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* [Bug c++/101940] New: Implement -fignored-attributes
@ 2021-08-16 21:05 mpolacek at gcc dot gnu.org
2021-08-17 7:48 ` [Bug c++/101940] " rguenth at gcc dot gnu.org
` (6 more replies)
0 siblings, 7 replies; 8+ messages in thread
From: mpolacek at gcc dot gnu.org @ 2021-08-16 21:05 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101940
Bug ID: 101940
Summary: Implement -fignored-attributes
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: enhancement
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: mpolacek at gcc dot gnu.org
Target Milestone: ---
It is desirable for -Wattributes to warn about e.g.
[[deprecate]] void g(); // typo, should warn
However, -Wattributes also warns about vendor-specific attributes (that's
because lookup_scoped_attribute_spec -> find_attribute_namespace finds
nothing), which, with -Werror, causes grief. We don't want the -Wattributes
warning for
[[company::attr]] void f();
GCC warns because it doesn't know the "company" namespace; it only knows the
"gnu" and "omp" namespaces. We could entirely disable warning about attributes
in unknown scopes but then the compiler would also miss typos like
[[company::attrx]] void f();
or
[[gmu::warn_used_result]] int write();
so that is not a viable solution. A workaround is to use a #pragma:
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wattributes"
[[company::attr]] void f() {}
#pragma GCC diagnostic pop
but that's a mouthful and awkward to use and could also hide typos. In fact,
any macro-based solution doesn't seem like a way forward.
So this RFE asks for -fignored-attributes=, which, IMHO, should take these
arguments:
company::attr
company::
clang
the last is a special option to ignore clang-only attributes. Maybe we could
also accept ::attr.
This option should go well with using @file: we could have a file containing
-fignored-attributes=vendor::attr1,vendor::attr2
and then invoke gcc with '@attrs' or similar.
It might also make sense to implement a #pragma to go along:
#pragma GCC ignored-attributes=vendor::attr1,vendor::attr2.
This should help with various static analysis tools and similar.
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug c++/101940] Implement -fignored-attributes
2021-08-16 21:05 [Bug c++/101940] New: Implement -fignored-attributes mpolacek at gcc dot gnu.org
@ 2021-08-17 7:48 ` rguenth at gcc dot gnu.org
2021-08-17 14:19 ` mpolacek at gcc dot gnu.org
` (5 subsequent siblings)
6 siblings, 0 replies; 8+ messages in thread
From: rguenth at gcc dot gnu.org @ 2021-08-17 7:48 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101940
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Version|unknown |12.0
--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
Or -Wno-attributes=company:: just like we have -Wno-error=subdiag?
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug c++/101940] Implement -fignored-attributes
2021-08-16 21:05 [Bug c++/101940] New: Implement -fignored-attributes mpolacek at gcc dot gnu.org
2021-08-17 7:48 ` [Bug c++/101940] " rguenth at gcc dot gnu.org
@ 2021-08-17 14:19 ` mpolacek at gcc dot gnu.org
2021-08-17 15:31 ` msebor at gcc dot gnu.org
` (4 subsequent siblings)
6 siblings, 0 replies; 8+ messages in thread
From: mpolacek at gcc dot gnu.org @ 2021-08-17 14:19 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101940
--- Comment #2 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Possibly. I thought I'd rather keep the names of the option and pragma the
same, but maybe that's not necessary.
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug c++/101940] Implement -fignored-attributes
2021-08-16 21:05 [Bug c++/101940] New: Implement -fignored-attributes mpolacek at gcc dot gnu.org
2021-08-17 7:48 ` [Bug c++/101940] " rguenth at gcc dot gnu.org
2021-08-17 14:19 ` mpolacek at gcc dot gnu.org
@ 2021-08-17 15:31 ` msebor at gcc dot gnu.org
2021-08-17 15:49 ` mpolacek at gcc dot gnu.org
` (3 subsequent siblings)
6 siblings, 0 replies; 8+ messages in thread
From: msebor at gcc dot gnu.org @ 2021-08-17 15:31 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101940
Martin Sebor <msebor at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |msebor at gcc dot gnu.org
Last reconfirmed| |2021-08-17
Ever confirmed|0 |1
Status|UNCONFIRMED |NEW
--- Comment #3 from Martin Sebor <msebor at gcc dot gnu.org> ---
If the only thing the new option is meant to control is -Wattributes warnings I
tend to agree that adding an optional argument to -Wattributes= would be a
natural enhancement. (Similar to -Wnormalized= or -Wsuggest-attribute= except
with a free-form string as an argument). I would expect the existing
diagnostic pragmas to work with it too:
#pragma GCC ignored "-Wattributes=vendor::attr1"
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug c++/101940] Implement -fignored-attributes
2021-08-16 21:05 [Bug c++/101940] New: Implement -fignored-attributes mpolacek at gcc dot gnu.org
` (2 preceding siblings ...)
2021-08-17 15:31 ` msebor at gcc dot gnu.org
@ 2021-08-17 15:49 ` mpolacek at gcc dot gnu.org
2021-09-20 17:07 ` [Bug c++/101940] Implement -Wno-attributes=vendor::attr mpolacek at gcc dot gnu.org
` (2 subsequent siblings)
6 siblings, 0 replies; 8+ messages in thread
From: mpolacek at gcc dot gnu.org @ 2021-08-17 15:49 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101940
Marek Polacek <mpolacek at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |ASSIGNED
Assignee|unassigned at gcc dot gnu.org |mpolacek at gcc dot gnu.org
--- Comment #4 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Good point, I like that!
So, mine, I guess.
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug c++/101940] Implement -Wno-attributes=vendor::attr
2021-08-16 21:05 [Bug c++/101940] New: Implement -fignored-attributes mpolacek at gcc dot gnu.org
` (3 preceding siblings ...)
2021-08-17 15:49 ` mpolacek at gcc dot gnu.org
@ 2021-09-20 17:07 ` mpolacek at gcc dot gnu.org
2021-11-10 14:26 ` cvs-commit at gcc dot gnu.org
2021-11-10 14:31 ` mpolacek at gcc dot gnu.org
6 siblings, 0 replies; 8+ messages in thread
From: mpolacek at gcc dot gnu.org @ 2021-09-20 17:07 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101940
--- Comment #5 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Patch posted:
https://gcc.gnu.org/pipermail/gcc-patches/2021-September/579858.html
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug c++/101940] Implement -Wno-attributes=vendor::attr
2021-08-16 21:05 [Bug c++/101940] New: Implement -fignored-attributes mpolacek at gcc dot gnu.org
` (4 preceding siblings ...)
2021-09-20 17:07 ` [Bug c++/101940] Implement -Wno-attributes=vendor::attr mpolacek at gcc dot gnu.org
@ 2021-11-10 14:26 ` cvs-commit at gcc dot gnu.org
2021-11-10 14:31 ` mpolacek at gcc dot gnu.org
6 siblings, 0 replies; 8+ messages in thread
From: cvs-commit at gcc dot gnu.org @ 2021-11-10 14:26 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101940
--- Comment #6 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The trunk branch has been updated by Marek Polacek <mpolacek@gcc.gnu.org>:
https://gcc.gnu.org/g:a1ad0d84d7fcbcaa7a697290387b911eb7e1bd46
commit r12-5123-ga1ad0d84d7fcbcaa7a697290387b911eb7e1bd46
Author: Marek Polacek <polacek@redhat.com>
Date: Thu Sep 9 09:17:27 2021 -0400
attribs: Implement -Wno-attributes=vendor::attr [PR101940]
It is desirable for -Wattributes to warn about e.g.
[[deprecate]] void g(); // typo, should warn
However, -Wattributes also warns about vendor-specific attributes
(that's because lookup_scoped_attribute_spec -> find_attribute_namespace
finds nothing), which, with -Werror, causes grief. We don't want the
-Wattributes warning for
[[company::attr]] void f();
GCC warns because it doesn't know the "company" namespace; it only knows
the "gnu" and "omp" namespaces. We could entirely disable warning about
attributes in unknown scopes but then the compiler would also miss typos
like
[[company::attrx]] void f();
or
[[gmu::warn_used_result]] int write();
so that is not a viable solution. A workaround is to use a #pragma:
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wattributes"
[[company::attr]] void f() {}
#pragma GCC diagnostic pop
but that's a mouthful and awkward to use and could also hide typos. In
fact, any macro-based solution doesn't seem like a way forward.
This patch implements -Wno-attributes=, which takes these arguments:
company::attr
company::
This option should go well with using @file: the user could have a file
containing
-Wno-attributes=vendor::attr1,vendor::attr2
and then invoke gcc with '@attrs' or similar.
I've also added a new pragma which has the same effect:
The pragma along with the new option should help with various static
analysis tools.
PR c++/101940
gcc/ChangeLog:
* attribs.c (struct scoped_attributes): Add a bool member.
(lookup_scoped_attribute_spec): Forward declare.
(register_scoped_attributes): New bool parameter, defaulted to
false. Use it.
(handle_ignored_attributes_option): New function.
(free_attr_data): New function.
(init_attributes): Call handle_ignored_attributes_option.
(attr_namespace_ignored_p): New function.
(decl_attributes): Check attr_namespace_ignored_p before
warning.
* attribs.h (free_attr_data): Declare.
(register_scoped_attributes): Adjust declaration.
(handle_ignored_attributes_option): Declare.
(canonicalize_attr_name): New function template.
(canonicalize_attr_name): Use it.
* common.opt (Wattributes=): New option with a variable.
* doc/extend.texi: Document #pragma GCC diagnostic
ignored_attributes.
* doc/invoke.texi: Document -Wno-attributes=.
* opts.c (common_handle_option) <case OPT_Wattributes_>: Handle.
* plugin.h (register_scoped_attributes): Adjust declaration.
* toplev.c (compile_file): Call free_attr_data.
gcc/c-family/ChangeLog:
* c-pragma.c (handle_pragma_diagnostic): Handle #pragma GCC
diagnostic
ignored_attributes.
gcc/testsuite/ChangeLog:
* c-c++-common/Wno-attributes-1.c: New test.
* c-c++-common/Wno-attributes-2.c: New test.
* c-c++-common/Wno-attributes-3.c: New test.
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug c++/101940] Implement -Wno-attributes=vendor::attr
2021-08-16 21:05 [Bug c++/101940] New: Implement -fignored-attributes mpolacek at gcc dot gnu.org
` (5 preceding siblings ...)
2021-11-10 14:26 ` cvs-commit at gcc dot gnu.org
@ 2021-11-10 14:31 ` mpolacek at gcc dot gnu.org
6 siblings, 0 replies; 8+ messages in thread
From: mpolacek at gcc dot gnu.org @ 2021-11-10 14:31 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101940
Marek Polacek <mpolacek at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|ASSIGNED |RESOLVED
Resolution|--- |FIXED
--- Comment #7 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Implemented in GCC 12. Will update changes.html.
^ permalink raw reply [flat|nested] 8+ messages in thread
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2021-08-16 21:05 [Bug c++/101940] New: Implement -fignored-attributes mpolacek at gcc dot gnu.org
2021-08-17 7:48 ` [Bug c++/101940] " rguenth at gcc dot gnu.org
2021-08-17 14:19 ` mpolacek at gcc dot gnu.org
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