[clang-format] Add new option PenaltyIndentedWhitespace

Reviewed By: MyDeveloperDay

Differential Revision: https://reviews.llvm.org/D90534

clang/docs/ClangFormatStyleOptions.rst

@@ -2301,6 +2301,10 @@ the configuration (without a prefix: ``Auto``).
 **PenaltyExcessCharacter** (``unsigned``)
   The penalty for each character outside of the column limit.
 
+**PenaltyIndentedWhitespace** (``unsigned``)
+  Penalty for each character of whitespace indentation
+  (counted relative to leading non-whitespace column).
+
 **PenaltyReturnTypeOnItsOwnLine** (``unsigned``)
   Penalty for putting the return type of a function onto its own
   line.

clang/include/clang/Format/Format.h

@@ -1913,6 +1913,10 @@ struct FormatStyle {
   /// line.
   unsigned PenaltyReturnTypeOnItsOwnLine;
 
+  /// Penalty for each character of whitespace indentation
+  /// (counted relative to leading non-whitespace column).
+  unsigned PenaltyIndentedWhitespace;
+
   /// The ``&`` and ``*`` alignment style.
   enum PointerAlignmentStyle {
     /// Align pointer to the left.

clang/lib/Format/ContinuationIndenter.cpp

@@ -785,6 +785,22 @@ unsigned ContinuationIndenter::addTokenOnNewLine(LineState &State,
 
   State.Column = getNewLineColumn(State);
 
+  // Add Penalty proportional to amount of whitespace away from FirstColumn
+  // This tends to penalize several lines that are far-right indented,
+  // and prefers a line-break prior to such a block, e.g:
+  //
+  // Constructor() :
+  //   member(value), looooooooooooooooong_member(
+  //                      looooooooooong_call(param_1, param_2, param_3))
+  // would then become
+  // Constructor() :
+  //   member(value),
+  //   looooooooooooooooong_member(
+  //       looooooooooong_call(param_1, param_2, param_3))
+  if (State.Column > State.FirstIndent)
+    Penalty +=
+        Style.PenaltyIndentedWhitespace * (State.Column - State.FirstIndent);
+
   // Indent nested blocks relative to this column, unless in a very specific
   // JavaScript special case where:
   //

clang/lib/Format/Format.cpp

@@ -590,6 +590,8 @@ template <> struct MappingTraits<FormatStyle> {
     IO.mapOptional("PenaltyExcessCharacter", Style.PenaltyExcessCharacter);
     IO.mapOptional("PenaltyReturnTypeOnItsOwnLine",
                    Style.PenaltyReturnTypeOnItsOwnLine);
+    IO.mapOptional("PenaltyIndentedWhitespace",
+                   Style.PenaltyIndentedWhitespace);
     IO.mapOptional("PointerAlignment", Style.PointerAlignment);
     IO.mapOptional("RawStringFormats", Style.RawStringFormats);
     IO.mapOptional("ReflowComments", Style.ReflowComments);
@@ -968,6 +970,7 @@ FormatStyle getLLVMStyle(FormatStyle::LanguageKind Language) {
   LLVMStyle.PenaltyReturnTypeOnItsOwnLine = 60;
   LLVMStyle.PenaltyBreakBeforeFirstCallParameter = 19;
   LLVMStyle.PenaltyBreakTemplateDeclaration = prec::Relational;
+  LLVMStyle.PenaltyIndentedWhitespace = 0;
 
   LLVMStyle.DisableFormat = false;
   LLVMStyle.SortIncludes = true;

clang/unittests/Format/FormatTest.cpp

@@ -17214,6 +17214,28 @@ TEST_F(FormatTest, LikelyUnlikely) {
                Style);
 }
 
+TEST_F(FormatTest, PenaltyIndentedWhitespace) {
+  verifyFormat("Constructor()\n"
+               "    : aaaaaa(aaaaaa), aaaaaaaaaaaaaaaaaaaaaaaaaaaaaa(\n"
+               "                          aaaa(aaaaaaaaaaaaaaaaaa, "
+               "aaaaaaaaaaaaaaaaaat))");
+  verifyFormat("Constructor()\n"
+               "    : aaaaaaaaaaaaa(aaaaaa), "
+               "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaa(aaaaaaaaaaaaaaaaaa)");
+
+  FormatStyle StyleWithWhitespacePenalty = getLLVMStyle();
+  StyleWithWhitespacePenalty.PenaltyIndentedWhitespace = 5;
+  verifyFormat("Constructor()\n"
+               "    : aaaaaa(aaaaaa),\n"
+               "      aaaaaaaaaaaaaaaaaaaaaaaaaaaaaa(\n"
+               "          aaaa(aaaaaaaaaaaaaaaaaa, aaaaaaaaaaaaaaaaaat))",
+               StyleWithWhitespacePenalty);
+  verifyFormat("Constructor()\n"
+               "    : aaaaaaaaaaaaa(aaaaaa), "
+               "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaa(aaaaaaaaaaaaaaaaaa)",
+               StyleWithWhitespacePenalty);
+}
+
 TEST_F(FormatTest, LLVMDefaultStyle) {
   FormatStyle Style = getLLVMStyle();
   verifyFormat("extern \"C\" {\n"