Assert enum type equivalence in UMA_HISTOGRAM_ENUMERATION

base/metrics/histogram_macros_internal.h

Index: base/metrics/histogram_macros_internal.h
diff --git a/base/metrics/histogram_macros_internal.h b/base/metrics/histogram_macros_internal.h
index 35a1021afac8f33b4f3938c483515f66354eaf25..2deb9284a177fa26a4e3ecdd155addcb96422f6e 100644
--- a/base/metrics/histogram_macros_internal.h
+++ b/base/metrics/histogram_macros_internal.h
@@ -100,10 +100,17 @@
 // 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.