> [...] I wonder how we can resolve this case:
> extern struct netif_stats le_stats[];
>
> static struct netif_dif le_ifs[] = {
> /* dif_unit dif_nsel dif_stats dif_private */
> { 0, NLE0CONF, &le_stats[0], le0conf, },
> };
> #define NLE_IFS (sizeof(le_ifs) / sizeof(le_ifs[0]))
>
> struct netif_stats le_stats[NLE_IFS];
That is not an extern declaration from a conceptual point of view; it's
just a forward declaration which happens to be implemented with a
(redundant) "extern" keyword. (Even strict def/ref systems must
implement the tentative-definition paradigm for multiple declarations
within a single translation unit - C99 6.9.2, paragraph 2 in
particular.)
Still, I think it could be improved.
I would say that:
- If le_stats is - or might be, eg, depending on #defines - used from
another file, the extern declaration should be moved into a .h used
by both files.
- If not, the extern should be converted to static and the later
declaration should have static added to it.
(I really wish C had chosen a different keyword for linkage control of
file-scope declarations; overloading static for storage duration
control at block scope and linkage control at file scope is ugly and
confusing.)
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