logging: Provide a specific MakeCheckOpValueString overload for functions

base/logging_unittest.cc

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/compiler_specific.h"
 #include "base/logging.h"
 #include "base/macros.h"
 
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
@@ skipping 199 matching lines @@
   DCHECK_EQ(0, 0) << mock_log_source.Log();
 #else
   DCHECK(mock_log_source.Log()) << mock_log_source.Log();
   DPCHECK(mock_log_source.Log()) << mock_log_source.Log();
   DCHECK_EQ(0, 0) << mock_log_source.Log();
   DCHECK_EQ(mock_log_source.Log(), static_cast<const char*>(NULL))
       << mock_log_source.Log();
 #endif
 }
 
+void DcheckEmptyFunction1() {
+  // Provide a body so that Release builds do not cause the compiler to
+  // optimize DcheckEmptyFunction1 and DcheckEmptyFunction2 as a single
+  // function, which breaks the Dcheck tests below.
+  LOG(INFO) << "DcheckEmptyFunction1";
+}
+void DcheckEmptyFunction2() {}
+
 TEST_F(LoggingTest, Dcheck) {
 #if defined(NDEBUG) && !defined(DCHECK_ALWAYS_ON)
   // Release build.
   EXPECT_FALSE(DCHECK_IS_ON());
   EXPECT_FALSE(DLOG_IS_ON(DCHECK));
 #elif defined(NDEBUG) && defined(DCHECK_ALWAYS_ON)
   // Release build with real DCHECKS.
   SetLogAssertHandler(&LogSink);
   EXPECT_TRUE(DCHECK_IS_ON());
   EXPECT_TRUE(DLOG_IS_ON(DCHECK));
@@ skipping 21 matching lines @@
   DCHECK_NE(p_not_null, nullptr);
   DCHECK_NE(nullptr, p_not_null);
   EXPECT_EQ(0, log_sink_call_count);
 
   // Test DCHECK on a scoped enum.
   enum class Animal { DOG, CAT };
   DCHECK_EQ(Animal::DOG, Animal::DOG);
   EXPECT_EQ(0, log_sink_call_count);
   DCHECK_EQ(Animal::DOG, Animal::CAT);
   EXPECT_EQ(DCHECK_IS_ON() ? 1 : 0, log_sink_call_count);
+
+  // Test DCHECK on functions and function pointers.
+  log_sink_call_count = 0;
+  void (*fp1)() = DcheckEmptyFunction1;
+  void (*fp2)() = DcheckEmptyFunction2;
+  void (*fp3)() = DcheckEmptyFunction1;
+  DCHECK_EQ(fp1, fp3);
+  EXPECT_EQ(DCHECK_IS_ON() ? 0 : 0, log_sink_call_count);

[Nico, 2016/11/23 18:21:10]

Err, replace `DCHECK_IS_ON() ? 0 : 0` with `0`? :-)

[Raphael Kubo da Costa (rakuco), 2016/11/23 18:58:09]

Brain fart :(

+  DCHECK_EQ(fp1, fp2);
+  EXPECT_EQ(DCHECK_IS_ON() ? 1 : 0, log_sink_call_count);
+  struct MemberFunctions {
+    static void MemberFunction1(){};

[Nico, 2016/11/23 18:21:10]

Actually, this isn't a member function, this is a regular function since it's
static. I think you want:
  struct MemberFunctions {
    void MemberFunction1() {}
    void MemberFunction2() {}
  };
  void (MemberFunctions::* mp1)() = &MemberFunctions::MemberFunction1;
  void (MemberFunctions::* mp2)() = &MemberFunctions::MemberFunction2;
  DCHECK_EQ(fp1, &MemberFunctions::MemberFunction1);
  DCHECK_EQ(fp2, &MemberFunctions::MemberFunction1);

Also, I'd move the first of these checks (and the whole struct decl) up so that
you can EXPECT_EQ(0, log_sink_call_count) after the first DCHECK

[Raphael Kubo da Costa (rakuco), 2016/11/23 18:58:09]

That works too; the reason I went for static functions is that I only started
working on it because wtf's ArrayBufferContents does

    DCHECK_EQ(s_adjustAmountOfExternalAllocatedMemoryFunction,
              defaultAdjustAmountOfExternalAllocatedMemoryFunction);

Having a static variable will require me to move the struct declaration out of
the function, so I guess I'll just go with actual member functions.

+    static void TestDCHECK() {
+      void (*fp)() = MemberFunction1;
+      DCHECK_EQ(fp, MemberFunction1);
+      EXPECT_EQ(DCHECK_IS_ON() ? 1 : 0, log_sink_call_count);
+      DCHECK_EQ(fp, TestDCHECK);
+      EXPECT_EQ(DCHECK_IS_ON() ? 2 : 0, log_sink_call_count);
+    }
+  };
+  MemberFunctions::TestDCHECK();
 }
 
 TEST_F(LoggingTest, DcheckReleaseBehavior) {
   int some_variable = 1;
   // These should still reference |some_variable| so we don't get
   // unused variable warnings.
   DCHECK(some_variable) << "test";
   DPCHECK(some_variable) << "test";
   DCHECK_EQ(some_variable, 1) << "test";
 }
@@ skipping 37 matching lines @@
     std::wstring wstr = L"Hello World";
     std::ostringstream ostr;
     ostr << wstr;
     EXPECT_EQ("Hello World", ostr.str());
   }
 }  // namespace nested_test
 
 }  // namespace
 
 }  // namespace logging