[Bug analyzer/119749] New: Functions with attribute malloc only warn of possibly-NULL use if attribute has a deallocator

[pietro.gcc at sociotechnical dot xyz via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119749

            Bug ID: 119749
           Summary: Functions with attribute malloc only warn of
                    possibly-NULL use if attribute has a deallocator
           Product: gcc
           Version: 15.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: analyzer
          Assignee: dmalcolm at gcc dot gnu.org
          Reporter: pietro.gcc at sociotechnical dot xyz
  Target Milestone: ---

When adding "__attribute__ ((__malloc__))" to a function the analyzer doesn't
warn that the function may return a null pointer.

If I add a deallocator to the attribute then the analyzer warns about the null
pointer. In the reproducer bellow it won't warn for "use_my_malloc" but will
for the other functions, including the one that uses the system malloc.

I'm using a build from trunk and running "gcc -fanalyzer -c test.c -o test.o".

--------
#include <stdlib.h>

extern void do_something (int*) __attribute__ ((__nonnull__));

extern void *my_malloc (size_t) __attribute__ ((__malloc__));

extern void *my_malloc_free (size_t) __attribute__ ((__malloc__, __malloc__
(free)));

extern void *my_malloc_free1 (size_t) __attribute__ ((__malloc__ (free, 1)));

int use_my_malloc () {
  int *something;
  something = (int *)my_malloc (16);

  do_something (something);

  return 0;
}

int use_my_malloc_free () {
  int *something;
  something = (int *)my_malloc_free (16);

  do_something (something);

  return 0;
}

int use_my_malloc_free1 () {
  int *something;
  something = (int *)my_malloc_free1 (16);

  do_something (something);

  return 0;
}

int use_system_malloc () {
  int *something;
  something = (int *)malloc (16);

  do_something (something);

  return 0;
}