With T({}), the {} specifically initializes the first constructor
parameter, rather than T directly. This is different from T{}, so we
need to check CONSTRUCTOR_IS_DIRECT_INIT.
Tested x86_64-pc-linux-gnu, applying to trunk.
commit 96fb2fc01280452682585dcc68038f54f416d034
Author: Jason Merrill <ja...@redhat.com>
Date: Fri Mar 16 09:00:37 2018 -0400
PR c++/83937 - wrong C++17 handling of init-list ctor argument.
* call.c (build_special_member_call): Don't convert an init-list
argument directly to the class type.
diff --git a/gcc/cp/call.c b/gcc/cp/call.c
index 67438ff2e94..4bd3190b42e 100644
--- a/gcc/cp/call.c
+++ b/gcc/cp/call.c
@@ -8829,7 +8829,12 @@ build_special_member_call (tree instance, tree name, vec<tree, va_gc> **args,
/* If we're using this to initialize a non-temporary object, don't
require the destructor to be accessible. */
sub_complain |= tf_no_cleanup;
- if (!reference_related_p (class_type, TREE_TYPE (arg)))
+ if (BRACE_ENCLOSED_INITIALIZER_P (arg)
+ && !CONSTRUCTOR_IS_DIRECT_INIT (arg))
+ /* An init-list arg needs to convert to the parm type (83937), so fall
+ through to normal processing. */
+ arg = error_mark_node;
+ else if (!reference_related_p (class_type, TREE_TYPE (arg)))
arg = perform_implicit_conversion_flags (class_type, arg,
sub_complain,
flags);
diff --git a/gcc/testsuite/g++.dg/cpp0x/initlist-ctor2.C b/gcc/testsuite/g++.dg/cpp0x/initlist-ctor2.C
new file mode 100644
index 00000000000..ebacec0cff5
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/initlist-ctor2.C
@@ -0,0 +1,15 @@
+// PR c++/83937
+// { dg-do run { target c++11 } }
+
+struct S
+{
+ S(int v = 42) {
+ if (v != int{})
+ __builtin_abort();
+ }
+};
+
+int main()
+{
+ S( {} );
+}
