[Bug c/116726] [14/15 Regression] compiler segfault when using certain struct redefinitions

[peter0x44 at disroot dot org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116726

--- Comment #6 from Peter Damianov <peter0x44 at disroot dot org> ---
Another testcase:
not an ICE, but I think rejects-valid
```
typedef void f(struct s1);
struct s1 {
  int f1;
};
typedef void f(struct s1);
```

<source>:5:14: error: conflicting types for 'f'; have 'void(struct s1)'
    5 | typedef void f(struct s1);
      |              ^
<source>:1:14: note: previous declaration of 'f' with type 'f' {aka
'void(struct s1)'}
    1 | typedef void f(struct s1);
      |              ^