[libcxx] Correctly handle invalid regex character class names

Summary:
Currently when a regular expression contains an invalid character
class name std::regex constructors throw an std::regex_error with
std::regex_constants::error_brack code.

This patch changes the code to std::regex_constants::error_ctype and
adds a test.

Reviewers: EricWF, mclow.lists

Reviewed By: mclow.lists

Subscribers: cfe-commits

Differential Revision: https://reviews.llvm.org/D42291

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@323322 91177308-0d34-0410-b5e6-96231b3b80d8

test/std/re/re.regex/re.regex.construct/bad_ctype.pass.cpp

@@ -0,0 +1,37 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: libcpp-no-exceptions
+// <regex>
+
+// template <class charT, class traits = regex_traits<charT>> class basic_regex;
+
+// template <class ST, class SA>
+//    basic_regex(const basic_string<charT, ST, SA>& s);
+
+#include <regex>
+#include <cassert>
+#include "test_macros.h"
+
+static bool error_ctype_thrown(const char *pat)
+{
+    bool result = false;
+    try {
+        std::regex re(pat);
+    } catch (const std::regex_error &ex) {
+        result = (ex.code() == std::regex_constants::error_ctype);
+    }
+    return result;
+}
+
+int main()
+{
+    assert(error_ctype_thrown("[[::]]"));
+    assert(error_ctype_thrown("[[:error:]]"));
+}