Emacs' C: static inline considered useless nowadays?

[Matt Armstrong]

For Emacs, I would think:

a) In header files, use Emacs' INLINE and NO_INLINE macros.

b) In .c files, use static, EXTERN_INLINE, but never 'inline' since it
does nothing.

I'm seeking confirmation (or refutation) of (a) and (b).  I'm not asking
generally, but for Emacs' C code.

Specifically, ignoring the uselesness of the function itself, assuming
the code is in a .c file, is the use of the "inline" keyword redundant
with static, below?

    static inline int
    add_two_int (int a, int b)
    {
        return a + b
    }

I've spent the last few decades coding with an undersanding that
"inline" is about linkage and allows one to place code in header files
so that it *may* be inlined, but that compilers long ago stopped using
it as a meaningful inlining hint.  But this is mostly colored by how gcc
and clang behave with C++, and not much else.

-- 
matt (sent from an Emacs running the feature/noverlay branch)