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* [Bug c++/94912] New: Non-consistent behaviour of VLAs compared to C
@ 2020-05-02 1:12 gabravier at gmail dot com
2020-05-02 21:46 ` [Bug c++/94912] Non-consistent behaviour of VLAs in C++ mode " msebor at gcc dot gnu.org
0 siblings, 1 reply; 2+ messages in thread
From: gabravier at gmail dot com @ 2020-05-02 1:12 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94912
Bug ID: 94912
Summary: Non-consistent behaviour of VLAs compared to C
Product: gcc
Version: 10.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: gabravier at gmail dot com
Target Milestone: ---
#include <stdbool.h>
#include <stdio.h>
bool f(int n)
{
typedef int A[n];
++n;
A a;
int b[n];
n -= 2;
typedef int C[n];
C c;
return (sizeof(a) < sizeof(b)) && (sizeof(a) > sizeof(c));
}
int main()
{
printf("%d", (int)f(10));
}
If compiled as C, this program will print 1. If compiled as C++, this program
will print 0. The C++ frontend seems to fail to take into account that the
`typedef`'s results are calculated at runtime based on the current value of
`n`.
^ permalink raw reply [flat|nested] 2+ messages in thread
* [Bug c++/94912] Non-consistent behaviour of VLAs in C++ mode compared to C
2020-05-02 1:12 [Bug c++/94912] New: Non-consistent behaviour of VLAs compared to C gabravier at gmail dot com
@ 2020-05-02 21:46 ` msebor at gcc dot gnu.org
0 siblings, 0 replies; 2+ messages in thread
From: msebor at gcc dot gnu.org @ 2020-05-02 21:46 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94912
Martin Sebor <msebor at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Resolution|--- |DUPLICATE
Status|UNCONFIRMED |RESOLVED
CC| |msebor at gcc dot gnu.org
--- Comment #1 from Martin Sebor <msebor at gcc dot gnu.org> ---
I think this is the same bug as reported in pr68531.
*** This bug has been marked as a duplicate of bug 68531 ***
^ permalink raw reply [flat|nested] 2+ messages in thread
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2020-05-02 1:12 [Bug c++/94912] New: Non-consistent behaviour of VLAs compared to C gabravier at gmail dot com
2020-05-02 21:46 ` [Bug c++/94912] Non-consistent behaviour of VLAs in C++ mode " msebor at gcc dot gnu.org
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