[Bug tree-optimization/101584] New: missing -Wuninitialized with an allocated object after a built-in call

[msebor at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101584

            Bug ID: 101584
           Summary: missing -Wuninitialized with an allocated object after
                    a built-in call
           Product: gcc
           Version: 11.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: msebor at gcc dot gnu.org
  Target Milestone: ---

The puts() calls below should be diagnosed by -Wuninitialized but aren't
because the alias analysis the warning relies on determines that the argument
and the result returned by malloc() or the VLA might alias each other.

$ cat a.c && gcc -O2 -S -Wall /build/tmp/a.c
void f  (const char *s)
{ 
  char *p = __builtin_malloc (__builtin_strlen (s));

  __builtin_printf ("%s", s);

  __builtin_puts (p);   // missing -Wununitialized
}


void g  (const char *s)
{
  char a[__builtin_strlen (s)];

  __builtin_printf ("%s", s);

  __builtin_puts (a);   // missing -Wununitialized
}