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git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@57394 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Lex/Lexer.cpp b/lib/Lex/Lexer.cpp
index e930f3def2e08b2b29443f797f37eed76165f695..63bf58a12c8fbba8166db2d433eb750cf199768e 100644 (file)
--- a/lib/Lex/Lexer.cpp
+++ b/lib/Lex/Lexer.cpp
@@ -113,6 +113,8 @@ Lexer::Lexer(SourceLocation fileloc, const LangOptions &features,
   Is_PragmaLexer = false;
   InitCharacterInfo();
   
+  // If a MemoryBuffer was specified, use its start as BufferStart. This affects
+  // the source location objects produced by this lexer.
   BufferStart = FromFile ? FromFile->getBufferStart() : BufStart;
   BufferPtr = BufStart;
   BufferEnd = BufEnd;