Revert r167801, "[preprocessor] When #including something that contributes no
tokens at all,". This change broke External/Nurbs in LLVM test-suite.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@167858 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Lex/Lexer.cpp b/lib/Lex/Lexer.cpp
index 6917645..bf0883e 100644
--- a/lib/Lex/Lexer.cpp
+++ b/lib/Lex/Lexer.cpp
@@ -2594,14 +2594,8 @@
       // Read the PP instance variable into an automatic variable, because
       // LexEndOfFile will often delete 'this'.
       Preprocessor *PPCache = PP;
-      bool EnableIncludedEOFCache = EnableIncludedEOF;
       if (LexEndOfFile(Result, CurPtr-1))  // Retreat back into the file.
         return;   // Got a token to return.
-
-      if (EnableIncludedEOFCache) {
-        Result.setKind(tok::included_eof);
-        return;
-      }
       assert(PPCache && "Raw buffer::LexEndOfFile should return a token");
       return PPCache->Lex(Result);
     }
@@ -3239,21 +3233,5 @@
     }
     goto LexNextToken;   // GCC isn't tail call eliminating.
   }
-
-  if (PreprocessorLexer *PPLex = PP->getCurrentLexer()) {
-    // If we #include something that contributes no tokens at all, return with
-    // a tok::included_eof instead of recursively continuing lexing.
-    // This avoids a stack overflow with a sequence of many empty #includes.
-    PPLex->setEnableIncludedEOF(true);
-    PP->Lex(Result);
-    if (Result.isNot(tok::included_eof)) {
-      if (Result.isNot(tok::eof) && Result.isNot(tok::eod))
-        PPLex->setEnableIncludedEOF(false);
-      return;
-    }
-    if (PP->isCurrentLexer(this))
-      goto LexNextToken;
-  }
-
   return PP->Lex(Result);
 }
diff --git a/lib/Lex/PreprocessorLexer.cpp b/lib/Lex/PreprocessorLexer.cpp
index 390d4c4..a64c84d 100644
--- a/lib/Lex/PreprocessorLexer.cpp
+++ b/lib/Lex/PreprocessorLexer.cpp
@@ -22,7 +22,7 @@
 PreprocessorLexer::PreprocessorLexer(Preprocessor *pp, FileID fid)
   : PP(pp), FID(fid), InitialNumSLocEntries(0),
     ParsingPreprocessorDirective(false),
-    ParsingFilename(false), LexingRawMode(false), EnableIncludedEOF(false) {
+    ParsingFilename(false), LexingRawMode(false) {
   if (pp)
     InitialNumSLocEntries = pp->getSourceManager().local_sloc_entry_size();
 }