1 files changed, 39 insertions, 18 deletions

diff --git a/absl/random/internal/uniform_helper.h b/absl/random/internal/uniform_helper.h
index ebcc374..9e89e52 100644
--- a/absl/random/internal/uniform_helper.h
+++ b/absl/random/internal/uniform_helper.h
@@ -30,12 +30,33 @@ class uniform_real_distribution;
 
 // Interval tag types which specify whether the interval is open or closed
 // on either boundary.
+
 namespace random_internal {
-struct IntervalClosedClosedT {};
-struct IntervalClosedOpenT {};
-struct IntervalOpenClosedT {};
-struct IntervalOpenOpenT {};
+template <typename T>
+struct TagTypeCompare {};
+
+template <typename T>
+constexpr bool operator==(TagTypeCompare<T>, TagTypeCompare<T>) {
+  // Tags are mono-states. They always compare equal.
+  return true;
+}
+template <typename T>
+constexpr bool operator!=(TagTypeCompare<T>, TagTypeCompare<T>) {
+  return false;
+}
 
+}  // namespace random_internal
+
+struct IntervalClosedClosedTag
+    : public random_internal::TagTypeCompare<IntervalClosedClosedTag> {};
+struct IntervalClosedOpenTag
+    : public random_internal::TagTypeCompare<IntervalClosedOpenTag> {};
+struct IntervalOpenClosedTag
+    : public random_internal::TagTypeCompare<IntervalOpenClosedTag> {};
+struct IntervalOpenOpenTag
+    : public random_internal::TagTypeCompare<IntervalOpenOpenTag> {};
+
+namespace random_internal {
 // The functions
 //    uniform_lower_bound(tag, a, b)
 // and
@@ -56,8 +77,8 @@ template <typename IntType, typename Tag>
 typename absl::enable_if_t<
     absl::conjunction<
         std::is_integral<IntType>,
-        absl::disjunction<std::is_same<Tag, IntervalOpenClosedT>,
-                          std::is_same<Tag, IntervalOpenOpenT>>>::value,
+        absl::disjunction<std::is_same<Tag, IntervalOpenClosedTag>,
+                          std::is_same<Tag, IntervalOpenOpenTag>>>::value,
     IntType>
 uniform_lower_bound(Tag, IntType a, IntType) {
   return a + 1;
@@ -67,8 +88,8 @@ template <typename FloatType, typename Tag>
 typename absl::enable_if_t<
     absl::conjunction<
         std::is_floating_point<FloatType>,
-        absl::disjunction<std::is_same<Tag, IntervalOpenClosedT>,
-                          std::is_same<Tag, IntervalOpenOpenT>>>::value,
+        absl::disjunction<std::is_same<Tag, IntervalOpenClosedTag>,
+                          std::is_same<Tag, IntervalOpenOpenTag>>>::value,
     FloatType>
 uniform_lower_bound(Tag, FloatType a, FloatType b) {
   return std::nextafter(a, b);
@@ -76,8 +97,8 @@ uniform_lower_bound(Tag, FloatType a, FloatType b) {
 
 template <typename NumType, typename Tag>
 typename absl::enable_if_t<
-    absl::disjunction<std::is_same<Tag, IntervalClosedClosedT>,
-                      std::is_same<Tag, IntervalClosedOpenT>>::value,
+    absl::disjunction<std::is_same<Tag, IntervalClosedClosedTag>,
+                      std::is_same<Tag, IntervalClosedOpenTag>>::value,
     NumType>
 uniform_lower_bound(Tag, NumType a, NumType) {
   return a;
@@ -87,8 +108,8 @@ template <typename IntType, typename Tag>
 typename absl::enable_if_t<
     absl::conjunction<
         std::is_integral<IntType>,
-        absl::disjunction<std::is_same<Tag, IntervalClosedOpenT>,
-                          std::is_same<Tag, IntervalOpenOpenT>>>::value,
+        absl::disjunction<std::is_same<Tag, IntervalClosedOpenTag>,
+                          std::is_same<Tag, IntervalOpenOpenTag>>>::value,
     IntType>
 uniform_upper_bound(Tag, IntType, IntType b) {
   return b - 1;
@@ -98,8 +119,8 @@ template <typename FloatType, typename Tag>
 typename absl::enable_if_t<
     absl::conjunction<
         std::is_floating_point<FloatType>,
-        absl::disjunction<std::is_same<Tag, IntervalClosedOpenT>,
-                          std::is_same<Tag, IntervalOpenOpenT>>>::value,
+        absl::disjunction<std::is_same<Tag, IntervalClosedOpenTag>,
+                          std::is_same<Tag, IntervalOpenOpenTag>>>::value,
     FloatType>
 uniform_upper_bound(Tag, FloatType, FloatType b) {
   return b;
@@ -109,8 +130,8 @@ template <typename IntType, typename Tag>
 typename absl::enable_if_t<
     absl::conjunction<
         std::is_integral<IntType>,
-        absl::disjunction<std::is_same<Tag, IntervalClosedClosedT>,
-                          std::is_same<Tag, IntervalOpenClosedT>>>::value,
+        absl::disjunction<std::is_same<Tag, IntervalClosedClosedTag>,
+                          std::is_same<Tag, IntervalOpenClosedTag>>>::value,
     IntType>
 uniform_upper_bound(Tag, IntType, IntType b) {
   return b;
@@ -120,8 +141,8 @@ template <typename FloatType, typename Tag>
 typename absl::enable_if_t<
     absl::conjunction<
         std::is_floating_point<FloatType>,
-        absl::disjunction<std::is_same<Tag, IntervalClosedClosedT>,
-                          std::is_same<Tag, IntervalOpenClosedT>>>::value,
+        absl::disjunction<std::is_same<Tag, IntervalClosedClosedTag>,
+                          std::is_same<Tag, IntervalOpenClosedTag>>>::value,
     FloatType>
 uniform_upper_bound(Tag, FloatType, FloatType b) {
   return std::nextafter(b, (std::numeric_limits<FloatType>::max)());