Format: add AlignAfterOpenBracketOptions

gedare · gedare · commit c7b34d10bb8f · 2025-01-28T00:26:47.000-07:00
Introduce new options to allow for control of AlwaysBreak and BlockIndent selectively for If conditional statements (as currently supported), other conditional statements (for/while/switch), and other statements. Fixes #67738. Fixes #79176. Fixes #80123.
diff --git a/clang/docs/ClangFormatStyleOptions.rst b/clang/docs/ClangFormatStyleOptions.rst
@@ -246,6 +246,66 @@ the configuration (without a prefix: ``Auto``).
 
 
 
+.. _AlignAfterOpenBracketBreak:
+
+**AlignAfterOpenBracketBreak** (``AlignAfterOpenBracketCustom``) :versionbadge:`clang-format 20` :ref:`¶ <AlignAfterOpenBracketBreak>`
+  Control of when ``AlignAfterOpenBracket`` breaks an opening bracket.
+
+  If ``AlignAfterOpenBracket`` is set to ``AlwaysBreak`` or ``BlockIndent``,
+  use this to specify how different cases of breaking the opening brackets
+  should be handled. Otherwise, this is ignored. Setting any of these to
+  ``false`` will cause them to not break. At least one of these must be set
+  to ``true``, otherwise a default (backward compatible) breaking behavior
+  is used. This is ignored for ``Align`` and ``DontAlign``.
+
+  .. code-block:: c++
+
+    # Example of usage:
+    AlignAfterOpenBracket: AlwaysBreak
+    AlignAfterOpenBracketBreak:
+      InIfConditionalStatements: true
+      InOtherConditionalStatements: false
+      Other: true
+
+  Nested configuration flags:
+
+  Precise control over breaking the opening bracket of
+  ``AlignAfterOpenBracket``.
+
+  .. code-block:: c++
+
+    # Should be declared this way:
+    AlignAfterOpenBracketBreak:
+      InIfConditionalStatements: true
+      InOtherConditionalStatements: false
+      Other: true
+
+  * ``bool InIfConditionalStatements`` Break inside if/else if statements.
+
+    .. code-block:: c++
+
+       true:                                  false:
+       if constexpr (                   vs.   if constexpr (a ||
+          a || b)                                           b)
+
+  * ``bool InOtherConditionalStatements`` Break inside conditional statements not covered by preceding options.
+    (``for/while/switch...``).
+
+    .. code-block:: c++
+
+       true:                                  false:
+       while (                          vs.   while (a &&
+          a && b ) {                                 b) {
+
+  * ``bool Other`` Break inside brackets not covered by preceding options.
+
+    .. code-block:: c++
+
+       true:                                  false:
+       someLongFunction(                vs.   someLongFunction(argument1,
+          argument1, argument2);                               argument2);
+
+
 .. _AlignArrayOfStructures:
 
 **AlignArrayOfStructures** (``ArrayInitializerAlignmentStyle``) :versionbadge:`clang-format 13` :ref:`¶ <AlignArrayOfStructures>`
diff --git a/clang/include/clang/Format/Format.h b/clang/include/clang/Format/Format.h
@@ -106,6 +106,78 @@ struct FormatStyle {
   /// \version 3.8
   BracketAlignmentStyle AlignAfterOpenBracket;
 
+  /// Precise control over breaking the opening bracket of
+  /// ``AlignAfterOpenBracket``.
+  /// \code
+  ///   # Should be declared this way:
+  ///   AlignAfterOpenBracketBreak:
+  ///     InIfConditionalStatements: true
+  ///     InOtherConditionalStatements: false
+  ///     Other: true
+  /// \endcode
+  struct AlignAfterOpenBracketCustom {
+    /// Break inside if/else if statements.
+    /// \code
+    ///    true:                                  false:
+    ///    if constexpr (                   vs.   if constexpr (a ||
+    ///       a || b)                                           b)
+    /// \endcode
+    bool InIfConditionalStatements;
+    /// Break inside conditional statements not covered by preceding options.
+    /// (``for/while/switch...``).
+    /// \code
+    ///    true:                                  false:
+    ///    while (                          vs.   while (a &&
+    ///       a && b ) {                                 b) {
+    /// \endcode
+    bool InOtherConditionalStatements;
+    /// Break inside brackets not covered by preceding options.
+    /// \code
+    ///    true:                                  false:
+    ///    someLongFunction(                vs.   someLongFunction(argument1,
+    ///       argument1, argument2);                               argument2);
+    /// \endcode
+    bool Other;
+
+    AlignAfterOpenBracketCustom()
+        : InIfConditionalStatements(false), InOtherConditionalStatements(false),
+          Other(false) {}
+
+    AlignAfterOpenBracketCustom(bool InIfConditionalStatements,
+                                bool InOtherConditionalStatements, bool Other)
+        : InIfConditionalStatements(InIfConditionalStatements),
+          InOtherConditionalStatements(InOtherConditionalStatements),
+          Other(Other) {}
+
+    bool operator==(const AlignAfterOpenBracketCustom &R) const {
+      return InIfConditionalStatements == R.InIfConditionalStatements &&
+             InOtherConditionalStatements == R.InOtherConditionalStatements &&
+             Other == R.Other;
+    }
+    bool operator!=(const AlignAfterOpenBracketCustom &R) const {
+      return !(*this == R);
+    }
+  };
+
+  /// Control of when ``AlignAfterOpenBracket`` breaks an opening bracket.
+  ///
+  /// If ``AlignAfterOpenBracket`` is set to ``AlwaysBreak`` or ``BlockIndent``,
+  /// use this to specify how different cases of breaking the opening brackets
+  /// should be handled. Otherwise, this is ignored. Setting any of these to
+  /// ``false`` will cause them to not break. At least one of these must be set
+  /// to ``true``, otherwise a default (backward compatible) breaking behavior
+  /// is used. This is ignored for ``Align`` and ``DontAlign``.
+  /// \code
+  ///   # Example of usage:
+  ///   AlignAfterOpenBracket: AlwaysBreak
+  ///   AlignAfterOpenBracketBreak:
+  ///     InIfConditionalStatements: true
+  ///     InOtherConditionalStatements: false
+  ///     Other: true
+  /// \endcode
+  /// \version 20
+  AlignAfterOpenBracketCustom AlignAfterOpenBracketBreak;
+
   /// Different style for aligning array initializers.
   enum ArrayInitializerAlignmentStyle : int8_t {
     /// Align array column and left justify the columns e.g.:
@@ -5198,6 +5270,7 @@ struct FormatStyle {
   bool operator==(const FormatStyle &R) const {
     return AccessModifierOffset == R.AccessModifierOffset &&
            AlignAfterOpenBracket == R.AlignAfterOpenBracket &&
+           AlignAfterOpenBracketBreak == R.AlignAfterOpenBracketBreak &&
            AlignArrayOfStructures == R.AlignArrayOfStructures &&
            AlignConsecutiveAssignments == R.AlignConsecutiveAssignments &&
            AlignConsecutiveBitFields == R.AlignConsecutiveBitFields &&
diff --git a/clang/lib/Format/ContinuationIndenter.cpp b/clang/lib/Format/ContinuationIndenter.cpp
@@ -799,6 +799,11 @@ void ContinuationIndenter::addTokenOnCurrentLine(LineState &State, bool DryRun,
   // parenthesis by disallowing any further line breaks if there is no line
   // break after the opening parenthesis. Don't break if it doesn't conserve
   // columns.
+  auto IsOtherConditional = [&](const FormatToken &Tok) {
+    return Tok.isOneOf(tok::kw_for, tok::kw_while, tok::kw_switch) ||
+           (Style.isJavaScript() && Tok.is(Keywords.kw_await) && Tok.Previous &&
+            Tok.Previous->is(tok::kw_for));
+  };
   auto IsOpeningBracket = [&](const FormatToken &Tok) {
     auto IsStartOfBracedList = [&]() {
       return Tok.is(tok::l_brace) && Tok.isNot(BK_Block) &&
@@ -811,10 +816,11 @@ void ContinuationIndenter::addTokenOnCurrentLine(LineState &State, bool DryRun,
     if (!Tok.Previous)
       return true;
     if (Tok.Previous->isIf())
-      return Style.AlignAfterOpenBracket == FormatStyle::BAS_AlwaysBreak;
-    return !Tok.Previous->isOneOf(TT_CastRParen, tok::kw_for, tok::kw_while,
-                                  tok::kw_switch) &&
-           !(Style.isJavaScript() && Tok.Previous->is(Keywords.kw_await));
+      return Style.AlignAfterOpenBracketBreak.InIfConditionalStatements;
+    if (IsOtherConditional(*Tok.Previous))
+      return Style.AlignAfterOpenBracketBreak.InOtherConditionalStatements;
+    return !Tok.Previous->is(TT_CastRParen) &&
+           Style.AlignAfterOpenBracketBreak.Other;
   };
   auto IsFunctionCallParen = [](const FormatToken &Tok) {
     return Tok.is(tok::l_paren) && Tok.ParameterCount > 0 && Tok.Previous &&
@@ -851,10 +857,15 @@ void ContinuationIndenter::addTokenOnCurrentLine(LineState &State, bool DryRun,
          Tok.isOneOf(tok::ellipsis, Keywords.kw_await))) {
       return true;
     }
-    const auto *Previous = Tok.Previous;
-    if (!Previous || (!Previous->isOneOf(TT_FunctionDeclarationLParen,
-                                         TT_LambdaDefinitionLParen) &&
-                      !IsFunctionCallParen(*Previous))) {
+    const auto *Previous = TokAfterLParen.Previous;
+    assert(Previous); // IsOpeningBracket(Previous)
+    if (Previous->Previous && (Previous->Previous->isIf() ||
+                               IsOtherConditional(*Previous->Previous))) {
+      return false;
+    }
+    if (!Previous->isOneOf(TT_FunctionDeclarationLParen,
+                           TT_LambdaDefinitionLParen) &&
+        !IsFunctionCallParen(*Previous)) {
       return true;
     }
     if (IsOpeningBracket(Tok) || IsInTemplateString(Tok))
@@ -1232,8 +1243,21 @@ unsigned ContinuationIndenter::addTokenOnNewLine(LineState &State,
   }
 
   if (PreviousNonComment && PreviousNonComment->is(tok::l_paren)) {
-    CurrentState.BreakBeforeClosingParen =
-        Style.AlignAfterOpenBracket == FormatStyle::BAS_BlockIndent;
+    CurrentState.BreakBeforeClosingParen = false;
+    if (Style.AlignAfterOpenBracket == FormatStyle::BAS_BlockIndent) {
+      auto Previous = PreviousNonComment->Previous;
+      if (Previous && Previous->isIf()) {
+        CurrentState.BreakBeforeClosingParen =
+            Style.AlignAfterOpenBracketBreak.InIfConditionalStatements;
+      } else if (Previous && Previous->isOneOf(tok::kw_for, tok::kw_while,
+                                               tok::kw_switch)) {
+        CurrentState.BreakBeforeClosingParen =
+            Style.AlignAfterOpenBracketBreak.InOtherConditionalStatements;
+      } else {
+        CurrentState.BreakBeforeClosingParen =
+            Style.AlignAfterOpenBracketBreak.Other;
+      }
+    }
   }
 
   if (CurrentState.AvoidBinPacking) {
diff --git a/clang/lib/Format/Format.cpp b/clang/lib/Format/Format.cpp
@@ -215,6 +215,16 @@ template <> struct ScalarEnumerationTraits<FormatStyle::BracketAlignmentStyle> {
   }
 };
 
+template <> struct MappingTraits<FormatStyle::AlignAfterOpenBracketCustom> {
+  static void mapping(IO &IO, FormatStyle::AlignAfterOpenBracketCustom &Value) {
+    IO.mapOptional("InIfConditionalStatements",
+                   Value.InIfConditionalStatements);
+    IO.mapOptional("InOtherConditionalStatements",
+                   Value.InOtherConditionalStatements);
+    IO.mapOptional("Other", Value.Other);
+  }
+};
+
 template <>
 struct ScalarEnumerationTraits<
     FormatStyle::BraceWrappingAfterControlStatementStyle> {
@@ -944,6 +954,8 @@ template <> struct MappingTraits<FormatStyle> {
 
     IO.mapOptional("AccessModifierOffset", Style.AccessModifierOffset);
     IO.mapOptional("AlignAfterOpenBracket", Style.AlignAfterOpenBracket);
+    IO.mapOptional("AlignAfterOpenBracketBreak",
+                   Style.AlignAfterOpenBracketBreak);
     IO.mapOptional("AlignArrayOfStructures", Style.AlignArrayOfStructures);
     IO.mapOptional("AlignConsecutiveAssignments",
                    Style.AlignConsecutiveAssignments);
@@ -1189,6 +1201,18 @@ template <> struct MappingTraits<FormatStyle> {
     IO.mapOptional("WrapNamespaceBodyWithEmptyLines",
                    Style.WrapNamespaceBodyWithEmptyLines);
 
+    // If AlignAfterOpenBracket was specified but AlignAfterOpenBracketBreak
+    // was not, initialize the latter for backwards compatibility.
+    if ((Style.AlignAfterOpenBracket == FormatStyle::BAS_AlwaysBreak ||
+         Style.AlignAfterOpenBracket == FormatStyle::BAS_BlockIndent) &&
+        Style.AlignAfterOpenBracketBreak ==
+            FormatStyle::AlignAfterOpenBracketCustom()) {
+      if (Style.AlignAfterOpenBracket == FormatStyle::BAS_AlwaysBreak)
+        Style.AlignAfterOpenBracketBreak.InIfConditionalStatements = true;
+      Style.AlignAfterOpenBracketBreak.InOtherConditionalStatements = false;
+      Style.AlignAfterOpenBracketBreak.Other = true;
+    }
+
     // If AlwaysBreakAfterDefinitionReturnType was specified but
     // BreakAfterReturnType was not, initialize the latter from the former for
     // backwards compatibility.
@@ -1472,6 +1496,7 @@ FormatStyle getLLVMStyle(FormatStyle::LanguageKind Language) {
   FormatStyle LLVMStyle;
   LLVMStyle.AccessModifierOffset = -2;
   LLVMStyle.AlignAfterOpenBracket = FormatStyle::BAS_Align;
+  LLVMStyle.AlignAfterOpenBracketBreak = {};
   LLVMStyle.AlignArrayOfStructures = FormatStyle::AIAS_None;
   LLVMStyle.AlignConsecutiveAssignments = {};
   LLVMStyle.AlignConsecutiveAssignments.PadOperators = true;
@@ -1786,6 +1811,7 @@ FormatStyle getGoogleStyle(FormatStyle::LanguageKind Language) {
     GoogleStyle.SpacesBeforeTrailingComments = 1;
   } else if (Language == FormatStyle::LK_JavaScript) {
     GoogleStyle.AlignAfterOpenBracket = FormatStyle::BAS_AlwaysBreak;
+    GoogleStyle.AlignAfterOpenBracketBreak = {true, false, true};
     GoogleStyle.AlignOperands = FormatStyle::OAS_DontAlign;
     GoogleStyle.AllowShortFunctionsOnASingleLine = FormatStyle::SFS_Empty;
     // TODO: still under discussion whether to switch to SLS_All.
diff --git a/clang/lib/Format/TokenAnnotator.cpp b/clang/lib/Format/TokenAnnotator.cpp
@@ -6165,7 +6165,13 @@ bool TokenAnnotator::canBreakBefore(const AnnotatedLine &Line,
     if (Next && Next->is(tok::l_paren))
       return false;
     const FormatToken *Previous = Right.MatchingParen->Previous;
-    return !(Previous && (Previous->is(tok::kw_for) || Previous->isIf()));
+    if (!Previous)
+      return true;
+    if (Previous->isOneOf(tok::kw_for, tok::kw_while, tok::kw_switch))
+      return Style.AlignAfterOpenBracketBreak.InOtherConditionalStatements;
+    if (Previous->isIf())
+      return Style.AlignAfterOpenBracketBreak.InIfConditionalStatements;
+    return Style.AlignAfterOpenBracketBreak.Other;
   }
 
   if (Left.isOneOf(tok::r_paren, TT_TrailingAnnotation) &&
diff --git a/clang/unittests/Format/ConfigParseTest.cpp b/clang/unittests/Format/ConfigParseTest.cpp
@@ -209,6 +209,11 @@ TEST(ConfigParseTest, ParsesConfigurationBools) {
   CHECK_PARSE_BOOL(SpaceBeforeSquareBrackets);
   CHECK_PARSE_BOOL(VerilogBreakBetweenInstancePorts);
 
+  CHECK_PARSE_NESTED_BOOL(AlignAfterOpenBracketBreak,
+                          InIfConditionalStatements);
+  CHECK_PARSE_NESTED_BOOL(AlignAfterOpenBracketBreak,
+                          InOtherConditionalStatements);
+  CHECK_PARSE_NESTED_BOOL(AlignAfterOpenBracketBreak, Other);
   CHECK_PARSE_NESTED_BOOL(AlignConsecutiveShortCaseStatements, Enabled);
   CHECK_PARSE_NESTED_BOOL(AlignConsecutiveShortCaseStatements,
                           AcrossEmptyLines);
@@ -523,6 +528,13 @@ TEST(ConfigParseTest, ParsesConfiguration) {
               FormatStyle::BAS_DontAlign);
   CHECK_PARSE("AlignAfterOpenBracket: true", AlignAfterOpenBracket,
               FormatStyle::BAS_Align);
+  Style.AlignAfterOpenBracket = FormatStyle::BAS_Align;
+  Style.AlignAfterOpenBracketBreak = {};
+  CHECK_PARSE("AlignAfterOpenBracket: AlwaysBreak", AlignAfterOpenBracketBreak,
+              FormatStyle::AlignAfterOpenBracketCustom(true, false, true));
+  Style.AlignAfterOpenBracketBreak = {};
+  CHECK_PARSE("AlignAfterOpenBracket: BlockIndent", AlignAfterOpenBracketBreak,
+              FormatStyle::AlignAfterOpenBracketCustom(false, false, true));
 
   Style.AlignEscapedNewlines = FormatStyle::ENAS_Left;
   CHECK_PARSE("AlignEscapedNewlines: DontAlign", AlignEscapedNewlines,
diff --git a/clang/unittests/Format/FormatTest.cpp b/clang/unittests/Format/FormatTest.cpp
