[Bug c/125350] New: Spurious -Wreturn-type if both an if condition is illegal but both branches return

[blubban at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=125350

            Bug ID: 125350
           Summary: Spurious -Wreturn-type if both an if condition is
                    illegal but both branches return
           Product: gcc
           Version: 16.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: blubban at gmail dot com
  Target Milestone: ---

int x()
{
        if (1 << 1.0)
                return 2;
        else
                return 3;
}

Needs -Wreturn-type (or compiling as C++, where it's on by default).
https://godbolt.org/z/MssvvsvEr


Expected:

<source>: In function 'x':
<source>:3:15: error: invalid operands to binary << (have 'int' and 'double')
    3 |         if (1 << 1.0)
      |               ^~


Actual: The above, but also

<source>:7:1: warning: control reaches end of non-void function [-Wreturn-type]
    7 | }
      | ^


(Originally found by forgetting a few operator== overloads in C++; I'm not sure
if this belongs in the C component, but I can't find a 'reproduces in both C
and C++' component.)