[gcc r12-6772] c++: consistently diagnose bare CTAD placeholder in fn return type

[Patrick Palka]

https://gcc.gnu.org/g:2cda2bfa3fd0f2a0122433d2d870843633e2a312

commit r12-6772-g2cda2bfa3fd0f2a0122433d2d870843633e2a312
Author: Patrick Palka <ppalka@redhat.com>
Date:   Thu Jan 20 09:22:27 2022 -0500

    c++: consistently diagnose bare CTAD placeholder in fn return type
    
    Relax slightly the existing check for diagnosing a bare CTAD placeholder
    as the return type of a function declarator to also handle the abstract
    declarator case.
    
    gcc/cp/ChangeLog:
    
            * decl.cc (grokdeclarator): Diagnose a CTAD placeholder as
            function return type even when !funcdecl_p.
    
    gcc/testsuite/ChangeLog:
    
            * g++.dg/other/pr88187.C: Adjust expected C++17 diagnostic.

Diff:
---
 gcc/cp/decl.cc                       | 6 +++---
 gcc/testsuite/g++.dg/other/pr88187.C | 2 +-
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/gcc/cp/decl.cc b/gcc/cp/decl.cc
index 2dade75c489..1cbe9a34be0 100644
--- a/gcc/cp/decl.cc
+++ b/gcc/cp/decl.cc
@@ -12647,11 +12647,11 @@ grokdeclarator (const cp_declarator *declarator,
 		if (!tmpl)
 		  if (tree late_auto = type_uses_auto (late_return_type))
 		    tmpl = CLASS_PLACEHOLDER_TEMPLATE (late_auto);
-		if (tmpl && funcdecl_p)
+		if (tmpl)
 		  {
-		    if (!dguide_name_p (unqualified_id))
+		    if (!funcdecl_p || !dguide_name_p (unqualified_id))
 		      {
-			error_at (declarator->id_loc, "deduced class "
+			error_at (typespec_loc, "deduced class "
 				  "type %qD in function return type",
 				  DECL_NAME (tmpl));
 			inform (DECL_SOURCE_LOCATION (tmpl),
diff --git a/gcc/testsuite/g++.dg/other/pr88187.C b/gcc/testsuite/g++.dg/other/pr88187.C
index 13466d3ce57..7812e3fd5b3 100644
--- a/gcc/testsuite/g++.dg/other/pr88187.C
+++ b/gcc/testsuite/g++.dg/other/pr88187.C
@@ -4,4 +4,4 @@
 template <int> struct A;
 void f (A ());	// { dg-error "6:variable or field 'f' declared void" "" { target c++14_down } }
 		// { dg-error "missing template arguments before '\\(' token" "" { target c++14_down } .-1 }
-		// { dg-error "placeholder .A. not permitted in this context" "" { target c++17 } .-2 }
+		// { dg-error "deduced class type 'A' in function return type" "" { target c++17 } .-2 }