MyDeveloperDay created this revision.
MyDeveloperDay added reviewers: HazardyKnusperkeks, owenpan, curdeius.
MyDeveloperDay added a project: clang-format.
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MyDeveloperDay requested review of this revision.
Herald added a project: clang.
As highlighted by https://github.com/llvm/llvm-project/issues/57609
Give more control when using the AllowShortCaseLabelsOnASingleLine to not put
fallthrough code onto the same line
switch (i) {
case 0: g(); [[fallthrough]];
case 1: f(); break;
}
whether that fallthrough is marked with the attribute or implicit
switch (i) {
case 0:
case 1: return i;
case 2:
case 3: i *= 2; break;
}
in these cases don't make them short
switch (i) {
case 0:
g();
[[fallthrough]];
case 1:
f();
break;
}
switch (i) {
case 0:
case 1:
return i;
case 2:
case 3:
i *= 2;
break;
}
Fixes: 57609
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D133571
Files:
clang/docs/ClangFormatStyleOptions.rst
clang/include/clang/Format/Format.h
clang/lib/Format/Format.cpp
clang/lib/Format/UnwrappedLineFormatter.cpp
clang/unittests/Format/FormatTest.cpp
Index: clang/unittests/Format/FormatTest.cpp
===================================================================
--- clang/unittests/Format/FormatTest.cpp
+++ clang/unittests/Format/FormatTest.cpp
@@ -2882,7 +2882,7 @@
TEST_F(FormatTest, ShortCaseLabels) {
FormatStyle Style = getLLVMStyle();
- Style.AllowShortCaseLabelsOnASingleLine = true;
+ Style.AllowShortCaseLabelsOnASingleLine = FormatStyle::SCLS_Always;
verifyFormat("switch (a) {\n"
"case 1: x = 1; break;\n"
"case 2: return;\n"
@@ -3011,7 +3011,7 @@
"}",
Style);
Style.ColumnLimit = 80;
- Style.AllowShortCaseLabelsOnASingleLine = false;
+ Style.AllowShortCaseLabelsOnASingleLine = FormatStyle::SCLS_Never;
Style.IndentCaseLabels = true;
EXPECT_EQ("switch (n) {\n"
" default /*comments*/:\n"
@@ -3026,7 +3026,7 @@
" return false;\n"
"}",
Style));
- Style.AllowShortCaseLabelsOnASingleLine = true;
+ Style.AllowShortCaseLabelsOnASingleLine = FormatStyle::SCLS_Always;
Style.BreakBeforeBraces = FormatStyle::BS_Custom;
Style.BraceWrapping.AfterCaseLabel = true;
Style.BraceWrapping.AfterControlStatement = FormatStyle::BWACS_Always;
@@ -3051,6 +3051,55 @@
" }\n"
"}",
Style));
+
+ Style.AllowShortCaseLabelsOnASingleLine = FormatStyle::SCLS_NoFallThrough;
+ /*
+ verifyFormat("switch (a)\n"
+ "{\n"
+ "case 1: x = 1; break;\n"
+ "case 2: return;\n"
+ "case 3:\n"
+ "case 4:\n"
+ "case 5: return;\n"
+ "case 6: // comment\n"
+ " return;\n"
+ "case 7:\n"
+ " // comment\n"
+ " return;\n"
+ "case 8:\n"
+ " x = 8; // comment\n"
+ " break;\n"
+ "default: y = 1; break;\n"
+ "}",
+ Style);
+ */
+ verifyFormat("switch (a)\n"
+ "{\n"
+ " case 0:\n"
+ " case 1:\n"
+ " x = 1;\n"
+ " break;\n"
+ " case 2: x = 2; break;\n"
+ " case 3:\n"
+ " x = 3;\n"
+ " [[fallthrough]];\n"
+ " case 4:\n"
+ " x = 4;\n"
+ " break;\n"
+ " default: y = 1; break;\n"
+ "}",
+ Style);
+ Style.AllowShortCaseLabelsOnASingleLine = FormatStyle::SCLS_Always;
+ verifyFormat("switch (a)\n"
+ "{\n"
+ " case 0:\n"
+ " case 1: x = 1; break;\n"
+ " case 2: x = 2; break;\n"
+ " case 3: x = 3; [[fallthrough]];\n"
+ " case 4: x = 4; break;\n"
+ " default: y = 1; break;\n"
+ "}",
+ Style);
}
TEST_F(FormatTest, FormatsLabels) {
@@ -20148,7 +20197,6 @@
CHECK_PARSE_BOOL(AlignTrailingComments);
CHECK_PARSE_BOOL(AllowAllArgumentsOnNextLine);
CHECK_PARSE_BOOL(AllowAllParametersOfDeclarationOnNextLine);
- CHECK_PARSE_BOOL(AllowShortCaseLabelsOnASingleLine);
CHECK_PARSE_BOOL(AllowShortEnumsOnASingleLine);
CHECK_PARSE_BOOL(AllowShortLoopsOnASingleLine);
CHECK_PARSE_BOOL(BinPackArguments);
@@ -20509,6 +20557,20 @@
CHECK_PARSE("AllowShortFunctionsOnASingleLine: true",
AllowShortFunctionsOnASingleLine, FormatStyle::SFS_All);
+ Style.AllowShortCaseLabelsOnASingleLine = FormatStyle::SCLS_Always;
+ CHECK_PARSE("AllowShortCaseLabelsOnASingleLine: Never",
+ AllowShortCaseLabelsOnASingleLine, FormatStyle::SCLS_Never);
+ CHECK_PARSE("AllowShortCaseLabelsOnASingleLine: Always",
+ AllowShortCaseLabelsOnASingleLine, FormatStyle::SCLS_Always);
+ CHECK_PARSE("AllowShortCaseLabelsOnASingleLine: NoFallThrough",
+ AllowShortCaseLabelsOnASingleLine,
+ FormatStyle::SCLS_NoFallThrough);
+ // For backward compatibility:
+ CHECK_PARSE("AllowShortCaseLabelsOnASingleLine: false",
+ AllowShortCaseLabelsOnASingleLine, FormatStyle::SCLS_Never);
+ CHECK_PARSE("AllowShortCaseLabelsOnASingleLine: true",
+ AllowShortCaseLabelsOnASingleLine, FormatStyle::SCLS_Always);
+
Style.SpaceAroundPointerQualifiers = FormatStyle::SAPQ_Both;
CHECK_PARSE("SpaceAroundPointerQualifiers: Default",
SpaceAroundPointerQualifiers, FormatStyle::SAPQ_Default);
Index: clang/lib/Format/UnwrappedLineFormatter.cpp
===================================================================
--- clang/lib/Format/UnwrappedLineFormatter.cpp
+++ clang/lib/Format/UnwrappedLineFormatter.cpp
@@ -564,7 +564,7 @@
}
if (TheLine->First->isOneOf(tok::kw_case, tok::kw_default)) {
return Style.AllowShortCaseLabelsOnASingleLine
- ? tryMergeShortCaseLabels(I, E, Limit)
+ ? tryMergeShortCaseLabels(I, E, Limit, PreviousLine, Style)
: 0;
}
if (TheLine->InPPDirective &&
@@ -632,13 +632,29 @@
unsigned
tryMergeShortCaseLabels(SmallVectorImpl<AnnotatedLine *>::const_iterator I,
SmallVectorImpl<AnnotatedLine *>::const_iterator E,
- unsigned Limit) {
+ unsigned Limit, const AnnotatedLine *PreviousLine,
+ const FormatStyle &Style) {
if (Limit == 0 || I + 1 == E ||
I[1]->First->isOneOf(tok::kw_case, tok::kw_default)) {
return 0;
}
if (I[0]->Last->is(tok::l_brace) || I[1]->First->is(tok::l_brace))
return 0;
+ bool NoFallThrough = Style.AllowShortCaseLabelsOnASingleLine ==
+ FormatStyle::SCLS_NoFallThrough;
+ // If the last thing on the line before was just case X: then don't merge.
+ if (NoFallThrough && PreviousLine && PreviousLine->Last &&
+ PreviousLine->Last->is(tok::colon))
+ return 0;
+ // Check if the last thing on the line before was an attribute and if so
+ // don't merge.
+ if (NoFallThrough && PreviousLine && PreviousLine->Last &&
+ PreviousLine->Last->Previous && PreviousLine->Last->Previous) {
+ auto *PrevPrev = PreviousLine->Last->Previous->Previous;
+ if (PrevPrev && PrevPrev->startsSequence(TT_AttributeSquare,
+ TT_AttributeSquare, tok::semi))
+ return 0;
+ }
unsigned NumStmts = 0;
unsigned Length = 0;
bool EndsWithComment = false;
@@ -652,6 +668,10 @@
break;
if (Line->First->isOneOf(tok::kw_case, tok::kw_default, tok::r_brace))
break;
+ // When the contents of the case contains an [[attribute]] don't merge it
+ // could be a fallthough.
+ if (NoFallThrough && Line->First->is(TT_AttributeSquare))
+ return 0;
if (Line->First->isOneOf(tok::kw_if, tok::kw_for, tok::kw_switch,
tok::kw_while) ||
EndsWithComment) {
Index: clang/lib/Format/Format.cpp
===================================================================
--- clang/lib/Format/Format.cpp
+++ clang/lib/Format/Format.cpp
@@ -591,6 +591,18 @@
}
};
+template <> struct ScalarEnumerationTraits<FormatStyle::ShortCaseLabelStyle> {
+ static void enumeration(IO &IO, FormatStyle::ShortCaseLabelStyle &Value) {
+ IO.enumCase(Value, "Never", FormatStyle::SCLS_Never);
+ IO.enumCase(Value, "Always", FormatStyle::SCLS_Always);
+ IO.enumCase(Value, "NoFallThrough", FormatStyle::SCLS_NoFallThrough);
+
+ // For backward compatibility.
+ IO.enumCase(Value, "false", FormatStyle::SCLS_Never);
+ IO.enumCase(Value, "true", FormatStyle::SCLS_Always);
+ }
+};
+
template <> struct MappingTraits<FormatStyle> {
static void mapping(IO &IO, FormatStyle &Style) {
// When reading, read the language first, we need it for getPredefinedStyle.
@@ -1196,7 +1208,7 @@
LLVMStyle.AllowShortEnumsOnASingleLine = true;
LLVMStyle.AllowShortFunctionsOnASingleLine = FormatStyle::SFS_All;
LLVMStyle.AllowShortBlocksOnASingleLine = FormatStyle::SBS_Never;
- LLVMStyle.AllowShortCaseLabelsOnASingleLine = false;
+ LLVMStyle.AllowShortCaseLabelsOnASingleLine = FormatStyle::SCLS_Never;
LLVMStyle.AllowShortIfStatementsOnASingleLine = FormatStyle::SIS_Never;
LLVMStyle.AllowShortLambdasOnASingleLine = FormatStyle::SLS_All;
LLVMStyle.AllowShortLoopsOnASingleLine = false;
@@ -1650,7 +1662,7 @@
Style.PenaltyReturnTypeOnItsOwnLine = 1000;
Style.AllowShortEnumsOnASingleLine = false;
Style.AllowShortFunctionsOnASingleLine = FormatStyle::SFS_None;
- Style.AllowShortCaseLabelsOnASingleLine = false;
+ Style.AllowShortCaseLabelsOnASingleLine = FormatStyle::SCLS_Never;
Style.AllowShortIfStatementsOnASingleLine = FormatStyle::SIS_Never;
Style.AllowShortLoopsOnASingleLine = false;
Style.AlwaysBreakAfterDefinitionReturnType = FormatStyle::DRTBS_None;
Index: clang/include/clang/Format/Format.h
===================================================================
--- clang/include/clang/Format/Format.h
+++ clang/include/clang/Format/Format.h
@@ -465,19 +465,40 @@
/// \version 3.5
ShortBlockStyle AllowShortBlocksOnASingleLine;
- /// If ``true``, short case labels will be contracted to a single line.
- /// \code
- /// true: false:
- /// switch (a) { vs. switch (a) {
- /// case 1: x = 1; break; case 1:
- /// case 2: return; x = 1;
- /// } break;
- /// case 2:
- /// return;
- /// }
- /// \endcode
+ /// Different styles for merging short case labels.
+ enum ShortCaseLabelStyle : int8_t {
+ /// Never merge case code
+ SCLS_Never,
+ /// Always contract 'simple' small case label code but
+ /// ignore cases where fallthrough occurs
+ /// (implicit or marked fallthrough)
+ /// \code
+ /// case 0:
+ /// case 1:
+ /// x = 1;
+ /// break;
+ /// case 2: x = 2; break;
+ /// case 3: x = 3;
+ /// [[fallthrough]];
+ /// case 4:
+ /// x = 4;
+ /// break;
+ /// \endcode
+ SCLS_NoFallThrough,
+ /// Always contract short case labels to a single line.
+ /// \code
+ /// case 0:
+ /// case 1: x = 1; break;
+ /// case 2: x = 2; break;
+ /// case 3: x = 3; [[fallthrough]];
+ /// case 4: x = 4; break;
+ /// \endcode
+ SCLS_Always
+ };
+
+ /// Determine if Short case labels will be contracted to a single line.
/// \version 3.6
- bool AllowShortCaseLabelsOnASingleLine;
+ ShortCaseLabelStyle AllowShortCaseLabelsOnASingleLine;
/// Different styles for merging short functions containing at most one
/// statement.
Index: clang/docs/ClangFormatStyleOptions.rst
===================================================================
--- clang/docs/ClangFormatStyleOptions.rst
+++ clang/docs/ClangFormatStyleOptions.rst
@@ -931,19 +931,44 @@
-**AllowShortCaseLabelsOnASingleLine** (``Boolean``) :versionbadge:`clang-format 3.6`
- If ``true``, short case labels will be contracted to a single line.
+**AllowShortCaseLabelsOnASingleLine** (``ShortCaseLabelStyle``) :versionbadge:`clang-format 3.6`
+ Determine if Short case labels will be contracted to a single line.
+
+ Possible values:
+
+ * ``SCLS_Never`` (in configuration: ``Never``)
+ Never merge case code
+
+ * ``SCLS_NoFallThrough`` (in configuration: ``NoFallThrough``)
+ Always contract 'simple' small case label code but
+ ignore cases where fallthrough occurs
+ (implicit or marked fallthrough)
+
+ .. code-block:: c++
+
+ case 0:
+ case 1:
+ x = 1;
+ break;
+ case 2: x = 2; break;
+ case 3: x = 3;
+ [[fallthrough]];
+ case 4:
+ x = 4;
+ break;
+
+ * ``SCLS_Always`` (in configuration: ``Always``)
+ Always contract short case labels to a single line.
+
+ .. code-block:: c++
+
+ case 0:
+ case 1: x = 1; break;
+ case 2: x = 2; break;
+ case 3: x = 3; [[fallthrough]];
+ case 4: x = 4; break;
- .. code-block:: c++
- true: false:
- switch (a) { vs. switch (a) {
- case 1: x = 1; break; case 1:
- case 2: return; x = 1;
- } break;
- case 2:
- return;
- }
**AllowShortEnumsOnASingleLine** (``Boolean``) :versionbadge:`clang-format 11`
Allow short enums on a single line.
@@ -3567,7 +3592,7 @@
.. code-block:: yaml
- QualifierOrder: ['inline', 'static', 'type', 'const']
+ QualifierOrder: ['inline', 'static' , 'type', 'const']
.. code-block:: c++
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