[clang] [clang-format] Add option to omit wrapping for empty records (PR #151970)
Tomáš Slanina via cfe-commits
cfe-commits at lists.llvm.org
Mon Aug 11 07:24:53 PDT 2025
https://github.com/itzexpoexpo updated https://github.com/llvm/llvm-project/pull/151970
>From 2c26e66e16bf2c42019e8a5bce421f106fcf978d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Tom=C3=A1=C5=A1=20Slanina?= <itzexpoexpo at gmail.com>
Date: Mon, 4 Aug 2025 15:19:53 +0200
Subject: [PATCH 1/3] [clang-format] Add option to omit wrapping for empty
records
Currently, clang-format does not allow empty records to be formatted
on a single line if the corresponding `BraceWrapping.After*` option
is set to true.
This results in unnecessarily wrapped code:
struct foo
{
int i;
};
struct bar
{
};
This patch adds the `BraceWrapping.WrapEmptyRecord` option, which
allows `class`, `struct`, and `union` declarations with empty bodies
to be formatted as one-liners, even when `AfterRecord: true`.
As such, the following becomes possible:
struct foo
{
int i;
};
struct bar {};
---
clang/include/clang/Format/Format.h | 28 ++++++++++++++++++++++
clang/lib/Format/Format.cpp | 13 +++++++++-
clang/lib/Format/TokenAnnotator.cpp | 9 +++----
clang/lib/Format/UnwrappedLineParser.cpp | 20 ++++++++++------
clang/unittests/Format/FormatTest.cpp | 30 ++++++++++++++++++++++++
5 files changed, 88 insertions(+), 12 deletions(-)
diff --git a/clang/include/clang/Format/Format.h b/clang/include/clang/Format/Format.h
index 31582a40de866..cc79dcb7b53ec 100644
--- a/clang/include/clang/Format/Format.h
+++ b/clang/include/clang/Format/Format.h
@@ -1355,6 +1355,32 @@ struct FormatStyle {
BWACS_Always
};
+ enum BraceWrapEmptyRecordStyle : int8_t {
+ /// Use default wrapping rules for records
+ /// (AfterClass,AfterStruct,AfterUnion)
+ /// \code
+ /// class foo
+ /// {
+ /// int foo;
+ /// };
+ ///
+ /// class foo
+ /// {
+ /// };
+ /// \endcode
+ BWER_Default,
+ /// Override wrapping for empty records
+ /// \code
+ /// class foo
+ /// {
+ /// int foo;
+ /// };
+ ///
+ /// class foo {};
+ /// \endcode
+ BWER_Never
+ };
+
/// Precise control over the wrapping of braces.
/// \code
/// # Should be declared this way:
@@ -1585,6 +1611,8 @@ struct FormatStyle {
/// \endcode
///
bool SplitEmptyNamespace;
+ /// Wrap empty record (``class``/``struct``/``union``).
+ BraceWrapEmptyRecordStyle WrapEmptyRecord;
};
/// Control of individual brace wrapping cases.
diff --git a/clang/lib/Format/Format.cpp b/clang/lib/Format/Format.cpp
index 063780721423f..0d72410f00c27 100644
--- a/clang/lib/Format/Format.cpp
+++ b/clang/lib/Format/Format.cpp
@@ -200,6 +200,7 @@ template <> struct MappingTraits<FormatStyle::BraceWrappingFlags> {
IO.mapOptional("SplitEmptyFunction", Wrapping.SplitEmptyFunction);
IO.mapOptional("SplitEmptyRecord", Wrapping.SplitEmptyRecord);
IO.mapOptional("SplitEmptyNamespace", Wrapping.SplitEmptyNamespace);
+ IO.mapOptional("WrapEmptyRecord", Wrapping.WrapEmptyRecord);
}
};
@@ -232,6 +233,15 @@ struct ScalarEnumerationTraits<
}
};
+template <>
+struct ScalarEnumerationTraits<FormatStyle::BraceWrapEmptyRecordStyle> {
+ static void enumeration(IO &IO,
+ FormatStyle::BraceWrapEmptyRecordStyle &Value) {
+ IO.enumCase(Value, "Default", FormatStyle::BWER_Default);
+ IO.enumCase(Value, "Never", FormatStyle::BWER_Never);
+ }
+};
+
template <>
struct ScalarEnumerationTraits<
FormatStyle::BreakBeforeConceptDeclarationsStyle> {
@@ -1392,7 +1402,8 @@ static void expandPresetsBraceWrapping(FormatStyle &Expanded) {
/*IndentBraces=*/false,
/*SplitEmptyFunction=*/true,
/*SplitEmptyRecord=*/true,
- /*SplitEmptyNamespace=*/true};
+ /*SplitEmptyNamespace=*/true,
+ /*WrapEmptyRecord=*/FormatStyle::BWER_Default};
switch (Expanded.BreakBeforeBraces) {
case FormatStyle::BS_Linux:
Expanded.BraceWrapping.AfterClass = true;
diff --git a/clang/lib/Format/TokenAnnotator.cpp b/clang/lib/Format/TokenAnnotator.cpp
index 4801d27b1395a..22132f6d2fd3b 100644
--- a/clang/lib/Format/TokenAnnotator.cpp
+++ b/clang/lib/Format/TokenAnnotator.cpp
@@ -5935,10 +5935,11 @@ bool TokenAnnotator::mustBreakBefore(const AnnotatedLine &Line,
// Don't attempt to interpret struct return types as structs.
if (Right.isNot(TT_FunctionLBrace)) {
- return (Line.startsWith(tok::kw_class) &&
- Style.BraceWrapping.AfterClass) ||
- (Line.startsWith(tok::kw_struct) &&
- Style.BraceWrapping.AfterStruct);
+ return ((Line.startsWith(tok::kw_class) &&
+ Style.BraceWrapping.AfterClass) ||
+ (Line.startsWith(tok::kw_struct) &&
+ Style.BraceWrapping.AfterStruct)) &&
+ Style.BraceWrapping.WrapEmptyRecord == FormatStyle::BWER_Default;
}
}
diff --git a/clang/lib/Format/UnwrappedLineParser.cpp b/clang/lib/Format/UnwrappedLineParser.cpp
index 91b8fdc8a3c38..e3efb0804d988 100644
--- a/clang/lib/Format/UnwrappedLineParser.cpp
+++ b/clang/lib/Format/UnwrappedLineParser.cpp
@@ -952,20 +952,26 @@ static bool isIIFE(const UnwrappedLine &Line,
}
static bool ShouldBreakBeforeBrace(const FormatStyle &Style,
- const FormatToken &InitialToken) {
+ const FormatToken &InitialToken,
+ const FormatToken &NextToken) {
tok::TokenKind Kind = InitialToken.Tok.getKind();
if (InitialToken.is(TT_NamespaceMacro))
Kind = tok::kw_namespace;
+ bool IsEmptyBlock = NextToken.is(tok::r_brace);
+ bool WrapRecordAllowed =
+ !(IsEmptyBlock &&
+ Style.BraceWrapping.WrapEmptyRecord == FormatStyle::BWER_Never);
+
switch (Kind) {
case tok::kw_namespace:
return Style.BraceWrapping.AfterNamespace;
case tok::kw_class:
- return Style.BraceWrapping.AfterClass;
+ return Style.BraceWrapping.AfterClass && WrapRecordAllowed;
case tok::kw_union:
- return Style.BraceWrapping.AfterUnion;
+ return Style.BraceWrapping.AfterUnion && WrapRecordAllowed;
case tok::kw_struct:
- return Style.BraceWrapping.AfterStruct;
+ return Style.BraceWrapping.AfterStruct && WrapRecordAllowed;
case tok::kw_enum:
return Style.BraceWrapping.AfterEnum;
default:
@@ -3191,7 +3197,7 @@ void UnwrappedLineParser::parseNamespace() {
if (FormatTok->is(tok::l_brace)) {
FormatTok->setFinalizedType(TT_NamespaceLBrace);
- if (ShouldBreakBeforeBrace(Style, InitialToken))
+ if (ShouldBreakBeforeBrace(Style, InitialToken, *Tokens->peekNextToken()))
addUnwrappedLine();
unsigned AddLevels =
@@ -3856,7 +3862,7 @@ bool UnwrappedLineParser::parseEnum() {
}
if (!Style.AllowShortEnumsOnASingleLine &&
- ShouldBreakBeforeBrace(Style, InitialToken)) {
+ ShouldBreakBeforeBrace(Style, InitialToken, *Tokens->peekNextToken())) {
addUnwrappedLine();
}
// Parse enum body.
@@ -4151,7 +4157,7 @@ void UnwrappedLineParser::parseRecord(bool ParseAsExpr, bool IsJavaRecord) {
if (ParseAsExpr) {
parseChildBlock();
} else {
- if (ShouldBreakBeforeBrace(Style, InitialToken))
+ if (ShouldBreakBeforeBrace(Style, InitialToken, *Tokens->peekNextToken()))
addUnwrappedLine();
unsigned AddLevels = Style.IndentAccessModifiers ? 2u : 1u;
diff --git a/clang/unittests/Format/FormatTest.cpp b/clang/unittests/Format/FormatTest.cpp
index 96cc650f52a5d..3a5233674bd0f 100644
--- a/clang/unittests/Format/FormatTest.cpp
+++ b/clang/unittests/Format/FormatTest.cpp
@@ -15615,6 +15615,36 @@ TEST_F(FormatTest, NeverMergeShortRecords) {
Style);
}
+TEST_F(FormatTest, WrapEmptyRecords) {
+ FormatStyle Style = getLLVMStyle();
+
+ Style.BreakBeforeBraces = FormatStyle::BS_Custom;
+ Style.BraceWrapping.AfterStruct = true;
+ Style.BraceWrapping.AfterClass = true;
+ Style.BraceWrapping.AfterUnion = true;
+ Style.BraceWrapping.SplitEmptyRecord = false;
+
+ verifyFormat("class foo\n{\n void bar();\n};", Style);
+ verifyFormat("class foo\n{};", Style);
+
+ verifyFormat("struct foo\n{\n int bar;\n};", Style);
+ verifyFormat("struct foo\n{};", Style);
+
+ verifyFormat("union foo\n{\n int bar;\n};", Style);
+ verifyFormat("union foo\n{};", Style);
+
+ Style.BraceWrapping.WrapEmptyRecord = FormatStyle::BWER_Never;
+
+ verifyFormat("class foo\n{\n void bar();\n};", Style);
+ verifyFormat("class foo {};", Style);
+
+ verifyFormat("struct foo\n{\n int bar;\n};", Style);
+ verifyFormat("struct foo {};", Style);
+
+ verifyFormat("union foo\n{\n int bar;\n};", Style);
+ verifyFormat("union foo {};", Style);
+}
+
TEST_F(FormatTest, UnderstandContextOfRecordTypeKeywords) {
// Elaborate type variable declarations.
verifyFormat("struct foo a = {bar};\nint n;");
>From ce10b36f779b54b07cd90dd4023c949166380327 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Tom=C3=A1=C5=A1=20Slanina?= <itzexpoexpo at gmail.com>
Date: Mon, 4 Aug 2025 16:11:48 +0200
Subject: [PATCH 2/3] Fix missing style option docs
---
clang/docs/ClangFormatStyleOptions.rst | 30 ++++++++++++++++++++++++++
1 file changed, 30 insertions(+)
diff --git a/clang/docs/ClangFormatStyleOptions.rst b/clang/docs/ClangFormatStyleOptions.rst
index 02986a94a656c..f3ee029b6c2bf 100644
--- a/clang/docs/ClangFormatStyleOptions.rst
+++ b/clang/docs/ClangFormatStyleOptions.rst
@@ -2579,6 +2579,36 @@ the configuration (without a prefix: ``Auto``).
{} {
}
+ * ``BraceWrapEmptyRecordStyle WrapEmptyRecord``
+ Wrap empty record (``class``/``struct``/``union``).
+
+ Possible values:
+
+ * ``BWËR_Never`` (in configuration: ``Never``)
+ Never wrap braces of empty records.
+
+ .. code-block:: c++
+
+ class foo
+ {
+ int foo;
+ };
+
+ class foo{};
+
+ * ``BWER_Default`` (in configuration: ``MultiLine``)
+ Use default wrapping rules for records. (``AfterClass``, ``AfterStruct``, ``AfterUnion``)
+
+ .. code-block:: c++
+
+ class foo
+ {
+ int foo;
+ };
+
+ class foo
+ {
+ };
.. _BracedInitializerIndentWidth:
>From 38318671aafe724c2c1208468585b884e614edfb Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Tom=C3=A1=C5=A1=20Slanina?= <itzexpoexpo at gmail.com>
Date: Mon, 11 Aug 2025 16:23:17 +0200
Subject: [PATCH 3/3] !fixup [clang-format] Add option to omit wrapping for
empty records
---
clang/docs/ClangFormatStyleOptions.rst | 22 ++++++++++---------
clang/include/clang/Format/Format.h | 28 ++++++++++++------------
clang/lib/Format/UnwrappedLineParser.cpp | 4 ++--
clang/unittests/Format/FormatTest.cpp | 24 +++++++++++++++-----
4 files changed, 46 insertions(+), 32 deletions(-)
diff --git a/clang/docs/ClangFormatStyleOptions.rst b/clang/docs/ClangFormatStyleOptions.rst
index f3ee029b6c2bf..8c3b0ad707851 100644
--- a/clang/docs/ClangFormatStyleOptions.rst
+++ b/clang/docs/ClangFormatStyleOptions.rst
@@ -2584,8 +2584,9 @@ the configuration (without a prefix: ``Auto``).
Possible values:
- * ``BWËR_Never`` (in configuration: ``Never``)
- Never wrap braces of empty records.
+ * ``BWER_Default`` (in configuration: ``Default``)
+ Use default wrapping rules for records
+ (``AfterClass``,``AfterStruct``,``AfterUnion``).
.. code-block:: c++
@@ -2593,11 +2594,12 @@ the configuration (without a prefix: ``Auto``).
{
int foo;
};
-
- class foo{};
- * ``BWER_Default`` (in configuration: ``MultiLine``)
- Use default wrapping rules for records. (``AfterClass``, ``AfterStruct``, ``AfterUnion``)
+ class foo
+ {};
+
+ * ``BWER_Never`` (in configuration: ``Never``)
+ Override wrapping for empty records.
.. code-block:: c++
@@ -2605,10 +2607,10 @@ the configuration (without a prefix: ``Auto``).
{
int foo;
};
-
- class foo
- {
- };
+
+ class foo {};
+
+
.. _BracedInitializerIndentWidth:
diff --git a/clang/include/clang/Format/Format.h b/clang/include/clang/Format/Format.h
index cc79dcb7b53ec..5d7d0fd9a48d6 100644
--- a/clang/include/clang/Format/Format.h
+++ b/clang/include/clang/Format/Format.h
@@ -1355,28 +1355,28 @@ struct FormatStyle {
BWACS_Always
};
+ /// Override wrapping of empty records.
enum BraceWrapEmptyRecordStyle : int8_t {
/// Use default wrapping rules for records
- /// (AfterClass,AfterStruct,AfterUnion)
+ /// (``AfterClass``,``AfterStruct``,``AfterUnion``).
/// \code
- /// class foo
- /// {
- /// int foo;
- /// };
+ /// class foo
+ /// {
+ /// int foo;
+ /// };
///
- /// class foo
- /// {
- /// };
+ /// class foo
+ /// {};
/// \endcode
BWER_Default,
- /// Override wrapping for empty records
+ /// Override wrapping for empty records.
/// \code
- /// class foo
- /// {
- /// int foo;
- /// };
+ /// class foo
+ /// {
+ /// int foo;
+ /// };
///
- /// class foo {};
+ /// class foo {};
/// \endcode
BWER_Never
};
diff --git a/clang/lib/Format/UnwrappedLineParser.cpp b/clang/lib/Format/UnwrappedLineParser.cpp
index e3efb0804d988..c6bb0103b2081 100644
--- a/clang/lib/Format/UnwrappedLineParser.cpp
+++ b/clang/lib/Format/UnwrappedLineParser.cpp
@@ -960,8 +960,8 @@ static bool ShouldBreakBeforeBrace(const FormatStyle &Style,
bool IsEmptyBlock = NextToken.is(tok::r_brace);
bool WrapRecordAllowed =
- !(IsEmptyBlock &&
- Style.BraceWrapping.WrapEmptyRecord == FormatStyle::BWER_Never);
+ !IsEmptyBlock ||
+ Style.BraceWrapping.WrapEmptyRecord != FormatStyle::BWER_Never;
switch (Kind) {
case tok::kw_namespace:
diff --git a/clang/unittests/Format/FormatTest.cpp b/clang/unittests/Format/FormatTest.cpp
index 3a5233674bd0f..c8dff7f2710da 100644
--- a/clang/unittests/Format/FormatTest.cpp
+++ b/clang/unittests/Format/FormatTest.cpp
@@ -15624,24 +15624,36 @@ TEST_F(FormatTest, WrapEmptyRecords) {
Style.BraceWrapping.AfterUnion = true;
Style.BraceWrapping.SplitEmptyRecord = false;
- verifyFormat("class foo\n{\n void bar();\n};", Style);
+ verifyFormat("class foo\n{\n"
+ " void bar();\n"
+ "};", Style);
verifyFormat("class foo\n{};", Style);
- verifyFormat("struct foo\n{\n int bar;\n};", Style);
+ verifyFormat("struct foo\n{\n"
+ " int bar;\n"
+ "};", Style);
verifyFormat("struct foo\n{};", Style);
- verifyFormat("union foo\n{\n int bar;\n};", Style);
+ verifyFormat("union foo\n{\n"
+ " int bar;\n"
+ "};", Style);
verifyFormat("union foo\n{};", Style);
Style.BraceWrapping.WrapEmptyRecord = FormatStyle::BWER_Never;
- verifyFormat("class foo\n{\n void bar();\n};", Style);
+ verifyFormat("class foo\n{\n"
+ " void bar();\n"
+ "};", Style);
verifyFormat("class foo {};", Style);
- verifyFormat("struct foo\n{\n int bar;\n};", Style);
+ verifyFormat("struct foo\n{\n"
+ " int bar;\n"
+ "};", Style);
verifyFormat("struct foo {};", Style);
- verifyFormat("union foo\n{\n int bar;\n};", Style);
+ verifyFormat("union foo\n{\n"
+ " int bar;\n"
+ "};", Style);
verifyFormat("union foo {};", Style);
}
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