Move StringSpaceUsedIncludingSelf to lite library.

This came up because Chromium downstream modifies the lite library in a way that
requires this function, but I'm upstreaming it because based on the comments in
repeated_field.h, this ought to allow resolution of an existing hack.

I don't know enough about the protobuf code to feel confident trying to resolve
this hack myself, so I've merely updated the TODO comments.

1 files changed, 12 insertions, 0 deletions

diff --git a/src/google/protobuf/generated_message_util.cc b/src/google/protobuf/generated_message_util.cc
index 53cae8b5..afaca2ee 100644
--- a/src/google/protobuf/generated_message_util.cc
+++ b/src/google/protobuf/generated_message_util.cc
@@ -60,6 +60,18 @@ void InitEmptyString() {
   OnShutdown(&DeleteEmptyString);
 }
 
+int StringSpaceUsedExcludingSelf(const string& str) {
+  const void* start = &str;
+  const void* end = &str + 1;
+
+  if (start <= str.data() && str.data() < end) {
+    // The string's data is stored inside the string object itself.
+    return 0;
+  } else {
+    return str.capacity();
+  }
+}
+
 
 }  // namespace internal
 }  // namespace protobuf