Implement -Wunused-label.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@114315 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Serialization/ASTReaderStmt.cpp b/lib/Serialization/ASTReaderStmt.cpp
index 6e8ad4f..7b0845d 100644
--- a/lib/Serialization/ASTReaderStmt.cpp
+++ b/lib/Serialization/ASTReaderStmt.cpp
@@ -219,6 +219,7 @@
   S->setID(Reader.GetIdentifierInfo(Record, Idx));
   S->setSubStmt(Reader.ReadSubStmt());
   S->setIdentLoc(SourceLocation::getFromRawEncoding(Record[Idx++]));
+  S->setUsed(Record[Idx++]);
   Reader.RecordLabelStmt(S, Record[Idx++]);
 }
 
diff --git a/lib/Serialization/ASTWriterStmt.cpp b/lib/Serialization/ASTWriterStmt.cpp
index 7a5b949..edd8002 100644
--- a/lib/Serialization/ASTWriterStmt.cpp
+++ b/lib/Serialization/ASTWriterStmt.cpp
@@ -213,6 +213,7 @@
   Writer.AddIdentifierRef(S->getID(), Record);
   Writer.AddStmt(S->getSubStmt());
   Writer.AddSourceLocation(S->getIdentLoc(), Record);
+  Record.push_back(S->isUsed());
   Record.push_back(Writer.GetLabelID(S));
   Code = serialization::STMT_LABEL;
 }