https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96407
Bug ID: 96407
Summary: LTO inlined functions don't inherit disabled warnings
Product: gcc
Version: 10.1.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: rjones at redhat dot com
Target Milestone: ---
This is a very reduced example from some real code where we are using -Werror
-Wstack-usage=5000.
We want most functions to have limited stack usage, but in some cases we have
carefully examined functions to ensure their stack usage isn't unbounded - but
it's hard to prove it - so we have disabled the warning for those functions.
--- test.c ---
#include <string.h>
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wstack-usage="
int
test (int i)
{
char str[i];
memset (str, 0, sizeof str);
return str[0]+i;
}
#pragma GCC diagnostic pop
--- main.c ---
#include <stdio.h>
extern int test (int i);
int
main (int argc, char *argv[])
{
int j = test (argc);
printf ("%d\n", j);
return 0;
}
---
$ gcc -O2 -flto main.c test.c -Werror -Wstack-usage=5000 -o a.out
main.c: In function ‘main’:
main.c:6:1: error: stack usage might be unbounded [-Werror=stack-usage=]
6 | main (int argc, char *argv[])
| ^
lto1: all warnings being treated as errors
Note that if you combine these two functions into a single file, it
does *not* warn/error, even though presumably it can easily inline the
test() function. So LTO seems to be causing the difference.
