[Bug c++/119498] New: Incompatible FMV functions not diagnosed

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119498

            Bug ID: 119498
           Summary: Incompatible FMV functions not diagnosed
           Product: gcc
           Version: 14.2.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: alfierichards at gcc dot gnu.org
  Target Milestone: ---

Cases such as 

```c
__attribute__ ((target_version("default")))
int foo (int a) {
    return 1;
}

__attribute__ ((target_version("sve")))
int foo (int a) {
    return 1;
}

__attribute__ ((target_version("sme")))
float foo (int a) {
    return 1;
}
```

There the return type is inconsistent and should not be compatible are not
diagnosed and create invalid output.

Aarch64 example
https://godbolt.org/z/E8s71Y1jK

X86 example:
https://godbolt.org/z/nbadoTTMW