Export of internal Abseil changes

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a78c34c705b15598ea00171d4ff8755e38fad863 by Derek Mauro <dmauro@google.com>:

Improve compiler support for ABSL_FALLTHROUGH_INTENDED

PiperOrigin-RevId: 370952333

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aed0c26f1a2aac98e217ad1b44ce4a858780a223 by Martijn Vels <mvels@google.com>:

Add Cordz instrumentation for Flatten

PiperOrigin-RevId: 370815149

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ff4a58d0109d39dc32ef7a5e5e669ca4e630c6d9 by Martijn Vels <mvels@google.com>:

Add Cordz instrumentation to RemovePrefix and RemoveSuffix

PiperOrigin-RevId: 370751602

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40220a058b30ddd89c6e547591488d15342137dd by Martijn Vels <mvels@google.com>:

Add Cordz instrumentation to operator=(string_view)

PiperOrigin-RevId: 370737600

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a2e49604f18b92e50b179b5477dfddb8f57538ca by Martijn Vels <mvels@google.com>:

Add cordz instrumentation for Subcord

PiperOrigin-RevId: 370724107

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bcc3902e04fb4f14270aef00e18908e6a88474cd by Derek Mauro <dmauro@google.com>:

Internal change

PiperOrigin-RevId: 370707219
GitOrigin-RevId: a78c34c705b15598ea00171d4ff8755e38fad863
Change-Id: I0270e536cbdeaf1f195199da822b314521de3b96

1 files changed, 30 insertions, 0 deletions

diff --git a/absl/strings/cord.h b/absl/strings/cord.h
index d5a13b34..d7b43247 100644
--- a/absl/strings/cord.h
+++ b/absl/strings/cord.h
@@ -692,6 +692,10 @@ class Cord {
   // called by Flatten() when the cord was not already flat.
   absl::string_view FlattenSlowPath();
 
+  // Copies `new_size` bytes starting at `pos` into `dest`. Requires at least
+  // `new_size` bytes to be available, and `new_size` to be <= kMaxInline.
+  void CopyDataAtPosition(size_t pos, size_t new_size, char* dest) const;
+
   // Actual cord contents are hidden inside the following simple
   // class so that we can isolate the bulk of cord.cc from changes
   // to the representation.
@@ -745,12 +749,21 @@ class Cord {
     // the CordzInfo instance is updated to reference the new `rep` value.
     void SetTree(CordRep* rep, const CordzUpdateScope& scope);
 
+    // Identical to SetTree(), except that `rep` is allowed to be null, in
+    // which case the current instance is reset to an empty value.
+    void SetTreeOrEmpty(CordRep* rep, const CordzUpdateScope& scope);
+
     // Sets the tree value for this instance, and randomly samples this cord.
     // This function disregards existing contents in `data_`, and should be
     // called when a Cord is 'promoted' from an 'uninitialized' or 'inlined'
     // value to a non-inlined (tree / ring) value.
     void EmplaceTree(CordRep* rep, MethodIdentifier method);
 
+    // Identical to EmplaceTree, except that it copies the parent stack from
+    // the provided `parent` data if the parent is sampled.
+    void EmplaceTree(CordRep* rep, const InlineData& parent,
+                     MethodIdentifier method);
+
     // Commits the change of a newly created, or updated `rep` root value into
     // this cord. `old_rep` indicates the old (inlined or tree) value of the
     // cord, and determines if the commit invokes SetTree() or EmplaceTree().
@@ -1071,6 +1084,12 @@ inline void Cord::InlineRep::EmplaceTree(CordRep* rep,
   CordzInfo::MaybeTrackCord(data_, method);
 }
 
+inline void Cord::InlineRep::EmplaceTree(CordRep* rep, const InlineData& parent,
+                                         MethodIdentifier method) {
+  data_.make_tree(rep);
+  CordzInfo::MaybeTrackCord(data_, parent, method);
+}
+
 inline void Cord::InlineRep::SetTree(CordRep* rep,
                                      const CordzUpdateScope& scope) {
   assert(rep);
@@ -1079,6 +1098,17 @@ inline void Cord::InlineRep::SetTree(CordRep* rep,
   scope.SetCordRep(rep);
 }
 
+inline void Cord::InlineRep::SetTreeOrEmpty(CordRep* rep,
+                                            const CordzUpdateScope& scope) {
+  assert(data_.is_tree());
+  if (rep) {
+    data_.set_tree(rep);
+  } else {
+    data_ = {};
+  }
+  scope.SetCordRep(rep);
+}
+
 inline void Cord::InlineRep::CommitTree(const CordRep* old_rep, CordRep* rep,
                                         const CordzUpdateScope& scope,
                                         MethodIdentifier method) {