Is __COUNTER__ macro portable?

Question

I have a piece of code which uses __COUNTER__ macro to generate unique names for variables.

Is this code portable ? I know that GCC and MSVS support it.

Answer 1

GCC manual, section Common Predefined Macros, states

The common predefined macros are GNU C extensions.

I've also never seen this macro in the C99, C11 or C++11 standards.

As for practical portability: Clang supports it, too.