clang-format: Improve token breaking behavior.

Two changes:
* Don't add an extra penalty on breaking the same token multiple times.
  Generally, we should prefer not to break, but once we break, the
  normal line breaking penalties apply.
* Slightly increase the penalty for breaking comments. In general, the
  author has put some thought into how to break the comment and we
  should not overwrite this unnecessarily.

With a 40-column column limit, formatting
  aaaaaa("aaaaaaaaaaaaaaaa aaaaaaaaaaaaaaaa aaaaaaaaaaaaaaaa");

Leads to:
Before:
  aaaaaa(
      "aaaaaaaaaaaaaaaa aaaaaaaaaaaaaaaa "
      "aaaaaaaaaaaaaaaa");

After:
  aaaaaa("aaaaaaaaaaaaaaaa "
         "aaaaaaaaaaaaaaaa "
         "aaaaaaaaaaaaaaaa");

llvm-svn: 189466

2 files changed, 5 insertions, 3 deletions

diff --git a/clang/lib/Format/ContinuationIndenter.cpp b/clang/lib/Format/ContinuationIndenter.cpp
index 798e4f3aecd..f4ae5cce01b 100644
--- a/clang/lib/Format/ContinuationIndenter.cpp
+++ b/clang/lib/Format/ContinuationIndenter.cpp
@@ -666,8 +666,7 @@ unsigned ContinuationIndenter::breakProtrudingToken(const FormatToken &Current,
       assert(NewRemainingTokenColumns < RemainingTokenColumns);
       if (!DryRun)
         Token->insertBreak(LineIndex, TailOffset, Split, Whitespaces);
-      Penalty += Current.is(tok::string_literal) ? Style.PenaltyBreakString
-                                                 : Style.PenaltyBreakComment;
+      Penalty += Current.SplitPenalty;
       unsigned ColumnsUsed =
           Token->getLineLengthAfterSplit(LineIndex, TailOffset, Split.first);
       if (ColumnsUsed > getColumnLimit()) {
@@ -691,6 +690,9 @@ unsigned ContinuationIndenter::breakProtrudingToken(const FormatToken &Current,
         State.Stack[i].BreakBeforeParameter = true;
     }
 
+    Penalty += Current.is(tok::string_literal) ? Style.PenaltyBreakString
+                                               : Style.PenaltyBreakComment;
+
     State.Stack.back().LastSpace = StartColumn;
   }
   return Penalty;
diff --git a/clang/lib/Format/Format.cpp b/clang/lib/Format/Format.cpp
index 1cd55d72973..3982ba6a771 100644
--- a/clang/lib/Format/Format.cpp
+++ b/clang/lib/Format/Format.cpp
@@ -152,7 +152,7 @@ namespace clang {
 namespace format {
 
 void setDefaultPenalties(FormatStyle &Style) {
-  Style.PenaltyBreakComment = 45;
+  Style.PenaltyBreakComment = 60;
   Style.PenaltyBreakFirstLessLess = 120;
   Style.PenaltyBreakString = 1000;
   Style.PenaltyExcessCharacter = 1000000;