2 files changed, 19 insertions, 2 deletions
diff --git a/include/clang/Lex/Preprocessor.h b/include/clang/Lex/Preprocessor.h
index 302d006ea16ca..712e1ab9fbf5f 100644
--- a/include/clang/Lex/Preprocessor.h
+++ b/include/clang/Lex/Preprocessor.h
@@ -1835,11 +1835,20 @@ private:
   /// \brief A fast PTH version of SkipExcludedConditionalBlock.
   void PTHSkipExcludedConditionalBlock();
 
+  /// Information about the result for evaluating an expression for a
+  /// preprocessor directive.
+  struct DirectiveEvalResult {
+    /// Whether the expression was evaluated as true or not.
+    bool Conditional;
+    /// True if the expression contained identifiers that were undefined.
+    bool IncludedUndefinedIds;
+  };
+
   /// \brief Evaluate an integer constant expression that may occur after a
-  /// \#if or \#elif directive and return it as a bool.
+  /// \#if or \#elif directive and return a \p DirectiveEvalResult object.
   ///
   /// If the expression is equivalent to "!defined(X)" return X in IfNDefMacro.
-  bool EvaluateDirectiveExpression(IdentifierInfo *&IfNDefMacro);
+  DirectiveEvalResult EvaluateDirectiveExpression(IdentifierInfo *&IfNDefMacro);
 
   /// \brief Install the standard preprocessor pragmas:
   /// \#pragma GCC poison/system_header/dependency and \#pragma once.
diff --git a/include/clang/Lex/PreprocessorOptions.h b/include/clang/Lex/PreprocessorOptions.h
index f536be8d8e691..d91c665cf1dd5 100644
--- a/include/clang/Lex/PreprocessorOptions.h
+++ b/include/clang/Lex/PreprocessorOptions.h
@@ -96,8 +96,15 @@ public:
   std::string TokenCache;
 
   /// When enabled, preprocessor is in a mode for parsing a single file only.
+  ///
+  /// Disables #includes of other files and if there are unresolved identifiers
+  /// in preprocessor directive conditions it causes all blocks to be parsed so
+  /// that the client can get the maximum amount of information from the parser.
   bool SingleFileParseMode = false;
 
+  /// When enabled, the preprocessor will construct editor placeholder tokens.
+  bool LexEditorPlaceholders = true;
+
   /// \brief True if the SourceManager should report the original file name for
   /// contents of files that were remapped to other files. Defaults to true.
   bool RemappedFilesKeepOriginalName;
@@ -185,6 +192,7 @@ public:
     ImplicitPTHInclude.clear();
     TokenCache.clear();
     SingleFileParseMode = false;
+    LexEditorPlaceholders = true;
     RetainRemappedFileBuffers = true;
     PrecompiledPreambleBytes.first = 0;
     PrecompiledPreambleBytes.second = 0;