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* [Bug c++/98994] New: Empty type with [[no_unique_address]] in union with constructor is not a constant expression
@ 2021-02-08 0:10 david at doublewise dot net
2021-02-08 9:35 ` [Bug c++/98994] [11 Regression] " rguenth at gcc dot gnu.org
` (4 more replies)
0 siblings, 5 replies; 6+ messages in thread
From: david at doublewise dot net @ 2021-02-08 0:10 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98994
Bug ID: 98994
Summary: Empty type with [[no_unique_address]] in union with
constructor is not a constant expression
Product: gcc
Version: 11.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: david at doublewise dot net
Target Milestone: ---
The following valid translation unit:
```
struct empty {};
union U {
constexpr U():
a()
{
}
[[no_unique_address]] empty a;
};
constexpr U u;
```
is incorrectly rejected by gcc 11 with the error:
```
<source>:12:13: error: 'U()' is not a constant expression
12 | constexpr U u;
| ^
<source>:12:13: error: 'U()' is not a constant expression because it refers to
an incompletely initialized variable
Compiler returned: 1
```
See it live: https://godbolt.org/z/PWcco3
This code was accepted in gcc 10.2.
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug c++/98994] [11 Regression] Empty type with [[no_unique_address]] in union with constructor is not a constant expression
2021-02-08 0:10 [Bug c++/98994] New: Empty type with [[no_unique_address]] in union with constructor is not a constant expression david at doublewise dot net
@ 2021-02-08 9:35 ` rguenth at gcc dot gnu.org
2021-02-08 9:40 ` [Bug c++/98994] [11 Regression] Empty type with [[no_unique_address]] in union with constructor is not a constant expression since r11-6918 jakub at gcc dot gnu.org
` (3 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: rguenth at gcc dot gnu.org @ 2021-02-08 9:35 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98994
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Summary|Empty type with |[11 Regression] Empty type
|[[no_unique_address]] in |with [[no_unique_address]]
|union with constructor is |in union with constructor
|not a constant expression |is not a constant
| |expression
Target Milestone|--- |11.0
Keywords| |rejects-valid
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug c++/98994] [11 Regression] Empty type with [[no_unique_address]] in union with constructor is not a constant expression since r11-6918
2021-02-08 0:10 [Bug c++/98994] New: Empty type with [[no_unique_address]] in union with constructor is not a constant expression david at doublewise dot net
2021-02-08 9:35 ` [Bug c++/98994] [11 Regression] " rguenth at gcc dot gnu.org
@ 2021-02-08 9:40 ` jakub at gcc dot gnu.org
2021-02-08 20:41 ` jason at gcc dot gnu.org
` (2 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: jakub at gcc dot gnu.org @ 2021-02-08 9:40 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98994
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Priority|P3 |P1
Summary|[11 Regression] Empty type |[11 Regression] Empty type
|with [[no_unique_address]] |with [[no_unique_address]]
|in union with constructor |in union with constructor
|is not a constant |is not a constant
|expression |expression since r11-6918
Last reconfirmed| |2021-02-08
Ever confirmed|0 |1
CC| |jakub at gcc dot gnu.org,
| |jason at gcc dot gnu.org
--- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Started with r11-6918-ga4dfd0f089af33f2af57bf422f9859405b9b4a16
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug c++/98994] [11 Regression] Empty type with [[no_unique_address]] in union with constructor is not a constant expression since r11-6918
2021-02-08 0:10 [Bug c++/98994] New: Empty type with [[no_unique_address]] in union with constructor is not a constant expression david at doublewise dot net
2021-02-08 9:35 ` [Bug c++/98994] [11 Regression] " rguenth at gcc dot gnu.org
2021-02-08 9:40 ` [Bug c++/98994] [11 Regression] Empty type with [[no_unique_address]] in union with constructor is not a constant expression since r11-6918 jakub at gcc dot gnu.org
@ 2021-02-08 20:41 ` jason at gcc dot gnu.org
2021-02-09 1:52 ` cvs-commit at gcc dot gnu.org
2021-02-09 14:35 ` jason at gcc dot gnu.org
4 siblings, 0 replies; 6+ messages in thread
From: jason at gcc dot gnu.org @ 2021-02-08 20:41 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98994
Jason Merrill <jason at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Assignee|unassigned at gcc dot gnu.org |jason at gcc dot gnu.org
Status|NEW |ASSIGNED
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug c++/98994] [11 Regression] Empty type with [[no_unique_address]] in union with constructor is not a constant expression since r11-6918
2021-02-08 0:10 [Bug c++/98994] New: Empty type with [[no_unique_address]] in union with constructor is not a constant expression david at doublewise dot net
` (2 preceding siblings ...)
2021-02-08 20:41 ` jason at gcc dot gnu.org
@ 2021-02-09 1:52 ` cvs-commit at gcc dot gnu.org
2021-02-09 14:35 ` jason at gcc dot gnu.org
4 siblings, 0 replies; 6+ messages in thread
From: cvs-commit at gcc dot gnu.org @ 2021-02-09 1:52 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98994
--- Comment #2 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Jason Merrill <jason@gcc.gnu.org>:
https://gcc.gnu.org/g:a8dd2b3e96590ceccead63d28fc91c956a5f1a73
commit r11-7141-ga8dd2b3e96590ceccead63d28fc91c956a5f1a73
Author: Jason Merrill <jason@redhat.com>
Date: Mon Feb 8 15:56:11 2021 -0500
c++: constexpr, union, and no_unique_address [PR98994]
My second patch for 97566 omits nested CONSTRUCTORs for empty fields, but
we
do want them for empty union members.
gcc/cp/ChangeLog:
PR c++/98994
PR c++/97566
* constexpr.c (cxx_eval_store_expression): Only skip empty fields
in
RECORD_TYPE.
gcc/testsuite/ChangeLog:
PR c++/98994
* g++.dg/cpp2a/no_unique_address12.C: New test.
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug c++/98994] [11 Regression] Empty type with [[no_unique_address]] in union with constructor is not a constant expression since r11-6918
2021-02-08 0:10 [Bug c++/98994] New: Empty type with [[no_unique_address]] in union with constructor is not a constant expression david at doublewise dot net
` (3 preceding siblings ...)
2021-02-09 1:52 ` cvs-commit at gcc dot gnu.org
@ 2021-02-09 14:35 ` jason at gcc dot gnu.org
4 siblings, 0 replies; 6+ messages in thread
From: jason at gcc dot gnu.org @ 2021-02-09 14:35 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98994
Jason Merrill <jason at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Resolution|--- |FIXED
Status|ASSIGNED |RESOLVED
--- Comment #3 from Jason Merrill <jason at gcc dot gnu.org> ---
Fixed.
^ permalink raw reply [flat|nested] 6+ messages in thread
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2021-02-08 0:10 [Bug c++/98994] New: Empty type with [[no_unique_address]] in union with constructor is not a constant expression david at doublewise dot net
2021-02-08 9:35 ` [Bug c++/98994] [11 Regression] " rguenth at gcc dot gnu.org
2021-02-08 9:40 ` [Bug c++/98994] [11 Regression] Empty type with [[no_unique_address]] in union with constructor is not a constant expression since r11-6918 jakub at gcc dot gnu.org
2021-02-08 20:41 ` jason at gcc dot gnu.org
2021-02-09 1:52 ` cvs-commit at gcc dot gnu.org
2021-02-09 14:35 ` jason at gcc dot gnu.org
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