Use stricter type checking in UMA_HISTOGRAM_ENUMERATION

base/metrics/histogram_macros_internal.h

 // Copyright 2016 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.
 
 #ifndef BASE_METRICS_HISTOGRAM_MACROS_INTERNAL_H_
 #define BASE_METRICS_HISTOGRAM_MACROS_INTERNAL_H_
 
 #include <stdint.h>
 
 #include <limits>
@@ skipping 122 matching lines @@
 //
 // Note the range checks verify two separate issues:
 // - that the declared enum max isn't out of range of HistogramBase::Sample
 // - that the declared enum max is > 0
 //
 // TODO(dcheng): This should assert that the passed in types are actually enum
 // types.
 #define INTERNAL_HISTOGRAM_ENUMERATION_WITH_FLAG(name, sample, boundary, flag) \
   do {                                                                         \
     static_assert(                                                             \
+        !std::is_enum<std::remove_const<std::remove_reference<decltype(        \

[dcheng, 2017/07/17 09:13:59]

I think std::decay can replace the use of
std::remove_const<std::remove_reference<...>> here and below.

+                boundary)>::type>::type>::value ||                             \
+            std::is_enum<std::remove_const<                                    \
+                std::remove_reference<decltype(sample)>::type>::type>::value,  \
+        "Unexpected: |boundary| is enum, but |sample| is not.");               \
+    static_assert(                                                             \
         !std::is_enum<decltype(sample)>::value ||                              \
             !std::is_enum<decltype(boundary)>::value ||                        \
             std::is_same<std::remove_const<decltype(sample)>::type,            \
                          std::remove_const<decltype(boundary)>::type>::value,  \
         "|sample| and |boundary| shouldn't be of different enums");            \
     static_assert(                                                             \
         static_cast<uintmax_t>(boundary) <                                     \
             static_cast<uintmax_t>(                                            \
                 std::numeric_limits<base::HistogramBase::Sample>::max()),      \
         "|boundary| is out of range of HistogramBase::Sample");                \
@@ skipping 30 matching lines @@
 // may be more efficient in memory if the total number of sample values is small
 // compared to the range of their values.
 #define INTERNAL_HISTOGRAM_SPARSE_SLOWLY(name, sample)                         \
     do {                                                                       \
       base::HistogramBase* histogram = base::SparseHistogram::FactoryGet(      \
           name, base::HistogramBase::kUmaTargetedHistogramFlag);               \
       histogram->Add(sample);                                                  \
     } while (0)
 
 #endif  // BASE_METRICS_HISTOGRAM_MACROS_INTERNAL_H_