| Message ID | 20170831210922.GA9227@ZenIV.linux.org.uk (mailing list archive) |
|---|---|
| State | Mainlined, archived |
| Headers | show |
On Thu, Aug 31, 2017 at 10:09:22PM +0100, Al Viro wrote: > On Thu, Aug 31, 2017 at 09:54:33PM +0100, Al Viro wrote: > > What a mess... Note that for non-vararg it *is* the right interpretation > > (with #define A(x) [x] we will have A() interpreted as "empty token sequence > > as the only argument", not "no arguments given"). For vararg case we > > normally do not need to distinguish "not given" and "empty" - the only > > thing that cares is exactly the ,## kludge. There with > > #define B(x,...) [x,##__VA_ARGS__] > > B(1) and B(1,) yield [1] and [1,] resp. And for everything other than > > "just ..." we even get it right... > > > > I see what's going on there; will post a fix in a few. > > > Fix macro argument parsing for (...) case > > Nasty corner case for the sake of ,##__VA_ARGS__ perversion - for something > like #define A(x,...) [x,##__VA_ARGS] we want A(1) to expand to [1] and > A(1,) - to [1,]. In other words, "no vararg given" and "vararg empty" are > different and need to be distinguished. Unfortunately, in case when there > was nothing but vararg we got it wrong - #define A(...) ,##__VA_ARGS ended > up with A() interpreted as "one empty argument" (as it would in non-vararg > case) rather than "zero arguments". > > Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> > --- > diff --git a/pre-process.c b/pre-process.c > index 74414df..8800dce 100644 > --- a/pre-process.c > +++ b/pre-process.c > @@ -296,9 +296,11 @@ static int collect_arguments(struct token *start, struct token *arglist, struct > for (count = 0; count < wanted; count++) { > struct argcount *p = &arglist->next->count; > next = collect_arg(start, p->vararg, &what->pos, p->normal); > - arglist = arglist->next->next; > if (eof_token(next)) > goto Eclosing; > + if (p->vararg && wanted == 1 && eof_token(start->next)) > + break; > + arglist = arglist->next->next; > args[count].arg = start->next; > args[count].n_normal = p->normal; > args[count].n_quoted = p->quoted; This looks plausible; we should also add a test for it, though. -- To unsubscribe from this list: send the line "unsubscribe linux-sparse" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/pre-process.c b/pre-process.c index 74414df..8800dce 100644 --- a/pre-process.c +++ b/pre-process.c @@ -296,9 +296,11 @@ static int collect_arguments(struct token *start, struct token *arglist, struct for (count = 0; count < wanted; count++) { struct argcount *p = &arglist->next->count; next = collect_arg(start, p->vararg, &what->pos, p->normal); - arglist = arglist->next->next; if (eof_token(next)) goto Eclosing; + if (p->vararg && wanted == 1 && eof_token(start->next)) + break; + arglist = arglist->next->next; args[count].arg = start->next; args[count].n_normal = p->normal; args[count].n_quoted = p->quoted;