C++ PATCH to fix ICE with invalid cast (PR c++/84493)

[Marek Polacek]

Here we can prevent a crash on invalid by using require_open where '{' is
expected.  require_open uses cp_parser_require whereas consume_open has
an assert:
gcc_assert (tok->type == traits_t::open_token_type);
which triggers here.

Bootstrapped/regtested on x86_64-linux, ok for trunk?

2018-02-21  Marek Polacek  <pola...@redhat.com>

        PR c++/84493
        * parser.c (cp_parser_braced_list): Use require_open instead of
        consume_open.

        * g++.dg/parse/error59.C: New test.

diff --git gcc/cp/parser.c gcc/cp/parser.c
index 2bb0d2da5fe..4fa546a086c 100644
--- gcc/cp/parser.c
+++ gcc/cp/parser.c
@@ -21925,7 +21925,7 @@ cp_parser_braced_list (cp_parser* parser, bool* 
non_constant_p)
 
   /* Consume the `{' token.  */
   matching_braces braces;
-  braces.consume_open (parser);
+  braces.require_open (parser);
   /* Create a CONSTRUCTOR to represent the braced-initializer.  */
   initializer = make_node (CONSTRUCTOR);
   /* If it's not a `}', then there is a non-trivial initializer.  */
diff --git gcc/testsuite/g++.dg/parse/error59.C 
gcc/testsuite/g++.dg/parse/error59.C
index e69de29bb2d..2c44e210366 100644
--- gcc/testsuite/g++.dg/parse/error59.C
+++ gcc/testsuite/g++.dg/parse/error59.C
@@ -0,0 +1,6 @@
+// PR c++/84493
+
+void foo()
+{
+  (struct {}x){}; // { dg-error "" }
+}

        Marek