[Bug preprocessor/55602] Does not generate Error message for redefined macros

[guojiufu at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55602



--- Comment #2 from Jeff Guo <guojiufu at gmail dot com> 2012-12-10 11:57:57 
UTC ---

-pedantic-errors is helpful if the redefined macros not guarded by "#pragma GCC

system_header"

--a.h --

#pragma GCC system_header

#define A 1

#define A 2

-----a.c----

#include "a.h"



int main(){

  return A;

}



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