https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91567
Bug ID: 91567
Summary: [10 Regression] Spurious -Wformat-overflow warnings
building glibc (32-bit only)
Product: gcc
Version: 10.0
Status: UNCONFIRMED
Keywords: diagnostic
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: jsm28 at gcc dot gnu.org
CC: msebor at gcc dot gnu.org
Target Milestone: ---
r274933 ("PR tree-optimization/83431 - -Wformat-truncation may incorrectly
report truncation") introduced spurious -Wformat-truncation warnings on the
following code, built with -O2 -Wall, for 32-bit systems only (e.g. x86_64 -m32
or -mx32 but not -m64). This is reduced from a build failure building glibc
for such systems with GCC trunk.
void f (char *);
void
g (char *s1, char *s2)
{
char b[1025];
__SIZE_TYPE__ n = __builtin_strlen (s1), d = __builtin_strlen (s2);
if (n + d + 1 >= 1025)
return;
__builtin_sprintf (b, "%s.%s", s1, s2);
f (b);
}
t.c: In function 'g':
t.c:9:26: warning: '%s' directive writing up to 2147483645 bytes into a region
of size 1025 [-Wformat-overflow=]
9 | __builtin_sprintf (b, "%s.%s", s1, s2);
| ^~
t.c:9:3: note: '__builtin_sprintf' output between 2 and 4294967292 bytes into a
destination of size 1025
9 | __builtin_sprintf (b, "%s.%s", s1, s2);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
