Re: [C++ Patch] PR 50810
I'm checking in this variant of your patch; mostly it just adds
-Wno-narrowing to the warning options used to build GCC, though there
are a few wording tweaks as well.
Tested x86_64-pc-linux-gnu, applying to trunk.
commit 6b5380306428a3e618027b3fc7a319ae2c520b35
Author: Jason Merrill ja...@redhat.com
Date: Tue Nov 1 11:56:30 2011 -0400
PR c++/50810
gcc/c-family
* c-opts.c (c_common_handle_option): Enable -Wnarrowing as part
of -Wall; include -Wnarrowing in -Wc++0x-compat; adjust default
Wnarrowing for C++0x and C++98.
* c.opt ([Wnarrowing]): Update.
gcc/cp
* typeck2.c (check_narrowing): Adjust OPT_Wnarrowing diagnostics.
(digest_init_r): Call check_narrowing irrespective of the C++ dialect.
* decl.c (check_initializer): Likewise.
* semantics.c (finish_compound_literal): Likewise.
gcc/
* configure.ac: Add -Wno-narrowing to warning options.
libcpp/
* configure.ac: Add -Wno-narrowing to warning options.
diff --git a/gcc/c-family/c-opts.c b/gcc/c-family/c-opts.c
index b56aec7..465bce3 100644
--- a/gcc/c-family/c-opts.c
+++ b/gcc/c-family/c-opts.c
@@ -406,6 +406,7 @@ c_common_handle_option (size_t scode, const char *arg, int value,
warn_reorder = value;
warn_cxx0x_compat = value;
warn_delnonvdtor = value;
+ warn_narrowing = value;
}
cpp_opts-warn_trigraphs = value;
@@ -436,6 +437,10 @@ c_common_handle_option (size_t scode, const char *arg, int value,
cpp_opts-warn_cxx_operator_names = value;
break;
+case OPT_Wc__0x_compat:
+ warn_narrowing = value;
+ break;
+
case OPT_Wdeprecated:
cpp_opts-cpp_warn_deprecated = value;
break;
@@ -997,10 +1002,17 @@ c_common_post_options (const char **pfilename)
if (warn_implicit_function_declaration == -1)
warn_implicit_function_declaration = flag_isoc99;
- /* If we're allowing C++0x constructs, don't warn about C++0x
- compatibility problems. */
if (cxx_dialect == cxx0x)
-warn_cxx0x_compat = 0;
+{
+ /* If we're allowing C++0x constructs, don't warn about C++98
+ identifiers which are keywords in C++0x. */
+ warn_cxx0x_compat = 0;
+
+ if (warn_narrowing == -1)
+ warn_narrowing = 1;
+}
+ else if (warn_narrowing == -1)
+warn_narrowing = 0;
if (flag_preprocess_only)
{
diff --git a/gcc/c-family/c.opt b/gcc/c-family/c.opt
index 438b8b0..0d7dc88 100644
--- a/gcc/c-family/c.opt
+++ b/gcc/c-family/c.opt
@@ -494,8 +494,8 @@ C ObjC C++ ObjC++ Warning
Warn about use of multi-character character constants
Wnarrowing
-C ObjC C++ ObjC++ Warning Var(warn_narrowing) Init(1)
--Wno-narrowing In C++0x mode, ignore ill-formed narrowing conversions within { }
+C ObjC C++ ObjC++ Warning Var(warn_narrowing) Init(-1)
+Warn about narrowing conversions within { } that are ill-formed in C++11
Wnested-externs
C ObjC Var(warn_nested_externs) Warning
diff --git a/gcc/configure b/gcc/configure
index 3b0b39b..35dbdd8 100755
--- a/gcc/configure
+++ b/gcc/configure
@@ -6394,11 +6394,12 @@ fi
# * 'long long'
# * variadic macros
# * overlong strings
+# * C++11 narrowing conversions in { }
# So, we only use -pedantic if we can disable those warnings.
loose_warn=
save_CFLAGS=$CFLAGS
-for option in -W -Wall -Wwrite-strings -Wcast-qual; do
+for option in -W -Wall -Wno-narrowing -Wwrite-strings -Wcast-qual; do
as_acx_Woption=`$as_echo acx_cv_prog_cc_warning_$option | $as_tr_sh`
{ $as_echo $as_me:${as_lineno-$LINENO}: checking whether $CC supports $option 5
diff --git a/gcc/configure.ac b/gcc/configure.ac
index dd6cf2f..9196996 100644
--- a/gcc/configure.ac
+++ b/gcc/configure.ac
@@ -329,10 +329,11 @@ GCC_STDINT_TYPES
# * 'long long'
# * variadic macros
# * overlong strings
+# * C++11 narrowing conversions in { }
# So, we only use -pedantic if we can disable those warnings.
ACX_PROG_CC_WARNING_OPTS(
- m4_quote(m4_do([-W -Wall -Wwrite-strings -Wcast-qual])), [loose_warn])
+ m4_quote(m4_do([-W -Wall -Wno-narrowing -Wwrite-strings -Wcast-qual])), [loose_warn])
ACX_PROG_CC_WARNING_OPTS(
m4_quote(m4_do([-Wstrict-prototypes -Wmissing-prototypes])),
[c_loose_warn])
diff --git a/gcc/cp/decl.c b/gcc/cp/decl.c
index 860556c..edbc783 100644
--- a/gcc/cp/decl.c
+++ b/gcc/cp/decl.c
@@ -5538,7 +5538,7 @@ check_initializer (tree decl, tree init, int flags, tree *cleanup)
else
{
init = reshape_init (type, init, tf_warning_or_error);
- if (cxx_dialect = cxx0x SCALAR_TYPE_P (type))
+ if (SCALAR_TYPE_P (type))
check_narrowing (type, init);
}
}
diff --git a/gcc/cp/semantics.c b/gcc/cp/semantics.c
index d76df51..a80aec6 100644
--- a/gcc/cp/semantics.c
+++ b/gcc/cp/semantics.c
@@ -2369,7 +2369,7 @@ finish_compound_literal (tree type, tree compound_literal,
check_array_initializer (NULL_TREE, type, compound_literal))
return error_mark_node;
compound_literal = reshape_init (type, compound_literal, complain);
- if
Re: [C++ Patch] PR 50810
On 11/02/2011 09:11 PM, Jason Merrill wrote: I'm checking in this variant of your patch; mostly it just adds -Wno-narrowing to the warning options used to build GCC, though there are a few wording tweaks as well. Tested x86_64-pc-linux-gnu, applying to trunk. Thanks! Paolo.
Re: [C++ Patch] PR 50810 (new try)
On Mon, Oct 24, 2011 at 6:47 AM, Paolo Carlini paolo.carl...@oracle.com wrote:
Hi,
the below is a new variant removing -Wc++0x-compat from -Wall (cannot be
added to -Wextra either because bootstrap passes -W) and also, as requested
by Gaby, preventing -Wno-narrowing from suppressing the warning in C++0x
mode (if the user really needs to silence it, -Wno-c++0x-compat works). I
also added a new testcase for that.
OK with a minor correction. This bit
+With -std=c++0x, @option{-Wno-c++0x-compat} can be used to suppress
+the diagnostic required by the standard.
should not be there. It is currently an accident of implementation
detail as opposed to a feature. It needs no advertisement.
Re: [C++ Patch] PR 50810 (new try)
Hi,
On Mon, Oct 24, 2011 at 6:47 AM, Paolo Carlinipaolo.carl...@oracle.com wrote:
Hi,
the below is a new variant removing -Wc++0x-compat from -Wall (cannot be
added to -Wextra either because bootstrap passes -W) and also, as requested
by Gaby, preventing -Wno-narrowing from suppressing the warning in C++0x
mode (if the user really needs to silence it, -Wno-c++0x-compat works). I
also added a new testcase for that.
OK with a minor correction. This bit
+With -std=c++0x, @option{-Wno-c++0x-compat} can be used to suppress
+the diagnostic required by the standard.
should not be there. It is currently an accident of implementation
detail as opposed to a feature. It needs no advertisement.
Ok. But I actively made it possible, if you want I can remove the
possibility altogether, the patch also becomes cleaner ;)
Paolo.
Re: [C++ Patch] PR 50810 (new try)
On 10/24/2011 02:18 PM, Paolo Carlini wrote:
OK with a minor correction. This bit
+With -std=c++0x, @option{-Wno-c++0x-compat} can be used to suppress
+the diagnostic required by the standard.
should not be there. It is currently an accident of implementation
detail as opposed to a feature. It needs no advertisement.
Ok. But I actively made it possible, if you want I can remove the
possibility altogether, the patch also becomes cleaner ;)
I can boot test the below, in other terms.
Paolo.
/c-family
2011-10-24 Paolo Carlini paolo.carl...@oracle.com
PR c++/50810
* c-opts.c (c_common_handle_option): Do not enable -Wc++0x-compat
as part of -Wall; handle -Wc++0x-compat.
(c_common_post_options): -std=c++0x enables -Wnarrowing.
* c.opt ([Wnarrowing]): Update.
/cp
2011-10-24 Paolo Carlini paolo.carl...@oracle.com
PR c++/50810
* typeck2.c (check_narrowing): Adjust OPT_Wnarrowing diagnostics.
(digest_init_r): Call check_narrowing irrespective of the C++ dialect.
* decl.c (check_initializer): Likewise.
* semantics.c (finish_compound_literal): Likewise.
/testsuite
2011-10-24 Paolo Carlini paolo.carl...@oracle.com
PR c++/50810
* g++.dg/cpp0x/warn_cxx0x2.C: New.
* g++.dg/cpp0x/warn_cxx0x3.C: Likewise.
* g++.dg/cpp0x/initlist55.C: Adjust.
2011-10-24 Paolo Carlini paolo.carl...@oracle.com
PR c++/50810
* doc/invoke.texi ([-Wall], [-Wnarrowing], [-Wc++0x-compat]): Update.
Index: doc/invoke.texi
===
--- doc/invoke.texi (revision 180373)
+++ doc/invoke.texi (working copy)
@@ -2365,17 +2365,16 @@ an instance of a derived class through a pointer t
base class does not have a virtual destructor. This warning is enabled
by @option{-Wall}.
-@item -Wno-narrowing @r{(C++ and Objective-C++ only)}
+@item -Wnarrowing @r{(C++ and Objective-C++ only)}
@opindex Wnarrowing
@opindex Wno-narrowing
-With -std=c++0x, suppress the diagnostic required by the standard for
-narrowing conversions within @samp{@{ @}}, e.g.
+Warn when a narrowing conversion occurs within @samp{@{ @}}, e.g.
@smallexample
int i = @{ 2.2 @}; // error: narrowing from double to int
@end smallexample
-This flag can be useful for compiling valid C++98 code in C++0x mode
+This flag is included in @option{-Wc++0x-compat}.
@item -Wnoexcept @r{(C++ and Objective-C++ only)}
@opindex Wnoexcept
@@ -2993,7 +2992,6 @@ Options} and @ref{Objective-C and Objective-C++ Di
@gccoptlist{-Waddress @gol
-Warray-bounds @r{(only with} @option{-O2}@r{)} @gol
--Wc++0x-compat @gol
-Wchar-subscripts @gol
-Wenum-compare @r{(in C/Objc; this is on by default in C++)} @gol
-Wimplicit-int @r{(C and Objective-C only)} @gol
@@ -4066,7 +4064,7 @@ ISO C and ISO C++, e.g.@: request for implicit con
@item -Wc++0x-compat @r{(C++ and Objective-C++ only)}
Warn about C++ constructs whose meaning differs between ISO C++ 1998 and
ISO C++ 200x, e.g., identifiers in ISO C++ 1998 that will become keywords
-in ISO C++ 200x. This warning is enabled by @option{-Wall}.
+in ISO C++ 200x. This warning turns on @option{-Wnarrowing}.
@item -Wcast-qual
@opindex Wcast-qual
Index: c-family/c.opt
===
--- c-family/c.opt (revision 180373)
+++ c-family/c.opt (working copy)
@@ -490,8 +490,8 @@ C ObjC C++ ObjC++ Warning
Warn about use of multi-character character constants
Wnarrowing
-C ObjC C++ ObjC++ Warning Var(warn_narrowing) Init(1)
--Wno-narrowing In C++0x mode, ignore ill-formed narrowing conversions within
{ }
+C ObjC C++ ObjC++ Warning Var(warn_narrowing) Init(-1) Warning
+Warn about ill-formed narrowing conversions within { }
Wnested-externs
C ObjC Var(warn_nested_externs) Warning
Index: c-family/c-opts.c
===
--- c-family/c-opts.c (revision 180373)
+++ c-family/c-opts.c (working copy)
@@ -404,7 +404,6 @@ c_common_handle_option (size_t scode, const char *
/* C++-specific warnings. */
warn_sign_compare = value;
warn_reorder = value;
- warn_cxx0x_compat = value;
warn_delnonvdtor = value;
}
@@ -436,6 +435,10 @@ c_common_handle_option (size_t scode, const char *
cpp_opts-warn_cxx_operator_names = value;
break;
+case OPT_Wc__0x_compat:
+ warn_narrowing = value;
+ break;
+
case OPT_Wdeprecated:
cpp_opts-cpp_warn_deprecated = value;
break;
@@ -997,10 +1000,15 @@ c_common_post_options (const char **pfilename)
if (warn_implicit_function_declaration == -1)
warn_implicit_function_declaration = flag_isoc99;
- /* If we're allowing C++0x constructs, don't warn about C++0x
- compatibility problems. */
if (cxx_dialect == cxx0x)
-warn_cxx0x_compat = 0;
+{
+ /* If
Re: [C++ Patch] PR 50810 (new try)
On Mon, Oct 24, 2011 at 7:18 AM, Paolo Carlini paolo.carl...@oracle.com wrote:
Hi,
On Mon, Oct 24, 2011 at 6:47 AM, Paolo Carlinipaolo.carl...@oracle.com
wrote:
Hi,
the below is a new variant removing -Wc++0x-compat from -Wall (cannot be
added to -Wextra either because bootstrap passes -W) and also, as
requested
by Gaby, preventing -Wno-narrowing from suppressing the warning in C++0x
mode (if the user really needs to silence it, -Wno-c++0x-compat works). I
also added a new testcase for that.
OK with a minor correction. This bit
+With -std=c++0x, @option{-Wno-c++0x-compat} can be used to suppress
+the diagnostic required by the standard.
should not be there. It is currently an accident of implementation
detail as opposed to a feature. It needs no advertisement.
Ok. But I actively made it possible, if you want I can remove the
possibility altogether, the patch also becomes cleaner ;)
Yes, I have been saying all long that -Wflag is not the way to
suppress a standard semantics. So, if you can make the patch
cleaner without that, then the better! :-)
Re: [C++ Patch] PR 50810 (new try)
On 10/24/2011 07:47 AM, Paolo Carlini wrote: the below is a new variant removing -Wc++0x-compat from -Wall (cannot be added to -Wextra either because bootstrap passes -W) I don't understand the rationale for this. If the warning is problematic for bootstrap, why not just add -Wno-narrowing to the bootstrap warning flags? I haven't read the whole discussion thread yet, though. and also, as requested by Gaby, preventing -Wno-narrowing from suppressing the warning in C++0x mode (if the user really needs to silence it, -Wno-c++0x-compat works). I also added a new testcase for that. No. I added -Wno-narrowing specifically to suppress the diagnostic in C++0x mode; see c++/49793. There are several diagnostics required by standards that can be suppressed by -Wno- flags, such as -Wno-long-long. Jason
Re: [C++ Patch] PR 50810 (new try)
On 10/24/2011 09:06 AM, Jason Merrill wrote: On 10/24/2011 07:47 AM, Paolo Carlini wrote: the below is a new variant removing -Wc++0x-compat from -Wall (cannot be added to -Wextra either because bootstrap passes -W) I don't understand the rationale for this. If the warning is problematic for bootstrap, why not just add -Wno-narrowing to the bootstrap warning flags? I haven't read the whole discussion thread yet, though. OK, I read it and still think this is the right solution. and also, as requested by Gaby, preventing -Wno-narrowing from suppressing the warning in C++0x mode (if the user really needs to silence it, -Wno-c++0x-compat works). I also added a new testcase for that. No. I added -Wno-narrowing specifically to suppress the diagnostic in C++0x mode; see c++/49793. There are several diagnostics required by standards that can be suppressed by -Wno- flags, such as -Wno-long-long. ...but I'm not strongly opposed to renaming the option, so long as its function remains. Jason
Re: [C++ Patch] PR 50810 (new try)
On Mon, Oct 24, 2011 at 8:06 AM, Jason Merrill ja...@redhat.com wrote: On 10/24/2011 07:47 AM, Paolo Carlini wrote: [...] and also, as requested by Gaby, preventing -Wno-narrowing from suppressing the warning in C++0x mode (if the user really needs to silence it, -Wno-c++0x-compat works). I also added a new testcase for that. No. I added -Wno-narrowing specifically to suppress the diagnostic in C++0x mode; see c++/49793. There are several diagnostics required by standards that can be suppressed by -Wno- flags, such as -Wno-long-long. I do not think I follow. The way we suppress a standard feature is through a non-W flag. -Wno-long-long should not have any effect at all in C++11. It may have an effect in C++03. -- Gaby
Re: [C++ Patch] PR 50810 (new try)
On 10/24/2011 09:26 AM, Gabriel Dos Reis wrote: On Mon, Oct 24, 2011 at 8:06 AM, Jason Merrillja...@redhat.com wrote: No. I added -Wno-narrowing specifically to suppress the diagnostic in C++0x mode; see c++/49793. There are several diagnostics required by standards that can be suppressed by -Wno- flags, such as -Wno-long-long. I do not think I follow. The way we suppress a standard feature is through a non-W flag. -Wno-long-long should not have any effect at all in C++11. It may have an effect in C++03. Right, -Wno-long-long is only useful in C++03 and C90. But it does in fact suppress a standard diagnostic. Jason
Re: [C++ Patch] PR 50810 (new try)
.. just to let you know guys, I'm already unassigned from the PR, but today I wanted to give it one (actually 3) more try. Given the controversy, I don't feel like further following the issue, it just makes me nervous. Eventually, feel free to adjust my patches to your likes. Paolo.
Re: [C++ Patch] PR 50810 (new try)
On Mon, Oct 24, 2011 at 8:29 AM, Jason Merrill ja...@redhat.com wrote: On 10/24/2011 09:26 AM, Gabriel Dos Reis wrote: On Mon, Oct 24, 2011 at 8:06 AM, Jason Merrillja...@redhat.com wrote: No. I added -Wno-narrowing specifically to suppress the diagnostic in C++0x mode; see c++/49793. There are several diagnostics required by standards that can be suppressed by -Wno- flags, such as -Wno-long-long. I do not think I follow. The way we suppress a standard feature is through a non-W flag. -Wno-long-long should not have any effect at all in C++11. It may have an effect in C++03. Right, -Wno-long-long is only useful in C++03 and C90. But it does in fact suppress a standard diagnostic. a diagnostic of an extension :-) Similarly, -Wno-narrowing suppresses diagnostic in C++03 when -Wc++0x-compat is in effect (therefore C++03). However, just like -Wno-long-long, it should not have any effect when -std=c++0x or -std=c++11.
Re: [C++ Patch] PR 50810 (new try)
On 10/24/2011 09:49 AM, Gabriel Dos Reis wrote: On Mon, Oct 24, 2011 at 8:29 AM, Jason Merrillja...@redhat.com wrote: Right, -Wno-long-long is only useful in C++03 and C90. But it does in fact suppress a standard diagnostic. a diagnostic of an extension :-) I'm not going to argue semantics any further. What change do you suggest that still allows users to suppress narrowing diagnostics in C++11? Jason
Re: [C++ Patch] PR 50810 (new try)
On Mon, Oct 24, 2011 at 9:10 AM, Jason Merrill ja...@redhat.com wrote: On 10/24/2011 09:49 AM, Gabriel Dos Reis wrote: On Mon, Oct 24, 2011 at 8:29 AM, Jason Merrillja...@redhat.com wrote: Right, -Wno-long-long is only useful in C++03 and C90. But it does in fact suppress a standard diagnostic. a diagnostic of an extension :-) I'm not going to argue semantics any further. What change do you suggest that still allows users to suppress narrowing diagnostics in C++11? Hmm, the narrowing semantics also affects SFINAE, not just simple declaration. If we want a flag that can also affect the outcome of overload resolution, it should one of the the -fflags, such as -fpermissive. -- Gaby
Re: [C++ Patch] PR 50810 (new try)
On 10/24/2011 10:39 AM, Gabriel Dos Reis wrote: Hmm, the narrowing semantics also affects SFINAE, not just simple declaration. If we want a flag that can also affect the outcome of overload resolution, it should one of the the -fflags, such as -fpermissive. I don't want the option to affect SFINAE, just suppress the diagnostic when tf_error is set. There are a number of similar places in the compiler where if tf_error is set we give a pedwarn and accept the code, but if tf_error is not set we fail. Jason
Re: [C++ Patch] PR 50810 (new try)
On Mon, Oct 24, 2011 at 9:53 AM, Jason Merrill ja...@redhat.com wrote: On 10/24/2011 10:39 AM, Gabriel Dos Reis wrote: Hmm, the narrowing semantics also affects SFINAE, not just simple declaration. If we want a flag that can also affect the outcome of overload resolution, it should one of the the -fflags, such as -fpermissive. I don't want the option to affect SFINAE, So, let me recap: 1. narrowing conversion is ill-formed in C++11; therefore a diagnostic is required. This has two implications: a. Normal scenario: a diagnostic is required and the program rejected. This is the one people complain about. b. SFINAE context: because the narrowing is ill-formed, the offernding expression (rather, the offending function) would just be silently ignored; no diagnostic is actually output. 2. -Wnarrowing warns about narrowing conversion, but does not reject the code. This is only for C++98, C++03, with -Wc++0x-compat While 1.b. looks like -Wnarrowing in sfinae context, it is not -Wno-narrowing because with -Wnarrowing we still accept the expression (as opposed to rejecting.) So, if you make -Wno-narrowing meaningful in C++11 mode then how can it not affect sfinae (case 1.b.) and still be consistent with the other case where a diagnostic is required the expression accepted? just suppress the diagnostic when tf_error is set. There are a number of similar places in the compiler where if tf_error is set we give a pedwarn and accept the code, but if tf_error is not set we fail.
Re: [C++ Patch] PR 50810 (new try)
On 10/24/2011 01:21 PM, Gabriel Dos Reis wrote: On Mon, Oct 24, 2011 at 9:53 AM, Jason Merrillja...@redhat.com wrote: So, if you make -Wno-narrowing meaningful in C++11 mode then how can it not affect sfinae (case 1.b.) and still be consistent with the other case where a diagnostic is required the expression accepted? Right, they will be inconsistent. But that consistency isn't relevant for legacy code, which can't have list-initialization in SFINAE context. Jason
Re: [C++ Patch] PR 50810 (new try)
On Mon, Oct 24, 2011 at 12:46 PM, Jason Merrill ja...@redhat.com wrote: On 10/24/2011 01:21 PM, Gabriel Dos Reis wrote: On Mon, Oct 24, 2011 at 9:53 AM, Jason Merrillja...@redhat.com wrote: So, if you make -Wno-narrowing meaningful in C++11 mode then how can it not affect sfinae (case 1.b.) and still be consistent with the other case where a diagnostic is required the expression accepted? Right, they will be inconsistent. But that consistency isn't relevant for legacy code, which can't have list-initialization in SFINAE context. yes, but how does the compiler distinguish a legacy code compiled under C++11 from non-legacy C++11 code? I have no problem with C++03 codes. I do not think they are affected. The problem is with C++11 codes. There is no reason for them to be subjected to the inconsistency, especially for codes in header files that are upgraded (beyond control of the end user) and included in legacy codes. The legacy code may not have list-initialization in sfinae context, but the upgraded header file may have, without the end user knowing. It is wrong for a -Wflag to introduce that inconsistency in new codes.
Re: [C++ Patch] PR 50810 (new try)
On 10/24/2011 02:13 PM, Gabriel Dos Reis wrote: yes, but how does the compiler distinguish a legacy code compiled under C++11 from non-legacy C++11 code? It doesn't. The problem is with C++11 codes. There is no reason for them to be subjected to the inconsistency, especially for codes in header files that are upgraded (beyond control of the end user) and included in legacy codes. The legacy code may not have list-initialization in sfinae context, but the upgraded header file may have, without the end user knowing. And that header is unaffected. Only initialization outside SFINAE context is affected. It is wrong for a -Wflag to introduce that inconsistency in new codes. What would you suggest instead? Jason
Re: [C++ Patch] PR 50810 (new try)
On Mon, Oct 24, 2011 at 1:17 PM, Jason Merrill ja...@redhat.com wrote:
On 10/24/2011 02:13 PM, Gabriel Dos Reis wrote:
The problem is with C++11 codes. There is no reason for them to be
subjected
to the inconsistency, especially for codes in header files that are
upgraded (beyond control of the end user) and included in legacy codes.
The legacy code may not have list-initialization in sfinae context, but
the upgraded header file may have, without the end user knowing.
And that header is unaffected. Only initialization outside SFINAE context
is affected.
I am afraid I do not understand why the header will
not be affected.
What about (testcase)
int f(char);
double f(...);
const int n = sizeof f({257});
?
It is wrong for a -Wflag to introduce that inconsistency in new codes.
What would you suggest instead?
An -fflag. If -fpermissive is too broad, then -flegacy-init or -flegacy
Re: [C++ Patch] PR 50810 (new try)
On 10/24/2011 02:47 PM, Gabriel Dos Reis wrote:
What about (testcase)
int f(char);
double f(...);
const int n = sizeof f({257});
?
The narrowing conversion would be marked as 'bad' and therefore the
second overload chosen. As before, the objective is to only change the
diagnostic, not the meaning of valid code.
Jason
Re: [C++ Patch] PR 50810 (new try)
On Mon, Oct 24, 2011 at 2:05 PM, Jason Merrill ja...@redhat.com wrote:
On 10/24/2011 02:47 PM, Gabriel Dos Reis wrote:
What about (testcase)
int f(char);
double f(...);
const int n = sizeof f({257});
?
The narrowing conversion would be marked as 'bad' and therefore the second
overload chosen. As before, the objective is to only change the diagnostic,
not the meaning of valid code.
OK. I think we may need better documentation of the behavior.
Re: [C++ Patch] PR 50810
On 10/23/2011 07:23 AM, Paolo Carlini wrote:
-@item -Wno-narrowing @r{(C++ and Objective-C++ only)}
+@item -Wnarrowing @r{(C++ and Objective-C++ only)}
@opindex Wnarrowing
@opindex Wno-narrowing
-With -std=c++0x, suppress the diagnostic required by the standard for
-narrowing conversions within @samp{@{ @}}, e.g.
+Warn when a narrowing conversion occurs within @samp{@{ @}}, e.g.
@smallexample
int i = @{ 2.2 @}; // error: narrowing from double to int
@end smallexample
-This flag can be useful for compiling valid C++98 code in C++0x mode.
+This flag is included in @option{-Wall} and @option{-Wc++0x-compat}.
Please still also talk about using -Wno-narrowing in C++0x mode here.
* g++.dg/cpp0x/warn_cxx0x.C: Rename to...
* g++.dg/cpp0x/warn_cxx0x1.C: ... this.
I wouldn't bother renaming, you can just add the new tests.
Jason
Re: [C++ Patch] PR 50810
Hi,
On 10/23/2011 07:23 AM, Paolo Carlini wrote:
-@item -Wno-narrowing @r{(C++ and Objective-C++ only)}
+@item -Wnarrowing @r{(C++ and Objective-C++ only)}
@opindex Wnarrowing
@opindex Wno-narrowing
-With -std=c++0x, suppress the diagnostic required by the standard for
-narrowing conversions within @samp{@{ @}}, e.g.
+Warn when a narrowing conversion occurs within @samp{@{ @}}, e.g.
@smallexample
int i = @{ 2.2 @}; // error: narrowing from double to int
@end smallexample
-This flag can be useful for compiling valid C++98 code in C++0x mode.
+This flag is included in @option{-Wall} and @option{-Wc++0x-compat}.
Please still also talk about using -Wno-narrowing in C++0x mode here.
I change it like this. Better?
Thanks,
Paolo.
///
/c-family
2011-10-23 Paolo Carlini paolo.carl...@oracle.com
PR c++/50810
* c-opts.c (c_common_handle_option): Enable -Wnarrowing as part
of -Wall; include -Wnarrowing in -Wc++0x-compat; adjust default
Wnarrowing for C++0x and C++98.
* c.opt ([Wnarrowing]): Update.
/cp
2011-10-23 Paolo Carlini paolo.carl...@oracle.com
PR c++/50810
* typeck2.c (check_narrowing): Adjust OPT_Wnarrowing diagnostics.
(digest_init_r): Call check_narrowing irrespective of the C++ dialect.
* decl.c (check_initializer): Likewise.
* semantics.c (finish_compound_literal): Likewise.
/testsuite
2011-10-23 Paolo Carlini paolo.carl...@oracle.com
PR c++/50810
* g++.dg/cpp0x/warn_cxx0x2.C: New.
* g++.dg/cpp0x/warn_cxx0x3.C: Likewise.
2011-10-23 Paolo Carlini paolo.carl...@oracle.com
PR c++/50810
* doc/invoke.texi ([-Wnarrowing], [-Wc++0x-compat]): Update.
Index: doc/invoke.texi
===
--- doc/invoke.texi (revision 180333)
+++ doc/invoke.texi (working copy)
@@ -2365,17 +2365,18 @@ an instance of a derived class through a pointer t
base class does not have a virtual destructor. This warning is enabled
by @option{-Wall}.
-@item -Wno-narrowing @r{(C++ and Objective-C++ only)}
+@item -Wnarrowing @r{(C++ and Objective-C++ only)}
@opindex Wnarrowing
@opindex Wno-narrowing
-With -std=c++0x, suppress the diagnostic required by the standard for
-narrowing conversions within @samp{@{ @}}, e.g.
+Warn when a narrowing conversion occurs within @samp{@{ @}}, e.g.
@smallexample
int i = @{ 2.2 @}; // error: narrowing from double to int
@end smallexample
-This flag can be useful for compiling valid C++98 code in C++0x mode.
+With -std=c++0x, @option{-Wno-narrowing} suppresses the diagnostic
+required by the standard. This flag is included in @option{-Wall} and
+@option{-Wc++0x-compat}.
@item -Wnoexcept @r{(C++ and Objective-C++ only)}
@opindex Wnoexcept
@@ -4066,7 +4067,8 @@ ISO C and ISO C++, e.g.@: request for implicit con
@item -Wc++0x-compat @r{(C++ and Objective-C++ only)}
Warn about C++ constructs whose meaning differs between ISO C++ 1998 and
ISO C++ 200x, e.g., identifiers in ISO C++ 1998 that will become keywords
-in ISO C++ 200x. This warning is enabled by @option{-Wall}.
+in ISO C++ 200x. This warning turns on @option{-Wnarrowing} and is
+enabled by @option{-Wall}.
@item -Wcast-qual
@opindex Wcast-qual
Index: c-family/c.opt
===
--- c-family/c.opt (revision 180333)
+++ c-family/c.opt (working copy)
@@ -490,8 +490,8 @@ C ObjC C++ ObjC++ Warning
Warn about use of multi-character character constants
Wnarrowing
-C ObjC C++ ObjC++ Warning Var(warn_narrowing) Init(1)
--Wno-narrowing In C++0x mode, ignore ill-formed narrowing conversions within
{ }
+C ObjC C++ ObjC++ Warning Var(warn_narrowing) Init(-1) Warning
+Warn about ill-formed narrowing conversions within { }
Wnested-externs
C ObjC Var(warn_nested_externs) Warning
Index: c-family/c-opts.c
===
--- c-family/c-opts.c (revision 180333)
+++ c-family/c-opts.c (working copy)
@@ -406,6 +406,7 @@ c_common_handle_option (size_t scode, const char *
warn_reorder = value;
warn_cxx0x_compat = value;
warn_delnonvdtor = value;
+ warn_narrowing = value;
}
cpp_opts-warn_trigraphs = value;
@@ -436,6 +437,10 @@ c_common_handle_option (size_t scode, const char *
cpp_opts-warn_cxx_operator_names = value;
break;
+case OPT_Wc__0x_compat:
+ warn_narrowing = value;
+ break;
+
case OPT_Wdeprecated:
cpp_opts-cpp_warn_deprecated = value;
break;
@@ -997,11 +1002,18 @@ c_common_post_options (const char **pfilename)
if (warn_implicit_function_declaration == -1)
warn_implicit_function_declaration = flag_isoc99;
- /* If we're allowing C++0x constructs, don't warn about C++0x
- compatibility problems. */
if (cxx_dialect == cxx0x)
-warn_cxx0x_compat = 0;
+{
+ /* If
Re: [C++ Patch] PR 50810
On 10/23/2011 11:00 AM, Paolo Carlini wrote:
+With -std=c++0x, @option{-Wno-narrowing} suppresses the diagnostic
+required by the standard. This flag is included in @option{-Wall} and
+@option{-Wc++0x-compat}.
I'd swap those two sentences. OK with that change.
Jason
