>From b34312d82b236601c348382d30e625558f37d40c Mon Sep 17 00:00:00 2001
From: centurion <centurion...@proton.me>
Date: Mon, 25 Mar 2024 01:57:21 +0400
Subject: [PATCH] c++: fix alias CTAD [PR114377]
PR c++/114377
gcc/cp/ChangeLog:
PR c++/114377
* pt.cc (find_template_parameter_info::found): Use TREE_TYPE for
TEMPLATE_DECL instead of DECL_INITIAL.
gcc/testsuite/ChangeLog:
* g++.dg/cpp2a/class-deduction-alias19.C: New test.
---
gcc/cp/pt.cc | 3 ++-
.../g++.dg/cpp2a/class-deduction-alias19.C | 15 +++++++++++++++
2 files changed, 17 insertions(+), 1 deletion(-)
create mode 100644 gcc/testsuite/g++.dg/cpp2a/class-deduction-alias19.C
diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
index 8cf0d5b7a8d..d8a02f1cd7f 100644
--- a/gcc/cp/pt.cc
+++ b/gcc/cp/pt.cc
@@ -11032,7 +11032,8 @@ find_template_parameter_info::found (tree parm)
{
if (TREE_CODE (parm) == TREE_LIST)
parm = TREE_VALUE (parm);
- if (TREE_CODE (parm) == TYPE_DECL)
+ if (TREE_CODE (parm) == TYPE_DECL
+ || TREE_CODE(parm) == TEMPLATE_DECL)
parm = TREE_TYPE (parm);
else
parm = DECL_INITIAL (parm);
diff --git a/gcc/testsuite/g++.dg/cpp2a/class-deduction-alias19.C
b/gcc/testsuite/g++.dg/cpp2a/class-deduction-alias19.C
new file mode 100644
index 00000000000..1ea79bd7691
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp2a/class-deduction-alias19.C
@@ -0,0 +1,15 @@
+// PR c++/114377
+// { dg-do compile { target c++20 } }
+
+template <template <typename> typename Iterator>
+struct K {};
+
+template <typename C, typename IteratorPolicy>
+class Foo {};
+
+template <typename C, template<typename> typename TTP>
+using Bar = Foo<C, K<TTP>>;
+
+void s() {
+ Bar(1); // { dg-error "failed|no match" }
+}
--
2.44.0
