLists.txt
  clang-tidy/modernize/ModernizeTidyModule.cpp
  clang-tidy/modernize/UseTrailingReturnTypeCheck.cpp
  clang-tidy/modernize/UseTrailingReturnTypeCheck.h
  docs/ReleaseNotes.rst
  docs/clang-tidy/checks/list.rst
  docs/clang-tidy/checks/modernize-use-trailing-return-type.rst
  test/clang-tidy/modernize-use-trailing-return-type.cpp

Index: test/clang-tidy/modernize-use-trailing-return-type.cpp
===
--- /dev/null
+++ test/clang-tidy/modernize-use-trailing-return-type.cpp
@@ -0,0 +1,513 @@
+// RUN: %check_clang_tidy %s modernize-use-trailing-return-type %t -- -- --std=c++14 -fdeclspec
+
+namespace std {
+template 
+class vector;
+
+template 
+class array;
+
+class string;
+
+template 
+auto declval() -> T;
+}
+
+//
+// Functions
+//
+
+int f();
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto f() -> int;{{$}}
+int ((f))();
+// CHECK-MESSAGES: :[[@LINE-1]]:7: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto ((f))() -> int;{{$}}
+int f(int);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto f(int) -> int;{{$}}
+int f(int arg);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto f(int arg) -> int;{{$}}
+int f(int arg1, int arg2, int arg3);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto f(int arg1, int arg2, int arg3) -> int;{{$}}
+int f(int arg1, int arg2, int arg3, ...);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto f(int arg1, int arg2, int arg3, ...) -> int;{{$}}
+template  int f(T t);
+// CHECK-MESSAGES: :[[@LINE-1]]:27: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}template  auto f(T t) -> int;{{$}}
+
+//
+// Functions with formatting
+//
+
+int a1() { return 42; }
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto a1() -> int { return 42; }{{$}}
+int a2() {
+return 42;
+}
+// CHECK-MESSAGES: :[[@LINE-3]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto a2() -> int {{{$}}
+int a3()
+{
+return 42;
+}
+// CHECK-MESSAGES: :[[@LINE-4]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto a3() -> int{{$}}
+int a4(int   arg   )   ;
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto a4(int   arg   ) -> int   ;{{$}}
+int a5
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto a5{{$}}
+(int arg);
+// CHECK-FIXES: {{^}}(int arg) -> int;{{$}}
+const
+int
+*
+a7
+// CHECK-MESSAGES: :[[@LINE-1]]:1: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+()
+// CHECK-FIXES: {{^}}() -> const{{$}}
+// CHECK-FIXES: {{^}}int{{$}}
+// CHECK-FIXES: {{^}}*{{$}}
+;
+
+int*a7(int arg);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto a7(int arg) -> int*;{{$}}
+template class C>
+Ca8(int arg);
+// CHECK-MESSAGES: :[[@LINE-1]]:7: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto a8(int arg) -> C;{{$}}
+
+
+//
+// Functions with qualifiers and specifiers
+//
+
+inline int d1(int arg);
+// CHECK-MESSAGES: :[[@LINE-1]]:12: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}inline auto d1(int arg) -> int;{{$}}
+extern "C" int d2(int arg);
+// CHECK-MESSAGES: :[[@LINE-1]]:16: warning: use a trailing return type for this function [modern

[PATCH] D56160: [clang-tidy] modernize-use-trailing-return-type check

[Bernhard Manfred Gruber via Phabricator via cfe-commits]

bernhardmgruber updated this revision to Diff 189993.
bernhardmgruber marked 8 inline comments as done.
bernhardmgruber added a comment.

- added support for __restrict
- added two dots at end of comments


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D56160/new/

https://reviews.llvm.org/D56160

Files:
  clang-tidy/modernize/CMakeLists.txt
  clang-tidy/modernize/ModernizeTidyModule.cpp
  clang-tidy/modernize/UseTrailingReturnTypeCheck.cpp
  clang-tidy/modernize/UseTrailingReturnTypeCheck.h
  docs/ReleaseNotes.rst
  docs/clang-tidy/checks/list.rst
  docs/clang-tidy/checks/modernize-use-trailing-return-type.rst
  test/clang-tidy/modernize-use-trailing-return-type.cpp

Index: test/clang-tidy/modernize-use-trailing-return-type.cpp
===
--- /dev/null
+++ test/clang-tidy/modernize-use-trailing-return-type.cpp
@@ -0,0 +1,445 @@
+// RUN: %check_clang_tidy %s modernize-use-trailing-return-type %t -- -- --std=c++14 -fdeclspec
+
+namespace std {
+template 
+class vector;
+
+template 
+class array;
+
+class string;
+
+template 
+auto declval() -> T;
+}
+
+//
+// Functions
+//
+
+int f();
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto f() -> int;{{$}}
+int ((f))();
+// CHECK-MESSAGES: :[[@LINE-1]]:7: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto ((f))() -> int;{{$}}
+int f(int);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto f(int) -> int;{{$}}
+int f(int arg);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto f(int arg) -> int;{{$}}
+int f(int arg1, int arg2, int arg3);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto f(int arg1, int arg2, int arg3) -> int;{{$}}
+int f(int arg1, int arg2, int arg3, ...);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto f(int arg1, int arg2, int arg3, ...) -> int;{{$}}
+template  int f(T t);
+// CHECK-MESSAGES: :[[@LINE-1]]:27: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}template  auto f(T t) -> int;{{$}}
+
+//
+// Functions with formatting
+//
+
+int a1() { return 42; }
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto a1() -> int { return 42; }{{$}}
+int a2() {
+return 42;
+}
+// CHECK-MESSAGES: :[[@LINE-3]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto a2() -> int {{{$}}
+int a3()
+{
+return 42;
+}
+// CHECK-MESSAGES: :[[@LINE-4]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto a3() -> int{{$}}
+int a4(int   arg   )   ;
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto a4(int   arg   ) -> int   ;{{$}}
+int a5
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto a5{{$}}
+(int arg);
+// CHECK-FIXES: {{^}}(int arg) -> int;{{$}}
+const
+int
+*
+a7
+// CHECK-MESSAGES: :[[@LINE-1]]:1: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+()
+// CHECK-FIXES: {{^}}() -> const{{$}}
+// CHECK-FIXES: {{^}}int{{$}}
+// CHECK-FIXES: {{^}}*{{$}}
+;
+
+int*a7(int arg);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto a7(int arg) -> int*;{{$}}
+template class C>
+Ca8(int arg);
+// CHECK-MESSAGES: :[[@LINE-1]]:7: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto a8(int arg) -> C;{{$}}
+
+
+//
+// Functions with qualifiers and specifiers
+//
+
+inline int d1(int arg);
+// CHECK-MESSAGES: :[[@LINE-1]]:12: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}inline auto d1(int arg) -> int;{{$}}
+extern "C" int d2(int arg);
+// CHECK-MESSAGES: :[[@LINE-1]]:16: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}extern "C" auto d2(int arg) -> int;{{$}}
+inline int d3(int arg) noexcept(true);
+// CHECK-MESSAGES: :[[@LINE-1]]:12: warning: use a trailing return type for t

[PATCH] D56160: [clang-tidy] modernize-use-trailing-return-type check

[Bernhard Manfred Gruber via Phabricator via cfe-commits]

bernhardmgruber updated this revision to Diff 189222.
bernhardmgruber marked 3 inline comments as done.
bernhardmgruber added a comment.

Fixed some little nits, thanks @JonasToth!


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D56160/new/

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Files:
  clang-tidy/modernize/CMakeLists.txt
  clang-tidy/modernize/ModernizeTidyModule.cpp
  clang-tidy/modernize/UseTrailingReturnTypeCheck.cpp
  clang-tidy/modernize/UseTrailingReturnTypeCheck.h
  docs/ReleaseNotes.rst
  docs/clang-tidy/checks/list.rst
  docs/clang-tidy/checks/modernize-use-trailing-return-type.rst
  test/clang-tidy/modernize-use-trailing-return-type.cpp

Index: test/clang-tidy/modernize-use-trailing-return-type.cpp
===
--- /dev/null
+++ test/clang-tidy/modernize-use-trailing-return-type.cpp
@@ -0,0 +1,437 @@
+// RUN: %check_clang_tidy %s modernize-use-trailing-return-type %t -- -- --std=c++14 -fdeclspec
+
+namespace std {
+template 
+class vector;
+
+template 
+class array;
+
+class string;
+
+template 
+auto declval() -> T;
+}
+
+//
+// Functions
+//
+
+int f();
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto f() -> int;{{$}}
+int ((f))();
+// CHECK-MESSAGES: :[[@LINE-1]]:7: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto ((f))() -> int;{{$}}
+int f(int);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto f(int) -> int;{{$}}
+int f(int arg);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto f(int arg) -> int;{{$}}
+int f(int arg1, int arg2, int arg3);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto f(int arg1, int arg2, int arg3) -> int;{{$}}
+int f(int arg1, int arg2, int arg3, ...);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto f(int arg1, int arg2, int arg3, ...) -> int;{{$}}
+template  int f(T t);
+// CHECK-MESSAGES: :[[@LINE-1]]:27: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}template  auto f(T t) -> int;{{$}}
+
+//
+// Functions with formatting
+//
+
+int a1() { return 42; }
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto a1() -> int { return 42; }{{$}}
+int a2() {
+return 42;
+}
+// CHECK-MESSAGES: :[[@LINE-3]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto a2() -> int {{{$}}
+int a3()
+{
+return 42;
+}
+// CHECK-MESSAGES: :[[@LINE-4]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto a3() -> int{{$}}
+int a4(int   arg   )   ;
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto a4(int   arg   ) -> int   ;{{$}}
+int a5
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto a5{{$}}
+(int arg);
+// CHECK-FIXES: {{^}}(int arg) -> int;{{$}}
+const
+int
+*
+a7
+// CHECK-MESSAGES: :[[@LINE-1]]:1: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+()
+// CHECK-FIXES: {{^}}() -> const{{$}}
+// CHECK-FIXES: {{^}}int{{$}}
+// CHECK-FIXES: {{^}}*{{$}}
+;
+
+int*a7(int arg);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto a7(int arg) -> int*;{{$}}
+template class C>
+Ca8(int arg);
+// CHECK-MESSAGES: :[[@LINE-1]]:7: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto a8(int arg) -> C;{{$}}
+
+
+//
+// Functions with qualifiers and specifiers
+//
+
+inline int d1(int arg);
+// CHECK-MESSAGES: :[[@LINE-1]]:12: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}inline auto d1(int arg) -> int;{{$}}
+extern "C" int d2(int arg);
+// CHECK-MESSAGES: :[[@LINE-1]]:16: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}extern "C" auto d2(int arg) -> int;{{$}}
+inline int d3(int arg) noexcept(true);
+// CHECK-MESSAGES: :[[@LINE-1]]:12: warning: use a trailing return type for this function [modernize-

[PATCH] D56160: [clang-tidy] modernize-use-trailing-return-type check

[Bernhard Manfred Gruber via Phabricator via cfe-commits]

bernhardmgruber added inline comments.



Comment at: clang-tidy/modernize/UseTrailingReturnCheck.cpp:335
+  StringRef ReturnType = tooling::fixit::getText(ReturnTypeCVRange, Ctx);
+  StringRef Auto = std::isspace(*ReturnType.end()) // FIXME (dereferencing end)
+   ? "auto"

JonasToth wrote:
> bernhardmgruber wrote:
> > FIXME: this feels wrong when I wrote it, but it works. I tried to fiddle 
> > with the ReturnTypeCVRange to include the next charakter, but I could not 
> > get it working without writing `tooling::fixit::getText` myself. Any ideas?
> That only works, because `StringRef` points within the orignal code buffer. 
> IMHO just adding the space always and letting clang-format do its job is 
> better then this potential out-of-bounds read.
> Maybe you could increase the `ReturnTypeCVRange` by one at the end, then its 
> fine.
I now retrieve the space after the return type explicitely. Using clang-format 
afterwards is not always possible on the code bases I work with, so I would 
like to not rely on it.


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[PATCH] D56160: [clang-tidy] modernize-use-trailing-return-type check

[Bernhard Manfred Gruber via Phabricator via cfe-commits]

bernhardmgruber updated this revision to Diff 188621.
bernhardmgruber marked 4 inline comments as done.
bernhardmgruber retitled this revision from "[clang-tidy] 
modernize-use-trailing-return check" to "[clang-tidy] 
modernize-use-trailing-return-type check".
bernhardmgruber added a comment.

- renamed the check to modernize-use-trailing-return-type
- fixed the out-of-bounds access to check whether there is a space after the 
return type


CHANGES SINCE LAST ACTION
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Files:
  clang-tidy/modernize/CMakeLists.txt
  clang-tidy/modernize/ModernizeTidyModule.cpp
  clang-tidy/modernize/UseTrailingReturnTypeCheck.cpp
  clang-tidy/modernize/UseTrailingReturnTypeCheck.h
  docs/ReleaseNotes.rst
  docs/clang-tidy/checks/list.rst
  docs/clang-tidy/checks/modernize-use-trailing-return-type.rst
  test/clang-tidy/modernize-use-trailing-return-type.cpp

Index: test/clang-tidy/modernize-use-trailing-return-type.cpp
===
--- /dev/null
+++ test/clang-tidy/modernize-use-trailing-return-type.cpp
@@ -0,0 +1,437 @@
+// RUN: %check_clang_tidy %s modernize-use-trailing-return-type %t -- -- --std=c++14 -fdeclspec
+
+namespace std {
+template 
+class vector;
+
+template 
+class array;
+
+class string;
+
+template 
+auto declval() -> T;
+}
+
+//
+// Functions
+//
+
+int f();
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto f() -> int;{{$}}
+int ((f))();
+// CHECK-MESSAGES: :[[@LINE-1]]:7: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto ((f))() -> int;{{$}}
+int f(int);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto f(int) -> int;{{$}}
+int f(int arg);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto f(int arg) -> int;{{$}}
+int f(int arg1, int arg2, int arg3);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto f(int arg1, int arg2, int arg3) -> int;{{$}}
+int f(int arg1, int arg2, int arg3, ...);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto f(int arg1, int arg2, int arg3, ...) -> int;{{$}}
+template  int f(T t);
+// CHECK-MESSAGES: :[[@LINE-1]]:27: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}template  auto f(T t) -> int;{{$}}
+
+//
+// Functions with formatting
+//
+
+int a1() { return 42; }
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto a1() -> int { return 42; }{{$}}
+int a2() {
+return 42;
+}
+// CHECK-MESSAGES: :[[@LINE-3]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto a2() -> int {{{$}}
+int a3()
+{
+return 42;
+}
+// CHECK-MESSAGES: :[[@LINE-4]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto a3() -> int{{$}}
+int a4(int   arg   )   ;
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto a4(int   arg   ) -> int   ;{{$}}
+int a5
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto a5{{$}}
+(int arg);
+// CHECK-FIXES: {{^}}(int arg) -> int;{{$}}
+const
+int
+*
+a7
+// CHECK-MESSAGES: :[[@LINE-1]]:1: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+()
+// CHECK-FIXES: {{^}}() -> const{{$}}
+// CHECK-FIXES: {{^}}int{{$}}
+// CHECK-FIXES: {{^}}*{{$}}
+;
+
+int*a7(int arg);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto a7(int arg) -> int*;{{$}}
+template class C>
+Ca8(int arg);
+// CHECK-MESSAGES: :[[@LINE-1]]:7: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}auto a8(int arg) -> C;{{$}}
+
+
+//
+// Functions with qualifiers and specifiers
+//
+
+inline int d1(int arg);
+// CHECK-MESSAGES: :[[@LINE-1]]:12: warning: use a trailing return type for this function [modernize-use-trailing-return-type]
+// CHECK-FIXES: {{^}}inline auto d1(int arg) -> int;{{$}}
+extern "C" int d2(int arg);
+// CHECK-MESSAGES: :[[@LINE-1]]:16: warning: use a trailing return typ

[PATCH] D56160: [clang-tidy] modernize-use-trailing-return check

[Bernhard Manfred Gruber via Phabricator via cfe-commits]

bernhardmgruber marked 2 inline comments as done.
bernhardmgruber added a comment.

Hi guys!

It took me far too long to come up with an update. Honestly, I was quite 
demotivated as it turned out preventing name collisions of unqualifed names 
after the rewrite was more difficult than I thought. Especially because this 
error occurs sparsely when I test the check on bigger code bases. The current 
approach with the AST visitor seems to work best and maybe I can even extend it 
at some point to automatically qualify colliding names. But for now, I would be 
really glad if we could achieve a state of the check that you guys can accept 
and commit.

I marked two lines with comments where I still need some feedback. Apart from 
that, I will run the check again on LLVM and other larger code bases to see if 
there are any further issues.

Thank you for your help!




Comment at: clang-tidy/modernize/UseTrailingReturnCheck.cpp:78
+  // TraverseTypeLoc().
+  // TODO: Maybe RecursiveASTVisitor should call
+  // getDerived().TraverseTypeLoc(...).

TODO: is this an issue in RecursiveASTVisitor or is this behavior intended? 
Everywhere else, it calls `getDerived().XXX();`



Comment at: clang-tidy/modernize/UseTrailingReturnCheck.cpp:335
+  StringRef ReturnType = tooling::fixit::getText(ReturnTypeCVRange, Ctx);
+  StringRef Auto = std::isspace(*ReturnType.end()) // FIXME (dereferencing end)
+   ? "auto"

FIXME: this feels wrong when I wrote it, but it works. I tried to fiddle with 
the ReturnTypeCVRange to include the next charakter, but I could not get it 
working without writing `tooling::fixit::getText` myself. Any ideas?


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[PATCH] D56160: [clang-tidy] modernize-use-trailing-return check

[Bernhard Manfred Gruber via Phabricator via cfe-commits]

bernhardmgruber updated this revision to Diff 188528.
bernhardmgruber marked 2 inline comments as done.
bernhardmgruber added a comment.
Herald added a subscriber: jdoerfert.

- rebased onto current master
- implemented a basic check for name collisions of unqualified names in the 
return type with function arugment names using RecursiveASTVisitor
- moved retrieval of `FunctionTypeLoc` out of 
`findTrailingReturnTypeSourceLocation()`
- replaced `F.getReturnType().hasLocalQualifiers()` by custom function 
`hasAnyNestedLocalQualifiers()`, as the former does not work if the qualifiers 
are not on the topmost type. E.g.: `const int*`. This is a PointerType without 
qualifiers, the const qualifier is part of the nested pointee type.
- inhibiting the rewrite, if the topmost return type is a `decltype` 
expression. the source range in this case does not include the expression in 
parenthesis after the `decltype`
- inserting an additional space after `auto` in case there was no space between 
the return type and the function name. E.g.: `int*f();`
- extended documentation with known limitations
- added more tests


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Files:
  clang-tidy/modernize/CMakeLists.txt
  clang-tidy/modernize/ModernizeTidyModule.cpp
  clang-tidy/modernize/UseTrailingReturnCheck.cpp
  clang-tidy/modernize/UseTrailingReturnCheck.h
  docs/ReleaseNotes.rst
  docs/clang-tidy/checks/list.rst
  docs/clang-tidy/checks/modernize-use-trailing-return.rst
  test/clang-tidy/modernize-use-trailing-return.cpp

Index: test/clang-tidy/modernize-use-trailing-return.cpp
===
--- /dev/null
+++ test/clang-tidy/modernize-use-trailing-return.cpp
@@ -0,0 +1,433 @@
+// RUN: %check_clang_tidy %s modernize-use-trailing-return %t -- -- --std=c++14 -fdeclspec
+
+namespace std {
+template 
+class vector;
+
+template 
+class array;
+
+class string;
+
+template 
+auto declval() -> T;
+}
+
+//
+// Functions
+//
+
+int f();
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto f() -> int;{{$}}
+int ((f))();
+// CHECK-MESSAGES: :[[@LINE-1]]:7: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto ((f))() -> int;{{$}}
+int f(int);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto f(int) -> int;{{$}}
+int f(int arg);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto f(int arg) -> int;{{$}}
+int f(int arg1, int arg2, int arg3);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto f(int arg1, int arg2, int arg3) -> int;{{$}}
+int f(int arg1, int arg2, int arg3, ...);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto f(int arg1, int arg2, int arg3, ...) -> int;{{$}}
+template  int f(T t);
+// CHECK-MESSAGES: :[[@LINE-1]]:27: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}template  auto f(T t) -> int;{{$}}
+
+//
+// Functions with formatting
+//
+
+int a1() { return 42; }
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto a1() -> int { return 42; }{{$}}
+int a2() {
+return 42;
+}
+// CHECK-MESSAGES: :[[@LINE-3]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto a2() -> int {{{$}}
+int a3()
+{
+return 42;
+}
+// CHECK-MESSAGES: :[[@LINE-4]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto a3() -> int{{$}}
+int a4(int   arg   )   ;
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto a4(int   arg   ) -> int   ;{{$}}
+int a5
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto a5{{$}}
+(int arg);
+// CHECK-FIXES: {{^}}(int arg) -> int;{{$}}
+const
+int
+*
+a7
+// CHECK-MESSAGES: :[[@LINE-1]]:1: warning: use a trailing return type for this function [modernize-use-trailing-return]
+()
+// CHECK-FIXES: {{^}}() -> const{{$}}
+// CHECK-FIXES: {{^}}int{{$}}
+// CHECK-FIXES: {{^}}*{{$}}
+;
+
+int*a7(int arg);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto a7(int arg) -> int*;{{$}}
+
+
+

[PATCH] D56160: [clang-tidy] modernize-use-trailing-return check

[Bernhard Manfred Gruber via Phabricator via cfe-commits]

bernhardmgruber marked 2 inline comments as done.
bernhardmgruber added a comment.

Thank you for the feedback!

@JonasToth I added tests for `decltype` and i can rewrite all signatures where 
`decltype` is not the top level expression. The reason is, that the source 
range of a `clang::DecltypeType` is not accurate, as it does not include the 
expression within the parenthesis following the `decltype` keyword. There is 
even a FIXME somewhere in the corresponding source file.

@aaron.ballman I am not sure what you mean and maybe you have not understood my 
issue correctly.

In D56160#1369986 , @aaron.ballman 
wrote:

> > ...
>
> I think you may be able to skip the lookup (which could get expensive) and 
> instead rely on the fact that the user must have explicitly written that type 
> as an elaborated type specifier when trying to calculate the source range for 
> the return type. I suspect what's happening right now is that 
> `findReturnTypeAndCVSourceRange()` isn't noticing the `struct` specifier and 
> that's why it's getting dropped. If the user wrote it as an elaborated type 
> specifier, we should probably retain that when shifting it to a trailing 
> return type.


Given the following source code before the rewriting:

  struct Object { long long value; };
  class C {
int Object;
struct Object m();
  };
  Object C::m() { return {0}; }

The member function `struct Object m();` needs to have a `struct` before 
`Object`, because otherwise, the return type would conflict with the member 
variable of the same name. On the contrary, the out-of-line definition `Object 
C::m() { return {0}; }` does not need the `struct`, as the scope of the return 
type does not include the member variables of class `C`. However, rewriting the 
out-of-line definition from `Object C::m() { return {0}; }` to `auto C::m() -> 
Object { return {0}; }` changes the scope of the return type, which now 
includes the member variable `int Object;` and results in a compilation error.
I do not understand what you meant by

> the user must have explicitly written that type as an elaborated type 
> specifier

because in case of the out-of-line defintion, the user is not required to do 
so. Also, when my check rewrites `struct Object m();`, it correctly produces 
`auto m() -> struct Object;` (`findReturnTypeAndCVSourceRange()` includes the 
`struct`).

I tried to circumvent the problem doing something like (F is the matched 
`FunctionDecl`)

  if (auto M = dyn_cast(F)) {
if (auto Name = M->getDeclaredReturnType().getBaseTypeIdentifier()) {
  auto result = M->getDeclContext()->lookup(Name);
  if (!result.empty()) {
// cannot do rewrite, collision
  }
}
  }

but then I noticed, the lookup is only performed in the scope of the member 
function's class, not including e.g. inherited classes. So if we extend the 
example with

  class D : public C {
  ::Object g();
  };
  Object D::g() {

(note that instead of `struct Object` we can also qualify the type with the 
namespace it comes from), then the `DeclContext` of the out-of-line definition 
of the member function `g` is empty (it least, I do not get an output when i 
call `dumpDeclContext`). So maybe the `DeclContext` is not the right tool for 
the job. How else can I query all visible names in which a given object (in 
this case the matched (member) function) is declared? So I can check that the 
name of the return type is not already taken in the scope of the trailing 
return type.

Here is btw. the function case:

  struct Object { long long value; };
  Object j1(unsigned Object) { return {Object * 2}; }

After the rewrite, the return type conflicts with the parameter name.

I appreciate any input! I will continue to explore the problem. Maybe I can get 
it working by inspecting a multitude of `DeclContext`s.


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[PATCH] D56160: [clang-tidy] modernize-use-trailing-return check

[Bernhard Manfred Gruber via Phabricator via cfe-commits]

bernhardmgruber added a comment.

Thank you again @JonasToth for all your valueable input! I could almost 
successfully run my check on the llvm/lib subfolder. I created a compilation 
database from within Visual Studio using an extension called SourceTrail 
.
 One of the issues was the following:

  struct Object { long long value; };
  class C {
int Object;
struct Object m();
  };
  Object C::m() { return {0}; }

If I rewrite this to the following

  struct Object { long long value; };
  class C {
int Object;
struct Object m();
  };
  auto C::m() -> Object { return {0}; }

a compilation error occurs afterwards, because Object now refers to the class 
member. I discovered a similar problem colliding with the name of a function 
argument. So essentially, I believe I now require a name lookup of the return 
type (if it is unqualified) in the scope of the function. In case such a name 
already exists, i have to prefix `struct/class` or perform no replacement. I 
looked at the documentation of `ASTContext`, but it seems all the good stuff is 
in `DeclContext`, which I have not available. How can I perform a name lookup 
inside the `check` member function?

Thank you for any tips! And thank you for the `decltype` hint, I will add some 
more tests.


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[PATCH] D56160: [clang-tidy] modernize-use-trailing-return check

[Bernhard Manfred Gruber via Phabricator via cfe-commits]

bernhardmgruber added a comment.

Thank you @JonasToth for providing more feedback! I will add a few more tests 
with templates. Maybe I should even try to run the check on Boost and see what 
happens.

In the meantime I might need some help: I tried running the check on LLVM last 
weekend using the run-clang-tidy.py file. The script eventually crashed with a 
segmentation fault (after 1.5 days, running on CentOS 7, 30GiB RAM) with no 
modifications of the source tree. I ran again and exported the fixes, but 
again, python failed to merge the yaml files and crashed (probably because it 
went out of memory). After manual merging, I ran clang-apply-replacements and 
it took a while, but then I also had zero modifications on my LLVM working 
copy. clang-apply-replacements reported a few overlapping refactorings and 
missing files, but that's it. What am I doing wrong?

And btw, is there an easy way to get a compilation database on Windows?

Many thanks!




Comment at: clang-tidy/modernize/UseTrailingReturnCheck.cpp:118
+  if (Info.hasMacroDefinition()) {
+diag(F.getLocation(), Message); // CV qualifiers in macros
+return {};

JonasToth wrote:
> Please improve that comment and here I would prefer a non-trailing comment, 
> too.
> Especially formulate whats with CV and macros, the meaning has to be guessed 
> (and can be guessed wrong).
replaced by "The CV qualifiers of the return type are inside macros"



Comment at: clang-tidy/modernize/UseTrailingReturnCheck.cpp:133
+  bool ExtendedLeft = false;
+  for (size_t i = 0; i < Tokens.size(); i++) {
+// if we found the beginning of the return type, include const and volatile

JonasToth wrote:
> please use uppercase `i` and `j` names for consistency.
i considered this with respect to the style guide, but it just looked far to 
unfamiliar to me. done.



Comment at: clang-tidy/modernize/UseTrailingReturnCheck.cpp:162
+  functionDecl(unless(anyOf(hasTrailingReturn(), returns(voidType()),
+returns(autoType()), cxxConversionDecl(),
+cxxMethodDecl(isImplicit()

JonasToth wrote:
> Shouldn't you include `returns(decltypeType())` as well?
good question! i have a unit test of the form `decltype(auto) f();` and it 
seems to be already excluded by `returns(autoType())`. but i could add your 
suggestion as well to make it more explicit that (for now) we will not rewrite 
functions returning `decltype(auto)`.



Comment at: test/clang-tidy/modernize-use-trailing-return.cpp:269
+auto l1 = [](int arg) {};
+auto l2 = [](int arg) -> double {};

JonasToth wrote:
> These tests are missing the great template fun :)
> 
> Lets start with those two examples:
> 
> ```
> template 
> [[maybe_unused]] typename Container::value_type const volatile&& 
> myFunnyFunction(Container& C) noexcept;
> ```
> 
> and
> 
> ```
> #define MAYBE_UNUSED_MACRO [[maybe_unused]]
> template 
> MAYBE_UNUSED_MACRO typename Container::value_type const volatile** const 
> myFunnyFunction(Container& C) noexcept;
> ```
> 
> Its not necessarily nice code, but I am sure something like this is somewhere 
> in boost for example ;)
You remind me of Jason Turner at CppCon 2018 who said, we should pick a toy 
project, for which we are sure we can handle it, because complexity will 
manifest itself in the details. This is exactly what is happening now.

Thank you for input, I added it to my tests!


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[PATCH] D56160: [clang-tidy] modernize-use-trailing-return check

[Bernhard Manfred Gruber via Phabricator via cfe-commits]

bernhardmgruber updated this revision to Diff 182385.
bernhardmgruber marked 19 inline comments as done.
bernhardmgruber added a comment.

Addressed most of the new review comments (mainly uppercasing start of 
comments).


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Files:
  clang-tidy/modernize/CMakeLists.txt
  clang-tidy/modernize/ModernizeTidyModule.cpp
  clang-tidy/modernize/UseTrailingReturnCheck.cpp
  clang-tidy/modernize/UseTrailingReturnCheck.h
  docs/ReleaseNotes.rst
  docs/clang-tidy/checks/list.rst
  docs/clang-tidy/checks/modernize-use-trailing-return.rst
  test/clang-tidy/modernize-use-trailing-return.cpp

Index: test/clang-tidy/modernize-use-trailing-return.cpp
===
--- /dev/null
+++ test/clang-tidy/modernize-use-trailing-return.cpp
@@ -0,0 +1,283 @@
+// RUN: %check_clang_tidy %s modernize-use-trailing-return %t -- -- --std=c++14 -fdeclspec
+
+namespace std {
+template 
+class vector;
+
+class string;
+}
+
+//
+// Functions
+//
+
+int f();
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto f() -> int;{{$}}
+int f(int);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto f(int) -> int;{{$}}
+int f(int arg);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto f(int arg) -> int;{{$}}
+int f(int arg1, int arg2, int arg3);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto f(int arg1, int arg2, int arg3) -> int;{{$}}
+int f(int arg1, int arg2, int arg3, ...);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto f(int arg1, int arg2, int arg3, ...) -> int;{{$}}
+template  int f(T t);
+// CHECK-MESSAGES: :[[@LINE-1]]:27: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}template  auto f(T t) -> int;{{$}}
+
+//
+// Functions with formatting
+//
+
+int a1() { return 42; }
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto a1() -> int { return 42; }{{$}}
+int a2() {
+return 42;
+}
+// CHECK-MESSAGES: :[[@LINE-3]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto a2() -> int {{{$}}
+int a3()
+{
+return 42;
+}
+// CHECK-MESSAGES: :[[@LINE-4]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto a3() -> int{{$}}
+int a4(int   arg   )   ;
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto a4(int   arg   ) -> int   ;{{$}}
+int a5
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto a5{{$}}
+(int arg);
+// CHECK-FIXES: {{^}}(int arg) -> int;{{$}}
+
+//
+// Functions with qualifiers and specifiers
+//
+
+inline int d1(int arg);
+// CHECK-MESSAGES: :[[@LINE-1]]:12: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}inline auto d1(int arg) -> int;{{$}}
+extern "C" int d2(int arg);
+// CHECK-MESSAGES: :[[@LINE-1]]:16: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}extern "C" auto d2(int arg) -> int;{{$}}
+inline int d3(int arg) noexcept(true);
+// CHECK-MESSAGES: :[[@LINE-1]]:12: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}inline auto d3(int arg) -> int noexcept(true);{{$}}
+inline int d4(int arg) try { } catch(...) { }
+// CHECK-MESSAGES: :[[@LINE-1]]:12: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}inline auto d4(int arg) -> int try { } catch(...) { }{{$}}
+
+//
+// Functions in namespaces
+//
+
+namespace N {
+int e1();
+}
+// CHECK-MESSAGES: :[[@LINE-2]]:9: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto e1() -> int;{{$}}
+int N::e1() {}
+// CHECK-MESSAGES: :[[@LINE-1]]:8: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto N::e1() -> int {}{{$}}
+
+//
+// Functions with complex return types
+//
+
+inline volatile const std::vector e2();
+// CHECK-MESSAGES: :[[@LINE-1]]:48: warning: use a trailing return type for this function [modernize-use-trailing-ret

[PATCH] D56160: [clang-tidy] modernize-use-trailing-return check

[Bernhard Manfred Gruber via Phabricator via cfe-commits]

bernhardmgruber updated this revision to Diff 181276.
bernhardmgruber added a comment.

Skipping the check for functions which do not have a valid location. This 
occurred when I run the check on the LLVM code base. It looked like the matcher 
matched something like a built in operator.


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Files:
  clang-tidy/modernize/CMakeLists.txt
  clang-tidy/modernize/ModernizeTidyModule.cpp
  clang-tidy/modernize/UseTrailingReturnCheck.cpp
  clang-tidy/modernize/UseTrailingReturnCheck.h
  docs/ReleaseNotes.rst
  docs/clang-tidy/checks/list.rst
  docs/clang-tidy/checks/modernize-use-trailing-return.rst
  test/clang-tidy/modernize-use-trailing-return.cpp

Index: test/clang-tidy/modernize-use-trailing-return.cpp
===
--- /dev/null
+++ test/clang-tidy/modernize-use-trailing-return.cpp
@@ -0,0 +1,269 @@
+// RUN: %check_clang_tidy %s modernize-use-trailing-return %t -- -- --std=c++14 -fdeclspec
+
+namespace std {
+template 
+class vector;
+
+class string;
+}
+
+//
+// Functions
+//
+
+int f();
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto f() -> int;{{$}}
+int f(int);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto f(int) -> int;{{$}}
+int f(int arg);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto f(int arg) -> int;{{$}}
+int f(int arg1, int arg2, int arg3);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto f(int arg1, int arg2, int arg3) -> int;{{$}}
+int f(int arg1, int arg2, int arg3, ...);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto f(int arg1, int arg2, int arg3, ...) -> int;{{$}}
+template  int f(T t);
+// CHECK-MESSAGES: :[[@LINE-1]]:27: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}template  auto f(T t) -> int;{{$}}
+
+//
+// Functions with formatting
+//
+
+int a1() { return 42; }
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto a1() -> int { return 42; }{{$}}
+int a2() {
+return 42;
+}
+// CHECK-MESSAGES: :[[@LINE-3]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto a2() -> int {{{$}}
+int a3()
+{
+return 42;
+}
+// CHECK-MESSAGES: :[[@LINE-4]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto a3() -> int{{$}}
+int a4(int   arg   )   ;
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto a4(int   arg   ) -> int   ;{{$}}
+int a5
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto a5{{$}}
+(int arg);
+// CHECK-FIXES: {{^}}(int arg) -> int;{{$}}
+
+//
+// Functions with qualifiers and specifiers
+//
+
+inline int d1(int arg);
+// CHECK-MESSAGES: :[[@LINE-1]]:12: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}inline auto d1(int arg) -> int;{{$}}
+extern "C" int d2(int arg);
+// CHECK-MESSAGES: :[[@LINE-1]]:16: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}extern "C" auto d2(int arg) -> int;{{$}}
+inline int d3(int arg) noexcept(true);
+// CHECK-MESSAGES: :[[@LINE-1]]:12: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}inline auto d3(int arg) -> int noexcept(true);{{$}}
+inline int d4(int arg) try { } catch(...) { }
+// CHECK-MESSAGES: :[[@LINE-1]]:12: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}inline auto d4(int arg) -> int try { } catch(...) { }{{$}}
+
+//
+// Functions in namespaces
+//
+
+namespace N {
+int e1();
+}
+// CHECK-MESSAGES: :[[@LINE-2]]:9: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto e1() -> int;{{$}}
+int N::e1() {}
+// CHECK-MESSAGES: :[[@LINE-1]]:8: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto N::e1() -> int {}{{$}}
+
+//
+// Functions with complex return types
+//
+
+inline volatile const std::vector e2();
+// CHECK-MESSAGES: :[[@LINE-1]]:48: warning: use a 

[PATCH] D56160: [clang-tidy] modernize-use-trailing-return check

[Bernhard Manfred Gruber via Phabricator via cfe-commits]

bernhardmgruber updated this revision to Diff 181051.
bernhardmgruber added a comment.

Fixed a warning when building with gcc. Added -fdeclspec when running tests to 
let them compile on Linux as well.


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Files:
  clang-tidy/modernize/CMakeLists.txt
  clang-tidy/modernize/ModernizeTidyModule.cpp
  clang-tidy/modernize/UseTrailingReturnCheck.cpp
  clang-tidy/modernize/UseTrailingReturnCheck.h
  docs/ReleaseNotes.rst
  docs/clang-tidy/checks/list.rst
  docs/clang-tidy/checks/modernize-use-trailing-return.rst
  test/clang-tidy/modernize-use-trailing-return.cpp

Index: test/clang-tidy/modernize-use-trailing-return.cpp
===
--- /dev/null
+++ test/clang-tidy/modernize-use-trailing-return.cpp
@@ -0,0 +1,269 @@
+// RUN: %check_clang_tidy %s modernize-use-trailing-return %t -- -- --std=c++14 -fdeclspec
+
+namespace std {
+template 
+class vector;
+
+class string;
+}
+
+//
+// Functions
+//
+
+int f();
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto f() -> int;{{$}}
+int f(int);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto f(int) -> int;{{$}}
+int f(int arg);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto f(int arg) -> int;{{$}}
+int f(int arg1, int arg2, int arg3);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto f(int arg1, int arg2, int arg3) -> int;{{$}}
+int f(int arg1, int arg2, int arg3, ...);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto f(int arg1, int arg2, int arg3, ...) -> int;{{$}}
+template  int f(T t);
+// CHECK-MESSAGES: :[[@LINE-1]]:27: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}template  auto f(T t) -> int;{{$}}
+
+//
+// Functions with formatting
+//
+
+int a1() { return 42; }
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto a1() -> int { return 42; }{{$}}
+int a2() {
+return 42;
+}
+// CHECK-MESSAGES: :[[@LINE-3]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto a2() -> int {{{$}}
+int a3()
+{
+return 42;
+}
+// CHECK-MESSAGES: :[[@LINE-4]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto a3() -> int{{$}}
+int a4(int   arg   )   ;
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto a4(int   arg   ) -> int   ;{{$}}
+int a5
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto a5{{$}}
+(int arg);
+// CHECK-FIXES: {{^}}(int arg) -> int;{{$}}
+
+//
+// Functions with qualifiers and specifiers
+//
+
+inline int d1(int arg);
+// CHECK-MESSAGES: :[[@LINE-1]]:12: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}inline auto d1(int arg) -> int;{{$}}
+extern "C" int d2(int arg);
+// CHECK-MESSAGES: :[[@LINE-1]]:16: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}extern "C" auto d2(int arg) -> int;{{$}}
+inline int d3(int arg) noexcept(true);
+// CHECK-MESSAGES: :[[@LINE-1]]:12: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}inline auto d3(int arg) -> int noexcept(true);{{$}}
+inline int d4(int arg) try { } catch(...) { }
+// CHECK-MESSAGES: :[[@LINE-1]]:12: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}inline auto d4(int arg) -> int try { } catch(...) { }{{$}}
+
+//
+// Functions in namespaces
+//
+
+namespace N {
+int e1();
+}
+// CHECK-MESSAGES: :[[@LINE-2]]:9: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto e1() -> int;{{$}}
+int N::e1() {}
+// CHECK-MESSAGES: :[[@LINE-1]]:8: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto N::e1() -> int {}{{$}}
+
+//
+// Functions with complex return types
+//
+
+inline volatile const std::vector e2();
+// CHECK-MESSAGES: :[[@LINE-1]]:48: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXE

[PATCH] D56160: [clang-tidy] modernize-use-trailing-return check

[Bernhard Manfred Gruber via Phabricator via cfe-commits]

bernhardmgruber updated this revision to Diff 181015.
bernhardmgruber added a comment.

rebased on current master (there was a conflict in the release notes)


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Files:
  clang-tidy/modernize/CMakeLists.txt
  clang-tidy/modernize/ModernizeTidyModule.cpp
  clang-tidy/modernize/UseTrailingReturnCheck.cpp
  clang-tidy/modernize/UseTrailingReturnCheck.h
  docs/ReleaseNotes.rst
  docs/clang-tidy/checks/list.rst
  docs/clang-tidy/checks/modernize-use-trailing-return.rst
  test/clang-tidy/modernize-use-trailing-return.cpp

Index: test/clang-tidy/modernize-use-trailing-return.cpp
===
--- /dev/null
+++ test/clang-tidy/modernize-use-trailing-return.cpp
@@ -0,0 +1,269 @@
+// RUN: %check_clang_tidy %s modernize-use-trailing-return %t -- -- --std=c++14
+
+namespace std {
+template 
+class vector;
+
+class string;
+}
+
+//
+// Functions
+//
+
+int f();
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto f() -> int;{{$}}
+int f(int);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto f(int) -> int;{{$}}
+int f(int arg);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto f(int arg) -> int;{{$}}
+int f(int arg1, int arg2, int arg3);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto f(int arg1, int arg2, int arg3) -> int;{{$}}
+int f(int arg1, int arg2, int arg3, ...);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto f(int arg1, int arg2, int arg3, ...) -> int;{{$}}
+template  int f(T t);
+// CHECK-MESSAGES: :[[@LINE-1]]:27: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}template  auto f(T t) -> int;{{$}}
+
+//
+// Functions with formatting
+//
+
+int a1() { return 42; }
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto a1() -> int { return 42; }{{$}}
+int a2() {
+return 42;
+}
+// CHECK-MESSAGES: :[[@LINE-3]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto a2() -> int {{{$}}
+int a3()
+{
+return 42;
+}
+// CHECK-MESSAGES: :[[@LINE-4]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto a3() -> int{{$}}
+int a4(int   arg   )   ;
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto a4(int   arg   ) -> int   ;{{$}}
+int a5
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto a5{{$}}
+(int arg);
+// CHECK-FIXES: {{^}}(int arg) -> int;{{$}}
+
+//
+// Functions with qualifiers and specifiers
+//
+
+inline int d1(int arg);
+// CHECK-MESSAGES: :[[@LINE-1]]:12: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}inline auto d1(int arg) -> int;{{$}}
+extern "C" int d2(int arg);
+// CHECK-MESSAGES: :[[@LINE-1]]:16: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}extern "C" auto d2(int arg) -> int;{{$}}
+inline int d3(int arg) noexcept(true);
+// CHECK-MESSAGES: :[[@LINE-1]]:12: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}inline auto d3(int arg) -> int noexcept(true);{{$}}
+inline int d4(int arg) try { } catch(...) { }
+// CHECK-MESSAGES: :[[@LINE-1]]:12: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}inline auto d4(int arg) -> int try { } catch(...) { }{{$}}
+
+//
+// Functions in namespaces
+//
+
+namespace N {
+int e1();
+}
+// CHECK-MESSAGES: :[[@LINE-2]]:9: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto e1() -> int;{{$}}
+int N::e1() {}
+// CHECK-MESSAGES: :[[@LINE-1]]:8: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto N::e1() -> int {}{{$}}
+
+//
+// Functions with complex return types
+//
+
+inline volatile const std::vector e2();
+// CHECK-MESSAGES: :[[@LINE-1]]:48: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}inline auto e2() -> volatile const std::vector;{

[PATCH] D56160: [clang-tidy] modernize-use-trailing-return check

[Bernhard Manfred Gruber via Phabricator via cfe-commits]

bernhardmgruber added a comment.

I am satisfied with the proposed feature set for now. I will try to run the 
check on LLVM itself in the next days as a final test. Are there anymore 
feature requests or changes from your sides?


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[PATCH] D56160: [clang-tidy] modernize-use-trailing-return check

[Bernhard Manfred Gruber via Phabricator via cfe-commits]

bernhardmgruber added inline comments.



Comment at: clang-tidy/modernize/UseTrailingReturnCheck.cpp:45
+std::string(Message) +
+" (no FixIt provided, function argument list end is inside 
macro)");
+return {};

Eugene.Zelenko wrote:
> MyDeveloperDay wrote:
> > bernhardmgruber wrote:
> > > JonasToth wrote:
> > > > I think you can ellide that extra message. Not emitting the fixit is 
> > > > clear already.
> > > I actually like having a reason why my check could not provide a FixIt. 
> > > Especially because there are multiple reasons why this might happen.
> > @bernhardmgruber I had the same comment given to me on a review recently 
> > with regard to diag message, let me try and help you with what I though was 
> > the rational... I think the premise is something like:
> > 
> > 1) "no FixIt provided" is implied by the fact it isn't fixed
> > 2) "function type source info is missing"  doesn't tell the developer what 
> > they have to do to have it be fixed
> > 
> > sure it helps you as the checker developer but probably that isn't much use 
> > to a developer using the checker on their code and so might confuse them.
> > 
> > It also makes grepping for messages in a log file difficult because it 
> > means multiple messages coming from your checker have a different pattern 
> > (although there might be a common sub pattern)
> > 
> > For the most part where a fixit is not supplied where it should someone 
> > would create a test case which you could consume in your tests
> > 
> > To be honest as a general observation as a newbie myself, what I've noticed 
> > is that a lot of checker review comments are very similar, 
> > 
> > 
> > 
> >   - 80 characters in rst files
> >   - clang-format
> >   - alphabetic order
> >   - Comments with proper puncuation
> >   - code in comments in ``XXX``
> >   - don't overly use auto
> >   - don't use anonymous namespace functions use static functions
> >   - run it on a big C++ project
> >   - run it over all of LLVM
> >   - consistency of coding style (elide unnecessary const)
> >   - elide unnecessary braces/brackets/code/etc..
> > 
> > 
> > 
> > We really should try and write a "Writing a clang checker, and getting it 
> > though review" primer, because I really feel for these "gaints" that we ask 
> > to review all this code, they must go over the same thing and have to 
> > present the same reasons time and time again...
> > 
> > which is why If you don't mind I'd like to try to help give something back 
> > by filling in some of the reasoning gaps here to a fellow new starter
> > 
> > 
> > 
> > 
> > 
> > 
> > 
> > 
> I would say that we should eat own dog food :-)
> 
> I'd love to see your documentation validation scripts as part of build!
> 
> We also should regularly run Clang-tidy on BuildBot. But first we must fix 
> existing warnings and no everybody happy if such cleanups performed by 
> outsiders.
> 
> See PR27267 for anonymous namespaces usage.
> 
> Clang-tidy has modernize-use-auto, but not check for LLVM guidelines 
> conformance.
> 
> Braces should be checked by readability-braces-around-statements, but proper 
> setup is needed.
> 
> Conformance to readability-else-after-return is another typical newbies 
> problem.
Thank you @MyDeveloperDay for the list of tips and rational behind the 
diagnostic messages. I will check this list in the future before I send new 
patches. Maybe it is really a good idea to put this list somewhere!



Comment at: test/clang-tidy/modernize-use-trailing-return.cpp:1
+// RUN: %check_clang_tidy %s modernize-use-trailing-return %t -- -- --std=c++14
+

MyDeveloperDay wrote:
> bernhardmgruber wrote:
> > MyDeveloperDay wrote:
> > > nit: is there a reason here why you say C++14 when the code checks for 
> > > C++11? 
> > Yes. The tests contain functions with deduced return types, such as `auto 
> > f();`. Those require C++14. The check itself is fine with C++11.
> I kind of half guessed it would be something like that after I hit submit,  I 
> noticed some checks add secondary test files which test the various versions 
> of C++, to be honest I found this useful for the checker I'm developing, 
> especially as the checker has some slightly different behavior with C++11 to 
> C++17, but maybe yours doesn't
> 
> to be honest i'm also fairly new here so don't know exactly the convention
> 
> examples where this is already done in other peoples checkers
> 
> modernize-deprecated-headers-cxx03.cpp
> modernize-deprecated-headers-cxx11.cpp
> 
> ```
> // RUN: %check_clang_tidy %s modernize-deprecated-headers %t -- 
> -extra-arg-before=-isystem%S/Inputs/modernize-deprecated-headers -- 
> -std=c++03 -v
> 
> // RUN: %check_clang_tidy %s modernize-deprecated-headers %t -- 
> -extra-arg-before=-isystem%S/Inputs/modernize-deprecated-headers -- 
> -std=c++11 -v
> 
> ```
> 
Thank you for the hint! I just split my tests into C++11 and C++14 versions, 
but then I r

[PATCH] D56160: [clang-tidy] modernize-use-trailing-return check

[Bernhard Manfred Gruber via Phabricator via cfe-commits]

bernhardmgruber updated this revision to Diff 180973.
bernhardmgruber marked 8 inline comments as done.
bernhardmgruber added a comment.

- Removed detailed diagnostic messages why FixIts could not be generated
- Excluded functions returning member pointers for now
- All tests run now


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Files:
  clang-tidy/modernize/CMakeLists.txt
  clang-tidy/modernize/ModernizeTidyModule.cpp
  clang-tidy/modernize/UseTrailingReturnCheck.cpp
  clang-tidy/modernize/UseTrailingReturnCheck.h
  docs/ReleaseNotes.rst
  docs/clang-tidy/checks/list.rst
  docs/clang-tidy/checks/modernize-use-trailing-return.rst
  test/clang-tidy/modernize-use-trailing-return.cpp

Index: test/clang-tidy/modernize-use-trailing-return.cpp
===
--- /dev/null
+++ test/clang-tidy/modernize-use-trailing-return.cpp
@@ -0,0 +1,269 @@
+// RUN: %check_clang_tidy %s modernize-use-trailing-return %t -- -- --std=c++14
+
+namespace std {
+template 
+class vector;
+
+class string;
+}
+
+//
+// Functions
+//
+
+int f();
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto f() -> int;{{$}}
+int f(int);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto f(int) -> int;{{$}}
+int f(int arg);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto f(int arg) -> int;{{$}}
+int f(int arg1, int arg2, int arg3);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto f(int arg1, int arg2, int arg3) -> int;{{$}}
+int f(int arg1, int arg2, int arg3, ...);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto f(int arg1, int arg2, int arg3, ...) -> int;{{$}}
+template  int f(T t);
+// CHECK-MESSAGES: :[[@LINE-1]]:27: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}template  auto f(T t) -> int;{{$}}
+
+//
+// Functions with formatting
+//
+
+int a1() { return 42; }
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto a1() -> int { return 42; }{{$}}
+int a2() {
+return 42;
+}
+// CHECK-MESSAGES: :[[@LINE-3]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto a2() -> int {{{$}}
+int a3()
+{
+return 42;
+}
+// CHECK-MESSAGES: :[[@LINE-4]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto a3() -> int{{$}}
+int a4(int   arg   )   ;
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto a4(int   arg   ) -> int   ;{{$}}
+int a5
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto a5{{$}}
+(int arg);
+// CHECK-FIXES: {{^}}(int arg) -> int;{{$}}
+
+//
+// Functions with qualifiers and specifiers
+//
+
+inline int d1(int arg);
+// CHECK-MESSAGES: :[[@LINE-1]]:12: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}inline auto d1(int arg) -> int;{{$}}
+extern "C" int d2(int arg);
+// CHECK-MESSAGES: :[[@LINE-1]]:16: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}extern "C" auto d2(int arg) -> int;{{$}}
+inline int d3(int arg) noexcept(true);
+// CHECK-MESSAGES: :[[@LINE-1]]:12: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}inline auto d3(int arg) -> int noexcept(true);{{$}}
+inline int d4(int arg) try { } catch(...) { }
+// CHECK-MESSAGES: :[[@LINE-1]]:12: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}inline auto d4(int arg) -> int try { } catch(...) { }{{$}}
+
+//
+// Functions in namespaces
+//
+
+namespace N {
+int e1();
+}
+// CHECK-MESSAGES: :[[@LINE-2]]:9: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto e1() -> int;{{$}}
+int N::e1() {}
+// CHECK-MESSAGES: :[[@LINE-1]]:8: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto N::e1() -> int {}{{$}}
+
+//
+// Functions with complex return types
+//
+
+inline volatile const std::vector e2();
+// CHECK-MESSAGES: :[[@LINE-1]]:48: warning: use a trailing retu

[PATCH] D56160: [clang-tidy] modernize-use-trailing-return check

[Bernhard Manfred Gruber via Phabricator via cfe-commits]

bernhardmgruber marked an inline comment as done.
bernhardmgruber added a comment.

I spent some time now to get member pointers as return values working and I am 
afraid but it seems there is a problem with the clang AST. Given the following 
code in my check (where `F` is a `FunctionDecl`):

  const TypeSourceInfo *TSI = F.getTypeSourceInfo();
  const FunctionTypeLoc FTL = 
TSI->getTypeLoc().IgnoreParens().getAs();
  auto rl = FTL.getReturnLoc();
  rl.getSourceRange().dump(SM);
  rl.getLocalSourceRange().dump(SM);
  rl.castAs().getSourceRange().dump(SM);
  rl.castAs().getLocalSourceRange().dump(SM);
  rl.castAs().getBeginLoc().dump(SM);
  rl.castAs().getStarLoc().dump(SM);

with the following input:

  namespace std {
  template 
  class vector;
  
  class string;
  }
  
  int std::vector::* e6();
  }

yields these source locations:

  <...\aa.cpp:8:1, col:5>
  <...\aa.cpp:8:5>
  <...\aa.cpp:8:1, col:5>
  <...\aa.cpp:8:5>
  ...\aa.cpp:8:1
  ...\aa.cpp:8:5

The first is the value I usually obtain via `F.getReturnTypeSourceRange()`. The 
following lines are what I saw in my debugger when I stepped into the 
implementation. I believe that `getStarLoc()` should point at the asterisk at 
column 31, not at std at column 5.

I did not find an easy workaround and I would like to avoid manual lexing 
because of the interference with macros. For now, I will just disable the check 
for member pointers.


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[PATCH] D56160: [clang-tidy] modernize-use-trailing-return check

[Bernhard Manfred Gruber via Phabricator via cfe-commits]

bernhardmgruber marked 2 inline comments as done.
bernhardmgruber added inline comments.



Comment at: test/clang-tidy/modernize-use-trailing-return.cpp:1
+// RUN: %check_clang_tidy %s modernize-use-trailing-return %t -- -- --std=c++14
+

MyDeveloperDay wrote:
> nit: is there a reason here why you say C++14 when the code checks for C++11? 
Yes. The tests contain functions with deduced return types, such as `auto 
f();`. Those require C++14. The check itself is fine with C++11.


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[PATCH] D56160: [clang-tidy] modernize-use-trailing-return check

[Bernhard Manfred Gruber via Phabricator via cfe-commits]

bernhardmgruber added a comment.

@JonasToth Do you really think I should drop the extra information on why I 
could not provide a FixIt? If truly yes, than I would like to keep them as 
comments.


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[PATCH] D56160: [clang-tidy] modernize-use-trailing-return check

[Bernhard Manfred Gruber via Phabricator via cfe-commits]

bernhardmgruber added inline comments.



Comment at: clang-tidy/modernize/UseTrailingReturnCheck.cpp:33
+  const TypeSourceInfo *TSI = F.getTypeSourceInfo();
+  assert(TSI);
+  const FunctionTypeLoc FTL =

JonasToth wrote:
> Please add an error-msg to the assertion like `assert(TSI && "Reason why this 
> must hold");`. Humanreadable for debugging.
I replaced the asserts by an error with a message. Honestly, I do not know when 
these might be nullptr. It just never occured during my tests.



Comment at: clang-tidy/modernize/UseTrailingReturnCheck.cpp:38
+
+  // if the function argument list ends inside of a macro, it is dangerous to
+  // start lexing from here, bail out

JonasToth wrote:
> Please make that comment (and all comments in general) full grammatical 
> sentence with correct punctuation.
I am not a native English speaker, but the only thing that might be odd about 
this sentence is that `, bail out`. Maybe a em-dash is what we need here, but 
this not Latex. Oh yes, and inside of a macro is also weird.

I will make it: if the function argument list ends inside a macro, it is 
dangerous to start lexing from here - bail out.

I will also add dots at the end of sentences, other checks seem to follow this 
convention (Personally, I do not like the punctuation at the end, as it does 
not add significant information)



Comment at: clang-tidy/modernize/UseTrailingReturnCheck.cpp:42
+  if (ClosingParen.isMacroID()) {
+diag(
+F.getLocation(),

JonasToth wrote:
> weird formatting, did clang-format do that?
I use the latest version of Visual Studio and it picks up .clang-format files 
and formats automatically when I save. I can try to run clang-format by hand.



Comment at: clang-tidy/modernize/UseTrailingReturnCheck.cpp:45
+std::string(Message) +
+" (no FixIt provided, function argument list end is inside 
macro)");
+return {};

JonasToth wrote:
> I think you can ellide that extra message. Not emitting the fixit is clear 
> already.
I actually like having a reason why my check could not provide a FixIt. 
Especially because there are multiple reasons why this might happen.



Comment at: clang-tidy/modernize/UseTrailingReturnCheck.cpp:46
+" (no FixIt provided, function argument list end is inside 
macro)");
+return {};
+  }

JonasToth wrote:
> Indiciator to use `llvm::Optional` as return type instead. What do you think?
I absolutely agree that optional is a great type. But SourceLocation has a 
sentinel/empty value, which can be queried using `Valid()/Invalid()`. 
SourceLocation has the optionality built in so to speak. I have also seen other 
checks using a default constructed source location to indicate no result. Using 
optional would make the function interface more clear, but then we could have 
the weird case of an initialized optional containing an invalid source 
location. I would like to leave it as it is.



Comment at: clang-tidy/modernize/UseTrailingReturnCheck.cpp:53
+  // skip subsequent CV and ref qualifiers
+  const std::pair Loc = SM.getDecomposedLoc(Result);
+  const StringRef File = SM.getBufferData(Loc.first);

JonasToth wrote:
> Values are usually not `const`'ed. Please change that for consistency.
I do not agree to have something mutable, that should not change. Especially, 
now that everything else around is const, I would be suspicious why the writer 
had not put a const here and where the variable is modified after its 
initialization. But if you require it for consistency, I can remove it.



Comment at: clang-tidy/modernize/UseTrailingReturnCheck.cpp:67
+
+if (T.is(tok::amp) || T.is(tok::ampamp) || T.is(tok::kw_const) ||
+T.is(tok::kw_volatile)) {

JonasToth wrote:
> why are pointers not relevant here?
> There should be `Token.oneOf()` or `Token.isOneOf()` or similar for this 
> usecase
I am lexing CV and ref qualifiers after the closing parenthesis of a function's 
argument list (i.e. a member function then). I do not know what you mean with 
pointers here. An asterisk cannot appear as a qualifier on a method AFAIK.

Thanks for the tip!



Comment at: clang-tidy/modernize/UseTrailingReturnCheck.cpp:173
+
+  if (F->getDeclaredReturnType()->isFunctionPointerType()) {
+diag(F->getLocation(), std::string(Message) +

JonasToth wrote:
> What about data-pointer-member types? 
> (https://en.cppreference.com/w/cpp/language/pointer point 2))
> Its an uncommon construct, but better catch it here instead of bug-reports.
Those are fine, because they do not span space before and behind the function 
name and argument list when declaring them. But member function pointer types 
also needed to be excluded. Thank you for leading me to this test case!

Edit: I just found out

[PATCH] D56160: [clang-tidy] modernize-use-trailing-return check

[Bernhard Manfred Gruber via Phabricator via cfe-commits]

bernhardmgruber updated this revision to Diff 180596.
bernhardmgruber marked 31 inline comments as done.
bernhardmgruber added a comment.

Fixed most of the issues pointed out by @JonasToth and added a few more tests. 
The tests with data member pointers currently fail and I will investiage this.


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Files:
  clang-tidy/modernize/CMakeLists.txt
  clang-tidy/modernize/ModernizeTidyModule.cpp
  clang-tidy/modernize/UseTrailingReturnCheck.cpp
  clang-tidy/modernize/UseTrailingReturnCheck.h
  docs/ReleaseNotes.rst
  docs/clang-tidy/checks/list.rst
  docs/clang-tidy/checks/modernize-use-trailing-return.rst
  test/clang-tidy/modernize-use-trailing-return.cpp

Index: test/clang-tidy/modernize-use-trailing-return.cpp
===
--- /dev/null
+++ test/clang-tidy/modernize-use-trailing-return.cpp
@@ -0,0 +1,271 @@
+// RUN: %check_clang_tidy %s modernize-use-trailing-return %t -- -- --std=c++14
+
+namespace std {
+template 
+class vector;
+
+class string;
+}
+
+//
+// Functions
+//
+
+int f();
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto f() -> int;{{$}}
+int f(int);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto f(int) -> int;{{$}}
+int f(int arg);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto f(int arg) -> int;{{$}}
+int f(int arg1, int arg2, int arg3);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto f(int arg1, int arg2, int arg3) -> int;{{$}}
+int f(int arg1, int arg2, int arg3, ...);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto f(int arg1, int arg2, int arg3, ...) -> int;{{$}}
+template  int f(T t);
+// CHECK-MESSAGES: :[[@LINE-1]]:27: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}template  auto f(T t) -> int;{{$}}
+
+//
+// Functions with formatting
+//
+
+int a1() { return 42; }
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto a1() -> int { return 42; }{{$}}
+int a2() {
+return 42;
+}
+// CHECK-MESSAGES: :[[@LINE-3]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto a2() -> int {{{$}}
+int a3()
+{
+return 42;
+}
+// CHECK-MESSAGES: :[[@LINE-4]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto a3() -> int{{$}}
+int a4(int   arg   )   ;
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto a4(int   arg   ) -> int   ;{{$}}
+int a5
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto a5{{$}}
+(int arg);
+// CHECK-FIXES: {{^}}(int arg) -> int;{{$}}
+
+//
+// Functions with qualifiers and specifiers
+//
+
+inline int d1(int arg);
+// CHECK-MESSAGES: :[[@LINE-1]]:12: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}inline auto d1(int arg) -> int;{{$}}
+extern "C" int d2(int arg);
+// CHECK-MESSAGES: :[[@LINE-1]]:16: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}extern "C" auto d2(int arg) -> int;{{$}}
+inline int d3(int arg) noexcept(true);
+// CHECK-MESSAGES: :[[@LINE-1]]:12: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}inline auto d3(int arg) -> int noexcept(true);{{$}}
+inline int d4(int arg) try { } catch(...) { }
+// CHECK-MESSAGES: :[[@LINE-1]]:12: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}inline auto d4(int arg) -> int try { } catch(...) { }{{$}}
+
+//
+// Functions in namespaces
+//
+
+namespace N {
+int e1();
+}
+// CHECK-MESSAGES: :[[@LINE-2]]:10: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto e1() -> int;{{$}}
+int N::e1() {}
+// CHECK-MESSAGES: :[[@LINE-1]]:9: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto N::e1() -> int {}{{$}}
+
+//
+// Functions with complex return types
+//
+
+inline volatile const std::vector e2();
+// CHECK-MESSAGES: :[[@LINE-1]]:48: warning: use a 

[PATCH] D56160: [clang-tidy] modernize-use-trailing-return check

[Bernhard Manfred Gruber via Phabricator via cfe-commits]

bernhardmgruber marked 4 inline comments as done.
bernhardmgruber added inline comments.



Comment at: test/clang-tidy/modernize-use-trailing-return.cpp:173
+auto l1 = [](int arg) {};
+auto l2 = [](int arg) -> double {};

JonasToth wrote:
> you could figure out the return type of the lambda if it contains a return, 
> otherwise it should be `void`.
I am sorry, but I do not understand what you want. Lambdas have trailing return 
types by default (if it is not left out and deduced). Do you want to 
explicitely generate the deduced return type? This is not what I intended. I 
want to rewrite old return types on the left to be trailing.


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[PATCH] D56160: [clang-tidy] modernize-use-trailing-return check

[Bernhard Manfred Gruber via Phabricator via cfe-commits]

bernhardmgruber updated this revision to Diff 180419.
bernhardmgruber added a comment.

Big thank you to @JonasToth for providing some macro test cases. I played a bit 
with macros and settled on the following behavior:

- if the closing parenthesis of the function is inside a macro, no FixIt will 
be created (I cannot relyably lex for subsequent CV and ref qualifiers and 
maybe we do not want to make changes in macros)
- if the return type is not CV qualified, i allow macros to be part of it 
because no lexing is required
- if the return type is CV qualified and contains macros, I provide no FixIt

I improved findTrailingReturnTypeSourceLocation() by discovering 
FunctionTypeLoc::getRParenLoc(). I still require some lexing for CV and ref 
qualifiers though.

I tried to improve findReturnTypeAndCVSourceRange() by finding a way to get the 
source range directly from the AST, but it seems the AST does not store source 
locations for CV qualifiers of types. I read that in the docs for 
QualifiedTypeLoc 
. 
So it seems I cannot circumvent finding the locations of const and volatile by 
my own.


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Files:
  clang-tidy/modernize/CMakeLists.txt
  clang-tidy/modernize/ModernizeTidyModule.cpp
  clang-tidy/modernize/UseTrailingReturnCheck.cpp
  clang-tidy/modernize/UseTrailingReturnCheck.h
  docs/ReleaseNotes.rst
  docs/clang-tidy/checks/list.rst
  docs/clang-tidy/checks/modernize-use-trailing-return.rst
  test/clang-tidy/modernize-use-trailing-return.cpp

Index: test/clang-tidy/modernize-use-trailing-return.cpp
===
--- /dev/null
+++ test/clang-tidy/modernize-use-trailing-return.cpp
@@ -0,0 +1,253 @@
+// RUN: %check_clang_tidy %s modernize-use-trailing-return %t -- -- --std=c++14
+
+namespace std {
+template 
+class vector;
+
+class string;
+}
+
+//
+// Functions
+//
+
+int f();
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto f() -> int;{{$}}
+int f(int);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto f(int) -> int;{{$}}
+int f(int arg);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto f(int arg) -> int;{{$}}
+int f(int arg1, int arg2, int arg3);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto f(int arg1, int arg2, int arg3) -> int;{{$}}
+int f(int arg1, int arg2, int arg3, ...);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto f(int arg1, int arg2, int arg3, ...) -> int;{{$}}
+template  int f(T t);
+// CHECK-MESSAGES: :[[@LINE-1]]:27: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}template  auto f(T t) -> int;{{$}}
+
+//
+// Functions with formatting
+//
+
+int a1() { return 42; }
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto a1() -> int { return 42; }{{$}}
+int a2() {
+return 42;
+}
+// CHECK-MESSAGES: :[[@LINE-3]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto a2() -> int {{{$}}
+int a3()
+{
+return 42;
+}
+// CHECK-MESSAGES: :[[@LINE-4]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto a3() -> int{{$}}
+int a4(int   arg   )   ;
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto a4(int   arg   ) -> int   ;{{$}}
+int a5
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto a5{{$}}
+(int arg);
+// CHECK-FIXES: {{^}}(int arg) -> int;{{$}}
+
+//
+// Functions with qualifiers and specifiers
+//
+
+inline int d1(int arg);
+// CHECK-MESSAGES: :[[@LINE-1]]:12: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}inline auto d1(int arg) -> int;{{$}}
+extern "C" int d2(int arg);
+// CHECK-MESSAGES: :[[@LINE-1]]:16: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}extern "C" auto d2(int arg) -> int;{{$}}
+inline int d3(int arg) noexcept(true);
+// CHECK-MESSAGES: :[[@LINE-1]]:12: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {

[PATCH] D56160: [clang-tidy] modernize-use-trailing-return check

[Bernhard Manfred Gruber via Phabricator via cfe-commits]

bernhardmgruber updated this revision to Diff 179986.
bernhardmgruber added a comment.

rebased from release_70 onto master


CHANGES SINCE LAST ACTION
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Files:
  clang-tidy/modernize/CMakeLists.txt
  clang-tidy/modernize/ModernizeTidyModule.cpp
  clang-tidy/modernize/UseTrailingReturnCheck.cpp
  clang-tidy/modernize/UseTrailingReturnCheck.h
  docs/ReleaseNotes.rst
  docs/clang-tidy/checks/list.rst
  docs/clang-tidy/checks/modernize-use-trailing-return.rst
  test/clang-tidy/modernize-use-trailing-return.cpp

Index: test/clang-tidy/modernize-use-trailing-return.cpp
===
--- /dev/null
+++ test/clang-tidy/modernize-use-trailing-return.cpp
@@ -0,0 +1,173 @@
+// RUN: %check_clang_tidy %s modernize-use-trailing-return %t -- -- --std=c++14
+
+namespace std {
+template 
+class vector;
+
+class string;
+}
+
+//
+// Samples triggering the check
+//
+
+int f();
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto f() -> int;{{$}}
+int f(int);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto f(int) -> int;{{$}}
+int f(int arg);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto f(int arg) -> int;{{$}}
+int f(int arg1, int arg2, int arg3);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto f(int arg1, int arg2, int arg3) -> int;{{$}}
+int f(int arg1, int arg2, int arg3, ...);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto f(int arg1, int arg2, int arg3, ...) -> int;{{$}}
+template  int f(T t);
+// CHECK-MESSAGES: :[[@LINE-1]]:27: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}template  auto f(T t) -> int;{{$}}
+int a1() { return 42; }
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto a1() -> int { return 42; }{{$}}
+int a2() {
+return 42;
+}
+// CHECK-MESSAGES: :[[@LINE-3]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto a2() -> int {{{$}}
+int a3()
+{
+return 42;
+}
+// CHECK-MESSAGES: :[[@LINE-4]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto a3() -> int{{$}}
+int b1(int   arg   )   ;
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto b1(int   arg   ) -> int   ;{{$}}
+int b2
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto b2{{$}}
+(int arg);
+// CHECK-FIXES: {{^}}(int arg) -> int;{{$}}
+inline int d1(int arg);
+// CHECK-MESSAGES: :[[@LINE-1]]:12: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}inline auto d1(int arg) -> int;{{$}}
+inline int d2(int arg) noexcept(true);
+// CHECK-MESSAGES: :[[@LINE-1]]:12: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}inline auto d2(int arg) -> int noexcept(true);{{$}}
+inline int d3(int arg) try { } catch(...) { }
+// CHECK-MESSAGES: :[[@LINE-1]]:12: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}inline auto d3(int arg) -> int try { } catch(...) { }{{$}}
+namespace N {
+bool e1();
+}
+// CHECK-MESSAGES: :[[@LINE-2]]:10: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto e1() -> bool;{{$}}
+inline volatile const std::vector e2();
+// CHECK-MESSAGES: :[[@LINE-1]]:48: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}inline auto e2() -> volatile const std::vector;{{$}}
+inline const std::vector volatile e2();
+// CHECK-MESSAGES: :[[@LINE-1]]:48: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}inline auto e2() -> const std::vector volatile;{{$}}
+inline std::vector const volatile e2();
+// CHECK-MESSAGES: :[[@LINE-1]]:48: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}inline auto e2() -> std::vector const volatile;{{$}}
+bool N::e1() {}
+// CHECK-MESSAGES: :[[@LINE-1]]:9: warning: use a trailing return type for this function [modernize-use-t

[PATCH] D56160: [clang-tidy] modernize-use-trailing-return check

[Bernhard Manfred Gruber via Phabricator via cfe-commits]

bernhardmgruber marked 2 inline comments as done.
bernhardmgruber added inline comments.



Comment at: test/clang-tidy/modernize-use-trailing-return.cpp:2
+// RUN: %check_clang_tidy %s modernize-use-trailing-return %t -- -- --std=c++14
+
+namespace std {

aaron.ballman wrote:
> lebedev.ri wrote:
> > Missing test coverage:
> > * macros
> > * is there tests for implicit functions?
> > * Out-of-line function with body.
> Also:
>   * functions with attributes in the type position `int f() [[]];`
>   * functions without attributes in the type position `[[]] int f();` and 
> `int f [[]] ();`
>   * lambdas?
>   * Special functions without return types, like constructors and destructors
>   * Conversion operators. `struct S {  operator int() const; };`
@lebedev.ri: I do not understand what kind of tests I should write for macros. 
Do you mean to rewrite functions inside macro definitions as well?

like rewriting
```
#define DEFINE_F int f();
```
into

```
#define DEFINE_F auto f() -> int;
```

Apart from that, I believe a lot of difficult trickery can be done with macros 
and I am fine without supporting those (i.e. omitting a possible rewrite, 
erroneus replacements should never happen). Can you come up with a particular 
example you would like to be rewritten?


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[PATCH] D56160: [clang-tidy] modernize-use-trailing-return check

[Bernhard Manfred Gruber via Phabricator via cfe-commits]

bernhardmgruber updated this revision to Diff 179961.
bernhardmgruber added a comment.

added more test cases, allowing check to run on out-of-line definitions and 
updated docs.


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Files:
  clang-tidy/modernize/CMakeLists.txt
  clang-tidy/modernize/ModernizeTidyModule.cpp
  clang-tidy/modernize/UseTrailingReturnCheck.cpp
  clang-tidy/modernize/UseTrailingReturnCheck.h
  docs/ReleaseNotes.rst
  docs/clang-tidy/checks/list.rst
  docs/clang-tidy/checks/modernize-use-trailing-return.rst
  test/clang-tidy/modernize-use-trailing-return.cpp

Index: test/clang-tidy/modernize-use-trailing-return.cpp
===
--- /dev/null
+++ test/clang-tidy/modernize-use-trailing-return.cpp
@@ -0,0 +1,173 @@
+// RUN: %check_clang_tidy %s modernize-use-trailing-return %t -- -- --std=c++14
+
+namespace std {
+template 
+class vector;
+
+class string;
+}
+
+//
+// Samples triggering the check
+//
+
+int f();
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto f() -> int;{{$}}
+int f(int);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto f(int) -> int;{{$}}
+int f(int arg);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto f(int arg) -> int;{{$}}
+int f(int arg1, int arg2, int arg3);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto f(int arg1, int arg2, int arg3) -> int;{{$}}
+int f(int arg1, int arg2, int arg3, ...);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto f(int arg1, int arg2, int arg3, ...) -> int;{{$}}
+template  int f(T t);
+// CHECK-MESSAGES: :[[@LINE-1]]:27: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}template  auto f(T t) -> int;{{$}}
+int a1() { return 42; }
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto a1() -> int { return 42; }{{$}}
+int a2() {
+return 42;
+}
+// CHECK-MESSAGES: :[[@LINE-3]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto a2() -> int {{{$}}
+int a3()
+{
+return 42;
+}
+// CHECK-MESSAGES: :[[@LINE-4]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto a3() -> int{{$}}
+int b1(int   arg   )   ;
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto b1(int   arg   ) -> int   ;{{$}}
+int b2
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto b2{{$}}
+(int arg);
+// CHECK-FIXES: {{^}}(int arg) -> int;{{$}}
+inline int d1(int arg);
+// CHECK-MESSAGES: :[[@LINE-1]]:12: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}inline auto d1(int arg) -> int;{{$}}
+inline int d2(int arg) noexcept(true);
+// CHECK-MESSAGES: :[[@LINE-1]]:12: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}inline auto d2(int arg) -> int noexcept(true);{{$}}
+inline int d3(int arg) try { } catch(...) { }
+// CHECK-MESSAGES: :[[@LINE-1]]:12: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}inline auto d3(int arg) -> int try { } catch(...) { }{{$}}
+namespace N {
+bool e1();
+}
+// CHECK-MESSAGES: :[[@LINE-2]]:10: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto e1() -> bool;{{$}}
+inline volatile const std::vector e2();
+// CHECK-MESSAGES: :[[@LINE-1]]:48: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}inline auto e2() -> volatile const std::vector;{{$}}
+inline const std::vector volatile e2();
+// CHECK-MESSAGES: :[[@LINE-1]]:48: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}inline auto e2() -> const std::vector volatile;{{$}}
+inline std::vector const volatile e2();
+// CHECK-MESSAGES: :[[@LINE-1]]:48: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}inline auto e2() -> std::vector const volatile;{{$}}
+bool N::e1() {}
+// CHECK-MESSAGES: :[[@LINE-1]]:9: warning: use a 

[PATCH] D56160: [clang-tidy] modernize-use-trailing-return check

[Bernhard Manfred Gruber via Phabricator via cfe-commits]

bernhardmgruber marked 10 inline comments as done.
bernhardmgruber added a comment.

I fixed most of the stylistic issues. Regarding the missing test cases, I will 
add those and do the necessary code changes. Thank you very much for pointing 
them out to me!




Comment at: clang-tidy/modernize/UseTrailingReturnCheck.cpp:21-22
+
+// very similar to UseOverrideCheck
+SourceLocation findTrailingReturnTypeLocation(const CharSourceRange &range,
+  const ASTContext &ctx,

lebedev.ri wrote:
> This function looks quite fragile.
> Is there no existing function elsewhere [in the support libraries] that does 
> this?
> There is no way to extract this from AST?
> 
I have not found one by browsing the doxygen documentation. I got inspired by 
ParseTokens in UseOverrideCheck.cpp. But I am an absolute beginner on the LLVM 
codebase, so please point me in a direction and I try to find something better!

There is also this in the documentation of [[ 
https://clang.llvm.org/doxygen/classclang_1_1FunctionDecl.html#a1ac2b87b937cc44d8980a898851c0c75
 | FunctionDecl::getReturnTypeSourceRange()]]: "This may omit qualifiers and 
other information with limited representation in the AST."
So maybe the AST really does not contain the locations of const/volatile and 
const/ref qualifiers



Comment at: clang-tidy/modernize/UseTrailingReturnCheck.cpp:91
+  Token t;
+  std::vector tokens;
+  while (!lexer.LexFromRawLexer(t)) {

lebedev.ri wrote:
> Wouldn't `SmallVector` be sufficient in most cases?
I believe return types with namespaces or template arguments produce more 
tokens, so I will go with SmallVector. But i did not do any 
measurements.



Comment at: clang-tidy/modernize/UseTrailingReturnCheck.cpp:161-163
+  const auto &ctx = *Result.Context;
+  const auto &sm = *Result.SourceManager;
+  const auto &opts = getLangOpts();

lebedev.ri wrote:
> 1. All the variables should be WithThisCase
> 2. Can't tell if the `auto` is ok here? 
> 
1. done
2. Is it important to know what types Result.Context and the others are? I am 
just passing them on to further functions because I have to, they are not 
relevant for the logic I am coding.


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[PATCH] D56160: [clang-tidy] modernize-use-trailing-return check

[Bernhard Manfred Gruber via Phabricator via cfe-commits]

bernhardmgruber updated this revision to Diff 179945.
bernhardmgruber marked 2 inline comments as done.

CHANGES SINCE LAST ACTION
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Files:
  clang-tidy/modernize/CMakeLists.txt
  clang-tidy/modernize/ModernizeTidyModule.cpp
  clang-tidy/modernize/UseTrailingReturnCheck.cpp
  clang-tidy/modernize/UseTrailingReturnCheck.h
  docs/clang-tidy/checks/modernize-use-trailing-return.rst
  test/clang-tidy/modernize-use-trailing-return.cpp

Index: test/clang-tidy/modernize-use-trailing-return.cpp
===
--- /dev/null
+++ test/clang-tidy/modernize-use-trailing-return.cpp
@@ -0,0 +1,144 @@
+// RUN: %check_clang_tidy %s modernize-use-trailing-return %t -- -- --std=c++14
+
+namespace std {
+template 
+class vector;
+
+class string;
+}
+
+//
+// Samples triggering the check
+//
+
+int f();
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto f() -> int;{{$}}
+int f(int);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto f(int) -> int;{{$}}
+int f(int arg);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto f(int arg) -> int;{{$}}
+int f(int arg1, int arg2, int arg3);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto f(int arg1, int arg2, int arg3) -> int;{{$}}
+int f(int arg1, int arg2, int arg3, ...);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto f(int arg1, int arg2, int arg3, ...) -> int;{{$}}
+template  int f(T t);
+// CHECK-MESSAGES: :[[@LINE-1]]:27: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}template  auto f(T t) -> int;{{$}}
+int a1() { return 42; }
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto a1() -> int { return 42; }{{$}}
+int a2() {
+return 42;
+}
+// CHECK-MESSAGES: :[[@LINE-3]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto a2() -> int {{{$}}
+int a3()
+{
+return 42;
+}
+// CHECK-MESSAGES: :[[@LINE-4]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto a3() -> int{{$}}
+int b(int   arg   )   ;
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto b(int   arg   ) -> int   ;{{$}}
+inline int d1(int arg);
+// CHECK-MESSAGES: :[[@LINE-1]]:12: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}inline auto d1(int arg) -> int;{{$}}
+inline int d2(int arg) noexcept(true);
+// CHECK-MESSAGES: :[[@LINE-1]]:12: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}inline auto d2(int arg) -> int noexcept(true);{{$}}
+inline int d3(int arg) try { } catch(...) { }
+// CHECK-MESSAGES: :[[@LINE-1]]:12: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}inline auto d3(int arg) -> int try { } catch(...) { }{{$}}
+namespace N {
+bool e1();
+}
+// CHECK-MESSAGES: :[[@LINE-2]]:10: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto e1() -> bool;{{$}}
+inline volatile const std::vector e2();
+// CHECK-MESSAGES: :[[@LINE-1]]:48: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}inline auto e2() -> volatile const std::vector;{{$}}
+inline const std::vector volatile e2();
+// CHECK-MESSAGES: :[[@LINE-1]]:48: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}inline auto e2() -> const std::vector volatile;{{$}}
+inline std::vector const volatile e2();
+// CHECK-MESSAGES: :[[@LINE-1]]:48: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}inline auto e2() -> std::vector const volatile;{{$}}
+bool N::e1() {}
+// CHECK-MESSAGES: :[[@LINE-1]]:9: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto N::e1() -> bool {}{{$}}
+int (*e3())(double);
+// CHECK-MESSAGES: :[[@LINE-1]]:7: warning: use a trailing return type for this function (FixIt not implemented) [modernize-use-trailing-return]
+// TODO: not matched by the AST matcher
+//decltype(auto) e4();
+//

[PATCH] D56160: [clang-tidy] modernize-use-trailing-return check

[Bernhard Manfred Gruber via Phabricator via cfe-commits]

bernhardmgruber updated this revision to Diff 179734.
bernhardmgruber added a comment.

updated diff to one with full context


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Files:
  clang-tidy/modernize/CMakeLists.txt
  clang-tidy/modernize/ModernizeTidyModule.cpp
  clang-tidy/modernize/UseTrailingReturnCheck.cpp
  clang-tidy/modernize/UseTrailingReturnCheck.h
  docs/clang-tidy/checks/modernize-use-trailing-return.rst
  test/clang-tidy/modernize-use-trailing-return.cpp

Index: test/clang-tidy/modernize-use-trailing-return.cpp
===
--- /dev/null
+++ test/clang-tidy/modernize-use-trailing-return.cpp
@@ -0,0 +1,144 @@
+// RUN: %check_clang_tidy %s modernize-use-trailing-return %t -- -- --std=c++14
+
+namespace std {
+template 
+class vector;
+
+class string;
+}
+
+//
+// Samples triggering the check
+//
+
+int f();
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto f() -> int;{{$}}
+int f(int);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto f(int) -> int;{{$}}
+int f(int arg);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto f(int arg) -> int;{{$}}
+int f(int arg1, int arg2, int arg3);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto f(int arg1, int arg2, int arg3) -> int;{{$}}
+int f(int arg1, int arg2, int arg3, ...);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto f(int arg1, int arg2, int arg3, ...) -> int;{{$}}
+template  int f(T t);
+// CHECK-MESSAGES: :[[@LINE-1]]:27: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}template  auto f(T t) -> int;{{$}}
+int a1() { return 42; }
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto a1() -> int { return 42; }{{$}}
+int a2() {
+return 42;
+}
+// CHECK-MESSAGES: :[[@LINE-3]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto a2() -> int {{{$}}
+int a3()
+{
+return 42;
+}
+// CHECK-MESSAGES: :[[@LINE-4]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto a3() -> int{{$}}
+int b(int   arg   )   ;
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto b(int   arg   ) -> int   ;{{$}}
+inline int d1(int arg);
+// CHECK-MESSAGES: :[[@LINE-1]]:12: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}inline auto d1(int arg) -> int;{{$}}
+inline int d2(int arg) noexcept(true);
+// CHECK-MESSAGES: :[[@LINE-1]]:12: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}inline auto d2(int arg) -> int noexcept(true);{{$}}
+inline int d3(int arg) try { } catch(...) { }
+// CHECK-MESSAGES: :[[@LINE-1]]:12: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}inline auto d3(int arg) -> int try { } catch(...) { }{{$}}
+namespace N {
+bool e1();
+}
+// CHECK-MESSAGES: :[[@LINE-2]]:10: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto e1() -> bool;{{$}}
+inline volatile const std::vector e2();
+// CHECK-MESSAGES: :[[@LINE-1]]:48: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}inline auto e2() -> volatile const std::vector;{{$}}
+inline const std::vector volatile e2();
+// CHECK-MESSAGES: :[[@LINE-1]]:48: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}inline auto e2() -> const std::vector volatile;{{$}}
+inline std::vector const volatile e2();
+// CHECK-MESSAGES: :[[@LINE-1]]:48: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}inline auto e2() -> std::vector const volatile;{{$}}
+bool N::e1() {}
+// CHECK-MESSAGES: :[[@LINE-1]]:9: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto N::e1() -> bool {}{{$}}
+int (*e3())(double);
+// CHECK-MESSAGES: :[[@LINE-1]]:7: warning: use a trailing return type for this function (FixIt not implemented) [modernize-use-trailing-return]
+// TODO: not matched by the AST matcher
+//d

[PATCH] D56160: [clang-tidy] modernize-use-trailing-return check

[Bernhard Manfred Gruber via Phabricator via cfe-commits]

bernhardmgruber added a comment.

Hi!

This is my first contribution to LLVM and I may not yet know the conventions 
here.

I decided to write this pass, as some work colleagues and me oftenly want to 
modernize legacy code bases. We like the trailing return type syntax available 
since C++11 and use it for new code. To keep a consistent code base, it would 
help a lot to automatically convert pre C++11 code to the new trailing return 
syntax. I strongly believe this will be handy for several other developers out 
there, although it probably should not be enabled by default.

I am happy to receive any feedback!


Repository:
  rCTE Clang Tools Extra

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[PATCH] D56160: created clang-tidy pass modernize-use-trailing-return

[Bernhard Manfred Gruber via Phabricator via cfe-commits]

bernhardmgruber created this revision.
bernhardmgruber added a reviewer: alexfh.
bernhardmgruber added a project: clang-tools-extra.
Herald added subscribers: cfe-commits, mgorny.

The new clang-tidy pass modernize-use-trailing-return rewrites function 
signatures to use a trailing return type.

A fair amount of tests are included.

Does not work on return types which span locations before and after the 
function name (e.g. functions returning function pointers). The pass may fail 
if the return types are from missing headers (e.g. when clang-tidy is run 
without a compilation database or all needed include directories)


Repository:
  rCTE Clang Tools Extra

https://reviews.llvm.org/D56160

Files:
  clang-tidy/modernize/CMakeLists.txt
  clang-tidy/modernize/ModernizeTidyModule.cpp
  clang-tidy/modernize/UseTrailingReturnCheck.cpp
  clang-tidy/modernize/UseTrailingReturnCheck.h
  docs/clang-tidy/checks/modernize-use-trailing-return.rst
  test/clang-tidy/modernize-use-trailing-return.cpp

Index: test/clang-tidy/modernize-use-trailing-return.cpp
===
--- /dev/null
+++ test/clang-tidy/modernize-use-trailing-return.cpp
@@ -0,0 +1,144 @@
+// RUN: %check_clang_tidy %s modernize-use-trailing-return %t -- -- --std=c++14
+
+namespace std {
+template 
+class vector;
+
+class string;
+}
+
+//
+// Samples triggering the check
+//
+
+int f();
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto f() -> int;{{$}}
+int f(int);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto f(int) -> int;{{$}}
+int f(int arg);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto f(int arg) -> int;{{$}}
+int f(int arg1, int arg2, int arg3);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto f(int arg1, int arg2, int arg3) -> int;{{$}}
+int f(int arg1, int arg2, int arg3, ...);
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto f(int arg1, int arg2, int arg3, ...) -> int;{{$}}
+template  int f(T t);
+// CHECK-MESSAGES: :[[@LINE-1]]:27: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}template  auto f(T t) -> int;{{$}}
+int a1() { return 42; }
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto a1() -> int { return 42; }{{$}}
+int a2() {
+return 42;
+}
+// CHECK-MESSAGES: :[[@LINE-3]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto a2() -> int {{{$}}
+int a3()
+{
+return 42;
+}
+// CHECK-MESSAGES: :[[@LINE-4]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto a3() -> int{{$}}
+int b(int   arg   )   ;
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto b(int   arg   ) -> int   ;{{$}}
+inline int d1(int arg);
+// CHECK-MESSAGES: :[[@LINE-1]]:12: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}inline auto d1(int arg) -> int;{{$}}
+inline int d2(int arg) noexcept(true);
+// CHECK-MESSAGES: :[[@LINE-1]]:12: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}inline auto d2(int arg) -> int noexcept(true);{{$}}
+inline int d3(int arg) try { } catch(...) { }
+// CHECK-MESSAGES: :[[@LINE-1]]:12: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}inline auto d3(int arg) -> int try { } catch(...) { }{{$}}
+namespace N {
+bool e1();
+}
+// CHECK-MESSAGES: :[[@LINE-2]]:10: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}auto e1() -> bool;{{$}}
+inline volatile const std::vector e2();
+// CHECK-MESSAGES: :[[@LINE-1]]:48: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}inline auto e2() -> volatile const std::vector;{{$}}
+inline const std::vector volatile e2();
+// CHECK-MESSAGES: :[[@LINE-1]]:48: warning: use a trailing return type for this function [modernize-use-trailing-return]
+// CHECK-FIXES: {{^}}inline auto e2() -> const std::vector volatile;{{$}}
+inline std::vector const volatile e2();
+// CHECK-MESSAGES: :[[@LINE-1]]:48: warning: use a trailing return type for this function [modernize-use-trailing-return]
+//