如何配置Clang-Format实现等号后换行并对齐运算符

问题背景 #

我正在配置Clang-Format，希望保留自己声明变量和Concept的代码风格。

期望的格式化样式 #

（开头制表符用⟶ 表示，空格用·表示）

template<typename T>
concept my_concept =
⟶ ····std::destructible<T>
⟶ and std::copy_constructible<T>
⟶ and std::default_initializable<T>
⟶ and requires(T t) {
⟶ ⟶ { t.expression() };
⟶ };

Clang-Format实际输出的样式 #

template<typename T>
concept my_concept = std::destructible<T> and std::copy_constructible<T>
⟶ and std::default_initializable<T> and requires(T t) {
⟶ ⟶ ⟶ ⟶ ⟶ ⟶ ⟶ ⟶ ⟶ ⟶ ⟶ ⟶ ··{ t.expression() };
⟶ ⟶ ⟶ ⟶ ⟶ ⟶ ⟶ ⟶ ⟶ ⟶ ⟶ ··};

待解决的三个问题 #

• Clang-Format用制表符对齐requires表达式
• Clang-Format对表达式进行二进制打包（bin packing）
• Clang-Format不在等号后换行，且不对齐and关键字

当前的.clang-format配置 #

---
Language: Cpp
# BasedOnStyle: Chromium
AlignAfterOpenBracket: BlockIndent
AccessModifierOffset: -4
AlignConsecutiveMacros: false
AlignConsecutiveAssignments: false
AlignConsecutiveBitFields: false
AlignConsecutiveDeclarations: false
AlignEscapedNewlines: Left
AlignOperands: DontAlign
AlignTrailingComments: false
AllowAllArgumentsOnNextLine: true
AllowAllConstructorInitializersOnNextLine: false
AllowAllParametersOfDeclarationOnNextLine: true
AllowShortEnumsOnASingleLine: false
AllowShortBlocksOnASingleLine: Always
AllowShortCaseLabelsOnASingleLine: true
AllowShortFunctionsOnASingleLine: Empty
AllowShortLambdasOnASingleLine: All
AlwaysBreakAfterReturnType: None
AlwaysBreakBeforeMultilineStrings: true
AlwaysBreakTemplateDeclarations: true
BinPackArguments: false
BinPackParameters: false
BitFieldColonSpacing: Both
AllowShortIfStatementsOnASingleLine: Never
AllowShortLoopsOnASingleLine: false
AlwaysBreakAfterDefinitionReturnType: None
AlwaysBreakAfterReturnType: None
AlwaysBreakBeforeMultilineStrings: true
AlwaysBreakTemplateDeclarations: Yes
BreakBeforeBinaryOperators: NonAssignment
BreakBeforeBraces: Custom
BraceWrapping:
  AfterCaseLabel: false
  AfterClass: false
  AfterControlStatement: Never
  AfterEnum: false
  AfterFunction: false
  AfterNamespace: false
  AfterStruct: false
  AfterUnion: false
  AfterExternBlock: false
  BeforeCatch: false
  BeforeElse: false
  BeforeLambdaBody: false
  BeforeWhile: false
  IndentBraces: false
  SplitEmptyFunction: false
  SplitEmptyRecord: false
  SplitEmptyNamespace: false
#BreakAfterAttributes: Always
BreakBeforeConceptDeclarations: Always
BreakBeforeTernaryOperators: true
BreakConstructorInitializers: AfterColon
BreakInheritanceList: AfterColon
BreakStringLiterals: true
ColumnLimit: 120
CompactNamespaces: false
ConstructorInitializerIndentWidth: 4
Cpp11BracedListStyle: true
BreakAfterJavaFieldAnnotations: true
CommentPragmas: '^ IWYU pragma:'
ConstructorInitializerAllOnOneLineOrOnePerLine: false
ContinuationIndentWidth: 4
DeriveLineEnding: false
DerivePointerAlignment: false
DisableFormat: false
EmptyLineAfterAccessModifier: Never
EmptyLineBeforeAccessModifier: Always
ExperimentalAutoDetectBinPacking: false
FixNamespaceComments: true
ForEachMacros:
  - foreach
  - Q_FOREACH
  - BOOST_FOREACH
IncludeBlocks: Regroup
IncludeCategories:
  - Regex: 'define.hpp'
    Priority: 5
  - Regex: '^<[a-z_]+>'
    Priority: 4
  - Regex: '^<.+\.h(pp)?>'
    Priority: 3
  - Regex: '^<.*'
    Priority: 2
  - Regex: '.*'
    Priority: 1
IncludeIsMainRegex: ''
IncludeIsMainSourceRegex: ''
IndentAccessModifiers: false
IndentCaseLabels: true
IndentCaseBlocks: false
IndentGotoLabels: false
IndentExternBlock: 
IndentPPDirectives: BeforeHash
IndentExternBlock: Indent
IndentWidth: 4
IndentWrappedFunctionNames: false
InsertBraces: true
#InsertNewlineAtEOF: true
InsertTrailingCommas: Wrapped
JavaScriptQuotes: Double
JavaScriptWrapImports: true
LambdaBodyIndentation: Signature
KeepEmptyLinesAtTheStartOfBlocks: false
MacroBlockBegin: ''
MacroBlockEnd: ''
MaxEmptyLinesToKeep: 1
NamespaceIndentation: All
ObjCBinPackProtocolList: Never
ObjCBlockIndentWidth: 2
ObjCBreakBeforeNestedBlockParam: true
ObjCSpaceAfterProperty: false
ObjCSpaceBeforeProtocolList: true
PackConstructorInitializers: NextLine
PenaltyBreakAssignment: 2
PenaltyBreakBeforeFirstCallParameter: 1
PenaltyBreakComment: 300
PenaltyBreakFirstLessLess: 120
PenaltyBreakString: 1000
PenaltyBreakTemplateDeclaration: 10
PenaltyExcessCharacter: 1000000
PenaltyReturnTypeOnItsOwnLine: 200
PointerAlignment: Left
QualifierAlignment: Custom
QualifierOrder: ['static', 'inline', 'constexpr', 'type', 'const', 'volatile']
RawStringFormats:
  - Language: Cpp
    Delimiters:
      - cc
      - CC
      - cpp
      - Cpp
      - CPP
      - 'c++'
      - 'C++'
    CanonicalDelimiter: ''
    BasedOnStyle: google
  - Language: TextProto
    Delimiters:
      - pb
      - PB
      - proto
      - PROTO
    EnclosingFunctions:
      - EqualsProto
      - EquivToProto
      - PARSE_PARTIAL_TEXT_PROTO
      - PARSE_TEST_PROTO
      - PARSE_TEXT_PROTO
      - ParseTextOrDie
      - ParseTextProtoOrDie
      - ParseTestProto
      - ParsePartialTestProto
    CanonicalDelimiter: ''
    BasedOnStyle: google
ReferenceAlignment: Left
#RemoveSemicolon: true
RequiresClausePosition: SingleLine
#RequiresExpressionIndentation: OuterScope
SeparateDefinitionBlocks: Always
ShortNamespaceLines: 8
ReflowComments: true
SortIncludes: true
SortUsingDeclarations: true
SpaceAfterCStyleCast: true
SpaceAfterLogicalNot: false
SpaceAfterTemplateKeyword: false
SpaceAroundPointerQualifiers: Before
SpaceBeforeAssignmentOperators: true
SpaceBeforeCaseColon: false
SpaceBeforeCpp11BracedList: false
SpaceBeforeCtorInitializerColon: true
SpaceBeforeInheritanceColon: true
SpaceBeforeParens: ControlStatementsExceptForEachMacros
SpaceBeforeRangeBasedForLoopColon: true
SpaceBeforeSquareBrackets: false
SpaceInEmptyBlock: false
SpaceInEmptyParentheses: false
SpacesBeforeTrailingComments: 4
SpacesInAngles: false
SpacesInConditionalStatement: false
SpacesInContainerLiterals: false
SpacesInCStyleCastParentheses: false
SpacesInParentheses: false
SpacesInSquareBrackets: false
Standard: c++20
StatementMacros:
  - Q_UNUSED
  - QT_REQUIRE_VERSION
TabWidth: 4
IndentWidth: 4
UseCRLF: false
UseTab: AlignWithSpaces
WhitespaceSensitiveMacros:
  - STRINGIZE
  - PP_STRINGIZE
  - BOOST_PP_STRINGIZE
...

解决方案 #

针对三个问题，修改以下配置项：

1. 解决requires表达式对齐问题 #

取消注释并设置RequiresExpressionIndentation: OuterScope，让requires块内的内容仅缩进一级，而非对齐到requires关键字的位置。

2. 禁用二进制打包 #

确保BinPackArguments和BinPackParameters已设为false，同时添加BinPackOperands: false禁止表达式的二进制打包行为。

3. 实现等号后换行并对齐and关键字 #

• 将BreakBeforeBinaryOperators从NonAssignment改为All，让每个and操作符都换行显示
• 设置BreakAfterEquals: Always，强制在等号后换行
• 将AlignOperands从DontAlign改为Align，让and关键字对齐到同一列

修改后的关键配置片段 #

# ... 其他配置保持不变 ...
BreakBeforeBinaryOperators: All
BreakAfterEquals: Always
AlignOperands: Align
BinPackOperands: false
RequiresExpressionIndentation: OuterScope
# ... 其他配置保持不变 ...

验证效果 #

修改后，Clang-Format会输出与期望一致的格式：

template<typename T>
concept my_concept =
    std::destructible<T>
and std::copy_constructible<T>
and std::default_initializable<T>
and requires(T t) {
    { t.expression() };
};

内容的提问来源于stack exchange，提问作者Guillaume Racicot