https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92333
Bug ID: 92333
Summary: missing variable name referencing VLA in warnings
Product: gcc
Version: 10.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: middle-end
Assignee: unassigned at gcc dot gnu.org
Reporter: msebor at gcc dot gnu.org
Target Milestone: ---
When referencing a VLA in late warnings like -Warray-bounds or
-Wstringop-overflow GCC neglects to mention the VLA's name or point at its
declaration, instead printing the generic like ‘({anonymous})’ because the VLA
is a DECL with no name and pointing to the closing curly brace of the function
body.
$ cat z.c && gcc -O2 -S -Wall z.c
const int a[] = { 1, 2, 3, 4, 5 };
void f (void*);
void g (void)
{
unsigned nelts = sizeof a / sizeof *a;
char vla[nelts];
__builtin_memcpy (vla, a, nelts * sizeof *a);
f (vla);
}
void h (void)
{
const int a[] = { 1, 2, 3, 4, 5 };
unsigned nelts = sizeof a / sizeof *a;
char vla[nelts];
__builtin_memcpy (vla, a, nelts * sizeof *a);
f (vla);
}
z.c: In function ‘g’:
z.c:9:3: warning: writing 20 bytes into a region of size 5
[-Wstringop-overflow=]
9 | __builtin_memcpy (vla, a, nelts * sizeof *a);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
z.c:20:1: note: destination object declared here
20 | }
| ^
z.c: In function ‘h’:
z.c:18:3: warning: array subscript 2 is outside array bounds of ‘unsigned
char[5]’ [-Warray-bounds]
18 | __builtin_memcpy (vla, a, nelts * sizeof *a);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
z.c:20:1: note: while referencing ‘({anonymous})’
20 | }
| ^
z.c:18:3: warning: array subscript 3 is outside array bounds of ‘unsigned
char[5]’ [-Warray-bounds]
18 | __builtin_memcpy (vla, a, nelts * sizeof *a);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
z.c:20:1: note: while referencing ‘({anonymous})’
20 | }
| ^
z.c:18:3: warning: array subscript 4 is outside array bounds of ‘unsigned
char[5]’ [-Warray-bounds]
18 | __builtin_memcpy (vla, a, nelts * sizeof *a);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
z.c:20:1: note: while referencing ‘({anonymous})’
20 | }
| ^
z.c:18:3: warning: writing 4 bytes into a region of size 1
[-Wstringop-overflow=]
18 | __builtin_memcpy (vla, a, nelts * sizeof *a);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
z.c:20:1: note: destination object declared here
20 | }
| ^
