[clang-format] Make NoLineBreakFormatter respect MustBreakBefore

[krasimir]

Summary

This patch makes NoLineBreakFormatter to insert a break before tokens where
MustBreakBefore is true.

[krasimir]

• Updated comments

[djasper]

Are there cases where this makes a difference? If so, add a test. If not, add something to the patch description to clarify.

lib/Format/TokenAnnotator.cpp

2473

Maybe add to the comment: "Import statements, especially in JavaScript, can be an exception to this rule."

[krasimir]

• Add comment about import statements.

lib/Format/TokenAnnotator.cpp

if (Right.is(tok::plus) && Left.is(tok::string_literal) && Right.Next &&
       return true;
   } else if (Style.Language == FormatStyle::LK_Cpp ||
              Style.Language == FormatStyle::LK_ObjC ||
              Style.Language == FormatStyle::LK_Proto) {
     if (Left.isStringLiteral() && Right.isStringLiteral())
       return true;
   }
 
   // If the last token before a '}', ']', or ')' is a comma or a trailing
   // comment, the intention is to insert a line break after it in order to make
   // shuffling around entries easier.
+  if (Style.JavaScriptWrapImports || Line.Type != LT_ImportStatement) {
     const FormatToken *BeforeClosingBrace = nullptr;
     if ((Left.isOneOf(tok::l_brace, TT_ArrayInitializerLSquare) ||
          (Style.Language == FormatStyle::LK_JavaScript &&
           Left.is(tok::l_paren))) &&
         Left.BlockKind != BK_Block && Left.MatchingParen)
       BeforeClosingBrace = Left.MatchingParen->Previous;
     else if (Right.MatchingParen &&
              (Right.MatchingParen->isOneOf(tok::l_brace,
                                            TT_ArrayInitializerLSquare) ||
               (Style.Language == FormatStyle::LK_JavaScript &&
                Right.MatchingParen->is(tok::l_paren))))
       BeforeClosingBrace = &Left;
     if (BeforeClosingBrace && (BeforeClosingBrace->is(tok::comma) ||
                                BeforeClosingBrace->isTrailingComment()))
       return true;
+  }
 
   if (Right.is(tok::comment))
     return Left.BlockKind != BK_BracedInit &&
            Left.isNot(TT_CtorInitializerColon) &&
            (Right.NewlinesBefore > 0 && Right.HasUnescapedNewline);
   if (Left.isTrailingComment())
     return true;
   if (Right.Previous->IsUnterminatedLiteral)

lib/Format/UnwrappedLineFormatter.cpp

public:
 
   /// \brief Puts all tokens into a single line.
   unsigned formatLine(const AnnotatedLine &Line, unsigned FirstIndent,
                       bool DryRun) override {
     unsigned Penalty = 0;
     LineState State = Indenter->getInitialState(FirstIndent, &Line, DryRun);
     while (State.NextToken) {
       formatChildren(State, /*Newline=*/false, DryRun, Penalty);
-      Indenter->addTokenToState(State, /*Newline=*/false, DryRun);
+      Indenter->addTokenToState(
+          State, /*Newline=*/State.NextToken->MustBreakBefore, DryRun);
     }
     return Penalty;
   }
 };
 
 /// \brief Finds the best way to break lines.
 class OptimizingLineFormatter : public LineFormatter {
 public: