On Tue, Apr 08, 2025 at 10:19:58AM +0200, Jakub Jelinek wrote:
> Hi!
>
> The following testcase ICEs after emitting one pedwarn (about using
> __VA_ARGS__ in a place where it shouldn't be used) and one error.
> The error is emitted by _cpp_save_parameter where it sees the node
> has been used already earlier. But unlike the other _cpp_save_parameter
> caller which does goto out; if it returns false, this call with explicit
> __VA_ARGS__ doesn't and if it increments number of parameters etc. after
> the error, we then try to unsave it twice.
>
> The following patch fixes it by doing the goto out in that case too,
> the macro will then not be considered as variable arguments macro,
> but for error recovery I think that is fine.
> The other option would be before the other _cpp_save_parameter caller
> check if the node is pfile->spec_nodes.n__VA_ARGS__ and in that case
> also error and goto out, but that seems more expensive than this for
> the common case that the macro definition is correct.
>
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
OK, thanks.
> 2025-04-08 Jakub Jelinek <ja...@redhat.com>
>
> PR preprocessor/118674
> * macro.cc (parse_params): If _cpp_save_parameter failed for
Maybe add "<case CPP_ELLIPSIS>".
> __VA_ARGS__, goto out.
>
> * gcc.dg/cpp/pr118674.c: New test.
>
> --- libcpp/macro.cc.jj 2025-01-02 11:47:49.413954299 +0100
> +++ libcpp/macro.cc 2025-04-07 10:44:50.351400123 +0200
> @@ -3610,9 +3610,10 @@ parse_params (cpp_reader *pfile, unsigne
> if (!prev_ident)
> {
> /* An ISO bare ellipsis. */
> - _cpp_save_parameter (pfile, nparms,
> - pfile->spec_nodes.n__VA_ARGS__,
> - pfile->spec_nodes.n__VA_ARGS__);
> + if (!_cpp_save_parameter (pfile, nparms,
> + pfile->spec_nodes.n__VA_ARGS__,
> + pfile->spec_nodes.n__VA_ARGS__))
> + goto out;
> nparms++;
> pfile->state.va_args_ok = 1;
> if (! CPP_OPTION (pfile, c99)
> --- gcc/testsuite/gcc.dg/cpp/pr118674.c.jj 2025-04-07 10:52:49.997718759
> +0200
> +++ gcc/testsuite/gcc.dg/cpp/pr118674.c 2025-04-07 10:53:34.026105696
> +0200
> @@ -0,0 +1,5 @@
> +/* PR preprocessor/118674 */
> +/* { dg-do preprocess } */
> +#define M(__VA_ARGS__, ...)
> +/* { dg-error "'__VA_ARGS__' can only appear in the expansion of a C99
> variadic macro" "" { target *-*-* } .-1 } */
> +/* { dg-error "duplicate macro parameter '__VA_ARGS__'" "" { target *-*-* }
> .-2 } */
Marek
