Export of internal Abseil changes

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fb671efb2a70f452f17a884b17cf18817b977a8f by Abseil Team <absl-team@google.com>:

Remove extra semicolon in ABSL_INTERNAL_ASSERT_IS_FULL macro

To fix compilation when empty statement warning is treated as error.

PiperOrigin-RevId: 438342663
Change-Id: I3067fbeffa2691888f37554e88f229f24fb55ecc

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a58c9396f1d88d11347aed36ef2e1b633071363c by Martijn Vels <mvels@google.com>:

Fix kMaxHeight bounds to kMaxDepth for CordrepBtreeNavigator

Added unit test (confirmed failure mode with old code) and extra assertion in the implementation.

PiperOrigin-RevId: 438327463
Change-Id: I32242c86b0c879b8a42cb9a92075e537d588e09f

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f348e85dbfc9187ef59085fa2b999374f1670338 by Jorge Gorbe Moya <jgorbe@google.com>:

Make the flags enum in `RefcountAndFlags` a named enum to workaround an lldb
issue (https://github.com/llvm/llvm-project/issues/54602).

PiperOrigin-RevId: 438146097
Change-Id: Ibc2ee26489d99de515a779a903b6458dd0befef7

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a960a3e9fb2a2e3418f806178e73d8566b78bc85 by Gennadiy Rozental <rogeeff@google.com>:

Introduce support for std::optional<T>/absl::optional<T> flag types.

PiperOrigin-RevId: 438129500
Change-Id: I3d925c0a7f9ce9f857277fac3b0bf664ccd3a95c
GitOrigin-RevId: fb671efb2a70f452f17a884b17cf18817b977a8f

3 files changed, 26 insertions, 3 deletions

diff --git a/absl/strings/internal/cord_internal.h b/absl/strings/internal/cord_internal.h
index 2087ffec..5ca5e589 100644
--- a/absl/strings/internal/cord_internal.h
+++ b/absl/strings/internal/cord_internal.h
@@ -156,7 +156,7 @@ class RefcountAndFlags {
   // used for the StringConstant constructor to avoid collecting immutable
   // constant cords.
   // kReservedFlag is reserved for future use.
-  enum {
+  enum Flags {
     kNumFlags = 2,
 
     kImmortalFlag = 0x1,
diff --git a/absl/strings/internal/cord_rep_btree_navigator.h b/absl/strings/internal/cord_rep_btree_navigator.h
index 971b92ed..3d581c87 100644
--- a/absl/strings/internal/cord_rep_btree_navigator.h
+++ b/absl/strings/internal/cord_rep_btree_navigator.h
@@ -143,8 +143,8 @@ class CordRepBtreeNavigator {
   // `index_` and `node_` contain the navigation state as the 'path' to the
   // current data edge which is at `node_[0]->Edge(index_[0])`. The contents
   // of these are undefined until the instance is initialized (`height_ >= 0`).
-  uint8_t index_[CordRepBtree::kMaxHeight];
-  CordRepBtree* node_[CordRepBtree::kMaxHeight];
+  uint8_t index_[CordRepBtree::kMaxDepth];
+  CordRepBtree* node_[CordRepBtree::kMaxDepth];
 };
 
 // Returns true if this instance is not empty.
@@ -173,6 +173,7 @@ template <CordRepBtree::EdgeType edge_type>
 inline CordRep* CordRepBtreeNavigator::Init(CordRepBtree* tree) {
   assert(tree != nullptr);
   assert(tree->size() > 0);
+  assert(tree->height() <= CordRepBtree::kMaxHeight);
   int height = height_ = tree->height();
   size_t index = tree->index(edge_type);
   node_[height] = tree;
@@ -206,6 +207,7 @@ inline CordRepBtreeNavigator::Position CordRepBtreeNavigator::Seek(
 inline CordRepBtreeNavigator::Position CordRepBtreeNavigator::InitOffset(
     CordRepBtree* tree, size_t offset) {
   assert(tree != nullptr);
+  assert(tree->height() <= CordRepBtree::kMaxHeight);
   if (ABSL_PREDICT_FALSE(offset >= tree->length)) return {nullptr, 0};
   height_ = tree->height();
   node_[height_] = tree;
diff --git a/absl/strings/internal/cord_rep_btree_navigator_test.cc b/absl/strings/internal/cord_rep_btree_navigator_test.cc
index ce09b199..4f9bd4e5 100644
--- a/absl/strings/internal/cord_rep_btree_navigator_test.cc
+++ b/absl/strings/internal/cord_rep_btree_navigator_test.cc
@@ -319,6 +319,27 @@ TEST_P(CordRepBtreeNavigatorTest, ReadBeyondLengthOfTree) {
   ASSERT_THAT(result.tree, Eq(nullptr));
 }
 
+TEST(CordRepBtreeNavigatorTest, NavigateMaximumTreeDepth) {
+  CordRepFlat* flat1 = MakeFlat("Hello world");
+  CordRepFlat* flat2 = MakeFlat("World Hello");
+
+  CordRepBtree* node = CordRepBtree::Create(flat1);
+  node = CordRepBtree::Append(node, flat2);
+  while (node->height() < CordRepBtree::kMaxHeight) {
+    node = CordRepBtree::New(node);
+  }
+
+  CordRepBtreeNavigator nav;
+  CordRep* edge = nav.InitFirst(node);
+  EXPECT_THAT(edge, Eq(flat1));
+  EXPECT_THAT(nav.Next(), Eq(flat2));
+  EXPECT_THAT(nav.Next(), Eq(nullptr));
+  EXPECT_THAT(nav.Previous(), Eq(flat1));
+  EXPECT_THAT(nav.Previous(), Eq(nullptr));
+
+  CordRep::Unref(node);
+}
+
 }  // namespace
 }  // namespace cord_internal
 ABSL_NAMESPACE_END