On Wed, Mar 17, 2021 at 06:17:26PM +0100, Christophe Leroy wrote: > > > Le 17/03/2021 à 13:23, Peter Zijlstra a écrit : > > On Wed, Mar 17, 2021 at 12:00:29PM +0100, Christophe Leroy wrote: > > > What do you mean ? 'extern' prototype is pointless for function prototypes > > > and deprecated, no new function prototypes should be added with the > > > 'extern' > > > keyword. > > > > > > checkpatch.pl tells you: "extern prototypes should be avoided in .h files" > > > > I have a very strong preference for extern on function decls, to match > > the extern on variable decl. > > You mean you also do 'static inline' variable declarations ?
That's a func definition, not a declaration. And you _can_ do static variable definitions in a header file just fine, although that's typically not what you'd want. Although sometimes I've seen people do: static const int my_var = 10; inline is an attribute that obviously doesn't work on variables. > Using the extern keyword on function prototypes is superfluous visual > noise so suggest removing it. I don't agree; and I think the C spec is actually wrong there (too). The thing is that it distinguishes between a forward declaration of a function in the same TU and an external declaration for a function in another TU. That is; if I see: void ponies(int legs); I expect that function to be defined later in the same TU. IOW it's a forward declaration. OTOH if I see: extern void ponies(int legs); I know I won't find it in this TU and the linker will end up involved. Now, the C people figured that distinction was useless and allowed sloppiness. But I still think there's merrit to that. And as mentioned earlier, it is consistent with variable declarations.
