We were deducing the wrong template argument when passing a function
template-id to a T&& parameter, because the code for resolving an
overloaded function based on a parameter type wasn't passing in an
argument expression to maybe_adjust_parameter_types_for_deduction. The
easy fix was to check the type, as functions are always lvalues.
Tested x86_64-pc-linux-gnu, applied to trunk.
commit e87037b708e895527437491e5c1f751ccd2b649a
Author: Jason Merrill <ja...@redhat.com>
Date: Mon Mar 28 16:40:55 2011 -0400
PR c++/48313
* pt.c (maybe_adjust_types_for_deduction): Handle T&& deduction
from overloaded function.
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index 9032dd9..dfc726a 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -13936,7 +13936,10 @@ maybe_adjust_types_for_deduction (unification_kind_t
strict,
&& TYPE_REF_IS_RVALUE (*parm)
&& TREE_CODE (TREE_TYPE (*parm)) == TEMPLATE_TYPE_PARM
&& cp_type_quals (TREE_TYPE (*parm)) == TYPE_UNQUALIFIED
- && arg_expr && real_lvalue_p (arg_expr))
+ && (arg_expr ? real_lvalue_p (arg_expr)
+ /* try_one_overload doesn't provide an arg_expr, but
+ functions are always lvalues. */
+ : TREE_CODE (*arg) == FUNCTION_TYPE))
*arg = build_reference_type (*arg);
/* [temp.deduct.call]
diff --git a/gcc/testsuite/g++.dg/cpp0x/rv-deduce2.C
b/gcc/testsuite/g++.dg/cpp0x/rv-deduce2.C
new file mode 100644
index 0000000..160296f
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/rv-deduce2.C
@@ -0,0 +1,18 @@
+// PR c++/48313
+// { dg-options -std=c++0x }
+
+template<typename F>
+void f(F&&) { }
+
+void g() { }
+
+template<typename T> void h() { }
+
+int main()
+{
+ f( g ); // OK
+ void (&p)() = h<int>;
+ f( p ); // OK
+ f( h<int> ); // ???
+}
+
