From f3902087886bb96c861224bf43fc39538d0ad9c5 Mon Sep 17 00:00:00 2001
From: Patrick Palka <ppalka@redhat.com>
Date: Wed, 22 Nov 2023 12:26:57 -0500
Subject: [PATCH] c++: alias template of non-template class [PR112633]

Bootstrapped and regtested on x86-64-pc-linux-gnu, does this look OK for
trunk/13?

-- >8 --

The entering_scope adjustment in tsubst_aggr_type assumes if an alias is
dependent, then so is the aliased type (and therefore it has template info)
but that's not true for the dependent alias template specialization ty1<T>
below which aliases the non-template class A.

	PR c++/112633

gcc/cp/ChangeLog:

	* pt.cc (tsubst_aggr_type): Handle empty TYPE_TEMPLATE_INFO
	in the entering_scope adjustment.

gcc/testsuite/ChangeLog:

	* g++.dg/cpp0x/alias-decl-75.C: New test.
---
 gcc/cp/pt.cc                               |  1 +
 gcc/testsuite/g++.dg/cpp0x/alias-decl-75.C | 13 +++++++++++++
 2 files changed, 14 insertions(+)
 create mode 100644 gcc/testsuite/g++.dg/cpp0x/alias-decl-75.C

diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
index 351fc18b600b..d135764278df 100644
--- a/gcc/cp/pt.cc
+++ b/gcc/cp/pt.cc
@@ -13978,6 +13978,7 @@ tsubst_aggr_type (tree t,
       if (entering_scope
 	  && CLASS_TYPE_P (t)
 	  && dependent_type_p (t)
+	  && TYPE_TEMPLATE_INFO (t)
 	  && TYPE_CANONICAL (t) == TREE_TYPE (TYPE_TI_TEMPLATE (t)))
 	t = TYPE_CANONICAL (t);
 
diff --git a/gcc/testsuite/g++.dg/cpp0x/alias-decl-75.C b/gcc/testsuite/g++.dg/cpp0x/alias-decl-75.C
new file mode 100644
index 000000000000..1a73a99856e9
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/alias-decl-75.C
@@ -0,0 +1,13 @@
+// PR c++/112633
+// { dg-do compile { target c++11 } }
+
+struct A { using type = void; };
+
+template<class>
+using ty1 = A;
+
+template<class T>
+using ty2 = typename ty1<T>::type;
+
+template<class T>
+ty2<T> f();