On Sat May 21 16:05:58 PDT 2016, 9...@9netics.com wrote:
> >> >> Waitmsg *exitsts = nil;
>
> i see; it's set but not used before it is assigned to again.
>
> i would expect the compiler to get the hint that it's initialization
> -- especially given that the value is 0 and the assignment is right
> with the declaration.
like i mentioned, gcc ignores variables that are set and not used, for
the most part. i think behavior is odd. there's nothing special about
assigning a simple type in a declaration.
for example
char *s = nil;
and
char *s;
s = nil;
are equivalent. gcc ignores both cases if they are not actually used.
one could add an automatic implicit USED in kenc by modifying
the doinit() in dcl.c, but i think that would be a mistake. i find extra
assignments make it harder to read the code, as one has to consider
the assignment might be used when evaluating how a variable is used.
there are some exceptions to the general rule, for non simple types,
where the assignment may change the size. and i'm gnoring some dark
corners of c99 like const int, which are not implemented in plan 9.
- erik
