[gcc r16-354] i386: -Wabi false positive with indirect call [PR60336]

[Jason Merrill via Gcc-cvs]

https://gcc.gnu.org/g:4af5de21363cfdd2be227c05dfdee7e053337f6a

commit r16-354-g4af5de21363cfdd2be227c05dfdee7e053337f6a
Author: Jason Merrill <ja...@redhat.com>
Date:   Thu May 1 11:40:17 2025 -0400

    i386: -Wabi false positive with indirect call [PR60336]
    
    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.

Diff:
---
 gcc/config/i386/i386.cc               | 11 ++++++++---
 gcc/testsuite/g++.dg/abi/pr60336-8a.C | 15 +++++++++++++++
 2 files changed, 23 insertions(+), 3 deletions(-)

diff --git a/gcc/config/i386/i386.cc b/gcc/config/i386/i386.cc
index 2f8403381384..cb348cb9cfb8 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 000000000000..a0518436e0eb
--- /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);
+}