On Thu, May 1, 2025 at 10:46 PM Jason Merrill <ja...@redhat.com> wrote:
>
> Tested x86_64-pc-linux-gnu, OK for trunk?
>
> -- 8< --
>
> This warning relies on the TRANSLATION_UNIT_WARN_EMPTY_P flag (set in
> cxx_init_decl_processing) to decide whether we want to warn about the GCC 8
> empty class parameter passing fix, but in a call through a function pointer
> we don't have a translation unit and so complain for any -Wabi flag, even
> now long after this was likely to be relevant.
>
> In that situation, let's check the TU for current_function_decl instead.
> And if we still can't come up with a TU, default to not warning.
>
> PR c++/60336
>
> gcc/ChangeLog:
>
> * config/i386/i386.cc (ix86_warn_parameter_passing_abi):
> If no target, check the current TU.
>
> gcc/testsuite/ChangeLog:
>
> * g++.dg/abi/pr60336-8a.C: New test.
LGTM.
Thanks,
Uros.
> ---
> gcc/config/i386/i386.cc | 11 ++++++++---
> gcc/testsuite/g++.dg/abi/pr60336-8a.C | 15 +++++++++++++++
> 2 files changed, 23 insertions(+), 3 deletions(-)
> create mode 100644 gcc/testsuite/g++.dg/abi/pr60336-8a.C
>
> diff --git a/gcc/config/i386/i386.cc b/gcc/config/i386/i386.cc
> index 2f840338138..cb348cb9cfb 100644
> --- a/gcc/config/i386/i386.cc
> +++ b/gcc/config/i386/i386.cc
> @@ -18084,9 +18084,14 @@ ix86_warn_parameter_passing_abi (cumulative_args_t
> cum_v, tree type)
> if (cum->decl && !TREE_PUBLIC (cum->decl))
> return;
>
> - const_tree ctx = get_ultimate_context (cum->decl);
> - if (ctx != NULL_TREE
> - && !TRANSLATION_UNIT_WARN_EMPTY_P (ctx))
> + tree decl = cum->decl;
> + if (!decl)
> + /* If we don't know the target, look at the current TU. */
> + decl = current_function_decl;
> +
> + const_tree ctx = get_ultimate_context (decl);
> + if (ctx == NULL_TREE
> + || !TRANSLATION_UNIT_WARN_EMPTY_P (ctx))
> return;
>
> /* If the actual size of the type is zero, then there is no change
> diff --git a/gcc/testsuite/g++.dg/abi/pr60336-8a.C
> b/gcc/testsuite/g++.dg/abi/pr60336-8a.C
> new file mode 100644
> index 00000000000..a0518436e0e
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/abi/pr60336-8a.C
> @@ -0,0 +1,15 @@
> +// { dg-do compile }
> +// { dg-options "-O2 -Wabi=12" }
> +
> +struct dummy { struct{} a[7][3]; };
> +
> +extern void test1 (struct dummy, ...);
> +extern void (*test2) (struct dummy, ...);
> +
> +void
> +foo ()
> +{
> + struct dummy a0;
> + test1 (a0, 42);
> + test2 (a0, 42);
> +}
>
> base-commit: 87c4460024dadef0aa1c767be146ad3831857ebe
> --
> 2.49.0
>
