enumtag.c:35:6: Enum tag enum e_tag defined more than once
   enumtag.c:12:6: Previous definition of enum e_tag
enumtag.c:35:6: Enum enum e_tag declared with members { E_M } but previously
                   declared with members { E_X, E_Y, E_Z }
   enumtag.c:12:6: Declaration of enum e_tag

Finished checking --- 2 code warnings, as expected