Hi,
today I spent some time on this: basing on r245826, when we started
ICEing. For example I wondered if we wanted to rework the use of
do_auto_deduction from build_new, and check CLASS_PLACEHOLDER_TEMPLATE
(auto_node) and possibly directly call do_class_deduction when d_init
stays NULL_TREE because vec_safe_length (*init) != 1 (
https://gcc.gnu.org/viewcvs/gcc/trunk/gcc/cp/init.c?r1=245826&r2=245825&pathrev=245826
). But that would require a non-static do_class_deduction and an
additional function call from build_new, not at all sure it's worth it.
Thus I'm just proposing the below, restoring the old diagnostic and
avoiding the ICE.
Thanks, Paolo.
////////////////
/cp
2018-02-14 Paolo Carlini <paolo.carl...@oracle.com>
PR c++/84350
* pt.c (do_auto_deduction): Don't check the TREE_TYPE of a null
init, early return.
/testsuite
2018-02-14 Paolo Carlini <paolo.carl...@oracle.com>
PR c++/84350
* g++.dg/cpp0x/auto49.C: New.
Index: cp/pt.c
===================================================================
--- cp/pt.c (revision 257659)
+++ cp/pt.c (working copy)
@@ -25975,7 +25975,7 @@ do_auto_deduction (tree type, tree init, tree auto
/* C++17 class template argument deduction. */
return do_class_deduction (type, tmpl, init, flags, complain);
- if (TREE_TYPE (init) == NULL_TREE)
+ if (init == NULL_TREE || TREE_TYPE (init) == NULL_TREE)
/* Nothing we can do with this, even in deduction context. */
return type;
Index: testsuite/g++.dg/cpp0x/auto49.C
===================================================================
--- testsuite/g++.dg/cpp0x/auto49.C (nonexistent)
+++ testsuite/g++.dg/cpp0x/auto49.C (working copy)
@@ -0,0 +1,12 @@
+// PR c++/84350
+// { dg-do compile { target c++11 } }
+
+template<typename... T> void foo(T... t)
+{
+ new auto(t...); // { dg-error "invalid use" }
+}
+
+void bar()
+{
+ foo();
+}
