[Bug sanitizer/104690] UBSan does not detect undefined behavior on function without a specified return value

[vincent-gcc at vinc17 dot net via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104690

--- Comment #3 from Vincent Lefèvre <vincent-gcc at vinc17 dot net> ---
Well, I can understand that this may be difficult in some cases. For instance:

static int f (void) { if (complex_condition_1) return 1; }

and used with

  if (complex_condition_2)
    printf ("%d\n", f ());
  else
    f ();

This means that the compiler would need to insert code to track non-specified
return values. That said, I suspect that in most practical cases (with a static
function), for instance as in PR116690, the compiler will be able to know
whether a non-specified return value is used at some point.