On Mon, Feb 24, 2020 at 1:24 PM Willy Tarreau [off-list ref] wrote:

Macro FDCS silently uses identifier "fdc" which may be either the
global one or a local one. Let's expand the macro to make this more
obvious.

Hmm. These macro expansions feel wrong to me.

Or rather, they look right as a first step - and it's probably worth
doing this just to have that "exact same code generation" step.

But I think there should be a second step (also with "exact same code
generation") which then renames the driver-global "fdc" index as
"current_fdc".

That way you'll _really_ see when you use the global vs local ones.
The local ones would continue to be just "fdc".

Because with just this patch, I don't think you actually get any more
obvious whether it's the global or local "fdc" index that is used.

So I'd like to see that second step that does the

    -static int fdc;                 /* current fdc */
    +static int current_fdc;

change.

We already call the global 'drive' variable 'current_drive', so it
really is 'fdc' that is misnamed and ambiguous because it then has two
different cases: the global 'fdc' and then the various shadowing local
'fdc' variables (or function arguments).

Mind adding that too? Slightly less automatic, I agree, because then
you really do have to disambiguate between the "is this the shadowed
use of a local 'fdc'" case or the "this is the global 'fdc' use" case.

Can coccinelle do that?

                Linus