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| author | Al Viro <viro@ZenIV.linux.org.uk> | 2017-08-31 22:09:22 +0100 |
|---|---|---|
| committer | Christopher Li <sparse@chrisli.org> | 2017-08-31 20:38:06 -0400 |
| commit | 23a393b1cd48ea50bff94fa4a1e2c02a5d78d9cb (patch) | |
| tree | da677fc04330c40052b29a697ee307eb4bd6333b | |
| parent | 958c11c35d98417eb6b948bffe2dffed14eb3320 (diff) | |
| download | sparse-dev-23a393b1cd48ea50bff94fa4a1e2c02a5d78d9cb.tar.gz | |
Sparse preprocessing bug with zero-arg variadic macros
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".
Reported-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Christopher Li <sparse@chrisli.org>
| -rw-r--r-- | pre-process.c | 4 | ||||
| -rw-r--r-- | validation/preprocessor/preprocessor23.c | 4 |
2 files changed, 7 insertions, 1 deletions
diff --git a/pre-process.c b/pre-process.c index 74414dfe..8800dce5 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; diff --git a/validation/preprocessor/preprocessor23.c b/validation/preprocessor/preprocessor23.c index 25be5085..a7784838 100644 --- a/validation/preprocessor/preprocessor23.c +++ b/validation/preprocessor/preprocessor23.c @@ -12,6 +12,9 @@ I(,) I(x,) I(,x) I(x,x) +#define J(...) ,##__VA_ARGS__ +J() +J(x) /* * check-name: Preprocessor #23 * check-command: sparse -E $file @@ -29,6 +32,7 @@ I(x,x) ,x ,x ,xx +,x * check-output-end * * check-error-start |