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[clang-format] Add BreakBeforeTemplateCloser option (llvm#118046)
In clang-format, multiline templates have the `>` on the same line as the last parameter: ```c++ template < typename Foo, typename Bar> void foo() { ``` I would like to add an option to put the `>` on the next line, like this: ```c++ template < typename Foo, typename Bar > void foo() { ``` An example of a large project that uses this style is NVIDIA's CUTLASS, here is an example: https://github.com/NVIDIA/cutlass/blob/main/include/cutlass/epilogue/dispatch_policy.hpp#L149-L156 My reasoning is that it reminds me of this style of braces: ```c++ if (foo()) { bar(); baz();} ``` Most people agree this is better: ```c++ if (foo()) { bar(); baz(); } ``` --------- Co-authored-by: Owen Pan <[email protected]>
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‎clang/docs/ClangFormatStyleOptions.rst

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@@ -3421,6 +3421,35 @@ the configuration (without a prefix: ``Auto``).
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.. _BreakBeforeTemplateCloser:
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**BreakBeforeTemplateCloser** (``Boolean``) :versionbadge:`clang-format 21` :ref:`<BreakBeforeTemplateCloser>`
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If ``true``, break before a template closing bracket (``>``) when there is
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a line break after the matching opening bracket (``<``).
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.. code-block:: c++
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true:
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template <typename Foo, typename Bar>
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template <typename Foo,
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typename Bar>
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template <
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typename Foo,
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typename Bar
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>
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false:
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template <typename Foo, typename Bar>
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template <typename Foo,
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typename Bar>
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template <
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typename Foo,
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typename Bar>
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.. _BreakBeforeTernaryOperators:
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**BreakBeforeTernaryOperators** (``Boolean``) :versionbadge:`clang-format 3.7` :ref:`<BreakBeforeTernaryOperators>`

‎clang/docs/ReleaseNotes.rst

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@@ -231,6 +231,8 @@ AST Matchers
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clang-format
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------------
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- Adds ``BreakBeforeTemplateCloser`` option.
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libclang
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--------
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‎clang/include/clang/Format/Format.h

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@@ -2252,6 +2252,33 @@ struct FormatStyle {
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/// \version 16
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BreakBeforeInlineASMColonStyle BreakBeforeInlineASMColon;
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/// If ``true``, break before a template closing bracket (``>``) when there is
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/// a line break after the matching opening bracket (``<``).
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/// \code
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/// true:
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/// template <typename Foo, typename Bar>
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///
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/// template <typename Foo,
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/// typename Bar>
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///
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/// template <
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/// typename Foo,
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/// typename Bar
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/// >
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///
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/// false:
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/// template <typename Foo, typename Bar>
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///
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/// template <typename Foo,
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/// typename Bar>
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///
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/// template <
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/// typename Foo,
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/// typename Bar>
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/// \endcode
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/// \version 21
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bool BreakBeforeTemplateCloser;
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/// If ``true``, ternary operators will be placed after line breaks.
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/// \code
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/// true:
@@ -5251,6 +5278,7 @@ struct FormatStyle {
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BreakBeforeBraces == R.BreakBeforeBraces &&
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BreakBeforeConceptDeclarations == R.BreakBeforeConceptDeclarations &&
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BreakBeforeInlineASMColon == R.BreakBeforeInlineASMColon &&
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BreakBeforeTemplateCloser == R.BreakBeforeTemplateCloser &&
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BreakBeforeTernaryOperators == R.BreakBeforeTernaryOperators &&
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BreakBinaryOperations == R.BreakBinaryOperations &&
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BreakConstructorInitializers == R.BreakConstructorInitializers &&

‎clang/lib/Format/ContinuationIndenter.cpp

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Original file line numberDiff line numberDiff line change
@@ -349,19 +349,22 @@ bool ContinuationIndenter::canBreak(const LineState &State) {
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}
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}
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// Don't allow breaking before a closing brace of a block-indented braced list
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// initializer if there isn't already a break.
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if (Current.is(tok::r_brace) && Current.MatchingParen &&
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Current.isBlockIndentedInitRBrace(Style)) {
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return CurrentState.BreakBeforeClosingBrace;
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}
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// Allow breaking before the right parens with block indentation if there was
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// a break after the left parens, which is tracked by BreakBeforeClosingParen.
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if (Style.AlignAfterOpenBracket == FormatStyle::BAS_BlockIndent &&
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Current.is(tok::r_paren)) {
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return CurrentState.BreakBeforeClosingParen;
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}
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// Don't allow breaking before a closing brace of a block-indented braced list
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// initializer if there isn't already a break.
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if (Current.is(tok::r_brace) && Current.MatchingParen &&
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Current.isBlockIndentedInitRBrace(Style)) {
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return CurrentState.BreakBeforeClosingBrace;
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}
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if (Style.BreakBeforeTemplateCloser && Current.is(TT_TemplateCloser))
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return CurrentState.BreakBeforeClosingAngle;
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// If binary operators are moved to the next line (including commas for some
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// styles of constructor initializers), that's always ok.
@@ -414,6 +417,8 @@ bool ContinuationIndenter::mustBreak(const LineState &State) {
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}
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if (CurrentState.BreakBeforeClosingParen && Current.is(tok::r_paren))
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return true;
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if (CurrentState.BreakBeforeClosingAngle && Current.is(TT_TemplateCloser))
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return true;
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if (Style.Language == FormatStyle::LK_ObjC &&
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Style.ObjCBreakBeforeNestedBlockParam &&
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Current.ObjCSelectorNameParts > 1 &&
@@ -1243,6 +1248,9 @@ unsigned ContinuationIndenter::addTokenOnNewLine(LineState &State,
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Style.AlignAfterOpenBracket == FormatStyle::BAS_BlockIndent;
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}
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if (PreviousNonComment && PreviousNonComment->is(TT_TemplateOpener))
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CurrentState.BreakBeforeClosingAngle = Style.BreakBeforeTemplateCloser;
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if (CurrentState.AvoidBinPacking) {
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// If we are breaking after '(', '{', '<', or this is the break after a ':'
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// to start a member initializer list in a constructor, this should not
@@ -1379,6 +1387,10 @@ unsigned ContinuationIndenter::getNewLineColumn(const LineState &State) {
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State.Stack.size() > 1) {
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return State.Stack[State.Stack.size() - 2].LastSpace;
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}
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if (Style.BreakBeforeTemplateCloser && Current.is(TT_TemplateCloser) &&
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State.Stack.size() > 1) {
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return State.Stack[State.Stack.size() - 2].LastSpace;
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}
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if (NextNonComment->is(TT_TemplateString) && NextNonComment->closesScope())
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return State.Stack[State.Stack.size() - 2].LastSpace;
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// Field labels in a nested type should be aligned to the brace. For example

‎clang/lib/Format/ContinuationIndenter.h

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@@ -200,14 +200,15 @@ struct ParenState {
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: Tok(Tok), Indent(Indent), LastSpace(LastSpace),
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NestedBlockIndent(Indent), IsAligned(false),
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BreakBeforeClosingBrace(false), BreakBeforeClosingParen(false),
203-
AvoidBinPacking(AvoidBinPacking), BreakBeforeParameter(false),
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NoLineBreak(NoLineBreak), NoLineBreakInOperand(false),
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LastOperatorWrapped(true), ContainsLineBreak(false),
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ContainsUnwrappedBuilder(false), AlignColons(true),
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ObjCSelectorNameFound(false), HasMultipleNestedBlocks(false),
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NestedBlockInlined(false), IsInsideObjCArrayLiteral(false),
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IsCSharpGenericTypeConstraint(false), IsChainedConditional(false),
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IsWrappedConditional(false), UnindentOperator(false) {}
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BreakBeforeClosingAngle(false), AvoidBinPacking(AvoidBinPacking),
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BreakBeforeParameter(false), NoLineBreak(NoLineBreak),
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NoLineBreakInOperand(false), LastOperatorWrapped(true),
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ContainsLineBreak(false), ContainsUnwrappedBuilder(false),
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AlignColons(true), ObjCSelectorNameFound(false),
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HasMultipleNestedBlocks(false), NestedBlockInlined(false),
209+
IsInsideObjCArrayLiteral(false), IsCSharpGenericTypeConstraint(false),
210+
IsChainedConditional(false), IsWrappedConditional(false),
211+
UnindentOperator(false) {}
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/// \brief The token opening this parenthesis level, or nullptr if this level
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/// is opened by fake parenthesis.
@@ -280,6 +281,9 @@ struct ParenState {
280281
/// was a newline after the beginning left paren.
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bool BreakBeforeClosingParen : 1;
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/// Whether a newline needs to be inserted before a closing angle `>`.
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bool BreakBeforeClosingAngle : 1;
286+
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/// Avoid bin packing, i.e. multiple parameters/elements on multiple
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/// lines, in this context.
285289
bool AvoidBinPacking : 1;
@@ -367,6 +371,8 @@ struct ParenState {
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return BreakBeforeClosingBrace;
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if (BreakBeforeClosingParen != Other.BreakBeforeClosingParen)
369373
return BreakBeforeClosingParen;
374+
if (BreakBeforeClosingAngle != Other.BreakBeforeClosingAngle)
375+
return BreakBeforeClosingAngle;
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if (QuestionColumn != Other.QuestionColumn)
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return QuestionColumn < Other.QuestionColumn;
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if (AvoidBinPacking != Other.AvoidBinPacking)

‎clang/lib/Format/Format.cpp

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@@ -1014,6 +1014,8 @@ template <> struct MappingTraits<FormatStyle> {
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IO.mapOptional("BreakBeforeBraces", Style.BreakBeforeBraces);
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IO.mapOptional("BreakBeforeInlineASMColon",
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Style.BreakBeforeInlineASMColon);
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IO.mapOptional("BreakBeforeTemplateCloser",
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Style.BreakBeforeTemplateCloser);
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IO.mapOptional("BreakBeforeTernaryOperators",
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Style.BreakBeforeTernaryOperators);
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IO.mapOptional("BreakBinaryOperations", Style.BreakBinaryOperations);
@@ -1535,6 +1537,7 @@ FormatStyle getLLVMStyle(FormatStyle::LanguageKind Language) {
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LLVMStyle.BreakBeforeBraces = FormatStyle::BS_Attach;
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LLVMStyle.BreakBeforeConceptDeclarations = FormatStyle::BBCDS_Always;
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LLVMStyle.BreakBeforeInlineASMColon = FormatStyle::BBIAS_OnlyMultiline;
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LLVMStyle.BreakBeforeTemplateCloser = false;
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LLVMStyle.BreakBeforeTernaryOperators = true;
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LLVMStyle.BreakBinaryOperations = FormatStyle::BBO_Never;
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LLVMStyle.BreakConstructorInitializers = FormatStyle::BCIS_BeforeColon;

‎clang/lib/Format/TokenAnnotator.cpp

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@@ -6180,6 +6180,9 @@ bool TokenAnnotator::canBreakBefore(const AnnotatedLine &Line,
61806180
return false;
61816181
}
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6183+
if (Right.is(TT_TemplateCloser))
6184+
return Style.BreakBeforeTemplateCloser;
6185+
61836186
if (Left.is(tok::at))
61846187
return false;
61856188
if (Left.Tok.getObjCKeywordID() == tok::objc_interface)
@@ -6328,8 +6331,6 @@ bool TokenAnnotator::canBreakBefore(const AnnotatedLine &Line,
63286331
if (Right.is(TT_ImplicitStringLiteral))
63296332
return false;
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6331-
if (Right.is(TT_TemplateCloser))
6332-
return false;
63336334
if (Right.is(tok::r_square) && Right.MatchingParen &&
63346335
Right.MatchingParen->is(TT_LambdaLSquare)) {
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return false;

‎clang/unittests/Format/ConfigParseTest.cpp

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@@ -170,6 +170,7 @@ TEST(ConfigParseTest, ParsesConfigurationBools) {
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CHECK_PARSE_BOOL(BinPackArguments);
171171
CHECK_PARSE_BOOL(BreakAdjacentStringLiterals);
172172
CHECK_PARSE_BOOL(BreakAfterJavaFieldAnnotations);
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CHECK_PARSE_BOOL(BreakBeforeTemplateCloser);
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CHECK_PARSE_BOOL(BreakBeforeTernaryOperators);
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CHECK_PARSE_BOOL(BreakStringLiterals);
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CHECK_PARSE_BOOL(CompactNamespaces);

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