clang-format: Allow customizing the penalty for breaking assignment

[Typz]

Summary

Add option to customize the penalty for breaking assignment

This allows increasing the priority of the assignment, to prefer spliting
an operation instead of splitting the assignment, e.g. :

int a = bbbbbbbbbbbbbbbb +
        cccccccccccccccc;

[Typz]

Updated commit description

[Typz]

ping?

[djasper]

Basically looks good, but please add a test case where the penalty is high show that it changes behavior.

[Typz]

Add test to verify the option actually has some effect

cfe/trunk/include/clang/Format/Format.h

   /// \brief Add a space after ``@property`` in Objective-C, i.e. use
   /// ``@property (readonly)`` instead of ``@property(readonly)``.
   bool ObjCSpaceAfterProperty;
 
   /// \brief Add a space in front of an Objective-C protocol list, i.e. use
   /// ``Foo <Protocol>`` instead of ``Foo<Protocol>``.
   bool ObjCSpaceBeforeProtocolList;
 
+  /// \brief The penalty for breaking around an assignment operator.
+  unsigned PenaltyBreakAssignment;
+
   /// \brief The penalty for breaking a function call after ``call(``.
   unsigned PenaltyBreakBeforeFirstCallParameter;
 
   /// \brief The penalty for each line break introduced inside a comment.
   unsigned PenaltyBreakComment;
 
   /// \brief The penalty for breaking before the first ``<<``.
   unsigned PenaltyBreakFirstLessLess;
return AccessModifierOffset == R.AccessModifierOffset &&
                R.KeepEmptyLinesAtTheStartOfBlocks &&
            MacroBlockBegin == R.MacroBlockBegin &&
            MacroBlockEnd == R.MacroBlockEnd &&
            MaxEmptyLinesToKeep == R.MaxEmptyLinesToKeep &&
            NamespaceIndentation == R.NamespaceIndentation &&
            ObjCBlockIndentWidth == R.ObjCBlockIndentWidth &&
            ObjCSpaceAfterProperty == R.ObjCSpaceAfterProperty &&
            ObjCSpaceBeforeProtocolList == R.ObjCSpaceBeforeProtocolList &&
+           PenaltyBreakAssignment ==
+               R.PenaltyBreakAssignment &&
            PenaltyBreakBeforeFirstCallParameter ==
                R.PenaltyBreakBeforeFirstCallParameter &&
            PenaltyBreakComment == R.PenaltyBreakComment &&
            PenaltyBreakFirstLessLess == R.PenaltyBreakFirstLessLess &&
            PenaltyBreakString == R.PenaltyBreakString &&
            PenaltyExcessCharacter == R.PenaltyExcessCharacter &&
            PenaltyReturnTypeOnItsOwnLine == R.PenaltyReturnTypeOnItsOwnLine &&
            PointerAlignment == R.PointerAlignment &&

cfe/trunk/lib/Format/Format.cpp

static void mapping(IO &IO, FormatStyle &Style) {
     IO.mapOptional("MacroBlockBegin", Style.MacroBlockBegin);
     IO.mapOptional("MacroBlockEnd", Style.MacroBlockEnd);
     IO.mapOptional("MaxEmptyLinesToKeep", Style.MaxEmptyLinesToKeep);
     IO.mapOptional("NamespaceIndentation", Style.NamespaceIndentation);
     IO.mapOptional("ObjCBlockIndentWidth", Style.ObjCBlockIndentWidth);
     IO.mapOptional("ObjCSpaceAfterProperty", Style.ObjCSpaceAfterProperty);
     IO.mapOptional("ObjCSpaceBeforeProtocolList",
                    Style.ObjCSpaceBeforeProtocolList);
+    IO.mapOptional("PenaltyBreakAssignment",
+                   Style.PenaltyBreakAssignment);
     IO.mapOptional("PenaltyBreakBeforeFirstCallParameter",
                    Style.PenaltyBreakBeforeFirstCallParameter);
     IO.mapOptional("PenaltyBreakComment", Style.PenaltyBreakComment);
     IO.mapOptional("PenaltyBreakFirstLessLess",
                    Style.PenaltyBreakFirstLessLess);
     IO.mapOptional("PenaltyBreakString", Style.PenaltyBreakString);
     IO.mapOptional("PenaltyExcessCharacter", Style.PenaltyExcessCharacter);
     IO.mapOptional("PenaltyReturnTypeOnItsOwnLine",
FormatStyle getLLVMStyle() {
   LLVMStyle.SpacesInContainerLiterals = true;
   LLVMStyle.SpacesInCStyleCastParentheses = false;
   LLVMStyle.SpaceAfterCStyleCast = false;
   LLVMStyle.SpaceAfterTemplateKeyword = true;
   LLVMStyle.SpaceBeforeParens = FormatStyle::SBPO_ControlStatements;
   LLVMStyle.SpaceBeforeAssignmentOperators = true;
   LLVMStyle.SpacesInAngles = false;
 
+  LLVMStyle.PenaltyBreakAssignment = prec::Assignment;
   LLVMStyle.PenaltyBreakComment = 300;
   LLVMStyle.PenaltyBreakFirstLessLess = 120;
   LLVMStyle.PenaltyBreakString = 1000;
   LLVMStyle.PenaltyExcessCharacter = 1000000;
   LLVMStyle.PenaltyReturnTypeOnItsOwnLine = 60;
   LLVMStyle.PenaltyBreakBeforeFirstCallParameter = 19;
 
   LLVMStyle.DisableFormat = false;

cfe/trunk/lib/Format/TokenAnnotator.cpp

if (Right.is(tok::lessless)) {
     if (!Left.is(tok::r_paren) || Right.OperatorIndex > 0)
       // Slightly prefer to break before the first one in log-like statements.
       return 2;
     return 1;
   }
   if (Left.is(TT_ConditionalExpr))
     return prec::Conditional;
   prec::Level Level = Left.getPrecedence();
-  if (Level != prec::Unknown)
-    return Level;
+  if (Level == prec::Unknown)
     Level = Right.getPrecedence();
+  if (Level == prec::Assignment)
+    return Style.PenaltyBreakAssignment;
   if (Level != prec::Unknown)
     return Level;
 
   return 3;
 }
 
 bool TokenAnnotator::spaceRequiredBetween(const AnnotatedLine &Line,
                                           const FormatToken &Left,

cfe/trunk/unittests/Format/FormatTest.cpp

verifyFormat(
       "aaaaaaaaaaaaaaaaaaaaaaaaaa aaaa = aaaaaaaaaaaaaa(0).aaaa().aaaaaaaaa(\n"
       "    aaaaaaaaaaaaaaaaaaa::aaaaaaaaaaaaaaaaaaaaa);");
   verifyFormat("unsigned OriginalStartColumn =\n"
                "    SourceMgr.getSpellingColumnNumber(\n"
                "        Current.FormatTok.getStartOfNonWhitespace()) -\n"
                "    1;");
 }
 
+TEST_F(FormatTest, ConfigurableBreakAssignmentPenalty) {
+  FormatStyle Style = getLLVMStyle();
+  verifyFormat("int aaaaaaaaaaaaaaaaaaaaaaaaaa =\n"
+               "    bbbbbbbbbbbbbbbbbbbbbbbbbb + cccccccccccccccccccccccccc;",
+               Style);
+
+  Style.PenaltyBreakAssignment = 20;
+  verifyFormat("int aaaaaaaaaaaaaaaaaaaaaaaaaa = bbbbbbbbbbbbbbbbbbbbbbbbbb +\n"
+               "                                 cccccccccccccccccccccccccc;",
+               Style);
+}
+
 TEST_F(FormatTest, AlignsAfterAssignments) {
   verifyFormat(
       "int Result = aaaaaaaaaaaaaaaaaaaaaaaaa + aaaaaaaaaaaaaaaaaaaaaaaaa +\n"
       "             aaaaaaaaaaaaaaaaaaaaaaaaa;");
   verifyFormat(
       "Result += aaaaaaaaaaaaaaaaaaaaaaaaa + aaaaaaaaaaaaaaaaaaaaaaaaa +\n"
       "          aaaaaaaaaaaaaaaaaaaaaaaaa;");
   verifyFormat(
TEST_F(FormatTest, ParsesConfiguration) {
   FormatStyle Style = {};
   Style.Language = FormatStyle::LK_Cpp;
   CHECK_PARSE("AccessModifierOffset: -1234", AccessModifierOffset, -1234);
   CHECK_PARSE("ConstructorInitializerIndentWidth: 1234",
               ConstructorInitializerIndentWidth, 1234u);
   CHECK_PARSE("ObjCBlockIndentWidth: 1234", ObjCBlockIndentWidth, 1234u);
   CHECK_PARSE("ColumnLimit: 1234", ColumnLimit, 1234u);
   CHECK_PARSE("MaxEmptyLinesToKeep: 1234", MaxEmptyLinesToKeep, 1234u);
+  CHECK_PARSE("PenaltyBreakAssignment: 1234",
+              PenaltyBreakAssignment, 1234u);
   CHECK_PARSE("PenaltyBreakBeforeFirstCallParameter: 1234",
               PenaltyBreakBeforeFirstCallParameter, 1234u);
   CHECK_PARSE("PenaltyExcessCharacter: 1234", PenaltyExcessCharacter, 1234u);
   CHECK_PARSE("PenaltyReturnTypeOnItsOwnLine: 1234",
               PenaltyReturnTypeOnItsOwnLine, 1234u);
   CHECK_PARSE("SpacesBeforeTrailingComments: 1234",
               SpacesBeforeTrailingComments, 1234u);
   CHECK_PARSE("IndentWidth: 32", IndentWidth, 32u);