Apply D28224: 'Throw exception after too many steps' Fixes PR#20291. Thanks to Tim Shen for the patch

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@313056 91177308-0d34-0410-b5e6-96231b3b80d8

test/std/re/re.alg/re.alg.match/exponential.pass.cpp

@@ -0,0 +1,46 @@
+//===----------------------------------------------------------------------===//
+//
+//                     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.
+//
+//===----------------------------------------------------------------------===//
+
+// <regex>
+
+// template <class BidirectionalIterator, class Allocator, class charT, class traits>
+//     bool
+//     regex_match(BidirectionalIterator first, BidirectionalIterator last,
+//                  match_results<BidirectionalIterator, Allocator>& m,
+//                  const basic_regex<charT, traits>& e,
+//                  regex_constants::match_flag_type flags = regex_constants::match_default);
+
+// Throw exception after spent too many cycles with respect to the length of the input string.
+
+#include <regex>
+#include <cassert>
+
+int main() {
+  for (std::regex_constants::syntax_option_type op :
+       {std::regex::ECMAScript, std::regex::extended, std::regex::egrep,
+        std::regex::awk}) {
+    try {
+      std::regex_match(
+          "aaaaaaaaaaaaaaaaaaaa",
+          std::regex(
+              "a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?aaaaaaaaaaaaaaaaaaaa",
+              op));
+      assert(false);
+    } catch (const std::regex_error &e) {
+      assert(e.code() == std::regex_constants::error_complexity);
+    }
+  }
+  std::string s(100000, 'a');
+  for (std::regex_constants::syntax_option_type op :
+       {std::regex::ECMAScript, std::regex::extended, std::regex::egrep,
+        std::regex::awk}) {
+    assert(std::regex_match(s, std::regex("a*", op)));
+  }
+  return 0;
+}

test/std/re/re.alg/re.alg.search/exponential.pass.cpp

@@ -0,0 +1,46 @@
+//===----------------------------------------------------------------------===//
+//
+//                     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.
+//
+//===----------------------------------------------------------------------===//
+
+// <regex>
+
+// template <class BidirectionalIterator, class Allocator, class charT, class traits>
+//     bool
+//     regex_search(BidirectionalIterator first, BidirectionalIterator last,
+//                  match_results<BidirectionalIterator, Allocator>& m,
+//                  const basic_regex<charT, traits>& e,
+//                  regex_constants::match_flag_type flags = regex_constants::match_default);
+
+// Throw exception after spent too many cycles with respect to the length of the input string.
+
+#include <regex>
+#include <cassert>
+
+int main() {
+  for (std::regex_constants::syntax_option_type op :
+       {std::regex::ECMAScript, std::regex::extended, std::regex::egrep,
+        std::regex::awk}) {
+    try {
+      std::regex_search(
+          "aaaaaaaaaaaaaaaaaaaa",
+          std::regex(
+              "a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?aaaaaaaaaaaaaaaaaaaa",
+              op));
+      assert(false);
+    } catch (const std::regex_error &e) {
+      assert(e.code() == std::regex_constants::error_complexity);
+    }
+  }
+  std::string s(100000, 'a');
+  for (std::regex_constants::syntax_option_type op :
+       {std::regex::ECMAScript, std::regex::extended, std::regex::egrep,
+        std::regex::awk}) {
+    assert(std::regex_search(s, std::regex("a*", op)));
+  }
+  return 0;
+}