3 files changed, 48 insertions, 10 deletions

diff --git a/lib/Format/Format.cpp b/lib/Format/Format.cpp
index 60b2f56745..8ea95c4862 100644
--- a/lib/Format/Format.cpp
+++ b/lib/Format/Format.cpp
@@ -434,9 +434,21 @@ private:
   /// each \c FormatToken.
   void replaceWhitespace(const FormatToken &Tok, unsigned NewLines,
                          unsigned Spaces) {
+    std::string NewLineText;
+    if (!Line.InPPDirective) {
+      NewLineText = std::string(NewLines, '\n');
+    } else if (NewLines > 0) {
+      unsigned Offset =
+          SourceMgr.getSpellingColumnNumber(Tok.WhiteSpaceStart) - 1;
+      for (unsigned i = 0; i < NewLines; ++i) {
+        NewLineText += std::string(Style.ColumnLimit - Offset - 1, ' ');
+        NewLineText += "\\\n";
+        Offset = 0;
+      }
+    }
     Replaces.insert(tooling::Replacement(
         SourceMgr, Tok.WhiteSpaceStart, Tok.WhiteSpaceLength,
-        std::string(NewLines, '\n') + std::string(Spaces, ' ')));
+        NewLineText + std::string(Spaces, ' ')));
   }
 
   /// \brief Add a new line and the required indent before the first Token
@@ -634,6 +646,9 @@ public:
       next();
       if (Index >= Tokens.size())
         return;
+      // It is the responsibility of the UnwrappedLineParser to make sure
+      // this sequence is not produced inside an unwrapped line.
+      assert(Tokens[Index].Tok.getIdentifierInfo() != NULL);
       switch (Tokens[Index].Tok.getIdentifierInfo()->getPPKeywordID()) {
       case tok::pp_include:
       case tok::pp_import:
@@ -969,7 +984,10 @@ public:
 
     // Consume and record whitespace until we find a significant token.
     while (FormatTok.Tok.is(tok::unknown)) {
-      FormatTok.NewlinesBefore += tokenText(FormatTok.Tok).count('\n');
+      StringRef Text = tokenText(FormatTok.Tok);
+      FormatTok.NewlinesBefore += Text.count('\n');
+      FormatTok.HasUnescapedNewline =
+          Text.count("\\\n") != FormatTok.NewlinesBefore;
       FormatTok.WhiteSpaceLength += FormatTok.Tok.getLength();
 
       if (FormatTok.Tok.is(tok::eof))
diff --git a/lib/Format/UnwrappedLineParser.cpp b/lib/Format/UnwrappedLineParser.cpp
index 78a1abdcf8..614125b943 100644
--- a/lib/Format/UnwrappedLineParser.cpp
+++ b/lib/Format/UnwrappedLineParser.cpp
@@ -80,13 +80,25 @@ bool UnwrappedLineParser::parseBlock(unsigned AddLevels) {
 }
 
 void UnwrappedLineParser::parsePPDirective() {
-  while (!eof()) {
-    nextToken();
-    if (FormatTok.NewlinesBefore > 0) {
-      addUnwrappedLine();
-      return;
-    }
+  assert(FormatTok.Tok.is(tok::hash) && "'#' expected");
+  nextToken();
+
+  Line.InPPDirective = true;
+  if (FormatTok.Tok.getIdentifierInfo() == NULL) {
+    addUnwrappedLine();
+    Line.InPPDirective = false;
+    return;
   }
+
+  do {
+    if (FormatTok.NewlinesBefore > 0 &&
+        FormatTok.HasUnescapedNewline) {
+      break;
+    }
+    nextToken();
+  } while (!eof());
+  addUnwrappedLine();
+  Line.InPPDirective = false;
 }
 
 void UnwrappedLineParser::parseComments() {
diff --git a/lib/Format/UnwrappedLineParser.h b/lib/Format/UnwrappedLineParser.h
index ccf437f507..9ed796d45b 100644
--- a/lib/Format/UnwrappedLineParser.h
+++ b/lib/Format/UnwrappedLineParser.h
@@ -30,7 +30,8 @@ namespace format {
 /// \brief A wrapper around a \c Token storing information about the
 /// whitespace characters preceeding it.
 struct FormatToken {
-  FormatToken() : NewlinesBefore(0), WhiteSpaceLength(0) {
+  FormatToken()
+      : NewlinesBefore(0), HasUnescapedNewline(false), WhiteSpaceLength(0) {
   }
 
   /// \brief The \c Token.
@@ -42,6 +43,10 @@ struct FormatToken {
   /// and thereby e.g. leave an empty line between two function definitions.
   unsigned NewlinesBefore;
 
+  /// \brief Whether there is at least one unescaped newline before the \c
+  /// Token.
+  bool HasUnescapedNewline;
+
   /// \brief The location of the start of the whitespace immediately preceeding
   /// the \c Token.
   ///
@@ -60,7 +65,7 @@ struct FormatToken {
 /// \c UnwrappedLineFormatter. The key property is that changing the formatting
 /// within an unwrapped line does not affect any other unwrapped lines.
 struct UnwrappedLine {
-  UnwrappedLine() : Level(0) {
+  UnwrappedLine() : Level(0), InPPDirective(false) {
   }
 
   /// \brief The \c Token comprising this \c UnwrappedLine.
@@ -68,6 +73,9 @@ struct UnwrappedLine {
 
   /// \brief The indent level of the \c UnwrappedLine.
   unsigned Level;
+
+  /// \brief Whether this \c UnwrappedLine is part of a preprocessor directive.
+  bool InPPDirective;
 };
 
 class UnwrappedLineConsumer {