[preprocessor] When #including something that contributes no tokens at all,

don't recursively continue lexing.

This avoids a stack overflow with a sequence of many empty #includes.
rdar://11988695

llvm-svn: 167801

1 files changed, 22 insertions, 0 deletions

diff --git a/clang/lib/Lex/Lexer.cpp b/clang/lib/Lex/Lexer.cpp
index e6e7ca5ee17..7983a6b3e86 100644
--- a/clang/lib/Lex/Lexer.cpp
+++ b/clang/lib/Lex/Lexer.cpp
@@ -2595,8 +2595,14 @@ LexNextToken:
       // 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);
     }
@@ -3234,5 +3240,21 @@ HandleDirective:
     }
     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);
 }