https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110694
Bug ID: 110694
Summary: False Positive -Werror=free-nonheap-object
Product: gcc
Version: 13.1.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: biggs at biggs dot xyz
Target Milestone: ---
Created attachment 55559
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=55559&action=edit
Source File
Observed on Trunk and 13.1.1
Consider:
```c
#include <stdlib.h>
typedef struct S S;
struct S {
int* i;
};
static S* s_constructor(void) {
S* s = malloc(sizeof(*s));
if (s) s->i = calloc(1, sizeof(*(s->i)));
return s;
}
static void s_destructor(S* s) {
if (!s) return;
free(s->i);
free(s);
}
static void s_destructor2(S s[static 1]) {
free(s->i);
free(s);
}
int main(void) {
S* s = s_constructor();
s_destructor(s);
s = s_constructor();
if (s) s_destructor2(s);
s = (void*) 0;
return EXIT_SUCCESS;
}
```
Compiling with gcc -Wall -Werror produces the error:
<source>: In function 's_destructor2':
<source>:23:5: error: 'free' called on unallocated object 's'
[-Werror=free-nonheap-object]
23 | free(s);
| ^~~~~~~
<source>:21:29: note: declared here
21 | static void s_destructor2(S s[static 1]) {
| ~~^~~~~~~~~~~
cc1: all warnings being treated as errors
However, there is no error when compiled with -O1 or higher optimization flag.
I don't think s_destructor2(S s[static 1]) should emit an error in the first
place though. The function definition should be compatible with s_destructor(S*
s).
