[Bug c/79696] missing -Wunused-result on calls to malloc() and calloc()

[msebor at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79696

Martin Sebor <msebor at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|WAITING                     |UNCONFIRMED
     Ever confirmed|1                           |0

--- Comment #3 from Martin Sebor <msebor at gcc dot gnu.org> ---
Whoops.  The test case is below.  Also, the calls to the functions are only
eliminated with optimization.  Otherwise they're emitted and the leaks allowed
to go undetected.  (For some reason I don't understand, Glibc only also marks
functions warn_unused_result with _FORTIFY_SOURCE, otherwise its __wur macro
that's used for this purpose expands to nothing.)

$ cat a.c && gcc -S -Wall -Wextra -Wpedantic -fdump-tree-optimized=/dev/stdout
a.c
void f (unsigned n)
{
  __builtin_malloc (n);
}

void g (unsigned n)
{
  __builtin_calloc (n, n);
}

void h (unsigned n)
{
  __builtin_aligned_alloc (n, 2);
}

;; Function f (f, funcdef_no=2, decl_uid=2364, cgraph_uid=2, symbol_order=2)

f (unsigned int n)
{
  long unsigned int _1;

  <bb 2> [0.00%] [count: INV]:
  _1 = (long unsigned int) n_2(D);
  __builtin_malloc (_1);
  return;

}



;; Function g (g, funcdef_no=3, decl_uid=2367, cgraph_uid=3, symbol_order=3)

g (unsigned int n)
{
  long unsigned int _1;
  long unsigned int _2;

  <bb 2> [0.00%] [count: INV]:
  _1 = (long unsigned int) n_3(D);
  _2 = (long unsigned int) n_3(D);
  __builtin_calloc (_2, _1);
  return;

}



;; Function h (h, funcdef_no=4, decl_uid=2370, cgraph_uid=4, symbol_order=4)

h (unsigned int n)
{
  long unsigned int _1;

  <bb 2> [0.00%] [count: INV]:
  _1 = (long unsigned int) n_2(D);
  __builtin_aligned_alloc (_1, 2);
  return;

}