Compiler output
prog.c:1:1: warning: data definition has no type or storage class [enabled by default]
prog.c:1:1: warning: type defaults to 'int' in declaration of 'a' [enabled by default]
prog.c:2:1: warning: data definition has no type or storage class [enabled by default]
prog.c:2:1: warning: type defaults to 'int' in declaration of 'b' [enabled by default]
prog.c:3:1: warning: data definition has no type or storage class [enabled by default]
prog.c:3:1: warning: type defaults to 'int' in declaration of 'c' [enabled by default]
prog.c:3:1: error: initializer element is not constant
