[Bug ipa/121642] New: ICF loses musttail due to inlining

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121642

            Bug ID: 121642
           Summary: ICF loses musttail due to inlining
           Product: gcc
           Version: 16.0
            Status: UNCONFIRMED
          Keywords: diagnostic, 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:
```
void f(int *a);
void h(void);

void g()
{
  int a;
  f(&a);
  [[gnu::musttail]] return h();
}

void g1()
{
  int a;
  f(&a);
  [[gnu::musttail]] return h();
}
```

Currently we tail call g but not in g1 as the musttail is now gone.