InclusionRewriter: Avoid duplicated BOM check

The lexer already knows its position in the file, so use that instead of
guessing it might be 3.

llvm-svn: 195910

1 files changed, 3 insertions, 7 deletions

diff --git a/clang/lib/Rewrite/Frontend/InclusionRewriter.cpp b/clang/lib/Rewrite/Frontend/InclusionRewriter.cpp
index 71ceb5f0b6a..176ea3f79dc 100644
--- a/clang/lib/Rewrite/Frontend/InclusionRewriter.cpp
+++ b/clang/lib/Rewrite/Frontend/InclusionRewriter.cpp
@@ -363,15 +363,11 @@ bool InclusionRewriter::Process(FileID FileId,
   if (SM.getFileIDSize(FileId) == 0)
     return false;
 
-  // The next byte to be copied from the source file
-  unsigned NextToWrite = 0;
+  // The next byte to be copied from the source file, which may be non-zero if
+  // the lexer handled a BOM.
+  unsigned NextToWrite = SM.getFileOffset(RawLex.getSourceLocation());
   int Line = 1; // The current input file line number.
 
-  // Ignore UTF-8 BOM, otherwise it'd end up somewhere else than the start
-  // of the resulting file.
-  if (FromFile.getBuffer().startswith("\xEF\xBB\xBF"))
-    NextToWrite = 3;
-
   Token RawToken;
   RawLex.LexFromRawLexer(RawToken);