`extern inline' vs `static inline'

[Igor Khavkine]

I've noticed that lots of headers in glibc use `extern inline'
to declare macro-like inline functions. However this paragraph
from the gcc documentation bothers me (C Extensions/Inline):

           For future compatibility with when GCC implements ISO C99 semantics
                 for inline functions, it is best to use `static inline' only.  
(The
                 existing semantics will remain available when `-std=gnu89' is
                 specified, but eventually the default will be `-std=gnu99' and 
that
                 will implement the C99 semantics, though it does not do so 
yet.)

Is there any advantage to using `extern inline' as opposed to
`static inline' with the current implementations of gcc? The only
difference that I've noticed is that `static inline' produces
a linkable version of a function if it cannot be inlined while
`extern inline' does not. But aren't most of these `extern inline'
functions already redefined elsewhere without `extern inline' to
provide linkable versions?

Thanks.

Igor