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* [Bug c/114831] New: typeof doesn't evaluate expression when it has variably modified type in some cases
@ 2024-04-24 1:48 mforney at mforney dot org
2024-05-18 11:54 ` [Bug c/114831] " uecker at gcc dot gnu.org
` (2 more replies)
0 siblings, 3 replies; 4+ messages in thread
From: mforney at mforney dot org @ 2024-04-24 1:48 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114831
Bug ID: 114831
Summary: typeof doesn't evaluate expression when it has
variably modified type in some cases
Product: gcc
Version: 14.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: mforney at mforney dot org
Target Milestone: ---
C23 introduced typeof, and 6.7.2.5p4 says
> If the type of the operand is a variably modified type, the operand
> is evaluated; otherwise, the operand is not evaluated.
However, gcc doesn't evaluate the operand when it has variably modified type in
some cases.
Consider the following program:
#include <stdio.h>
int n = 1;
int main(void) {
int a[n], (*p)[n] = 0;
typeof(puts("&a is variably-modified"), &a) p1;
typeof(puts("p is variably-modified"), p) p2;
typeof(puts("p1 is variably-modified"), p1) p3;
typeof(puts("p2 is variably-modified"), p2) p4;
}
All four of the typeof operands have the same type, int (*)[n]. But when I run
this program it prints just:
p is variably-modified
p2 is variably-modified
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug c/114831] typeof doesn't evaluate expression when it has variably modified type in some cases 2024-04-24 1:48 [Bug c/114831] New: typeof doesn't evaluate expression when it has variably modified type in some cases mforney at mforney dot org @ 2024-05-18 11:54 ` uecker at gcc dot gnu.org 2024-05-18 20:21 ` muecker at gwdg dot de 2024-05-24 15:02 ` cvs-commit at gcc dot gnu.org 2 siblings, 0 replies; 4+ messages in thread From: uecker at gcc dot gnu.org @ 2024-05-18 11:54 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114831 uecker at gcc dot gnu.org changed: What |Removed |Added ---------------------------------------------------------------------------- Status|UNCONFIRMED |NEW Last reconfirmed| |2024-05-18 CC| |uecker at gcc dot gnu.org Ever confirmed|0 |1 --- Comment #1 from uecker at gcc dot gnu.org --- Confirmed. We need to propagate C_TYPE_VARIABLY_MODIFIED correctly for address of an array-to-pointer-decay. ^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug c/114831] typeof doesn't evaluate expression when it has variably modified type in some cases 2024-04-24 1:48 [Bug c/114831] New: typeof doesn't evaluate expression when it has variably modified type in some cases mforney at mforney dot org 2024-05-18 11:54 ` [Bug c/114831] " uecker at gcc dot gnu.org @ 2024-05-18 20:21 ` muecker at gwdg dot de 2024-05-24 15:02 ` cvs-commit at gcc dot gnu.org 2 siblings, 0 replies; 4+ messages in thread From: muecker at gwdg dot de @ 2024-05-18 20:21 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114831 Martin Uecker <muecker at gwdg dot de> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |muecker at gwdg dot de --- Comment #2 from Martin Uecker <muecker at gwdg dot de> --- PATCH: https://gcc.gnu.org/pipermail/gcc-patches/2024-May/652089.html ^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug c/114831] typeof doesn't evaluate expression when it has variably modified type in some cases 2024-04-24 1:48 [Bug c/114831] New: typeof doesn't evaluate expression when it has variably modified type in some cases mforney at mforney dot org 2024-05-18 11:54 ` [Bug c/114831] " uecker at gcc dot gnu.org 2024-05-18 20:21 ` muecker at gwdg dot de @ 2024-05-24 15:02 ` cvs-commit at gcc dot gnu.org 2 siblings, 0 replies; 4+ messages in thread From: cvs-commit at gcc dot gnu.org @ 2024-05-24 15:02 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114831 --- Comment #3 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Martin Uecker <uecker@gcc.gnu.org>: https://gcc.gnu.org/g:9f1798c1a93257526196a3c19828e40fb28ac551 commit r15-825-g9f1798c1a93257526196a3c19828e40fb28ac551 Author: Martin Uecker <uecker@tugraz.at> Date: Sat May 18 14:40:02 2024 +0200 c: Fix for some variably modified types not being recognized [PR114831] We did not evaluate expressions with variably modified types correctly in typeof and did not produce warnings when jumping over declarations using typeof. After addressof or array-to-pointer decay we construct new pointer types that have to be marked variably modified if the pointer target is variably modified. 2024-05-18 Martin Uecker <uecker@tugraz.at> PR c/114831 gcc/c/ * c-typeck.cc (array_to_pointer_conversion, build_unary_op): Propagate flag to pointer target. gcc/testsuite/ * gcc.dg/pr114831-1.c: New test. * gcc.dg/pr114831-2.c: New test. * gcc.dg/gnu23-varmod-1.c: New test. * gcc.dg/gnu23-varmod-2.c: New test. ^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2024-05-24 15:02 UTC | newest] Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2024-04-24 1:48 [Bug c/114831] New: typeof doesn't evaluate expression when it has variably modified type in some cases mforney at mforney dot org 2024-05-18 11:54 ` [Bug c/114831] " uecker at gcc dot gnu.org 2024-05-18 20:21 ` muecker at gwdg dot de 2024-05-24 15:02 ` cvs-commit at gcc dot gnu.org
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