In this testcase, we were failing to consider declval<_Args1> as
value-dependent, even though it is due to the use of a type parameter.
We previously just handled TEMPLATE_ID_EXPR as a normal binary
expression and assumed that a TREE_VEC was always non-dependent.
Tested x86_64-pc-linux-gnu, applied to trunk and 4.6.
commit 877698d7630d958bfbe1e7a7a69c8a4290c486a2
Author: Jason Merrill <ja...@redhat.com>
Date: Tue Mar 29 13:05:08 2011 -0400
PR c++/48319
* pt.c (value_dependent_expression_p): Handle TEMPLATE_ID_EXPR.
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index dfc726a..aa0901b 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -18218,6 +18218,11 @@ value_dependent_expression_p (tree expression)
return false;
}
+ case TEMPLATE_ID_EXPR:
+ /* If a TEMPLATE_ID_EXPR involves a dependent name, it will be
+ type-dependent. */
+ return type_dependent_expression_p (expression);
+
default:
/* A constant expression is value-dependent if any subexpression is
value-dependent. */
diff --git a/gcc/testsuite/g++.dg/cpp0x/dependent1.C
b/gcc/testsuite/g++.dg/cpp0x/dependent1.C
new file mode 100644
index 0000000..1ceeeaf
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/dependent1.C
@@ -0,0 +1,25 @@
+// PR c++/48319
+// { dg-options -std=c++0x }
+// We were failing to recognize declval<_Args1> as dependent.
+
+template<typename Tp> Tp declval() noexcept;
+
+template<typename _Tp>
+class __is_constructible_helper
+{
+ typedef char __one;
+ typedef struct { char __arr[2]; } __two;
+
+ template<typename _Tp1, typename... _Args1>
+ static decltype(_Tp1(declval<_Args1>()...), __one()) __test(int);
+
+ template<typename, typename...>
+ static __two __test(...);
+
+public:
+ static const bool __value = sizeof(__test<_Tp>(0)) == 1;
+};
+
+int main() {
+ return __is_constructible_helper<int>::__value;
+}
