[Bug c++/118486] [OpenMP] declare_variant - bogus diagnostic 'not found' when only return-type is wrong

[burnus at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118486

Tobias Burnus <burnus at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |rejects-valid

--- Comment #2 from Tobias Burnus <burnus at gcc dot gnu.org> ---
Actually, it seems to be a general struct-returning issue.
The following compiles with clang++-19 but g++ rejects it with the same error:

  struct NotAnInt {};
  NotAnInt expl();
#pragma omp declare variant(expl) match(user={condition(1)})
  NotAnInt base();

void f() {
  NotAnInt x;
  x = base();
}

* * *

The following patch seems to fix all issues mentioned here:

--- a/gcc/cp/decl.cc
+++ b/gcc/cp/decl.cc
@@ -8552,6 +8552,9 @@ omp_declare_variant_finalize_one (tree decl, tree attr)
   if (variant == error_mark_node && !processing_template_decl)
     return true;

+  if (TREE_CODE (variant) == TARGET_EXPR)
+    variant = TARGET_EXPR_INITIAL (variant);
+
   variant = cp_get_callee_fndecl_nofold (STRIP_REFERENCE_REF (variant));
   input_location = save_loc;