logging: update XCHECK_EQ() to use objectToString()

Summary:
Update the `XCHECK_EQ()` macros to use `folly::logging::objectToString()` to
format the message on failure.

This ensures that `XCHECK_EQ()` will successfully compile and work with any
arguments.  Previously it would fail to compile if called with arguments that
did not work with `folly::to<std::string>()`

Reviewed By: chadaustin

Differential Revision: D14545301

fbshipit-source-id: 442657a1770f30cbf01462ad62d32301e60490e5

folly/logging/test/fatal_test.py

@@ -18,6 +18,7 @@ import os
 import re
 import signal
 import subprocess
+import sys
 import unittest
 
 
@@ -209,6 +210,23 @@ class FatalTests(unittest.TestCase):
         expected_msg = "Check failed: ++x == 7 (6 vs. 7)"
         self.assertRegex(err, self.get_crash_regex(expected_msg.encode("utf-8")))
 
+    def test_xcheck_custom_object(self):
+        err = self.run_helper("--xcheck_eq_custom_struct")
+        if sys.byteorder == "little":
+            obj1_hexdump = "01 00 00 00 02 00 00 00"
+            obj2_hexdump = "01 00 00 00 ef cd ab 12"
+        else:
+            obj1_hexdump = "00 00 00 01 00 00 00 02"
+            obj2_hexdump = "00 00 00 01 12 ab cd ef"
+
+        expected_msg = (
+            "Check failed: MyStruct(1, 2) == m ("
+            f"[MyStruct of size 8: {obj1_hexdump}] vs. "
+            f"[MyStruct of size 8: {obj2_hexdump}]"
+            ")"
+        )
+        self.assertRegex(err, self.get_crash_regex(expected_msg.encode("utf-8")))
+
     def _test_xcheck_cmp(
         self, flag, value, op, extra_msg=" extra user args", expect_failure=True
     ):

folly/logging/test/helpers/FatalHelper.cpp

@@ -56,6 +56,15 @@ DEFINE_bool(
     test_xcheck_eq_evalutates_once,
     false,
     "Test an XCHECK_EQ() statement where the arguments have side effects");
+DEFINE_bool(
+    xcheck_eq_custom_struct,
+    false,
+    "Test an XCHECK_EQ() statement with a custom structure, "
+    "to test log message formatting");
+DEFINE_bool(
+    xcheck_eq_pointers,
+    false,
+    "Test an XCHECK_EQ() statement with pointer arguments");
 
 using folly::LogLevel;
 
@@ -111,6 +120,18 @@ std::string fbLogFatalCheck() {
   // about a missing return statement here.
 }
 
+struct MyStruct {
+  MyStruct(uint32_t a, uint32_t b) : a(a), b(b) {}
+  uint32_t a;
+  uint32_t b;
+};
+bool operator==(const MyStruct& s1, const MyStruct& s2) {
+  return (s1.a == s2.a) && (s1.b == s2.b);
+}
+bool operator<=(const MyStruct& s1, const MyStruct& s2) {
+  return !(s1 == s2);
+}
+
 /*
  * This is a simple helper program to exercise the LOG(FATAL) functionality.
  */
@@ -148,6 +169,14 @@ int main(int argc, char* argv[]) {
     int x = 5;
     XCHECK_EQ(++x, 7);
   }
+  if (FLAGS_xcheck_eq_custom_struct) {
+    auto m = MyStruct(1, 0x12abcdef);
+    XCHECK_EQ(MyStruct(1, 2), m);
+  }
+  if (FLAGS_xcheck_eq_pointers) {
+    int localInt = 5;
+    XCHECK_EQ(&argc, &localInt);
+  }
 
   // Do the remainder of the work in a separate helper function.
   //

folly/logging/xlog.h

@@ -21,6 +21,7 @@
 #include <folly/logging/LogStream.h>
 #include <folly/logging/Logger.h>
 #include <folly/logging/LoggerDB.h>
+#include <folly/logging/ObjectToString.h>
 #include <folly/logging/RateLimiter.h>
 #include <cstdlib>
 
@@ -370,7 +371,13 @@ std::unique_ptr<std::string> XCheckOpImpl(
     return nullptr;
   }
   return std::make_unique<std::string>(folly::to<std::string>(
-      "Check failed: ", checkStr, " (", arg1, " vs. ", arg2, ")"));
+      "Check failed: ",
+      checkStr,
+      " (",
+      ::folly::logging::objectToString(arg1),
+      " vs. ",
+      folly::logging::objectToString(arg2),
+      ")"));
 }
 } // namespace detail
 } // namespace folly