C++ PATCH for c++/83808, ICE with VLA initialization

[Jason Merrill]

Since my patch for 69847 stopped us from giving a STRING_CST VLA type,
the check in process_init_constructor_array to make sure our
initializer has the right type breaks.  Let's just adjust the sanity
check to look through arrays rather than try to be more specific.

Tested x86_64-pc-linux-gnu, applying to trunk.

commit 44cef54536ebec8b054767235330bfb86bea912f
Author: Jason Merrill <ja...@redhat.com>
Date:   Thu Apr 5 12:01:35 2018 -0400

            PR c++/83808 - ICE with VLA initialization.
    
            * typeck2.c (process_init_constructor_array): Don't require a VLA
            initializer to have VLA type.

diff --git a/gcc/cp/typeck2.c b/gcc/cp/typeck2.c
index 3bdeae1501f..e5f9a68ec58 100644
--- a/gcc/cp/typeck2.c
+++ b/gcc/cp/typeck2.c
@@ -1319,9 +1319,11 @@ process_init_constructor_array (tree type, tree init, int nested,
       ce->value
 	= massage_init_elt (TREE_TYPE (type), ce->value, nested, complain);
 
-      if (ce->value != error_mark_node)
-	gcc_assert (same_type_ignoring_top_level_qualifiers_p
-		      (TREE_TYPE (type), TREE_TYPE (ce->value)));
+      gcc_checking_assert
+	(ce->value == error_mark_node
+	 || (same_type_ignoring_top_level_qualifiers_p
+	     (strip_array_types (TREE_TYPE (type)),
+	      strip_array_types (TREE_TYPE (ce->value)))));
 
       flags |= picflag_from_initializer (ce->value);
     }
diff --git a/gcc/testsuite/g++.dg/ext/vla19.C b/gcc/testsuite/g++.dg/ext/vla19.C
new file mode 100644
index 00000000000..287a0d5a381
--- /dev/null
+++ b/gcc/testsuite/g++.dg/ext/vla19.C
@@ -0,0 +1,16 @@
+// PR c++/83808
+// { dg-additional-options "-Wno-vla" }
+
+struct R { int r; };
+void baz (char *, char *, char *, char *);
+
+void
+foo ()
+{
+  const R a = { 12 };
+  char b[1][a.r] = { { "12345678901" } };
+  char c[a.r] = { "12345678901" };
+  char d[1][a.r] = { { '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '\0' } };
+  char e[a.r] = { '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '\0' };
+  baz (b[0], c, d[0], e);
+}