What does extern inline do?

Question

I understand that inline by itself is a suggestion to the compiler, and at its discretion it may or may not inline the function, and it will also produce linkab

Answer 1

The situation with inline, static inline and extern inline is complicated, not least because gcc and C99 define slightly different meanings for their behavior (and presumably C++, as well). You can find some useful and detailed information about what they do in C here.