This patch prevents the initializer from being checked when it is
dependent. It also sets the type of a dependent template-id referring
to a variable template to be unknown, making such expressions type
dependent.
2014-08-07 Andrew Sutton <andrew.n.sut...@gmail.com>
* pt.c (lookup_template_variable): Make the type unspecified if
any template arguments are dependent.
* decl.c (cp_finish_decl): Don't check the initializer if it is
value-dependent.
New test included.
Andrew Sutton
On Wed, Aug 6, 2014 at 9:34 PM, Jason Merrill <ja...@redhat.com> wrote:
> On 08/05/2014 04:06 PM, Paolo Carlini wrote:
>>
>> Great. I will double check but var-templ4.C fails for me with an ICE.
>
>
> Hunh, I wonder how I missed that.
>
> Here's what I'm checking in; we want to unset DECL_COMDAT for variable
> templates, too.
>
>
Index: gcc/testsuite/g++.dg/cpp1y/var-templ6.C
===================================================================
--- gcc/testsuite/g++.dg/cpp1y/var-templ6.C (revision 0)
+++ gcc/testsuite/g++.dg/cpp1y/var-templ6.C (revision 0)
@@ -0,0 +1,12 @@
+// { dg-options "-std=c++1y" }
+
+template<typename T>
+ constexpr bool Class = __is_class(T);
+
+template<typename T>
+ constexpr bool Test = Class<T>;
+
+struct S { };
+
+static_assert(!Test<int>, "");
+static_assert(Test<S>, "");
Index: gcc/cp/decl.c
===================================================================
--- gcc/cp/decl.c (revision 213667)
+++ gcc/cp/decl.c (working copy)
@@ -6417,19 +6417,20 @@ cp_finish_decl (tree decl, tree init, bo
DECL_INITIAL (decl) = NULL_TREE;
}
+ bool value_dependent_p = init && value_dependent_init_p (init);
+
/* Generally, initializers in templates are expanded when the
template is instantiated. But, if DECL is a variable constant
then it can be used in future constant expressions, so its value
must be available. */
-
- if (!VAR_P (decl) || dependent_type_p (type))
+ if (!VAR_P (decl) || type_dependent_p || value_dependent_p)
/* We can't do anything if the decl has dependent type. */;
else if (init
&& init_const_expr_p
&& !type_dependent_p
&& decl_maybe_constant_var_p (decl)
&& !type_dependent_init_p (init)
- && !value_dependent_init_p (init))
+ && !value_dependent_p)
{
/* This variable seems to be a non-dependent constant, so process
its initializer. If check_initializer returns non-null the
Index: gcc/cp/pt.c
===================================================================
--- gcc/cp/pt.c (revision 213667)
+++ gcc/cp/pt.c (working copy)
@@ -8260,13 +8260,23 @@ lookup_template_class (tree d1, tree arg
return ret;
}
-/* Return a TEMPLATE_ID_EXPR for the given variable template and ARGLIST. */
+/* Return a TEMPLATE_ID_EXPR for the given variable template and ARGLIST.
+ If the ARGLIST refers to any template parameters, the type of the
+ expression is the unknown_type_node since the template-id could
+ refer to an explicit or partial specialization.
+*/
tree
lookup_template_variable (tree templ, tree arglist)
{
- return build2 (TEMPLATE_ID_EXPR, TREE_TYPE (templ), templ, arglist);
+ tree type;
+ if (uses_template_parms (arglist))
+ type = unknown_type_node;
+ else
+ type = TREE_TYPE (templ);
+ return build2 (TEMPLATE_ID_EXPR, type, templ, arglist);
}
+
struct pair_fn_data
{
