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Jun 25, 2024
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[clang-format] Add option to remove leading blank lines #91221

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48 changes: 38 additions & 10 deletions clang/docs/ClangFormatStyleOptions.rst
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Expand Up @@ -4443,23 +4443,51 @@ the configuration (without a prefix: ``Auto``).
false:
import {VeryLongImportsAreAnnoying, VeryLongImportsAreAnnoying, VeryLongImportsAreAnnoying,} from "some/module.js"

.. _KeepEmptyLines:

**KeepEmptyLines** (``KeepEmptyLinesStyle``) :versionbadge:`clang-format 19` :ref:`¶ <KeepEmptyLines>`
Which empty lines are kept. See ``MaxEmptyLinesToKeep`` for how many
consecutive empty lines are kept.

Nested configuration flags:

Options regarding which empty lines are kept.

For example, the config below will remove empty lines at start of the
file, end of the file, and start of blocks.


.. code-block:: c++

KeepEmptyLines:
AtEndOfFile: false
AtStartOfBlock: false
AtStartOfFile: false

* ``bool AtEndOfFile`` Keep empty lines at end of file.

* ``bool AtStartOfBlock`` Keep empty lines at start of a block.

.. code-block:: c++

true: false:
if (foo) { vs. if (foo) {
bar();
bar(); }
}

* ``bool AtStartOfFile`` Keep empty lines at start of file.


.. _KeepEmptyLinesAtEOF:

**KeepEmptyLinesAtEOF** (``Boolean``) :versionbadge:`clang-format 17` :ref:`¶ <KeepEmptyLinesAtEOF>`
Keep empty lines (up to ``MaxEmptyLinesToKeep``) at end of file.
This option is deprecated. See ``AtEndOfFile`` of ``KeepEmptyLines``.

.. _KeepEmptyLinesAtTheStartOfBlocks:

**KeepEmptyLinesAtTheStartOfBlocks** (``Boolean``) :versionbadge:`clang-format 3.7` :ref:`¶ <KeepEmptyLinesAtTheStartOfBlocks>`
If true, the empty line at the start of blocks is kept.

.. code-block:: c++

true: false:
if (foo) { vs. if (foo) {
bar();
bar(); }
}
This option is deprecated. See ``AtStartOfBlock`` of ``KeepEmptyLines``.

.. _LambdaBodyIndentation:

Expand Down
2 changes: 2 additions & 0 deletions clang/docs/ReleaseNotes.rst
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Expand Up @@ -1110,6 +1110,8 @@ clang-format
- Adds ``AllowShortCaseExpressionOnASingleLine`` option.
- Adds ``AlignCaseArrows`` suboption to ``AlignConsecutiveShortCaseStatements``.
- Adds ``LeftWithLastLine`` suboption to ``AlignEscapedNewlines``.
- Adds ``KeepEmptyLines`` option to deprecate ``KeepEmptyLinesAtEOF``
and ``KeepEmptyLinesAtTheStartOfBlocks``.

libclang
--------
Expand Down
56 changes: 41 additions & 15 deletions clang/include/clang/Format/Format.h
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Expand Up @@ -3095,20 +3095,49 @@ struct FormatStyle {
bool JavaScriptWrapImports;
// clang-format on

/// Keep empty lines (up to ``MaxEmptyLinesToKeep``) at end of file.
/// \version 17
bool KeepEmptyLinesAtEOF;

/// If true, the empty line at the start of blocks is kept.
/// Options regarding which empty lines are kept.
///
/// For example, the config below will remove empty lines at start of the
/// file, end of the file, and start of blocks.
///
/// \code
/// true: false:
/// if (foo) { vs. if (foo) {
/// bar();
/// bar(); }
/// }
/// KeepEmptyLines:
/// AtEndOfFile: false
/// AtStartOfBlock: false
/// AtStartOfFile: false
/// \endcode
struct KeepEmptyLinesStyle {
/// Keep empty lines at end of file.
bool AtEndOfFile;
/// Keep empty lines at start of a block.
/// \code
/// true: false:
/// if (foo) { vs. if (foo) {
/// bar();
/// bar(); }
/// }
/// \endcode
bool AtStartOfBlock;
/// Keep empty lines at start of file.
bool AtStartOfFile;
bool operator==(const KeepEmptyLinesStyle &R) const {
return AtEndOfFile == R.AtEndOfFile &&
AtStartOfBlock == R.AtStartOfBlock &&
AtStartOfFile == R.AtStartOfFile;
}
};
/// Which empty lines are kept. See ``MaxEmptyLinesToKeep`` for how many
/// consecutive empty lines are kept.
/// \version 19
KeepEmptyLinesStyle KeepEmptyLines;

/// This option is deprecated. See ``AtEndOfFile`` of ``KeepEmptyLines``.
/// \version 17
// bool KeepEmptyLinesAtEOF;

/// This option is deprecated. See ``AtStartOfBlock`` of ``KeepEmptyLines``.
/// \version 3.7
bool KeepEmptyLinesAtTheStartOfBlocks;
// bool KeepEmptyLinesAtTheStartOfBlocks;

/// Indentation logic for lambda bodies.
enum LambdaBodyIndentationKind : int8_t {
Expand Down Expand Up @@ -5033,10 +5062,7 @@ struct FormatStyle {
JavaImportGroups == R.JavaImportGroups &&
JavaScriptQuotes == R.JavaScriptQuotes &&
JavaScriptWrapImports == R.JavaScriptWrapImports &&
KeepEmptyLinesAtEOF == R.KeepEmptyLinesAtEOF &&
KeepEmptyLinesAtTheStartOfBlocks ==
R.KeepEmptyLinesAtTheStartOfBlocks &&
Language == R.Language &&
KeepEmptyLines == R.KeepEmptyLines && Language == R.Language &&
LambdaBodyIndentation == R.LambdaBodyIndentation &&
LineEnding == R.LineEnding && MacroBlockBegin == R.MacroBlockBegin &&
MacroBlockEnd == R.MacroBlockEnd && Macros == R.Macros &&
Expand Down
24 changes: 18 additions & 6 deletions clang/lib/Format/Format.cpp
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Expand Up @@ -369,6 +369,14 @@ template <> struct ScalarEnumerationTraits<FormatStyle::JavaScriptQuoteStyle> {
}
};

template <> struct MappingTraits<FormatStyle::KeepEmptyLinesStyle> {
static void mapping(IO &IO, FormatStyle::KeepEmptyLinesStyle &Value) {
IO.mapOptional("AtEndOfFile", Value.AtEndOfFile);
IO.mapOptional("AtStartOfBlock", Value.AtStartOfBlock);
IO.mapOptional("AtStartOfFile", Value.AtStartOfFile);
}
};

template <> struct ScalarEnumerationTraits<FormatStyle::LanguageKind> {
static void enumeration(IO &IO, FormatStyle::LanguageKind &Value) {
IO.enumCase(Value, "Cpp", FormatStyle::LK_Cpp);
Expand Down Expand Up @@ -869,6 +877,9 @@ template <> struct MappingTraits<FormatStyle> {
OnCurrentLine);
IO.mapOptional("DeriveLineEnding", DeriveLineEnding);
IO.mapOptional("DerivePointerBinding", Style.DerivePointerAlignment);
IO.mapOptional("KeepEmptyLinesAtEOF", Style.KeepEmptyLines.AtEndOfFile);
IO.mapOptional("KeepEmptyLinesAtTheStartOfBlocks",
Style.KeepEmptyLines.AtStartOfBlock);
IO.mapOptional("IndentFunctionDeclarationAfterType",
Style.IndentWrappedFunctionNames);
IO.mapOptional("IndentRequires", Style.IndentRequiresClause);
Expand Down Expand Up @@ -1004,9 +1015,7 @@ template <> struct MappingTraits<FormatStyle> {
IO.mapOptional("JavaImportGroups", Style.JavaImportGroups);
IO.mapOptional("JavaScriptQuotes", Style.JavaScriptQuotes);
IO.mapOptional("JavaScriptWrapImports", Style.JavaScriptWrapImports);
IO.mapOptional("KeepEmptyLinesAtTheStartOfBlocks",
Style.KeepEmptyLinesAtTheStartOfBlocks);
IO.mapOptional("KeepEmptyLinesAtEOF", Style.KeepEmptyLinesAtEOF);
IO.mapOptional("KeepEmptyLines", Style.KeepEmptyLines);
IO.mapOptional("LambdaBodyIndentation", Style.LambdaBodyIndentation);
IO.mapOptional("LineEnding", Style.LineEnding);
IO.mapOptional("MacroBlockBegin", Style.MacroBlockBegin);
Expand Down Expand Up @@ -1517,8 +1526,11 @@ FormatStyle getLLVMStyle(FormatStyle::LanguageKind Language) {
/*Hex=*/0, /*HexMinDigits=*/0};
LLVMStyle.JavaScriptQuotes = FormatStyle::JSQS_Leave;
LLVMStyle.JavaScriptWrapImports = true;
LLVMStyle.KeepEmptyLinesAtEOF = false;
LLVMStyle.KeepEmptyLinesAtTheStartOfBlocks = true;
LLVMStyle.KeepEmptyLines = {
/*AtEndOfFile=*/false,
/*AtStartOfBlock=*/true,
/*AtStartOfFile=*/true,
};
LLVMStyle.LambdaBodyIndentation = FormatStyle::LBI_Signature;
LLVMStyle.Language = Language;
LLVMStyle.LineEnding = FormatStyle::LE_DeriveLF;
Expand Down Expand Up @@ -1641,7 +1653,7 @@ FormatStyle getGoogleStyle(FormatStyle::LanguageKind Language) {
{".*", 3, 0, false}};
GoogleStyle.IncludeStyle.IncludeIsMainRegex = "([-_](test|unittest))?$";
GoogleStyle.IndentCaseLabels = true;
GoogleStyle.KeepEmptyLinesAtTheStartOfBlocks = false;
GoogleStyle.KeepEmptyLines.AtStartOfBlock = false;
GoogleStyle.ObjCBinPackProtocolList = FormatStyle::BPS_Never;
GoogleStyle.ObjCSpaceAfterProperty = false;
GoogleStyle.ObjCSpaceBeforeProtocolList = true;
Expand Down
12 changes: 7 additions & 5 deletions clang/lib/Format/UnwrappedLineFormatter.cpp
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Expand Up @@ -1478,11 +1478,13 @@ static auto computeNewlines(const AnnotatedLine &Line,
Newlines = std::min(Newlines, 1u);
if (Newlines == 0 && !RootToken.IsFirst)
Newlines = 1;
if (RootToken.IsFirst && !RootToken.HasUnescapedNewline)
if (RootToken.IsFirst &&
(!Style.KeepEmptyLines.AtStartOfFile || !RootToken.HasUnescapedNewline)) {
Newlines = 0;
}

// Remove empty lines after "{".
if (!Style.KeepEmptyLinesAtTheStartOfBlocks && PreviousLine &&
if (!Style.KeepEmptyLines.AtStartOfBlock && PreviousLine &&
PreviousLine->Last->is(tok::l_brace) &&
!PreviousLine->startsWithNamespace() &&
!(PrevPrevLine && PrevPrevLine->startsWithNamespace() &&
Expand Down Expand Up @@ -1554,9 +1556,9 @@ void UnwrappedLineFormatter::formatFirstToken(
unsigned NewlineIndent) {
FormatToken &RootToken = *Line.First;
if (RootToken.is(tok::eof)) {
unsigned Newlines =
std::min(RootToken.NewlinesBefore,
Style.KeepEmptyLinesAtEOF ? Style.MaxEmptyLinesToKeep + 1 : 1);
unsigned Newlines = std::min(
RootToken.NewlinesBefore,
Style.KeepEmptyLines.AtEndOfFile ? Style.MaxEmptyLinesToKeep + 1 : 1);
unsigned TokenIndent = Newlines ? NewlineIndent : 0;
Whitespaces->replaceWhitespace(RootToken, Newlines, TokenIndent,
TokenIndent);
Expand Down
8 changes: 6 additions & 2 deletions clang/unittests/Format/ConfigParseTest.cpp
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Expand Up @@ -178,8 +178,9 @@ TEST(ConfigParseTest, ParsesConfigurationBools) {
CHECK_PARSE_BOOL(IndentWrappedFunctionNames);
CHECK_PARSE_BOOL(InsertBraces);
CHECK_PARSE_BOOL(InsertNewlineAtEOF);
CHECK_PARSE_BOOL(KeepEmptyLinesAtEOF);
CHECK_PARSE_BOOL(KeepEmptyLinesAtTheStartOfBlocks);
CHECK_PARSE_BOOL_FIELD(KeepEmptyLines.AtEndOfFile, "KeepEmptyLinesAtEOF");
CHECK_PARSE_BOOL_FIELD(KeepEmptyLines.AtStartOfBlock,
"KeepEmptyLinesAtTheStartOfBlocks");
CHECK_PARSE_BOOL(ObjCSpaceAfterProperty);
CHECK_PARSE_BOOL(ObjCSpaceBeforeProtocolList);
CHECK_PARSE_BOOL(Cpp11BracedListStyle);
Expand Down Expand Up @@ -226,6 +227,9 @@ TEST(ConfigParseTest, ParsesConfigurationBools) {
CHECK_PARSE_NESTED_BOOL(BraceWrapping, SplitEmptyFunction);
CHECK_PARSE_NESTED_BOOL(BraceWrapping, SplitEmptyRecord);
CHECK_PARSE_NESTED_BOOL(BraceWrapping, SplitEmptyNamespace);
CHECK_PARSE_NESTED_BOOL(KeepEmptyLines, AtEndOfFile);
CHECK_PARSE_NESTED_BOOL(KeepEmptyLines, AtStartOfBlock);
CHECK_PARSE_NESTED_BOOL(KeepEmptyLines, AtStartOfFile);
CHECK_PARSE_NESTED_BOOL(SpaceBeforeParensOptions, AfterControlStatements);
CHECK_PARSE_NESTED_BOOL(SpaceBeforeParensOptions, AfterForeachMacros);
CHECK_PARSE_NESTED_BOOL(SpaceBeforeParensOptions,
Expand Down
15 changes: 12 additions & 3 deletions clang/unittests/Format/FormatTest.cpp
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Expand Up @@ -45,6 +45,10 @@ TEST_F(FormatTest, FormatsGlobalStatementsAt0) {
verifyFormat("\nint i;", " \n\t \v \f int i;");
verifyFormat("int i;\nint j;", " int i; int j;");
verifyFormat("int i;\nint j;", " int i;\n int j;");

auto Style = getLLVMStyle();
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An empty line before auto Style = ...?

Style.KeepEmptyLines.AtStartOfFile = false;
verifyFormat("int i;", " \n\t \v \f int i;", Style);
}

TEST_F(FormatTest, FormatsUnwrappedLinesAtFirstFormat) {
Expand Down Expand Up @@ -163,7 +167,7 @@ TEST_F(FormatTest, RemovesEmptyLines) {
auto CustomStyle = getLLVMStyle();
CustomStyle.BreakBeforeBraces = FormatStyle::BS_Custom;
CustomStyle.BraceWrapping.AfterNamespace = true;
CustomStyle.KeepEmptyLinesAtTheStartOfBlocks = false;
CustomStyle.KeepEmptyLines.AtStartOfBlock = false;
verifyFormat("namespace N\n"
"{\n"
"\n"
Expand Down Expand Up @@ -389,7 +393,7 @@ TEST_F(FormatTest, RemovesEmptyLines) {
Style.BreakBeforeBraces = FormatStyle::BS_Custom;
Style.BraceWrapping.AfterClass = true;
Style.BraceWrapping.AfterFunction = true;
Style.KeepEmptyLinesAtTheStartOfBlocks = false;
Style.KeepEmptyLines.AtStartOfBlock = false;

verifyFormat("class Foo\n"
"{\n"
Expand Down Expand Up @@ -21956,6 +21960,11 @@ TEST_F(FormatTest, HandlesUTF8BOM) {
verifyFormat("\xef\xbb\xbf");
verifyFormat("\xef\xbb\xbf#include <iostream>");
verifyFormat("\xef\xbb\xbf\n#include <iostream>");

auto Style = getLLVMStyle();
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Ditto.

Style.KeepEmptyLines.AtStartOfFile = false;
verifyFormat("\xef\xbb\xbf#include <iostream>",
"\xef\xbb\xbf\n#include <iostream>", Style);
}

// FIXME: Encode Cyrillic and CJK characters below to appease MS compilers.
Expand Down Expand Up @@ -27230,7 +27239,7 @@ TEST_F(FormatTest, InsertNewlineAtEOF) {

TEST_F(FormatTest, KeepEmptyLinesAtEOF) {
FormatStyle Style = getLLVMStyle();
Style.KeepEmptyLinesAtEOF = true;
Style.KeepEmptyLines.AtEndOfFile = true;

const StringRef Code{"int i;\n\n"};
verifyNoChange(Code, Style);
Expand Down
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