Export of internal Abseil changes

--
017c3924d21132085bc20c9be0ae469bfbf2c56c by Gennadiy Rozental <rogeeff@google.com>:

Import of CCTZ from GitHub.

PiperOrigin-RevId: 338723934

--
8b08c23d7b05232e283b1388cee3eb5bebc2d9c4 by Derek Mauro <dmauro@google.com>:

Add script to test GCC floor (the minimum version of GCC we support,
currently the GCC 5 series)

PiperOrigin-RevId: 338708581

--
afa440ac7c843126b4f99b89ebc071dda1d85a4d by Abseil Team <absl-team@google.com>:

Fix typo in documentation of StatusOr::value_or() ('of' -> 'if').

PiperOrigin-RevId: 338690089

--
97d5008865327fc36b942b96de0d0cacfb909df5 by Derek Mauro <dmauro@google.com>:

Import of CCTZ from GitHub.

PiperOrigin-RevId: 338568224

--
da5e09a7fedb3217329465d9206b7cbc6677176b by Abseil Team <absl-team@google.com>:

Add `absl_btree_prefer_linear_node_search`

Allow keys of `btree_set`, `btree_map`, `btree_multiset`, and `btree_multimap`
to opt-in to linear search (instead of binary search).  Linear search was
used previously for arithmetic types with `key_compare` of `std::greater`
or `std::less`.

For example, this would be useful for key types that wrap an integer
and define their own cheap `operator<()`.

```
 class K {
  public:
   using absl_btree_prefer_linear_node_search = std::true_type;
   ...
  private:
   friend bool operator<(K a, K b) { return a.k_ < b.k_; }
   int k_;
 };

 absl::btree_map<K, V> m;  // Uses linear search
 assert((absl::btree_map<K, V>::testonly_uses_linear_node_search()));
```

PiperOrigin-RevId: 338476553

--
c56ead7ce6b0a5ad32e3a42904c686448a69451e by Gennadiy Rozental <rogeeff@google.com>:

Import of CCTZ from GitHub.

PiperOrigin-RevId: 338419417
GitOrigin-RevId: 017c3924d21132085bc20c9be0ae469bfbf2c56c
Change-Id: I1199f3ae917280a3ef20ccc6038abbe34d96ec0b

absl/container/btree_test.cc

@@ -1216,6 +1216,70 @@ class BtreeNodePeer {
 
 
 namespace {
 namespace {
 
 
+class BtreeMapTest : public ::testing::Test {
+ public:
+  struct Key {};
+  struct Cmp {
+    template <typename T>
+    bool operator()(T, T) const {
+      return false;
+    }
+  };
+
+  struct KeyLin {
+    using absl_btree_prefer_linear_node_search = std::true_type;
+  };
+  struct CmpLin : Cmp {
+    using absl_btree_prefer_linear_node_search = std::true_type;
+  };
+
+  struct KeyBin {
+    using absl_btree_prefer_linear_node_search = std::false_type;
+  };
+  struct CmpBin : Cmp {
+    using absl_btree_prefer_linear_node_search = std::false_type;
+  };
+
+  template <typename K, typename C>
+  static bool IsLinear() {
+    return BtreeNodePeer::UsesLinearNodeSearch<absl::btree_map<K, int, C>>();
+  }
+};
+
+TEST_F(BtreeMapTest, TestLinearSearchPreferredForKeyLinearViaAlias) {
+  // Test requesting linear search by directly exporting an alias.
+  EXPECT_FALSE((IsLinear<Key, Cmp>()));
+  EXPECT_TRUE((IsLinear<KeyLin, Cmp>()));
+  EXPECT_TRUE((IsLinear<Key, CmpLin>()));
+  EXPECT_TRUE((IsLinear<KeyLin, CmpLin>()));
+}
+
+TEST_F(BtreeMapTest, LinearChoiceTree) {
+  // Cmp has precedence, and is forcing binary
+  EXPECT_FALSE((IsLinear<Key, CmpBin>()));
+  EXPECT_FALSE((IsLinear<KeyLin, CmpBin>()));
+  EXPECT_FALSE((IsLinear<KeyBin, CmpBin>()));
+  EXPECT_FALSE((IsLinear<int, CmpBin>()));
+  EXPECT_FALSE((IsLinear<std::string, CmpBin>()));
+  // Cmp has precedence, and is forcing linear
+  EXPECT_TRUE((IsLinear<Key, CmpLin>()));
+  EXPECT_TRUE((IsLinear<KeyLin, CmpLin>()));
+  EXPECT_TRUE((IsLinear<KeyBin, CmpLin>()));
+  EXPECT_TRUE((IsLinear<int, CmpLin>()));
+  EXPECT_TRUE((IsLinear<std::string, CmpLin>()));
+  // Cmp has no preference, Key determines linear vs binary.
+  EXPECT_FALSE((IsLinear<Key, Cmp>()));
+  EXPECT_TRUE((IsLinear<KeyLin, Cmp>()));
+  EXPECT_FALSE((IsLinear<KeyBin, Cmp>()));
+  // arithmetic key w/ std::less or std::greater: linear
+  EXPECT_TRUE((IsLinear<int, std::less<int>>()));
+  EXPECT_TRUE((IsLinear<double, std::greater<double>>()));
+  // arithmetic key w/ custom compare: binary
+  EXPECT_FALSE((IsLinear<int, Cmp>()));
+  // non-arithmetic key: binary
+  EXPECT_FALSE((IsLinear<std::string, std::less<std::string>>()));
+}
+
 TEST(Btree, BtreeMapCanHoldMoveOnlyTypes) {
 TEST(Btree, BtreeMapCanHoldMoveOnlyTypes) {
   absl::btree_map<std::string, std::unique_ptr<std::string>> m;
   absl::btree_map<std::string, std::unique_ptr<std::string>> m;
 
 

absl/container/internal/btree.h

@@ -182,6 +182,38 @@ struct key_compare_to_adapter<std::greater<absl::Cord>> {
   using type = StringBtreeDefaultGreater;
   using type = StringBtreeDefaultGreater;
 };
 };
 
 
+// Detects an 'absl_btree_prefer_linear_node_search' member. This is
+// a protocol used as an opt-in or opt-out of linear search.
+//
+//  For example, this would be useful for key types that wrap an integer
+//  and define their own cheap operator<(). For example:
+//
+//   class K {
+//    public:
+//     using absl_btree_prefer_linear_node_search = std::true_type;
+//     ...
+//    private:
+//     friend bool operator<(K a, K b) { return a.k_ < b.k_; }
+//     int k_;
+//   };
+//
+//   btree_map<K, V> m;  // Uses linear search
+//
+// If T has the preference tag, then it has a preference.
+// Btree will use the tag's truth value.
+template <typename T, typename = void>
+struct has_linear_node_search_preference : std::false_type {};
+template <typename T, typename = void>
+struct prefers_linear_node_search : std::false_type {};
+template <typename T>
+struct has_linear_node_search_preference<
+    T, absl::void_t<typename T::absl_btree_prefer_linear_node_search>>
+    : std::true_type {};
+template <typename T>
+struct prefers_linear_node_search<
+    T, absl::void_t<typename T::absl_btree_prefer_linear_node_search>>
+    : T::absl_btree_prefer_linear_node_search {};
+
 template <typename Key, typename Compare, typename Alloc, int TargetNodeSize,
 template <typename Key, typename Compare, typename Alloc, int TargetNodeSize,
           bool Multi, typename SlotPolicy>
           bool Multi, typename SlotPolicy>
 struct common_params {
 struct common_params {
@@ -424,15 +456,22 @@ class btree_node {
   using difference_type = typename Params::difference_type;
   using difference_type = typename Params::difference_type;
 
 
   // Btree decides whether to use linear node search as follows:
   // Btree decides whether to use linear node search as follows:
+  //   - If the comparator expresses a preference, use that.
+  //   - If the key expresses a preference, use that.
   //   - If the key is arithmetic and the comparator is std::less or
   //   - If the key is arithmetic and the comparator is std::less or
   //     std::greater, choose linear.
   //     std::greater, choose linear.
   //   - Otherwise, choose binary.
   //   - Otherwise, choose binary.
   // TODO(ezb): Might make sense to add condition(s) based on node-size.
   // TODO(ezb): Might make sense to add condition(s) based on node-size.
   using use_linear_search = std::integral_constant<
   using use_linear_search = std::integral_constant<
       bool,
       bool,
-                std::is_arithmetic<key_type>::value &&
+      has_linear_node_search_preference<key_compare>::value
+          ? prefers_linear_node_search<key_compare>::value
+          : has_linear_node_search_preference<key_type>::value
+                ? prefers_linear_node_search<key_type>::value
+                : std::is_arithmetic<key_type>::value &&
                       (std::is_same<std::less<key_type>, key_compare>::value ||
                       (std::is_same<std::less<key_type>, key_compare>::value ||
-                     std::is_same<std::greater<key_type>, key_compare>::value)>;
+                       std::is_same<std::greater<key_type>,
+                                    key_compare>::value)>;
 
 
   // This class is organized by gtl::Layout as if it had the following
   // This class is organized by gtl::Layout as if it had the following
   // structure:
   // structure:

absl/status/statusor.h

@@ -542,7 +542,7 @@ class StatusOr : private internal_statusor::StatusOrData<T>,
 
 
   // StatusOr<T>::value_or()
   // StatusOr<T>::value_or()
   //
   //
-  // Returns the current value of `this->ok() == true`. Otherwise constructs a
+  // Returns the current value if `this->ok() == true`. Otherwise constructs a
   // value using the provided `default_value`.
   // value using the provided `default_value`.
   //
   //
   // Unlike `value`, this function returns by value, copying the current value
   // Unlike `value`, this function returns by value, copying the current value

absl/time/internal/cctz/include/cctz/civil_time_detail.h

@@ -416,16 +416,10 @@ class civil_time {
 
 
   // Assigning arithmetic.
   // Assigning arithmetic.
   CONSTEXPR_M civil_time& operator+=(diff_t n) noexcept {
   CONSTEXPR_M civil_time& operator+=(diff_t n) noexcept {
-    f_ = step(T{}, f_, n);
-    return *this;
+    return *this = *this + n;
   }
   }
   CONSTEXPR_M civil_time& operator-=(diff_t n) noexcept {
   CONSTEXPR_M civil_time& operator-=(diff_t n) noexcept {
-    if (n != (std::numeric_limits<diff_t>::min)()) {
-      f_ = step(T{}, f_, -n);
-    } else {
-      f_ = step(T{}, step(T{}, f_, -(n + 1)), 1);
-    }
-    return *this;
+    return *this = *this - n;
   }
   }
   CONSTEXPR_M civil_time& operator++() noexcept { return *this += 1; }
   CONSTEXPR_M civil_time& operator++() noexcept { return *this += 1; }
   CONSTEXPR_M civil_time operator++(int) noexcept {
   CONSTEXPR_M civil_time operator++(int) noexcept {
@@ -442,13 +436,15 @@ class civil_time {
 
 
   // Binary arithmetic operators.
   // Binary arithmetic operators.
   friend CONSTEXPR_F civil_time operator+(civil_time a, diff_t n) noexcept {
   friend CONSTEXPR_F civil_time operator+(civil_time a, diff_t n) noexcept {
-    return a += n;
+    return civil_time(step(T{}, a.f_, n));
   }
   }
   friend CONSTEXPR_F civil_time operator+(diff_t n, civil_time a) noexcept {
   friend CONSTEXPR_F civil_time operator+(diff_t n, civil_time a) noexcept {
-    return a += n;
+    return a + n;
   }
   }
   friend CONSTEXPR_F civil_time operator-(civil_time a, diff_t n) noexcept {
   friend CONSTEXPR_F civil_time operator-(civil_time a, diff_t n) noexcept {
-    return a -= n;
+    return n != (std::numeric_limits<diff_t>::min)()
+               ? civil_time(step(T{}, a.f_, -n))
+               : civil_time(step(T{}, step(T{}, a.f_, -(n + 1)), 1));
   }
   }
   friend CONSTEXPR_F diff_t operator-(civil_time lhs, civil_time rhs) noexcept {
   friend CONSTEXPR_F diff_t operator-(civil_time lhs, civil_time rhs) noexcept {
     return difference(T{}, lhs.f_, rhs.f_);
     return difference(T{}, lhs.f_, rhs.f_);

absl/time/internal/cctz/testdata/version

-2020a
+2020d

ci/linux_docker_containers.sh

@@ -18,4 +18,5 @@
 readonly LINUX_ALPINE_CONTAINER="gcr.io/google.com/absl-177019/alpine:20191016"
 readonly LINUX_ALPINE_CONTAINER="gcr.io/google.com/absl-177019/alpine:20191016"
 readonly LINUX_CLANG_LATEST_CONTAINER="gcr.io/google.com/absl-177019/linux_hybrid-latest:20201008"
 readonly LINUX_CLANG_LATEST_CONTAINER="gcr.io/google.com/absl-177019/linux_hybrid-latest:20201008"
 readonly LINUX_GCC_LATEST_CONTAINER="gcr.io/google.com/absl-177019/linux_hybrid-latest:20201008"
 readonly LINUX_GCC_LATEST_CONTAINER="gcr.io/google.com/absl-177019/linux_hybrid-latest:20201008"
+readonly LINUX_GCC_FLOOR_CONTAINER="gcr.io/google.com/absl-177019/linux_gcc-floor:20201015"
 readonly LINUX_GCC_49_CONTAINER="gcr.io/google.com/absl-177019/linux_gcc-4.9:20191018"
 readonly LINUX_GCC_49_CONTAINER="gcr.io/google.com/absl-177019/linux_gcc-4.9:20191018"

ci/linux_gcc-floor_libstdcxx_bazel.sh

+#!/bin/bash
+#
+# Copyright 2020 The Abseil Authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# This script that can be invoked to test abseil-cpp in a hermetic environment
+# using a Docker image on Linux. You must have Docker installed to use this
+# script.
+
+set -euox pipefail
+
+if [[ -z ${ABSEIL_ROOT:-} ]]; then
+  ABSEIL_ROOT="$(realpath $(dirname ${0})/..)"
+fi
+
+if [[ -z ${STD:-} ]]; then
+  STD="c++11 c++14"
+fi
+
+if [[ -z ${COMPILATION_MODE:-} ]]; then
+  COMPILATION_MODE="fastbuild opt"
+fi
+
+if [[ -z ${EXCEPTIONS_MODE:-} ]]; then
+  EXCEPTIONS_MODE="-fno-exceptions -fexceptions"
+fi
+
+source "${ABSEIL_ROOT}/ci/linux_docker_containers.sh"
+readonly DOCKER_CONTAINER=${LINUX_GCC_FLOOR_CONTAINER}
+
+# USE_BAZEL_CACHE=1 only works on Kokoro.
+# Without access to the credentials this won't work.
+if [[ ${USE_BAZEL_CACHE:-0} -ne 0 ]]; then
+  DOCKER_EXTRA_ARGS="--volume=${KOKORO_KEYSTORE_DIR}:/keystore:ro ${DOCKER_EXTRA_ARGS:-}"
+  # Bazel doesn't track changes to tools outside of the workspace
+  # (e.g. /usr/bin/gcc), so by appending the docker container to the
+  # remote_http_cache url, we make changes to the container part of
+  # the cache key. Hashing the key is to make it shorter and url-safe.
+  container_key=$(echo ${DOCKER_CONTAINER} | sha256sum | head -c 16)
+  BAZEL_EXTRA_ARGS="--remote_http_cache=https://storage.googleapis.com/absl-bazel-remote-cache/${container_key} --google_credentials=/keystore/73103_absl-bazel-remote-cache ${BAZEL_EXTRA_ARGS:-}"
+fi
+
+# Avoid depending on external sites like GitHub by checking --distdir for
+# external dependencies first.
+# https://docs.bazel.build/versions/master/guide.html#distdir
+if [[ ${KOKORO_GFILE_DIR:-} ]] && [[ -d "${KOKORO_GFILE_DIR}/distdir" ]]; then
+  DOCKER_EXTRA_ARGS="--volume=${KOKORO_GFILE_DIR}/distdir:/distdir:ro ${DOCKER_EXTRA_ARGS:-}"
+  BAZEL_EXTRA_ARGS="--distdir=/distdir ${BAZEL_EXTRA_ARGS:-}"
+fi
+
+for std in ${STD}; do
+  for compilation_mode in ${COMPILATION_MODE}; do
+    for exceptions_mode in ${EXCEPTIONS_MODE}; do
+      echo "--------------------------------------------------------------------"
+      time docker run \
+        --volume="${ABSEIL_ROOT}:/abseil-cpp:ro" \
+        --workdir=/abseil-cpp \
+        --cap-add=SYS_PTRACE \
+        --rm \
+        -e CC="/usr/local/bin/gcc" \
+        -e BAZEL_CXXOPTS="-std=${std}" \
+        ${DOCKER_EXTRA_ARGS:-} \
+        ${DOCKER_CONTAINER} \
+        /usr/local/bin/bazel test ... \
+          --compilation_mode="${compilation_mode}" \
+          --copt="${exceptions_mode}" \
+          --copt=-Werror \
+          --define="absl=1" \
+          --keep_going \
+          --show_timestamps \
+          --test_env="GTEST_INSTALL_FAILURE_SIGNAL_HANDLER=1" \
+          --test_env="TZDIR=/abseil-cpp/absl/time/internal/cctz/testdata/zoneinfo" \
+          --test_output=errors \
+          --test_tag_filters=-benchmark \
+          ${BAZEL_EXTRA_ARGS:-}
+    done
+  done
+done