https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79768
--- Comment #7 from Eric Gallager <egallager at gcc dot gnu.org> ---
(In reply to Jeffrey A. Law from comment #6)
> Eric. Thanks for the BZ maintenance. It's definitely appreciated.
>
> For bugs like this (very sensitive to unrelated code generator changes) it
> is often worth the time to bisect to what change fixed the bug. That helps
> us identify something that just went latent vs something that actually got
> fixed.
I wish I could bisect but I don't exactly have the computing resources on this
old laptop for the whole bisection process; is that something I could do on the
gcc compile farm?
>
> I happened to have been looking at this yesterday so I had a bit of state.
> I'm pretty sure this just went latent. Martin L's recent changes to switch
> handling result in dropping the switch into an if-else which we often
> optimize/analyze better.
>
> A slight tweak to keep Martin L's changes from firing brings the warning
> back.
>
>
> #include <stdio.h>
> #include <stdlib.h>
>
> static int mk (int **a, int **b, int **c) {
> if (!(*a = malloc (sizeof (int)))) goto a_err;
> if (!(*b = malloc (sizeof (int)))) goto b_err;
> if (!(*c = malloc (sizeof (int)))) goto c_err;
>
> return 1; c_err:
> free (*b); b_err:
> free (*a); a_err:
> return 0;
> }
>
> static void fin (int *a, int *b, int *c) {
> free (c);
> free (b);
> free (a);
> }
>
> int main (void) {
> int *a, *b, *c, x, flag = mk (&a, &b, &c);
> while ((x = getchar ()) != -1) {
> if (flag) switch (x) {
> case 0:
> break;
> case 0xdeadbeef:
> goto retm;
> default:
> goto retn;
> } else if (x) goto retn;
> }
> retn:
> if (flag) fin (a, b, c);
> return 0;
> retm:
> if (flag) fin (a, b, c);
> return 0;
> }
> ~
Yup, confirmed that this brings the warning back.
