implicit int and implicit declaration of functions with gcc compiler

Question

I read in the c99 Standard:

-remove implicit function declaration,

-remove implicit int.

But when I try to compile this code with gcc comp

Answer 1

Two points: first, it may (usually does) take a specific set of flags to get a compiler to conform with the standard.

Second, all that's required by the standard is that the implementation issue a "diagnostic" in the case of an error -- but it's up to the implementation to define what is or isn't a diagnostic. It's free to say a "warning" is a diagnostic if it wants to. When a diagnostic is issued, it may quit compiling, or it can compile the code anyway.

Bottom line: what it's doing is probably enough to conform, for whatever that's worth.