[libc++] Add regression test for std::hash implementation in ABI v1

Differential Revision: https://reviews.llvm.org/D144107

GitOrigin-RevId: 23d43e6977576ed318a9c81cec256d75f5d49ded

test/libcxx/utilities/utility/__murmur2_or_cityhash.abi-v1.pass.cpp

diff --git a/test/libcxx/utilities/utility/__murmur2_or_cityhash.pass.cpp b/test/libcxx/utilities/utility/__murmur2_or_cityhash.abi-v1.pass.cpp
similarity index 63%
copy from test/libcxx/utilities/utility/__murmur2_or_cityhash.pass.cpp
copy to test/libcxx/utilities/utility/__murmur2_or_cityhash.abi-v1.pass.cpp
index 13fc9c3..3f8557a 100644
--- a/test/libcxx/utilities/utility/__murmur2_or_cityhash.pass.cpp
+++ b/test/libcxx/utilities/utility/__murmur2_or_cityhash.abi-v1.pass.cpp
@@ -6,13 +6,14 @@
 //
 //===----------------------------------------------------------------------===//
 
-// Test the CityHash implementation is correct.
-
 // UNSUPPORTED: c++03
 
-// In ABI v1, our CityHash implementation is incorrect and fixing it would
-// be an ABI break.
-// REQUIRES: libcpp-abi-version=2
+// Test that the CityHash implementation returns the results we expect.
+//
+// Note that this implementation is technically incorrect, however changing it is
+// an ABI break. This test ensures that we don't unintentionally break the ABI v1
+// by "fixing" the hash implementation.
+// REQUIRES: libcpp-abi-version=1
 
 #include <cassert>
 #include <string>
@@ -33,15 +34,16 @@
 
 int main(int, char**) {
   const std::pair<std::string, uint64_t> TestCases[] = {
-      {CityHash[0], CHOOSE_BY_ENDIANESS(0x4382a8d0fe8edb17ULL, 0xca84e809bef16fbcULL)},
-      {CityHash[1], CHOOSE_BY_ENDIANESS(0xecefb080a6854061ULL, 0xd7feb824250272dcULL)},
-      {CityHash[2], CHOOSE_BY_ENDIANESS(0x169ea3aebf908d6dULL, 0xea8cef3ca6f6e368ULL)},
-      {CityHash[3], CHOOSE_BY_ENDIANESS(0xe18298a2760f09faULL, 0xf33a7700bb7a94a8ULL)},
+      {CityHash[0], CHOOSE_BY_ENDIANESS(0x87c69099911bab7eULL, 0x297621d7fa436a3ULL)},
+      {CityHash[1], CHOOSE_BY_ENDIANESS(0x87c69099911bab7eULL, 0xb17be531dde56e57ULL)},
+      {CityHash[2], CHOOSE_BY_ENDIANESS(0x85322632e188694aULL, 0xe14f578b688e266dULL)},
+      {CityHash[3], CHOOSE_BY_ENDIANESS(0x85322632e188694aULL, 0xca5a764a0450eac6ULL)},
   };
 
   std::__murmur2_or_cityhash<uint64_t> h64;
   for (const auto& test_case : TestCases) {
     assert(h64(test_case.first.data(), test_case.first.size()) == test_case.second);
   }
+
   return 0;
 }

test/libcxx/utilities/utility/__murmur2_or_cityhash.abi-v2.pass.cpp

diff --git a/test/libcxx/utilities/utility/__murmur2_or_cityhash.pass.cpp b/test/libcxx/utilities/utility/__murmur2_or_cityhash.abi-v2.pass.cpp
similarity index 96%
rename from test/libcxx/utilities/utility/__murmur2_or_cityhash.pass.cpp
rename to test/libcxx/utilities/utility/__murmur2_or_cityhash.abi-v2.pass.cpp
index 13fc9c3..01f8b88 100644
--- a/test/libcxx/utilities/utility/__murmur2_or_cityhash.pass.cpp
+++ b/test/libcxx/utilities/utility/__murmur2_or_cityhash.abi-v2.pass.cpp
@@ -6,10 +6,10 @@
 //
 //===----------------------------------------------------------------------===//
 
-// Test the CityHash implementation is correct.
-
 // UNSUPPORTED: c++03
 
+// Test that the CityHash implementation is correct.
+//
 // In ABI v1, our CityHash implementation is incorrect and fixing it would
 // be an ABI break.
 // REQUIRES: libcpp-abi-version=2