On 17 January 2017 at 11:03, vijay nag wrote: > Hello Gcc, > > I came across this nasty C code of an enumerator and a macro having > the same name. Although this is a buggy code, I found it surprising > that GCC compiles in one of the cases(snippet 1) while in the other > compiler flags an error(snippet 2). Would be interested to know why > the order of definitions/declarations matter and what C standards the > compiler is adhering to ? Just look at the preprocessed code, it should be obvious. Macros aren't defined until they're defined. When the macro is defined after the enumerator it can't change it and you get a valid enumerator definition, FOO = 1. When the macro is defined earlier it produces an invalid enumerator, 0xDEADBEEF = 1 What isn't clear?
