PR c++/86205 - ICE with ?: of throw and template-id.

My patch for 64372 removed a bogus lvalue-rvalue conversion for one arm of a
?: expression where the other arm is a throw.  But we still need to require
any overload to be resolved, even though we aren't getting that from
decay_conversion anymore.

	* pt.c (resolve_nondeduced_context_or_error): Split out from...
	* typeck.c (decay_conversion): ...here.
	* call.c (build_conditional_expr_1): Use it.

From-SVN: r268058

gcc/cp/ChangeLog

@@ -1,5 +1,10 @@
 2019-01-17  Jason Merrill  <jason@redhat.com>
 
+	PR c++/86205 - ICE with ?: of throw and template-id.
+	* pt.c (resolve_nondeduced_context_or_error): Split out from...
+	* typeck.c (decay_conversion): ...here.
+	* call.c (build_conditional_expr_1): Use it.
+
 	PR c++/86740, ICE with constexpr if and nested generic lambdas.
 	* tree.c (cp_walk_subtrees): Handle LAMBDA_EXPR.
 

gcc/cp/call.c

@@ -5067,6 +5067,19 @@ build_conditional_expr_1 (const op_location_t &loc,
   arg3_type = unlowered_expr_type (arg3);
   if (VOID_TYPE_P (arg2_type) || VOID_TYPE_P (arg3_type))
     {
+      /* 'void' won't help in resolving an overloaded expression on the
+	 other side, so require it to resolve by itself.  */
+      if (arg2_type == unknown_type_node)
+	{
+	  arg2 = resolve_nondeduced_context_or_error (arg2, complain);
+	  arg2_type = TREE_TYPE (arg2);
+	}
+      if (arg3_type == unknown_type_node)
+	{
+	  arg3 = resolve_nondeduced_context_or_error (arg3, complain);
+	  arg3_type = TREE_TYPE (arg3);
+	}
+
       /* [expr.cond]
 
 	 One of the following shall hold:

gcc/cp/cp-tree.h

@@ -6831,6 +6831,7 @@ extern tree get_template_innermost_arguments	(const_tree);
 extern tree get_template_argument_pack_elems	(const_tree);
 extern tree get_function_template_decl		(const_tree);
 extern tree resolve_nondeduced_context		(tree, tsubst_flags_t);
+extern tree resolve_nondeduced_context_or_error	(tree, tsubst_flags_t);
 extern hashval_t iterative_hash_template_arg (tree arg, hashval_t val);
 extern tree coerce_template_parms               (tree, tree, tree);
 extern tree coerce_template_parms               (tree, tree, tree, tsubst_flags_t);

gcc/cp/pt.c

@@ -21147,6 +21147,21 @@ resolve_nondeduced_context (tree orig_expr, tsubst_flags_t complain)
   return orig_expr;
 }
 
+/* As above, but error out if the expression remains overloaded.  */
+
+tree
+resolve_nondeduced_context_or_error (tree exp, tsubst_flags_t complain)
+{
+  exp = resolve_nondeduced_context (exp, complain);
+  if (type_unknown_p (exp))
+    {
+      if (complain & tf_error)
+	cxx_incomplete_type_error (exp, TREE_TYPE (exp));
+      return error_mark_node;
+    }
+  return exp;
+}
+
 /* Subroutine of resolve_overloaded_unification; does deduction for a single
    overload.  Fills TARGS with any deduced arguments, or error_mark_node if
    different overloads deduce different arguments for a given parm.

gcc/cp/typeck.c

@@ -2009,13 +2009,7 @@ decay_conversion (tree exp,
   if (type == error_mark_node)
     return error_mark_node;
 
-  exp = resolve_nondeduced_context (exp, complain);
-  if (type_unknown_p (exp))
-    {
-      if (complain & tf_error)
-	cxx_incomplete_type_error (exp, TREE_TYPE (exp));
-      return error_mark_node;
-    }
+  exp = resolve_nondeduced_context_or_error (exp, complain);
 
   code = TREE_CODE (type);
 

gcc/testsuite/g++.dg/cpp0x/cond2.C

@@ -0,0 +1,14 @@
+// PR c++/86205
+// { dg-do compile { target c++11 } }
+
+bool b;
+
+template < class T > int f ()
+{
+  return 0;
+}
+
+template < class T > auto g () -> decltype (b ? f < int > : throw 0)
+{
+  return b ? f<int> : throw 0;
+}