Two issues here: one, we were failing to look through references when
comparing types, so we decided that a function type in a template
non-type argument didn't match a reference-to-function type in the
type of the non-type parameter.
With that fixed, I also needed to move the C++17 non-type auto
handling down past that type comparison.
Tested x86_64-pc-linux-gnu, applying to trunk and 7.
commit ecd071290cad1fcfb33eee3889f94dd1e9374b24
Author: Jason Merrill <ja...@redhat.com>
Date: Fri Jun 16 13:10:53 2017 -0400
PR c++/81102 - Wrong error with partial specialization.
* pt.c (unify) [TEMPLATE_PARM_INDEX]: Strip reference when comparing
types. Do type deduction later.
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index b055507..8c6499f 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -20632,18 +20632,6 @@ unify (tree tparms, tree targs, tree parm, tree arg,
int strict,
return x;
}
- if (cxx_dialect >= cxx1z
- /* We deduce from array bounds in try_array_deduction. */
- && !(strict & UNIFY_ALLOW_INTEGER)
- && uses_template_parms (TREE_TYPE (parm))
- && !type_uses_auto (TREE_TYPE (parm)))
- {
- tree atype = TREE_TYPE (arg);
- RECUR_AND_CHECK_FAILURE (tparms, targs,
- TREE_TYPE (parm), atype,
- UNIFY_ALLOW_NONE, explain_p);
- }
-
/* [temp.deduct.type] If, in the declaration of a function template
with a non-type template-parameter, the non-type
template-parameter is used in an expression in the function
@@ -20664,7 +20652,8 @@ unify (tree tparms, tree targs, tree parm, tree arg,
int strict,
/* Template-parameter dependent expression. Just accept it for now.
It will later be processed in convert_template_argument. */
;
- else if (same_type_p (TREE_TYPE (arg), tparm))
+ else if (same_type_p (non_reference (TREE_TYPE (arg)),
+ non_reference (tparm)))
/* OK */;
else if ((strict & UNIFY_ALLOW_INTEGER)
&& CP_INTEGRAL_TYPE_P (tparm))
@@ -20673,9 +20662,22 @@ unify (tree tparms, tree targs, tree parm, tree arg,
int strict,
corresponding parameter. */
arg = fold (build_nop (tparm, arg));
else if (uses_template_parms (tparm))
- /* We haven't deduced the type of this parameter yet. Try again
- later. */
- return unify_success (explain_p);
+ {
+ /* We haven't deduced the type of this parameter yet. */
+ if (cxx_dialect >= cxx1z
+ /* We deduce from array bounds in try_array_deduction. */
+ && !(strict & UNIFY_ALLOW_INTEGER))
+ {
+ /* Deduce it from the non-type argument. */
+ tree atype = TREE_TYPE (arg);
+ RECUR_AND_CHECK_FAILURE (tparms, targs,
+ tparm, atype,
+ UNIFY_ALLOW_NONE, explain_p);
+ }
+ else
+ /* Try again later. */
+ return unify_success (explain_p);
+ }
else
return unify_type_mismatch (explain_p, tparm, TREE_TYPE (arg));
diff --git a/gcc/testsuite/g++.dg/template/partial-specialization7.C
b/gcc/testsuite/g++.dg/template/partial-specialization7.C
new file mode 100644
index 0000000..aa42191
--- /dev/null
+++ b/gcc/testsuite/g++.dg/template/partial-specialization7.C
@@ -0,0 +1,40 @@
+// PR c++/81102
+
+template <typename FuncSig, FuncSig f>
+struct HelperWrapper;
+
+// [...]
+
+template <typename Ret, Ret (&Func)()>
+struct HelperWrapper<Ret (&)(), Func>
+{
+ static inline int WrapFuncT(const int)
+ {
+ return 0; // Changed
+ }
+};
+
+// Unary
+template <typename Ret, typename Arg1, Ret (&Func)(Arg1)>
+struct HelperWrapper<Ret (&)(Arg1), Func>
+{
+ static inline int WrapFuncT(const int)
+ {
+ return 1; // Changed
+ }
+};
+
+// Binary
+template <typename Ret, typename Arg1, typename Arg2, Ret (&Func)(Arg1, Arg2)>
+struct HelperWrapper<Ret (&)(Arg1, Arg2), Func>
+{
+ static inline int WrapFuncT(const int)
+ {
+ return 2; // Changed
+ }
+};
+
+int main()
+{
+ return 0;
+}
diff --git a/gcc/testsuite/g++.dg/template/partial5.C
b/gcc/testsuite/g++.dg/template/partial5.C
index 1b56fb3..ee45a93 100644
--- a/gcc/testsuite/g++.dg/template/partial5.C
+++ b/gcc/testsuite/g++.dg/template/partial5.C
@@ -14,7 +14,7 @@ template<typename T, typename T::foo V>
struct Y { };
template<typename T, typename U, U v>
-struct Y<T, v> { }; // { dg-error "" }
+struct Y<T, v> { }; // { dg-error "" "" { target { ! c++1z } } }
template<typename T, T V>
