[libcxx] Add test to check min/max requirement to regular expression

This commit adds tests that repeated characters in regular expressions
are within numeric limits, and that a <= b in a regex like `x{a,b}`.

Thanks to Andrey Maksimov for the patch.

Differential Revision: https://reviews.llvm.org/D62816

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@362525 91177308-0d34-0410-b5e6-96231b3b80d8

test/std/re/re.grammar/excessive_brace_min_max.pass.cpp

@@ -0,0 +1,67 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// <regex>
+// UNSUPPORTED: libcpp-no-exceptions
+// UNSUPPORTED: c++98, c++03
+
+// the "n" and "m" in `a{n,m}` should be within the numeric limits.
+// requirement "m >= n" should be checked.
+
+#include <regex>
+#include <cassert>
+#include "test_macros.h"
+
+int main(int, char**) {
+  // test that `n <= m`
+  for (std::regex_constants::syntax_option_type op :
+       {std::regex::basic}) {
+    try {
+      TEST_IGNORE_NODISCARD std::regex("a\\{3,2\\}", op);
+      assert(false);
+    } catch (const std::regex_error &e) {
+      assert(e.code() == std::regex_constants::error_badbrace);
+      LIBCPP_ASSERT(e.code() == std::regex_constants::error_badbrace);
+    }
+  }
+  for (std::regex_constants::syntax_option_type op :
+       {std::regex::ECMAScript, std::regex::extended, std::regex::egrep,
+        std::regex::awk}) {
+    try {
+      TEST_IGNORE_NODISCARD std::regex("a{3,2}", op);
+      assert(false);
+    } catch (const std::regex_error &e) {
+      assert(e.code() == std::regex_constants::error_badbrace);
+      LIBCPP_ASSERT(e.code() == std::regex_constants::error_badbrace);
+    }
+  }
+
+  // test that both bounds are within the limit
+  for (std::regex_constants::syntax_option_type op :
+       {std::regex::basic}) {
+    try {
+      TEST_IGNORE_NODISCARD std::regex("a\\{100000000000000000000,10000000000000000000\\}", op);
+      assert(false);
+    } catch (const std::regex_error &e) {
+      assert(e.code() == std::regex_constants::error_badbrace);
+      LIBCPP_ASSERT(e.code() == std::regex_constants::error_badbrace);
+    }
+  }
+  for (std::regex_constants::syntax_option_type op :
+       {std::regex::ECMAScript, std::regex::extended, std::regex::egrep,
+        std::regex::awk}) {
+    try {
+      TEST_IGNORE_NODISCARD std::regex("a{100000000000000000000,10000000000000000000}", op);
+      assert(false);
+    } catch (const std::regex_error &e) {
+      assert(e.code() == std::regex_constants::error_badbrace);
+      LIBCPP_ASSERT(e.code() == std::regex_constants::error_badbrace);
+    }
+  }
+  return 0;
+}