[PATCH] D113828: [clang-tidy] Fix false positives in `fuchsia-trailing-return` check involving deduction guides

[Aaron Ballman via Phabricator via cfe-commits]

aaron.ballman closed this revision.
aaron.ballman added a comment.

In D113828#3165101 , @fwolff wrote:

> In D113828#3164016 , @aaron.ballman 
> wrote:
>
>> LGTM! Can you add a release note about the bug fix?
>
> Done. Thank you for the review! Can you also commit it for me? You can use 
> name and email as in `6259016361345e09f0607ef4e037e00bcbe4bd40`. Thanks!

I've commit on your behalf in 844a8d3cecb4cc40e5d9694bcf111518910ea2ff 
, thanks! 
Btw, you might want to consider obtaining your own commit privileges now that 
you have several patches under your belt. For more information on that, see: 
https://llvm.org/docs/DeveloperPolicy.html#obtaining-commit-access


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[PATCH] D113828: [clang-tidy] Fix false positives in `fuchsia-trailing-return` check involving deduction guides

[Fabian Wolff via Phabricator via cfe-commits]

fwolff updated this revision to Diff 391102.
fwolff added a comment.

In D113828#3164016 , @aaron.ballman 
wrote:

> LGTM! Can you add a release note about the bug fix?

Done. Thank you for the review! Can you also commit it for me? You can use name 
and email as in `6259016361345e09f0607ef4e037e00bcbe4bd40`. Thanks!


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Files:
  clang-tools-extra/clang-tidy/fuchsia/TrailingReturnCheck.cpp
  clang-tools-extra/docs/ReleaseNotes.rst
  clang-tools-extra/test/clang-tidy/checkers/fuchsia-trailing-return.cpp


Index: clang-tools-extra/test/clang-tidy/checkers/fuchsia-trailing-return.cpp
===
--- clang-tools-extra/test/clang-tidy/checkers/fuchsia-trailing-return.cpp
+++ clang-tools-extra/test/clang-tidy/checkers/fuchsia-trailing-return.cpp
@@ -1,9 +1,9 @@
-// RUN: %check_clang_tidy %s fuchsia-trailing-return %t
+// RUN: %check_clang_tidy -std=c++17-or-later %s fuchsia-trailing-return %t
 
 int add_one(const int arg) { return arg; }
 
 auto get_add_one() -> int (*)(const int) {
-  // CHECK-MESSAGES: [[@LINE-1]]:1: warning: a trailing return type is 
disallowed for this type of declaration
+  // CHECK-MESSAGES: [[@LINE-1]]:1: warning: a trailing return type is 
disallowed for this function declaration
   // CHECK-NEXT: auto get_add_one() -> int (*)(const int) {
   return add_one;
 }
@@ -21,3 +21,31 @@
 auto fn(const T1 , const T2 ) -> decltype(lhs + rhs) {
   return lhs + rhs;
 }
+
+// Now check that implicit and explicit C++17 deduction guides don't trigger 
this warning (PR#47614).
+
+template 
+struct ImplicitDeductionGuides {
+  ImplicitDeductionGuides(const T &);
+};
+
+template 
+struct pair {
+  A first;
+  B second;
+};
+
+template 
+struct UserDefinedDeductionGuides {
+  UserDefinedDeductionGuides(T);
+  template 
+  UserDefinedDeductionGuides(T1, T2);
+};
+
+template 
+UserDefinedDeductionGuides(T1, T2) -> UserDefinedDeductionGuides>;
+
+void foo() {
+  ImplicitDeductionGuides X(42);
+  UserDefinedDeductionGuides s(1, "abc");
+}
Index: clang-tools-extra/docs/ReleaseNotes.rst
===
--- clang-tools-extra/docs/ReleaseNotes.rst
+++ clang-tools-extra/docs/ReleaseNotes.rst
@@ -140,6 +140,9 @@
   ` to diagnose and fix 
functional
   casts, to achieve feature parity with the corresponding ``cpplint.py`` check.
 
+- Fixed a false positive in :doc:`fuchsia-trailing-return
+  ` for C++17 deduction guides.
+
 Removed checks
 ^^
 
Index: clang-tools-extra/clang-tidy/fuchsia/TrailingReturnCheck.cpp
===
--- clang-tools-extra/clang-tidy/fuchsia/TrailingReturnCheck.cpp
+++ clang-tools-extra/clang-tidy/fuchsia/TrailingReturnCheck.cpp
@@ -17,12 +17,6 @@
 namespace tidy {
 namespace fuchsia {
 
-namespace {
-AST_MATCHER(FunctionDecl, hasTrailingReturn) {
-  return Node.getType()->castAs()->hasTrailingReturn();
-}
-} // namespace
-
 void TrailingReturnCheck::registerMatchers(MatchFinder *Finder) {
   // Functions that have trailing returns are disallowed, except for those
   // using decltype specifiers and lambda with otherwise unutterable
@@ -30,15 +24,16 @@
   Finder->addMatcher(
   functionDecl(hasTrailingReturn(),
unless(anyOf(returns(decltypeType()),
-hasParent(cxxRecordDecl(isLambda())
+hasParent(cxxRecordDecl(isLambda())),
+cxxDeductionGuideDecl(
   .bind("decl"),
   this);
 }
 
 void TrailingReturnCheck::check(const MatchFinder::MatchResult ) {
-  if (const auto *D = Result.Nodes.getNodeAs("decl"))
+  if (const auto *D = Result.Nodes.getNodeAs("decl"))
 diag(D->getBeginLoc(),
- "a trailing return type is disallowed for this type of declaration");
+ "a trailing return type is disallowed for this function declaration");
 }
 
 } // namespace fuchsia


Index: clang-tools-extra/test/clang-tidy/checkers/fuchsia-trailing-return.cpp
===
--- clang-tools-extra/test/clang-tidy/checkers/fuchsia-trailing-return.cpp
+++ clang-tools-extra/test/clang-tidy/checkers/fuchsia-trailing-return.cpp
@@ -1,9 +1,9 @@
-// RUN: %check_clang_tidy %s fuchsia-trailing-return %t
+// RUN: %check_clang_tidy -std=c++17-or-later %s fuchsia-trailing-return %t
 
 int add_one(const int arg) { return arg; }
 
 auto get_add_one() -> int (*)(const int) {
-  // CHECK-MESSAGES: [[@LINE-1]]:1: warning: a trailing return type is disallowed for this type of declaration
+  // CHECK-MESSAGES: [[@LINE-1]]:1: warning: a trailing return type is disallowed for this function declaration
   // CHECK-NEXT: auto get_add_one() -> int (*)(const int) {
   return add_one;
 }
@@ -21,3 +21,31 @@
 auto fn(const T1 , const 

[PATCH] D113828: [clang-tidy] Fix false positives in `fuchsia-trailing-return` check involving deduction guides

[Aaron Ballman via Phabricator via cfe-commits]

aaron.ballman accepted this revision.
aaron.ballman added a comment.
This revision is now accepted and ready to land.

LGTM! Can you add a release note about the bug fix?


Repository:
  rG LLVM Github Monorepo

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[PATCH] D113828: [clang-tidy] Fix false positives in `fuchsia-trailing-return` check involving deduction guides

[Julie Hockett via Phabricator via cfe-commits]

juliehockett resigned from this revision.
juliehockett added a comment.

Apologies, i's been a good long while since I was active in this area. @phosek 
is the most likely to know who would be the best contact in the future.


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[PATCH] D113828: [clang-tidy] Fix false positives in `fuchsia-trailing-return` check involving deduction guides

[Fabian Wolff via Phabricator via cfe-commits]

fwolff created this revision.
fwolff added reviewers: alexfh, aaron.ballman, mizvekov.
fwolff added a project: clang-tools-extra.
Herald added subscribers: carlosgalvezp, abrachet, phosek, xazax.hun.
fwolff requested review of this revision.
Herald added a subscriber: cfe-commits.

Fixes PR#47614. Deduction guides, implicit or user-defined, look like function 
declarations in the AST. They aren't really functions, though, and they always 
have a trailing return type, so it doesn't make sense to issue this warning for 
them.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D113828

Files:
  clang-tools-extra/clang-tidy/fuchsia/TrailingReturnCheck.cpp
  clang-tools-extra/test/clang-tidy/checkers/fuchsia-trailing-return.cpp


Index: clang-tools-extra/test/clang-tidy/checkers/fuchsia-trailing-return.cpp
===
--- clang-tools-extra/test/clang-tidy/checkers/fuchsia-trailing-return.cpp
+++ clang-tools-extra/test/clang-tidy/checkers/fuchsia-trailing-return.cpp
@@ -1,9 +1,9 @@
-// RUN: %check_clang_tidy %s fuchsia-trailing-return %t
+// RUN: %check_clang_tidy -std=c++17-or-later %s fuchsia-trailing-return %t
 
 int add_one(const int arg) { return arg; }
 
 auto get_add_one() -> int (*)(const int) {
-  // CHECK-MESSAGES: [[@LINE-1]]:1: warning: a trailing return type is 
disallowed for this type of declaration
+  // CHECK-MESSAGES: [[@LINE-1]]:1: warning: a trailing return type is 
disallowed for this function declaration
   // CHECK-NEXT: auto get_add_one() -> int (*)(const int) {
   return add_one;
 }
@@ -21,3 +21,31 @@
 auto fn(const T1 , const T2 ) -> decltype(lhs + rhs) {
   return lhs + rhs;
 }
+
+// Now check that implicit and explicit C++17 deduction guides don't trigger 
this warning (PR#47614).
+
+template 
+struct ImplicitDeductionGuides {
+  ImplicitDeductionGuides(const T &);
+};
+
+template 
+struct pair {
+  A first;
+  B second;
+};
+
+template 
+struct UserDefinedDeductionGuides {
+  UserDefinedDeductionGuides(T);
+  template 
+  UserDefinedDeductionGuides(T1, T2);
+};
+
+template 
+UserDefinedDeductionGuides(T1, T2) -> UserDefinedDeductionGuides>;
+
+void foo() {
+  ImplicitDeductionGuides X(42);
+  UserDefinedDeductionGuides s(1, "abc");
+}
Index: clang-tools-extra/clang-tidy/fuchsia/TrailingReturnCheck.cpp
===
--- clang-tools-extra/clang-tidy/fuchsia/TrailingReturnCheck.cpp
+++ clang-tools-extra/clang-tidy/fuchsia/TrailingReturnCheck.cpp
@@ -17,12 +17,6 @@
 namespace tidy {
 namespace fuchsia {
 
-namespace {
-AST_MATCHER(FunctionDecl, hasTrailingReturn) {
-  return Node.getType()->castAs()->hasTrailingReturn();
-}
-} // namespace
-
 void TrailingReturnCheck::registerMatchers(MatchFinder *Finder) {
   // Functions that have trailing returns are disallowed, except for those
   // using decltype specifiers and lambda with otherwise unutterable
@@ -30,15 +24,16 @@
   Finder->addMatcher(
   functionDecl(hasTrailingReturn(),
unless(anyOf(returns(decltypeType()),
-hasParent(cxxRecordDecl(isLambda())
+hasParent(cxxRecordDecl(isLambda())),
+cxxDeductionGuideDecl(
   .bind("decl"),
   this);
 }
 
 void TrailingReturnCheck::check(const MatchFinder::MatchResult ) {
-  if (const auto *D = Result.Nodes.getNodeAs("decl"))
+  if (const auto *D = Result.Nodes.getNodeAs("decl"))
 diag(D->getBeginLoc(),
- "a trailing return type is disallowed for this type of declaration");
+ "a trailing return type is disallowed for this function declaration");
 }
 
 } // namespace fuchsia


Index: clang-tools-extra/test/clang-tidy/checkers/fuchsia-trailing-return.cpp
===
--- clang-tools-extra/test/clang-tidy/checkers/fuchsia-trailing-return.cpp
+++ clang-tools-extra/test/clang-tidy/checkers/fuchsia-trailing-return.cpp
@@ -1,9 +1,9 @@
-// RUN: %check_clang_tidy %s fuchsia-trailing-return %t
+// RUN: %check_clang_tidy -std=c++17-or-later %s fuchsia-trailing-return %t
 
 int add_one(const int arg) { return arg; }
 
 auto get_add_one() -> int (*)(const int) {
-  // CHECK-MESSAGES: [[@LINE-1]]:1: warning: a trailing return type is disallowed for this type of declaration
+  // CHECK-MESSAGES: [[@LINE-1]]:1: warning: a trailing return type is disallowed for this function declaration
   // CHECK-NEXT: auto get_add_one() -> int (*)(const int) {
   return add_one;
 }
@@ -21,3 +21,31 @@
 auto fn(const T1 , const T2 ) -> decltype(lhs + rhs) {
   return lhs + rhs;
 }
+
+// Now check that implicit and explicit C++17 deduction guides don't trigger this warning (PR#47614).
+
+template 
+struct ImplicitDeductionGuides {
+  ImplicitDeductionGuides(const T &);
+};
+
+template 
+struct pair {
+  A first;
+  B second;
+};
+
+template 
+struct UserDefinedDeductionGuides {
+