Should one never use static inline function?

Question

There are two implications of using the inline keyword(§ 7.1.3/4):

1. It hints the compiler that substitution of function body at the point

Answer 1

I may not be completely right about this, but as far as I know declaring a function static inline is the only way to make (or allow) the compiler to generate a machine code where the function really is not defined in the compiled code at all, and all you have is a direct substitution of the function call into a sequence of instructions, like it were just a regular procedure body, with no trace in the machine code of a procedure call relative to that function definition from the source code.

That is, only with static inline you can really substitute the use of a macro, inline by itself is not enough.

A simple Google search for "static inline" will show you compiler documentation pages that talk about it. I guess this should be enough to answer your question, and say, "no, it is not practically useless". Here is one example of a site discussing the use of inline, and specifically of static inline http://www.greenend.org.uk/rjk/tech/inline.html