[Bug c++/125682] New: nodiscard class does not warn for statement expression

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=125682

            Bug ID: 125682
           Summary: nodiscard class does not warn for statement expression
           Product: gcc
           Version: 16.0
            Status: UNCONFIRMED
          Keywords: diagnostic, stmt-expr
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: pinskia at gcc dot gnu.org
  Target Milestone: ---

Take:
```
struct [[nodiscard]] MyNodiscardInt {
  int x;
};

MyNodiscardInt my_func() {
  return MyNodiscardInt{ 0 };
}

#define MY_MACRO() \
  ({ my_func(); })

int f() {
    MY_MACRO();
    return 0;
}
```

I would have expected a warning for stmt expression since the result is
discarded.