foo.c:2:6: warning: return type of 'main' is not 'int' [-Wmain]
    2 | void main()
      |      ^~~~
foo.c: In function 'main':
foo.c:16:12: warning: 'return' with a value, in function returning void [-Wreturn-type]
   16 |     return 0;
      |            ^
foo.c:2:6: note: declared here
    2 | void main()
      |      ^~~~

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