[Bug ipa/119483] New: musttail vs noreturn discovery

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119483

            Bug ID: 119483
           Summary: musttail vs noreturn discovery
           Product: gcc
           Version: 15.0
            Status: UNCONFIRMED
          Keywords: tail-call
          Severity: normal
          Priority: P3
         Component: ipa
          Assignee: unassigned at gcc dot gnu.org
          Reporter: pinskia at gcc dot gnu.org
  Target Milestone: ---

Take:
```
[[gnu::noreturn]]
extern void x();

[[gnu::noinline]]
static int f(int)
{
  x();
  return 0;
}

int g(int);
int h(int t)
{
  if (t == 1)
  [[clang::musttail]]
    return f(1);
  [[clang::musttail]]
  return g(t);
}

```

This fails with GCC and not clang because GCC discovers that x is noreturn and
then rejects the tail call.

Note this might be or might not be part of PR 119376, I have not checked fully
yet.