https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81650
Bug ID: 81650
Summary: gcc -m32 mishandles
-Walloc-size-larger-than=9223372036854775807
Product: gcc
Version: 7.1.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: eggert at gnu dot org
Target Milestone: ---
This is following up a Gnulib bug report:
http://lists.gnu.org/archive/html/bug-gnulib/2017-07/msg00150.html
which appears to stem from a bug in GCC. To reproduce the problem, compile the
following program:
extern void *malloc (unsigned long);
int
main (void)
{
return !malloc (5);
}
with this shell command:
gcc -m32 -Walloc-size-larger-than=9223372036854775807 -S foo.c
On Fedora 26, gcc 7.1.1 20170622 (Red Hat 7.1.1-3) outputs the following false
alarm:
foo.c: In function 'main':
foo.c:5:11: warning: argument 1 value '5' exceeds maximum object size -1
[-Walloc-size-larger-than=]
return !malloc (5);
^~~~~~~~~~
foo.c:1:14: note: in a call to allocation function 'malloc' declared here
extern void *malloc (unsigned long);
^~~~~~
GCC works correctly (i.e., silently) if -m32 is omitted. Evidently GCC is not
doing the right thing when the operand of -Walloc-size-larger-than is too
large: such an operand should be treated as infinity, not as -1.
