Export of internal Abseil changes

--
d6748c733a70cd74ad9b76a0c9cd6b3fe2cecacf by Xiaoyi Zhang <zhangxy@google.com>:

Remove empty block, to address alerts reported in
https://github.com/abseil/abseil-cpp/issues/368.

PiperOrigin-RevId: 265099887

--
232e2036b5668d6d1296b881f9347756d84541ee by Derek Mauro <dmauro@google.com>:

Make the Linux Bazel CI scripts test with the exception mode explicitly set.

PiperOrigin-RevId: 265092105

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942a40696c2c9b833be03e92d22a6ede7bccb6d4 by Xiaoyi Zhang <zhangxy@google.com>:

Import https://github.com/abseil/abseil-cpp/pull/372.
Suppress the unused variable warning on GCC, i.e. "-Wunused-variable".

PiperOrigin-RevId: 265063925

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7ef90796b52cbdc260afc77cf47206f9356471d0 by Xiaoyi Zhang <zhangxy@google.com>:

Add quotes to `ABSL_COMMON_INCLUDE_DIRS` since it's a list and may contain a
`;`. This addresses https://github.com/abseil/abseil-cpp/issues/373.

PiperOrigin-RevId: 265059077

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43f3ae742e00b83672ad6c5bc5b17fdb8f9fe6fe by Gennadiy Rozental <rogeeff@google.com>:

Internal re-organization

PiperOrigin-RevId: 264913945

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6a2adf9c08ee1d98cc6b2855a676345c6495294a by Andy Soffer <asoffer@google.com>:

Publicly expose type names for uniform interval tags as in, for example, absl::IntervalClosedClosedTag, and add equality comparison operators.

PiperOrigin-RevId: 264861162

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3c90c6e05fd61d56b419cd2d39dab8f17b8711b8 by Abseil Team <absl-team@google.com>:

Add validity check on returned frame pointer.

PiperOrigin-RevId: 264858823

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2db87e0cfa0c6bea7ba81684b834cb8a73b7d748 by Gennadiy Rozental <rogeeff@google.com>:

Add MUST_USE_RESULT attribute to absl::GetFlag to prevent accidental misuse.

PiperOrigin-RevId: 264782762
GitOrigin-RevId: d6748c733a70cd74ad9b76a0c9cd6b3fe2cecacf
Change-Id: I169e9c5358e4f63000c1255e806d26b8afecf5ff

1 files changed, 39 insertions, 18 deletions

diff --git a/absl/random/internal/uniform_helper.h b/absl/random/internal/uniform_helper.h
index ebcc3744b188..9e89e5268071 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)());