https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97552
Bug ID: 97552
Summary: missing waning passing null to a VLA argument declared
[static]
Product: gcc
Version: 11.0
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: ---
The call to f0() below is diagnosed as expected because the [static N] notation
implies that the argument must have at least N elements.
The call to f1() shouldn't be diagnosed because without [static] and witout
attribute nonnull the function should be expected to gracefully deal with null
a pointer when the bound is zero.
But because of the [static] the call to f2() should again be diagnosed, even
when n is zero.
$ cat a.c && /build/gcc-master/gcc/xgcc -B /build/gcc-master/gcc -O2 -S -Wall
a.c
void f0 (int, int a[static 0]); // a must be an array
void f1 (int n, int a[n]); // a can be null
void f2 (int n, int a[static n]); // a must be an array
void h (void)
{
f0 (0, 0); // warning (good)
f1 (0, 0); // no warning (good)
f2 (0, 0); // missing warning
}
a.c: In function ‘h’:
a.c:7:3: warning: argument 2 to ‘int[static 4]’ is null where non-null expected
[-Wnonnull]
7 | f0 (0, 0); // warning (good)
| ^~~~~~~~~
a.c:1:6: note: in a call to function ‘f0’
1 | void f0 (int, int a[static 0]); // a must be an array
| ^~
See https://gcc.gnu.org/pipermail/gcc/2020-October/234036.html for more
context.
