[libc++] Add test to ensure that the mangling of types stays the same (#143556)

libcxx/test/libcxx/mangled_names.pass.cpp

@@ -0,0 +1,74 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+// We're using `string::starts_with` in this test
+// UNSUPPORTED: c++03, c++11, c++14, c++17
+
+// Make sure that the mangling of our public types stays the same
+
+// UNSUPPORTED: no-rtti, msvc
+
+#include <cassert>
+#include <charconv>
+#include <iostream>
+#include <map>
+#include <typeinfo>
+#include <string>
+#include <string_view>
+
+template <class>
+struct mangling {};
+
+struct test_struct {};
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+struct ns_mangling {};
+_LIBCPP_END_NAMESPACE_STD
+
+namespace std::__name {
+struct ns_mangling {};
+} // namespace std::__name
+
+namespace std::__long_name_to_make_sure_multiple_digits_work {
+struct ns_mangling {};
+} // namespace std::__long_name_to_make_sure_multiple_digits_work
+
+std::string get_std_inline_namespace_mangling(const std::type_info& info) {
+  std::string name = info.name();
+  assert(name.starts_with("NSt"));
+  unsigned name_len;
+  auto res = std::from_chars(name.data() + 3, name.data() + name.size(), name_len);
+  assert(res.ec == std::errc{});
+  return std::move(name).substr(0, (res.ptr + name_len) - name.data());
+}
+
+void expect_mangling(const std::type_info& info, std::string expected_name) {
+  if (expected_name != info.name())
+    std::__libcpp_verbose_abort("Expected: '%s'\n     Got: '%s'\n", expected_name.c_str(), info.name());
+}
+
+// Mangling names are really long, but splitting it up into multiple lines doesn't make it any more readable
+// clang-format off
+int main(int, char**) {
+  // self-test inline namespace recovery
+  assert(get_std_inline_namespace_mangling(typeid(std::__name::ns_mangling)) == "NSt6__name");
+  assert(get_std_inline_namespace_mangling(typeid(std::__long_name_to_make_sure_multiple_digits_work::ns_mangling)) == "NSt45__long_name_to_make_sure_multiple_digits_work");
+
+  // selftest
+  expect_mangling(typeid(test_struct), "11test_struct");
+
+  std::string ns_std = get_std_inline_namespace_mangling(typeid(std::ns_mangling));
+  std::string ptrdiff = typeid(std::ptrdiff_t).name();
+
+  // std::map
+  expect_mangling(typeid(std::map<int, int>), ns_std + "3mapIiiNS_4lessIiEENS_9allocatorINS_4pairIKiiEEEEEE");
+  expect_mangling(typeid(std::map<int, int>::iterator), ns_std + "14__map_iteratorINS_15__tree_iteratorINS_12__value_typeIiiEEPNS_11__tree_nodeIS3_PvEE" + ptrdiff +"EEEE");
+  expect_mangling(typeid(std::map<int, int>::const_iterator), ns_std + "20__map_const_iteratorINS_21__tree_const_iteratorINS_12__value_typeIiiEEPNS_11__tree_nodeIS3_PvEE" + ptrdiff + "EEEE");
+
+  return 0;
+}