4 files changed, 34 insertions, 1 deletions

diff --git a/clang/lib/Format/BreakableToken.cpp b/clang/lib/Format/BreakableToken.cpp
index 8031ab9cd28..bbf3d88eec4 100644
--- a/clang/lib/Format/BreakableToken.cpp
+++ b/clang/lib/Format/BreakableToken.cpp
@@ -599,6 +599,12 @@ unsigned BreakableBlockComment::getLineLengthAfterSplitBefore(
   }
 }
 
+bool BreakableBlockComment::introducesBreakBefore(unsigned LineIndex) const {
+  // A break is introduced when we want delimiters on newline.
+  return LineIndex == 0 && DelimitersOnNewline &&
+         Lines[0].substr(1).find_first_not_of(Blanks) != StringRef::npos;
+}
+
 void BreakableBlockComment::replaceWhitespaceBefore(
     unsigned LineIndex, unsigned PreviousEndColumn, unsigned ColumnLimit,
     Split SplitBefore, WhitespaceManager &Whitespaces) {
diff --git a/clang/lib/Format/BreakableToken.h b/clang/lib/Format/BreakableToken.h
index 630e927e8fc..8c2dc741d1e 100644
--- a/clang/lib/Format/BreakableToken.h
+++ b/clang/lib/Format/BreakableToken.h
@@ -58,6 +58,8 @@ struct FormatStyle;
 /// operations that might be executed before the main line breaking occurs:
 /// - getSplitBefore, for finding a split such that the content preceding it
 ///   needs to be specially reflown,
+/// - introducesBreakBefore, for checking if reformatting the beginning
+///   of the content introduces a line break before it,
 /// - getLineLengthAfterSplitBefore, for calculating the line length in columns
 ///   of the remainder of the content after the beginning of the content has
 ///   been reformatted, and
@@ -135,6 +137,12 @@ public:
     return Split(StringRef::npos, 0);
   }
 
+  /// \brief Returns if a break before the content at \p LineIndex will be
+  /// inserted after the whitespace preceding the content has been reformatted.
+  virtual bool introducesBreakBefore(unsigned LineIndex) const {
+    return false;
+  }
+
   /// \brief Returns the number of columns required to format the piece of line
   /// at \p LineIndex after the content preceding the whitespace range specified
   /// \p SplitBefore has been reformatted, but before any breaks are made to
@@ -339,6 +347,7 @@ public:
   Split getSplitBefore(unsigned LineIndex, unsigned PreviousEndColumn,
                        unsigned ColumnLimit,
                        llvm::Regex &CommentPragmasRegex) const override;
+  bool introducesBreakBefore(unsigned LineIndex) const override;
   unsigned getLineLengthAfterSplitBefore(unsigned LineIndex,
                                          unsigned TailOffset,
                                          unsigned PreviousEndColumn,
diff --git a/clang/lib/Format/ContinuationIndenter.cpp b/clang/lib/Format/ContinuationIndenter.cpp
index b438a3f64e7..b57b8de2e70 100644
--- a/clang/lib/Format/ContinuationIndenter.cpp
+++ b/clang/lib/Format/ContinuationIndenter.cpp
@@ -106,6 +106,7 @@ LineState ContinuationIndenter::getInitialState(unsigned FirstIndent,
                                    /*AvoidBinPacking=*/false,
                                    /*NoLineBreak=*/false));
   State.LineContainsContinuedForLoopSection = false;
+  State.NoContinuation = false;
   State.StartOfStringLiteral = 0;
   State.StartOfLineLevel = 0;
   State.LowestLevelOnLine = 0;
@@ -322,6 +323,12 @@ bool ContinuationIndenter::mustBreak(const LineState &State) {
                                      Previous.TokenText == "\'\\n\'"))))
     return true;
 
+  if (Previous.is(TT_BlockComment) && Previous.IsMultiline)
+    return true;
+
+  if (State.NoContinuation)
+    return true;
+
   return false;
 }
 
@@ -331,6 +338,8 @@ unsigned ContinuationIndenter::addTokenToState(LineState &State, bool Newline,
   const FormatToken &Current = *State.NextToken;
 
   assert(!State.Stack.empty());
+  State.NoContinuation = false;
+
   if ((Current.is(TT_ImplicitStringLiteral) &&
        (Current.Previous->Tok.getIdentifierInfo() == nullptr ||
         Current.Previous->Tok.getIdentifierInfo()->getPPKeywordID() ==
@@ -1286,7 +1295,7 @@ unsigned ContinuationIndenter::breakProtrudingToken(const FormatToken &Current,
       return 0;
     }
   } else if (Current.is(TT_BlockComment)) {
-    if (!Current.isTrailingComment() || !Style.ReflowComments ||
+    if (!Style.ReflowComments ||
         // If a comment token switches formatting, like
         // /* clang-format on */, we don't want to break it further,
         // but we may still want to adjust its indentation.
@@ -1332,6 +1341,7 @@ unsigned ContinuationIndenter::breakProtrudingToken(const FormatToken &Current,
     ReflowInProgress = SplitBefore.first != StringRef::npos;
     TailOffset =
         ReflowInProgress ? (SplitBefore.first + SplitBefore.second) : 0;
+    BreakInserted = BreakInserted || Token->introducesBreakBefore(LineIndex);
     if (!DryRun)
       Token->replaceWhitespaceBefore(LineIndex, RemainingTokenColumns,
                                      RemainingSpace, SplitBefore, Whitespaces);
@@ -1408,6 +1418,9 @@ unsigned ContinuationIndenter::breakProtrudingToken(const FormatToken &Current,
         State.Stack[i].BreakBeforeParameter = true;
     }
 
+    if (Current.is(TT_BlockComment))
+      State.NoContinuation = true;
+
     Penalty += Current.isStringLiteral() ? Style.PenaltyBreakString
                                          : Style.PenaltyBreakComment;
 
diff --git a/clang/lib/Format/ContinuationIndenter.h b/clang/lib/Format/ContinuationIndenter.h
index 9a06aa6f626..631129c1ea1 100644
--- a/clang/lib/Format/ContinuationIndenter.h
+++ b/clang/lib/Format/ContinuationIndenter.h
@@ -318,6 +318,9 @@ struct LineState {
   /// \brief \c true if this line contains a continued for-loop section.
   bool LineContainsContinuedForLoopSection;
 
+  /// \brief \c true if \p NextToken should not continue this line.
+  bool NoContinuation;
+
   /// \brief The \c NestingLevel at the start of this line.
   unsigned StartOfLineLevel;
 
@@ -364,6 +367,8 @@ struct LineState {
     if (LineContainsContinuedForLoopSection !=
         Other.LineContainsContinuedForLoopSection)
       return LineContainsContinuedForLoopSection;
+    if (NoContinuation != Other.NoContinuation)
+      return NoContinuation;
     if (StartOfLineLevel != Other.StartOfLineLevel)
       return StartOfLineLevel < Other.StartOfLineLevel;
     if (LowestLevelOnLine != Other.LowestLevelOnLine)