Add ATTRIBUTE_LIFETIME_BOUND to Cord iterator methods

PiperOrigin-RevId: 555515105
Change-Id: I00929a869880cddd932ed2a08adb8f762a582738

absl/strings/cord.h

@@ -515,7 +515,7 @@ class Cord {
   //                                         absl::string_view s) {
   //     return std::find(c.chunk_begin(), c.chunk_end(), s);
   //   }
-  ChunkIterator chunk_begin() const;
+  ChunkIterator chunk_begin() const ABSL_ATTRIBUTE_LIFETIME_BOUND;
 
   // Cord::chunk_end()
   //
@@ -524,7 +524,7 @@ class Cord {
   // Generally, prefer using `Cord::Chunks()` within a range-based for loop for
   // iterating over the chunks of a Cord. This method may be useful for getting
   // a `ChunkIterator` where range-based for-loops may not be available.
-  ChunkIterator chunk_end() const;
+  ChunkIterator chunk_end() const ABSL_ATTRIBUTE_LIFETIME_BOUND;
 
   //----------------------------------------------------------------------------
   // Cord::ChunkRange
@@ -578,7 +578,7 @@ class Cord {
   //       // The temporary Cord returned by CordFactory has been destroyed!
   //     }
   //   }
-  ChunkRange Chunks() const;
+  ChunkRange Chunks() const ABSL_ATTRIBUTE_LIFETIME_BOUND;
 
   //----------------------------------------------------------------------------
   // Cord::CharIterator
@@ -658,7 +658,7 @@ class Cord {
   // Generally, prefer using `Cord::Chars()` within a range-based for loop for
   // iterating over the chunks of a Cord. This method may be useful for getting
   // a `CharIterator` where range-based for-loops may not be available.
-  CharIterator char_begin() const;
+  CharIterator char_begin() const ABSL_ATTRIBUTE_LIFETIME_BOUND;
 
   // Cord::char_end()
   //
@@ -667,7 +667,7 @@ class Cord {
   // Generally, prefer using `Cord::Chars()` within a range-based for loop for
   // iterating over the chunks of a Cord. This method may be useful for getting
   // a `CharIterator` where range-based for-loops are not useful.
-  CharIterator char_end() const;
+  CharIterator char_end() const ABSL_ATTRIBUTE_LIFETIME_BOUND;
 
   // Cord::CharRange
   //
@@ -719,7 +719,7 @@ class Cord {
   //       // The temporary Cord returned by CordFactory has been destroyed!
   //     }
   //   }
-  CharRange Chars() const;
+  CharRange Chars() const ABSL_ATTRIBUTE_LIFETIME_BOUND;
 
   // Cord::operator[]
   //