Hello,
In the example accompanying this patch, check_instantiated_arg tries
to ensure that a non-type template argument should be a constant if it
has integral or enumeration type.
The problem is that an alias template which type-id is, e.g, an
integer, looks like an argument that has integral/enumeration type:
its TREE_TYPE is an integer type. So check_instantiated_arg
mistenkaly barks that this integral non-type argument is not a
constant.
I am proposing to tighten the test in check_instantiated_arg to allow
type template (and thus aliast template) arguments.
Bootstrapped and tested on x86_64-unknown-linux-gnu against trunk.
gcc/cp/
PR c++/52343
* pt.c (check_instantiated_arg): Allow type template arguments.
gcc/testsuite/
PR c++/52343
* g++.dg/cpp0x/alias-decl-29.C: New test.
---
gcc/cp/pt.c | 4 +++-
gcc/testsuite/g++.dg/cpp0x/alias-decl-29.C | 10 ++++++++++
2 files changed, 13 insertions(+), 1 deletion(-)
create mode 100644 gcc/testsuite/g++.dg/cpp0x/alias-decl-29.C
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index 1b3f039..e2e8311 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -14425,7 +14425,9 @@ check_instantiated_arg (tree tmpl, tree t,
tsubst_flags_t complain)
constant. */
else if (TREE_TYPE (t)
&& INTEGRAL_OR_ENUMERATION_TYPE_P (TREE_TYPE (t))
- && !TREE_CONSTANT (t))
+ && !TREE_CONSTANT (t)
+ /* Class template and alias template arguments should be OK. */
+ && !DECL_TYPE_TEMPLATE_P (t))
{
if (complain & tf_error)
error ("integral expression %qE is not constant", t);
diff --git a/gcc/testsuite/g++.dg/cpp0x/alias-decl-29.C
b/gcc/testsuite/g++.dg/cpp0x/alias-decl-29.C
new file mode 100644
index 0000000..f6cc695
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/alias-decl-29.C
@@ -0,0 +1,10 @@
+// Origin: PR c++/52343
+// { dg-do compile { target c++11 } }
+
+template<typename>
+using A = int;
+
+template<template<class> class>
+struct B {};
+
+B<A> b;
--
Dodji
