public inbox for gcc-bugs@sourceware.org
help / color / mirror / Atom feed
* [Bug c++/104994] New: extern thread_local declaration rejected in constexpr
@ 2022-03-20 22:50 hstong at ca dot ibm.com
2022-03-21 10:37 ` [Bug c++/104994] " jakub at gcc dot gnu.org
` (9 more replies)
0 siblings, 10 replies; 11+ messages in thread
From: hstong at ca dot ibm.com @ 2022-03-20 22:50 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104994
Bug ID: 104994
Summary: extern thread_local declaration rejected in constexpr
Product: gcc
Version: 12.0
Status: UNCONFIRMED
Keywords: rejects-valid
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: hstong at ca dot ibm.com
Target Milestone: ---
GCC rejects block-scope extern declarations with the `thread_local` keyword in
constexpr bodies. The relevant wording (prior to removal by P2242
<https://wg21.link/p2242>) prohibits only definitions.
### SOURCE (<stdin>):
constexpr void f() {
extern thread_local int x;
}
### COMPILER INVOCATION:
g++ -fsyntax-only -std=c++20 -xc++ -
### ACTUAL OUTPUT:
<stdin>: In function 'constexpr void f()':
<stdin>:2:27: error: 'x' declared 'thread_local' in 'constexpr' function only
available with '-std=c++2b' or '-std=gnu++2b'
### EXPECTED OUTPUT:
Clean compile.
### COMPILER VERSION INFO (g++ -v):
Using built-in specs.
COLLECT_GCC=/opt/wandbox/gcc-head/bin/g++
COLLECT_LTO_WRAPPER=/opt/wandbox/gcc-head/libexec/gcc/x86_64-pc-linux-gnu/12.0.1/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../source/configure --prefix=/opt/wandbox/gcc-head
--enable-languages=c,c++ --disable-multilib --without-ppl --without-cloog-ppl
--enable-checking=release --disable-nls --enable-lto
LDFLAGS=-Wl,-rpath,/opt/wandbox/gcc-head/lib,-rpath,/opt/wandbox/gcc-head/lib64,-rpath,/opt/wandbox/gcc-head/lib32
Thread model: posix
Supported LTO compression algorithms: zlib
gcc version 12.0.1 20220319 (experimental) (GCC)
^ permalink raw reply [flat|nested] 11+ messages in thread
* [Bug c++/104994] extern thread_local declaration rejected in constexpr
2022-03-20 22:50 [Bug c++/104994] New: extern thread_local declaration rejected in constexpr hstong at ca dot ibm.com
@ 2022-03-21 10:37 ` jakub at gcc dot gnu.org
2022-03-21 10:44 ` jakub at gcc dot gnu.org
` (8 subsequent siblings)
9 siblings, 0 replies; 11+ messages in thread
From: jakub at gcc dot gnu.org @ 2022-03-21 10:37 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104994
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |jakub at gcc dot gnu.org
--- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
So, is
constexpr bool foo() { extern thread_local int x; return true; }
static_assert (foo (), "");
valid C++14/17 and invalid C++20/23 then (the new P2242 wording says
"a control flow that passes through a declaration of a variable with static or
thread storage duration;")?
^ permalink raw reply [flat|nested] 11+ messages in thread
* [Bug c++/104994] extern thread_local declaration rejected in constexpr
2022-03-20 22:50 [Bug c++/104994] New: extern thread_local declaration rejected in constexpr hstong at ca dot ibm.com
2022-03-21 10:37 ` [Bug c++/104994] " jakub at gcc dot gnu.org
@ 2022-03-21 10:44 ` jakub at gcc dot gnu.org
2022-03-21 13:56 ` redi at gcc dot gnu.org
` (7 subsequent siblings)
9 siblings, 0 replies; 11+ messages in thread
From: jakub at gcc dot gnu.org @ 2022-03-21 10:44 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104994
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |jason at gcc dot gnu.org
--- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Jason, thoughts on this?
It is true that clang++ accepts the #c0 testcase, both clang++ and g++ accept
const thread_local int a = 1;
constexpr int foo () { return a; }
static_assert (foo () == 1, "");
^ permalink raw reply [flat|nested] 11+ messages in thread
* [Bug c++/104994] extern thread_local declaration rejected in constexpr
2022-03-20 22:50 [Bug c++/104994] New: extern thread_local declaration rejected in constexpr hstong at ca dot ibm.com
2022-03-21 10:37 ` [Bug c++/104994] " jakub at gcc dot gnu.org
2022-03-21 10:44 ` jakub at gcc dot gnu.org
@ 2022-03-21 13:56 ` redi at gcc dot gnu.org
2022-03-21 13:57 ` redi at gcc dot gnu.org
` (6 subsequent siblings)
9 siblings, 0 replies; 11+ messages in thread
From: redi at gcc dot gnu.org @ 2022-03-21 13:56 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104994
--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Ville says that P2242 did not intend to add new restrictions, so this was valid
in C++20, and should still be valid in C++23 even if control flow passes over
that non-local declaration. We might have a defect in the current draft,
because it seems to forbid it.
^ permalink raw reply [flat|nested] 11+ messages in thread
* [Bug c++/104994] extern thread_local declaration rejected in constexpr
2022-03-20 22:50 [Bug c++/104994] New: extern thread_local declaration rejected in constexpr hstong at ca dot ibm.com
` (2 preceding siblings ...)
2022-03-21 13:56 ` redi at gcc dot gnu.org
@ 2022-03-21 13:57 ` redi at gcc dot gnu.org
2022-03-21 15:26 ` jakub at gcc dot gnu.org
` (5 subsequent siblings)
9 siblings, 0 replies; 11+ messages in thread
From: redi at gcc dot gnu.org @ 2022-03-21 13:57 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104994
--- Comment #4 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to Jonathan Wakely from comment #3)
> We might have a defect in the
> current draft, because it seems to forbid it.
Oh, which Hubert already filed:
https://cplusplus.github.io/CWG/issues/2552.html
^ permalink raw reply [flat|nested] 11+ messages in thread
* [Bug c++/104994] extern thread_local declaration rejected in constexpr
2022-03-20 22:50 [Bug c++/104994] New: extern thread_local declaration rejected in constexpr hstong at ca dot ibm.com
` (3 preceding siblings ...)
2022-03-21 13:57 ` redi at gcc dot gnu.org
@ 2022-03-21 15:26 ` jakub at gcc dot gnu.org
2022-03-24 9:13 ` cvs-commit at gcc dot gnu.org
` (4 subsequent siblings)
9 siblings, 0 replies; 11+ messages in thread
From: jakub at gcc dot gnu.org @ 2022-03-21 15:26 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104994
--- Comment #5 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Created attachment 52657
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=52657&action=edit
gcc12-pr104994.patch
Untested fix. This anticipates that CWG. If we wouldn't, we should
temporarily revert those changes for the passing through case.
^ permalink raw reply [flat|nested] 11+ messages in thread
* [Bug c++/104994] extern thread_local declaration rejected in constexpr
2022-03-20 22:50 [Bug c++/104994] New: extern thread_local declaration rejected in constexpr hstong at ca dot ibm.com
` (4 preceding siblings ...)
2022-03-21 15:26 ` jakub at gcc dot gnu.org
@ 2022-03-24 9:13 ` cvs-commit at gcc dot gnu.org
2022-03-29 5:54 ` cvs-commit at gcc dot gnu.org
` (3 subsequent siblings)
9 siblings, 0 replies; 11+ messages in thread
From: cvs-commit at gcc dot gnu.org @ 2022-03-24 9:13 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104994
--- Comment #6 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Jakub Jelinek <jakub@gcc.gnu.org>:
https://gcc.gnu.org/g:72124f487ccb5c8065dd5f7b8fba254600b7e611
commit r12-7793-g72124f487ccb5c8065dd5f7b8fba254600b7e611
Author: Jakub Jelinek <jakub@redhat.com>
Date: Thu Mar 24 10:12:25 2022 +0100
c++: extern thread_local declarations in constexpr [PR104994]
C++14 to C++20 apparently should allow extern thread_local declarations in
constexpr functions, however useless they are there (because accessing
such vars is not valid in a constant expression, perhaps sizeof/decltype).
P2242 changed that for C++23 to passing through declaration but
https://cplusplus.github.io/CWG/issues/2552.html
has been filed for it yesterday.
The following patch implements the proposed wording of CWG 2552 in addition
to fixing the C++14 - C++20 handling bug.
If you'd like instead to keep the current pedantic C++23 wording for now,
that would mean taking out the first hunk (cxx_eval_constant_expression)
and
g++.dg/cpp23/constexpr-nonlit2.C hunk.
2022-03-24 Jakub Jelinek <jakub@redhat.com>
PR c++/104994
* constexpr.cc (cxx_eval_constant_expression): Don't diagnose
passing
through extern thread_local declarations. Change wording from
declaration to definition.
(potential_constant_expression_1): Don't diagnose extern
thread_local
declarations. Change wording from declared to defined.
* decl.cc (start_decl): Likewise.
* g++.dg/diagnostic/constexpr1.C: Change expected diagnostic
wording
from declared to defined.
* g++.dg/cpp23/constexpr-nonlit1.C: Likewise.
(garply): Change dg-error into dg-bogus.
* g++.dg/cpp23/constexpr-nonlit2.C: Change expected diagnostic
wording
from declaration to definition.
* g++.dg/cpp23/constexpr-nonlit6.C: Change expected diagnostic
wording
from declared to defined.
* g++.dg/cpp23/constexpr-nonlit7.C: New test.
* g++.dg/cpp2a/constexpr-try5.C: Change expected diagnostic wording
from declared to defined.
* g++.dg/cpp2a/consteval3.C: Likewise.
^ permalink raw reply [flat|nested] 11+ messages in thread
* [Bug c++/104994] extern thread_local declaration rejected in constexpr
2022-03-20 22:50 [Bug c++/104994] New: extern thread_local declaration rejected in constexpr hstong at ca dot ibm.com
` (5 preceding siblings ...)
2022-03-24 9:13 ` cvs-commit at gcc dot gnu.org
@ 2022-03-29 5:54 ` cvs-commit at gcc dot gnu.org
2022-05-10 8:25 ` cvs-commit at gcc dot gnu.org
` (2 subsequent siblings)
9 siblings, 0 replies; 11+ messages in thread
From: cvs-commit at gcc dot gnu.org @ 2022-03-29 5:54 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104994
--- Comment #7 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-11 branch has been updated by Jakub Jelinek
<jakub@gcc.gnu.org>:
https://gcc.gnu.org/g:51b5fa6b4257850c99094f2cf7ece949b00a7826
commit r11-9734-g51b5fa6b4257850c99094f2cf7ece949b00a7826
Author: Jakub Jelinek <jakub@redhat.com>
Date: Thu Mar 24 10:12:25 2022 +0100
c++: extern thread_local declarations in constexpr [PR104994]
C++14 to C++20 apparently should allow extern thread_local declarations in
constexpr functions, however useless they are there (because accessing
such vars is not valid in a constant expression, perhaps sizeof/decltype).
P2242 changed that for C++23 to passing through declaration but
https://cplusplus.github.io/CWG/issues/2552.html
has been filed for it yesterday.
2022-03-24 Jakub Jelinek <jakub@redhat.com>
PR c++/104994
* constexpr.c (potential_constant_expression_1): Don't diagnose
extern
thread_local declarations.
* decl.c (start_decl): Likewise.
* g++.dg/cpp23/constexpr-nonlit7.C: New test.
(cherry picked from commit 72124f487ccb5c8065dd5f7b8fba254600b7e611)
^ permalink raw reply [flat|nested] 11+ messages in thread
* [Bug c++/104994] extern thread_local declaration rejected in constexpr
2022-03-20 22:50 [Bug c++/104994] New: extern thread_local declaration rejected in constexpr hstong at ca dot ibm.com
` (6 preceding siblings ...)
2022-03-29 5:54 ` cvs-commit at gcc dot gnu.org
@ 2022-05-10 8:25 ` cvs-commit at gcc dot gnu.org
2022-05-11 6:25 ` cvs-commit at gcc dot gnu.org
2022-05-11 6:36 ` jakub at gcc dot gnu.org
9 siblings, 0 replies; 11+ messages in thread
From: cvs-commit at gcc dot gnu.org @ 2022-05-10 8:25 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104994
--- Comment #8 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-10 branch has been updated by Jakub Jelinek
<jakub@gcc.gnu.org>:
https://gcc.gnu.org/g:125234a3b78138e22112bb3f207df987817b6818
commit r10-10698-g125234a3b78138e22112bb3f207df987817b6818
Author: Jakub Jelinek <jakub@redhat.com>
Date: Thu Mar 24 10:12:25 2022 +0100
c++: extern thread_local declarations in constexpr [PR104994]
C++14 to C++20 apparently should allow extern thread_local declarations in
constexpr functions, however useless they are there (because accessing
such vars is not valid in a constant expression, perhaps sizeof/decltype).
P2242 changed that for C++23 to passing through declaration but
https://cplusplus.github.io/CWG/issues/2552.html
has been filed for it yesterday.
2022-03-24 Jakub Jelinek <jakub@redhat.com>
PR c++/104994
* constexpr.c (potential_constant_expression_1): Don't diagnose
extern
thread_local declarations.
* decl.c (start_decl): Likewise.
* g++.dg/cpp2a/constexpr-nonlit7.C: New test.
(cherry picked from commit 72124f487ccb5c8065dd5f7b8fba254600b7e611)
^ permalink raw reply [flat|nested] 11+ messages in thread
* [Bug c++/104994] extern thread_local declaration rejected in constexpr
2022-03-20 22:50 [Bug c++/104994] New: extern thread_local declaration rejected in constexpr hstong at ca dot ibm.com
` (7 preceding siblings ...)
2022-05-10 8:25 ` cvs-commit at gcc dot gnu.org
@ 2022-05-11 6:25 ` cvs-commit at gcc dot gnu.org
2022-05-11 6:36 ` jakub at gcc dot gnu.org
9 siblings, 0 replies; 11+ messages in thread
From: cvs-commit at gcc dot gnu.org @ 2022-05-11 6:25 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104994
--- Comment #9 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-9 branch has been updated by Jakub Jelinek
<jakub@gcc.gnu.org>:
https://gcc.gnu.org/g:54bccc8e05f6f9480b50c4edfb2a364d344e72c0
commit r9-10141-g54bccc8e05f6f9480b50c4edfb2a364d344e72c0
Author: Jakub Jelinek <jakub@redhat.com>
Date: Thu Mar 24 10:12:25 2022 +0100
c++: extern thread_local declarations in constexpr [PR104994]
C++14 to C++20 apparently should allow extern thread_local declarations in
constexpr functions, however useless they are there (because accessing
such vars is not valid in a constant expression, perhaps sizeof/decltype).
P2242 changed that for C++23 to passing through declaration but
https://cplusplus.github.io/CWG/issues/2552.html
has been filed for it yesterday.
2022-03-24 Jakub Jelinek <jakub@redhat.com>
PR c++/104994
* constexpr.c (potential_constant_expression_1): Don't diagnose
extern
thread_local declarations.
* decl.c (start_decl): Likewise.
* g++.dg/cpp2a/constexpr-nonlit7.C: New test.
(cherry picked from commit 72124f487ccb5c8065dd5f7b8fba254600b7e611)
^ permalink raw reply [flat|nested] 11+ messages in thread
* [Bug c++/104994] extern thread_local declaration rejected in constexpr
2022-03-20 22:50 [Bug c++/104994] New: extern thread_local declaration rejected in constexpr hstong at ca dot ibm.com
` (8 preceding siblings ...)
2022-05-11 6:25 ` cvs-commit at gcc dot gnu.org
@ 2022-05-11 6:36 ` jakub at gcc dot gnu.org
9 siblings, 0 replies; 11+ messages in thread
From: jakub at gcc dot gnu.org @ 2022-05-11 6:36 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104994
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Resolution|--- |FIXED
Status|UNCONFIRMED |RESOLVED
--- Comment #10 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Fixed.
^ permalink raw reply [flat|nested] 11+ messages in thread
end of thread, other threads:[~2022-05-11 6:36 UTC | newest]
Thread overview: 11+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2022-03-20 22:50 [Bug c++/104994] New: extern thread_local declaration rejected in constexpr hstong at ca dot ibm.com
2022-03-21 10:37 ` [Bug c++/104994] " jakub at gcc dot gnu.org
2022-03-21 10:44 ` jakub at gcc dot gnu.org
2022-03-21 13:56 ` redi at gcc dot gnu.org
2022-03-21 13:57 ` redi at gcc dot gnu.org
2022-03-21 15:26 ` jakub at gcc dot gnu.org
2022-03-24 9:13 ` cvs-commit at gcc dot gnu.org
2022-03-29 5:54 ` cvs-commit at gcc dot gnu.org
2022-05-10 8:25 ` cvs-commit at gcc dot gnu.org
2022-05-11 6:25 ` cvs-commit at gcc dot gnu.org
2022-05-11 6:36 ` jakub at gcc dot gnu.org
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).