From 4e2cdb1ddb5f6ace909358775e94bfe23046ad5a Mon Sep 17 00:00:00 2001
From: Jason Merrill <jason@redhat.com>
Date: Thu, 23 Mar 2023 18:20:52 -0400
Subject: [PATCH] c++: default template arg, partial ordering [PR105481]
The default argument code in type_unification_real was assuming that all
targs we've deduced by that point are non-dependent, but that's not the case
for partial ordering.
PR c++/105481
gcc/cp/ChangeLog:
* pt.cc (type_unification_real): Adjust for partial ordering.
gcc/testsuite/ChangeLog:
* g++.dg/cpp0x/fntmpdefarg-partial1.C: New test.
---
gcc/cp/pt.cc | 18 ++++++++++++++----
.../g++.dg/cpp0x/fntmpdefarg-partial1.C | 8 ++++++++
2 files changed, 22 insertions(+), 4 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/cpp0x/fntmpdefarg-partial1.C
diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
index 40deedc9ba93..3bb98ebeac13 100644
--- a/gcc/cp/pt.cc
+++ b/gcc/cp/pt.cc
@@ -23304,14 +23304,24 @@ type_unification_real (tree tparms,
return unify_parameter_deduction_failure (explain_p, tparm);
}
+ /* During partial ordering, we deduce dependent template args. */
+ bool any_dependent_targs = false;
+
/* Now substitute into the default template arguments. */
for (i = 0; i < ntparms; i++)
{
tree targ = TREE_VEC_ELT (targs, i);
tree tparm = TREE_VEC_ELT (tparms, i);
- if (targ || tparm == error_mark_node)
+ if (targ)
+ {
+ if (!any_dependent_targs && dependent_template_arg_p (targ))
+ any_dependent_targs = true;
+ continue;
+ }
+ if (tparm == error_mark_node)
continue;
+
tree parm = TREE_VALUE (tparm);
tree arg = TREE_PURPOSE (tparm);
reopen_deferring_access_checks (*checks);
@@ -23347,9 +23357,9 @@ type_unification_real (tree tparms,
do this substitution without processing_template_decl. This
is important if the default argument contains something that
might be instantiation-dependent like access (87480). */
- processing_template_decl_sentinel s;
+ processing_template_decl_sentinel s (!any_dependent_targs);
tree substed = NULL_TREE;
- if (saw_undeduced == 1)
+ if (saw_undeduced == 1 && !any_dependent_targs)
{
/* First instatiate in template context, in case we still
depend on undeduced template parameters. */
@@ -23372,7 +23382,7 @@ type_unification_real (tree tparms,
complain, i, NULL_TREE);
else if (saw_undeduced == 1)
arg = NULL_TREE;
- else
+ else if (!any_dependent_targs)
arg = error_mark_node;
}
diff --git a/gcc/testsuite/g++.dg/cpp0x/fntmpdefarg-partial1.C b/gcc/testsuite/g++.dg/cpp0x/fntmpdefarg-partial1.C
new file mode 100644
index 000000000000..2a6783e566b0
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/fntmpdefarg-partial1.C
@@ -0,0 +1,8 @@
+// PR c++/105481
+// { dg-do compile { target c++11 } }
+
+template<unsigned> struct uint;
+template<unsigned N> uint<N> f(const uint<N> &);
+template<unsigned N, typename T, typename = uint<N>> uint<N> f(T);
+using X = uint<1>;
+X (*fp)(X const &) = f;
--
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