On 10/9/25 9:34 PM, Patrick Palka wrote:
Bootstrapped and regtested on x86_64-pc-linux-gnu, does his look
OK for trunk and backports?
OK for both.
-- >8 --
The r13-6098 change to make TYPENAME_TYPE no longer always ignore
non-type bindings needs another exception: base-specifiers that are
represented as TYPENAME_TYPE, which by [class.derived.general]/2 lookup
for which must be type-only. This patch fixes this by giving such
TYPENAME_TYPES a tag type of class_type rather than typename_type so
that we trea them like elaborated-type-specifiers (lookup for which is
also type-only).
PR c++/122192
gcc/cp/ChangeLog:
* decl.cc (make_typename_type): Document base-specifier as
another type-only lookup case.
* parser.cc (cp_parser_class_name): Propagate tag_type to
make_typename_type instead of hardcoding typename_type.
(cp_parser_base_specifier): Pass class_type instead of
typename_type as tag_type to cp_parser_class_name.
gcc/testsuite/ChangeLog:
* g++.dg/template/dependent-base6.C: New test.
---
gcc/cp/decl.cc | 4 +++-
gcc/cp/parser.cc | 5 ++---
gcc/testsuite/g++.dg/template/dependent-base6.C | 12 ++++++++++++
3 files changed, 17 insertions(+), 4 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/template/dependent-base6.C
diff --git a/gcc/cp/decl.cc b/gcc/cp/decl.cc
index 885be3b2cecf..da7d149b29f5 100644
--- a/gcc/cp/decl.cc
+++ b/gcc/cp/decl.cc
@@ -5036,7 +5036,9 @@ make_typename_type (tree context, tree name, enum
tag_types tag_type,
- the tag corresponds to a class-key or 'enum' so
[basic.lookup.elab] applies, or
- the tag corresponds to scope_type or tf_qualifying_scope is
- set so [basic.lookup.qual]/1 applies.
+ set so [basic.lookup.qual]/1 applies, or
+ - we're inside a base-specifier so [class.derived.general]/2 applies;
+ the tag will already be class_type in that case.
TODO: If we'd set/track the scope_type tag thoroughly on all
TYPENAME_TYPEs that are followed by :: then we wouldn't need the
tf_qualifying_scope flag. */
diff --git a/gcc/cp/parser.cc b/gcc/cp/parser.cc
index 362cddbaf692..6b206062c043 100644
--- a/gcc/cp/parser.cc
+++ b/gcc/cp/parser.cc
@@ -28023,8 +28023,7 @@ cp_parser_class_name (cp_parser *parser,
/* If this is a typename, create a TYPENAME_TYPE. */
if (typename_p && decl != error_mark_node)
{
- decl = make_typename_type (scope, decl, typename_type,
- /*complain=*/tf_error);
+ decl = make_typename_type (scope, decl, tag_type, /*complain=*/tf_error);
if (decl != error_mark_node)
decl = TYPE_NAME (decl);
}
@@ -30425,7 +30424,7 @@ cp_parser_base_specifier (cp_parser* parser)
type = cp_parser_class_name (parser,
class_scope_p,
template_p,
- typename_type,
+ class_type,
/*check_dependency_p=*/true,
/*class_head_p=*/false,
/*is_declaration=*/true);
diff --git a/gcc/testsuite/g++.dg/template/dependent-base6.C
b/gcc/testsuite/g++.dg/template/dependent-base6.C
new file mode 100644
index 000000000000..0a91e6412bed
--- /dev/null
+++ b/gcc/testsuite/g++.dg/template/dependent-base6.C
@@ -0,0 +1,12 @@
+// PR c++/122192
+// Verify name lookup within a base-specifier is type-only.
+
+struct A {
+ int B;
+ struct B { };
+};
+
+struct S1 : A::B { }; // OK
+
+template<class T> struct S2 : T::B { }; // OK too
+template struct S2<A>;
