Assert enum type equivalence 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 "base/atomicops.h"
 #include "base/logging.h"
 #include "base/metrics/histogram.h"
@@ skipping 82 matching lines @@
                                                    bucket_count, flag)         \
     STATIC_HISTOGRAM_POINTER_BLOCK(                                            \
         name, Add(sample),                                                     \
         base::Histogram::FactoryGet(name, min, max, bucket_count, flag))
 
 // This is a helper macro used by other macros and shouldn't be used directly.
 // One additional bucket is created in the LinearHistogram for the illegal
 // values >= boundary_value so that mistakes in calling the UMA enumeration
 // macros can be detected.
 #define INTERNAL_HISTOGRAM_ENUMERATION_WITH_FLAG(name, sample, boundary, flag) \
+  do {                                                                         \
+    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_HISTOGRAM_POINTER_BLOCK(                                            \
-        name, Add(sample),                                                     \
-        base::LinearHistogram::FactoryGet(                                     \
-            name, 1, boundary, boundary + 1, flag))
+        name, Add(sample), base::LinearHistogram::FactoryGet(                  \
+                               name, 1, boundary, boundary + 1, flag));        \

[dcheng, 2016/11/17 05:09:55]

I know the ship has sailed (and we're migrating off legacy IPC) but I really
wish legacy IPC and histograms had agreed on how to define the max value.

+  } while (0)
 
 // This is a helper macro used by other macros and shouldn't be used directly.
 // This is necessary to expand __COUNTER__ to an actual value.
 #define INTERNAL_SCOPED_UMA_HISTOGRAM_TIMER_EXPANDER(name, is_long, key)       \
   INTERNAL_SCOPED_UMA_HISTOGRAM_TIMER_UNIQUE(name, is_long, key)
 
 // This is a helper macro used by other macros and shouldn't be used directly.
 #define INTERNAL_SCOPED_UMA_HISTOGRAM_TIMER_UNIQUE(name, is_long, key)         \
   class ScopedHistogramTimer##key {                                            \
    public:                                                                     \
@@ skipping 16 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_