4 files changed, 12 insertions, 13 deletions
diff --git a/clang/lib/Frontend/FrontendActions.cpp b/clang/lib/Frontend/FrontendActions.cpp
index 3e3483d2c6b..86460f17d0f 100644
--- a/clang/lib/Frontend/FrontendActions.cpp
+++ b/clang/lib/Frontend/FrontendActions.cpp
@@ -591,7 +591,7 @@ void PrintPreambleAction::ExecuteAction() {
   auto Buffer = CI.getFileManager().getBufferForFile(getCurrentFile());
   if (Buffer) {
     unsigned Preamble =
-        Lexer::ComputePreamble((*Buffer)->getBuffer(), CI.getLangOpts()).first;
+        Lexer::ComputePreamble((*Buffer)->getBuffer(), CI.getLangOpts()).Size;
     llvm::outs().write((*Buffer)->getBufferStart(), Preamble);
   }
 }
diff --git a/clang/lib/Frontend/PrecompiledPreamble.cpp b/clang/lib/Frontend/PrecompiledPreamble.cpp
index cd7446189cc..bd6770acdff 100644
--- a/clang/lib/Frontend/PrecompiledPreamble.cpp
+++ b/clang/lib/Frontend/PrecompiledPreamble.cpp
@@ -195,8 +195,7 @@ template <class T> bool moveOnNoError(llvm::ErrorOr<T> Val, T &Output) {
 PreambleBounds clang::ComputePreambleBounds(const LangOptions &LangOpts,
                                             llvm::MemoryBuffer *Buffer,
                                             unsigned MaxLines) {
-  auto Pre = Lexer::ComputePreamble(Buffer->getBuffer(), LangOpts, MaxLines);
-  return PreambleBounds(Pre.first, Pre.second);
+  return Lexer::ComputePreamble(Buffer->getBuffer(), LangOpts, MaxLines);
 }
 
 llvm::ErrorOr<PrecompiledPreamble> PrecompiledPreamble::Build(
diff --git a/clang/lib/Lex/Lexer.cpp b/clang/lib/Lex/Lexer.cpp
index 928c24d94c3..b7f97a583db 100644
--- a/clang/lib/Lex/Lexer.cpp
+++ b/clang/lib/Lex/Lexer.cpp
@@ -552,9 +552,9 @@ namespace {
 
 } // end anonymous namespace
 
-std::pair<unsigned, bool> Lexer::ComputePreamble(StringRef Buffer,
-                                                 const LangOptions &LangOpts,
-                                                 unsigned MaxLines) {
+PreambleBounds Lexer::ComputePreamble(StringRef Buffer,
+                                      const LangOptions &LangOpts,
+                                      unsigned MaxLines) {
   // Create a lexer starting at the beginning of the file. Note that we use a
   // "fake" file source location at offset 1 so that the lexer will track our
   // position within the file.
@@ -688,7 +688,7 @@ std::pair<unsigned, bool> Lexer::ComputePreamble(StringRef Buffer,
   else
     End = TheTok.getLocation();
 
-  return std::make_pair(End.getRawEncoding() - StartLoc.getRawEncoding(),
+  return PreambleBounds(End.getRawEncoding() - FileLoc.getRawEncoding(),
                         TheTok.isAtStartOfLine());
 }
 
@@ -1394,9 +1394,9 @@ Slash:
 // Helper methods for lexing.
 //===----------------------------------------------------------------------===//
 
-/// \brief Routine that indiscriminately skips bytes in the source file.
-void Lexer::SkipBytes(unsigned Bytes, bool StartOfLine) {
-  BufferPtr += Bytes;
+/// \brief Routine that indiscriminately sets the offset into the source file.
+void Lexer::SetByteOffset(unsigned Offset, bool StartOfLine) {
+  BufferPtr = BufferStart + Offset;
   if (BufferPtr > BufferEnd)
     BufferPtr = BufferEnd;
   // FIXME: What exactly does the StartOfLine bit mean?  There are two
diff --git a/clang/lib/Lex/Preprocessor.cpp b/clang/lib/Lex/Preprocessor.cpp
index e1294994df5..1f9a469bc59 100644
--- a/clang/lib/Lex/Preprocessor.cpp
+++ b/clang/lib/Lex/Preprocessor.cpp
@@ -516,9 +516,9 @@ void Preprocessor::EnterMainSourceFile() {
     // If we've been asked to skip bytes in the main file (e.g., as part of a
     // precompiled preamble), do so now.
     if (SkipMainFilePreamble.first > 0)
-      CurLexer->SkipBytes(SkipMainFilePreamble.first, 
-                          SkipMainFilePreamble.second);
-    
+      CurLexer->SetByteOffset(SkipMainFilePreamble.first,
+                              SkipMainFilePreamble.second);
+
     // Tell the header info that the main file was entered.  If the file is later
     // #imported, it won't be re-entered.
     if (const FileEntry *FE = SourceMgr.getFileEntryForID(MainFileID))