foo.c: In function 'F':
foo.c:14:24: warning: 'return' with a value, in function returning void [-Wreturn-type]
   14 |                 return 0;
      |                        ^
foo.c:4:6: note: declared here
    4 | void F()
      |      ^
foo.c:28:16: warning: 'return' with a value, in function returning void [-Wreturn-type]
   28 |         return 0;
      |                ^
foo.c:4:6: note: declared here
    4 | void F()
      |      ^

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