[Bug c++/116404] New: nodiscard is not warned on casts (non void)

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116404

            Bug ID: 116404
           Summary: nodiscard is not warned on casts (non void)
           Product: gcc
           Version: 15.0
            Status: UNCONFIRMED
          Keywords: diagnostic
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: pinskia at gcc dot gnu.org
  Target Milestone: ---

Take:
```
[[nodiscard]] int f(); /* { dg-message "declared here" } */

void g() {
  (unsigned int)f(); /* { dg-warning "ignoring return value of " } */
}
```

I had assumed this would warn but currently GCC does not.

Both MSVC and clang warn here too.