[Bug tree-optimization/80936] New: bcmp, bcopy, and bzero not declared nonnull

["msebor at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80936

            Bug ID: 80936
           Summary: bcmp, bcopy, and bzero not declared nonnull
           Product: gcc
           Version: 7.0
            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 -Wnonnull option is expected to trigger a warning when a null pointer is
being passed to a function known to require a non-null argument.  GCC issues
this warning for functions like memcmp, memcpy, and memset but fails to issue
it for calls to the similar bcmp, bcopy, and bzero functions.  It looks like
the latter three built-ins are not declared with the nonnull attribute in
builtins.def.

$ cat z.c && gcc -O2 -S -Wall -Wextra z.c
void zero0 (void *p, unsigned n)
{
  if (p == 0)
    __builtin_memset (p, 0, n);   // warning, good
}

void zero1 (void *p, unsigned n)
{
  if (p == 0)
    __builtin_bzero (p, n);   // missing warning
}

void copy0 (void *p, const void *q, unsigned n)
{
  if (p == 0)
    __builtin_memcpy (p, q, n);   // warning, good
}

void copy1 (void *p, const void *q, unsigned n)
{
  if (q == 0)
    __builtin_memcpy (p, q, n);   // warning, good
}

void copy2 (void *p, const void *q, unsigned n)
{
  if (p == 0)
    __builtin_bcopy (q, p, n);   // missing warning
}

void copy3 (void *p, const void *q, unsigned n)
{
  if (q == 0)
    __builtin_bcopy (q, p, n);   // missing warning
}

int cmp0 (const void *p, const void *q, unsigned n)
{
  if (p == 0)
    return __builtin_memcmp (p, q, n);   // warning, good
  return 0;
}

int cmp1 (const void *p, const void *q, unsigned n)
{
  if (q == 0)
    return __builtin_memcmp (p, q, n);   // warning, good
  return 0;
}

int cmp2 (const void *p, const void *q, unsigned n)
{
  if (p == 0)
   return  __builtin_bcmp (p, q, n);   // missing warning
  return 0;
}

int cmp3 (const void *p, const void *q, unsigned n)
{
  if (q == 0)
   return  __builtin_bcmp (p, q, n);   // missing warning
  return 0;
}

z.c: In function ‘zero0’:
z.c:4:5: warning: argument 1 null where non-null expected [-Wnonnull]
     __builtin_memset (p, 0, n);   // warning, good
     ^~~~~~~~~~~~~~~~~~~~~~~~~~
z.c:4:5: note: in a call to built-in function ‘__builtin_memset’
z.c: In function ‘copy0’:
z.c:16:5: warning: argument 1 null where non-null expected [-Wnonnull]
     __builtin_memcpy (p, q, n);   // warning, good
     ^~~~~~~~~~~~~~~~~~~~~~~~~~
z.c:16:5: note: in a call to built-in function ‘__builtin_memcpy’
z.c: In function ‘copy1’:
z.c:22:5: warning: argument 2 null where non-null expected [-Wnonnull]
     __builtin_memcpy (p, q, n);   // warning, good
     ^~~~~~~~~~~~~~~~~~~~~~~~~~
z.c:22:5: note: in a call to built-in function ‘__builtin_memcpy’
z.c: In function ‘cmp0’:
z.c:40:12: warning: argument 1 null where non-null expected [-Wnonnull]
     return __builtin_memcmp (p, q, n);   // warning, good
            ^~~~~~~~~~~~~~~~~~~~~~~~~~
z.c:40:12: note: in a call to built-in function ‘__builtin_memcmp’
z.c: In function ‘cmp1’:
z.c:47:12: warning: argument 2 null where non-null expected [-Wnonnull]
     return __builtin_memcmp (p, q, n);   // warning, good
            ^~~~~~~~~~~~~~~~~~~~~~~~~~
z.c:47:12: note: in a call to built-in function ‘__builtin_memcmp’