My changes to handle incomplete packs ended up splitting the late loop
in type_unification_real into two loops, one to check whether there are
any non-type template parameters that still have a dependent type, and
then another to apply default arguments. This breaks the testcase in
55724, which depends on the default argument for a type parameter in
order to deduce the value of a non-type parameter. I tried just
combining the two loops again to see what breaks, and nothing does.
Tested x86_64-pc-linux-gnu, applying to trunk and 4.7.
commit c6ea657d938078a53448dbb8b4438d9c94679fb3
Author: Jason Merrill <ja...@redhat.com>
Date: Wed Dec 19 06:15:24 2012 -0500
PR c++/55724
* pt.c (type_unification_real): Re-combine post-deduction loops.
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index a21522b..1b3f039 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -15333,13 +15333,19 @@ type_unification_real (tree tparms,
? tf_warning_or_error
: tf_none);
- /* Check to see if we need another pass before we start clearing
- ARGUMENT_PACK_INCOMPLETE_P. */
for (i = 0; i < ntparms; i++)
{
tree targ = TREE_VEC_ELT (targs, i);
tree tparm = TREE_VEC_ELT (tparms, i);
+ /* Clear the "incomplete" flags on all argument packs now so that
+ substituting them into later default arguments works. */
+ if (targ && ARGUMENT_PACK_P (targ))
+ {
+ ARGUMENT_PACK_INCOMPLETE_P (targ) = 0;
+ ARGUMENT_PACK_EXPLICIT_ARGS (targ) = NULL_TREE;
+ }
+
if (targ || tparm == error_mark_node)
continue;
tparm = TREE_VALUE (tparm);
@@ -15352,24 +15358,6 @@ type_unification_real (tree tparms,
&& uses_template_parms (TREE_TYPE (tparm))
&& !saw_undeduced++)
goto again;
- }
-
- for (i = 0; i < ntparms; i++)
- {
- tree targ = TREE_VEC_ELT (targs, i);
- tree tparm = TREE_VEC_ELT (tparms, i);
-
- /* Clear the "incomplete" flags on all argument packs now so that
- substituting them into later default arguments works. */
- if (targ && ARGUMENT_PACK_P (targ))
- {
- ARGUMENT_PACK_INCOMPLETE_P (targ) = 0;
- ARGUMENT_PACK_EXPLICIT_ARGS (targ) = NULL_TREE;
- }
-
- if (targ || tparm == error_mark_node)
- continue;
- tparm = TREE_VALUE (tparm);
/* Core issue #226 (C++0x) [temp.deduct]:
diff --git a/gcc/testsuite/g++.dg/cpp0x/fntmpdefarg4.C b/gcc/testsuite/g++.dg/cpp0x/fntmpdefarg4.C
new file mode 100644
index 0000000..0248b60
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/fntmpdefarg4.C
@@ -0,0 +1,6 @@
+// PR c++/55724
+// { dg-options -std=c++11 }
+
+template<int N> struct S {};
+template<typename T = int, T N> void f(S<N>) {}
+int main() { S<1> s; f(s); }
