logging: Provide a specific MakeCheckOpValueString overload for functions

base/logging.h

Index: base/logging.h
diff --git a/base/logging.h b/base/logging.h
index 714545c02bb06ac7f1b31e8a007b671e6dc11d6d..22964cb3cfb546b55651d1912d12f364bf30e937 100644
--- a/base/logging.h
+++ b/base/logging.h
@@ -527,12 +527,24 @@ class CheckOpResult {
 // it uses the definition for operator<<, with a few special cases below.
 template <typename T>
 inline typename std::enable_if<
-    base::internal::SupportsOstreamOperator<const T&>::value,
+    base::internal::SupportsOstreamOperator<const T&>::value &&
+        !std::is_function<typename std::remove_pointer<T>::type>::value,
     void>::type
 MakeCheckOpValueString(std::ostream* os, const T& v) {
   (*os) << v;
 }
 
+// Provide an overload for functions and function pointers, which are otherwise
+// implicitly converted to bool (MSVC seems to be the exception) and produce

[Nico, 2016/11/23 18:09:26]

This comment is a bit confusing as written. I'd reword it as:

// Provide an overload for functions and function pointers. Function pointers
don't implicitly
// convert to void* but do implicitly convert to bool, so without this function
pointers are always
// printed as 1 or 0. (MSVC isn't standards-conforming here and converts
function pointers to
// regular pointers, so this is a no-op for MSVC.)

+// unhelpful values.
+template <typename T>
+inline typename std::enable_if<
+    std::is_function<typename std::remove_pointer<T>::type>::value,
+    void>::type
+MakeCheckOpValueString(std::ostream* os, const T& v) {
+  (*os) << reinterpret_cast<const void*>(v);
+}
+
 // We need overloads for enums that don't support operator<<.
 // (i.e. scoped enums where no operator<< overload was declared).
 template <typename T>