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sam-mccallsam-mccall
committedOct 2, 2019
[ClangFormat] Future-proof Standard option, allow floating or pinning to arbitrary lang version
Summary: The historical context: - clang-format was written when C++11 was current, and the main language-version concern was >> vs > > template-closers. An option was added to allow selection of the 03/11 behavior, or auto-detection. - there was no option to choose simply "latest standard" so anyone who didn't ever want 03 behavior or auto-detection specified Cpp11. - In r185149 this option started to affect lexer mode. - no options were added to cover c++14, as parsing/formatting didn't change that much. The usage of Cpp11 to mean "latest" became codified e.g. in r206263 - c++17 added some new constructs. These were mostly backwards-compatible and so not used in old programs, so having no way to turn them off was OK. - c++20 added some new constructs and keywords (e.g. co_*) that changed the meaning of existing programs, and people started to complain that the c++20 parsing couldn't be turned off. New plan: - Default ('Auto') behavior remains unchanged: parse as latest, format template-closers based on input. - Add new 'Latest' option that more clearly expresses the intent "use modern features" that many projects have chosen for their .clang-format files. - Allow pinning to *any* language version, using the same name as clang -std: c++03, c++11, c++14 etc. These set precise lexer options, and any clang-format code depending on these can use a >= check. - For backwards compatibility, `Cpp11` is an alias for `Latest`, not `c++11`. This matches the historical documented semantics of this option. This spelling (and `Cpp03`) are deprecated. Reviewers: klimek, modocache Subscribers: cfe-commits Tags: #clang Differential Revision: https://reviews.llvm.org/D67541 llvm-svn: 373439
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‎clang/docs/ClangFormatStyleOptions.rst

+22-6
Original file line numberDiff line numberDiff line change
@@ -2288,22 +2288,38 @@ the configuration (without a prefix: ``Auto``).
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std::unique_ptr<int[]> foo() {} // Won't be affected
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**Standard** (``LanguageStandard``)
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Format compatible with this standard, e.g. use ``A<A<int> >``
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instead of ``A<A<int>>`` for ``LS_Cpp03``.
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.. code-block:: c++
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c++03: latest:
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vector<set<int> > x; vs. vector<set<int>> x;
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Parse and format C++ constructs compatible with this standard.
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Possible values:
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* ``LS_Cpp03`` (in configuration: ``Cpp03``)
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* ``LS_Cpp03`` (in configuration: ``c++03``)
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Use C++03-compatible syntax.
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2299-
* ``LS_Cpp11`` (in configuration: ``Cpp11``)
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Use features of C++11, C++14 and C++1z (e.g. ``A<A<int>>`` instead of
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``A<A<int> >``).
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* ``LS_Cpp11`` (in configuration: ``c++11``)
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Use C++11-compatible syntax.
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* ``LS_Cpp14`` (in configuration: ``c++14``)
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Use C++14-compatible syntax.
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* ``LS_Cpp17`` (in configuration: ``c++17``)
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Use C++17-compatible syntax.
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* ``LS_Cpp20`` (in configuration: ``c++20``)
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Use C++20-compatible syntax.
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* ``LS_Latest`` (in configuration: ``Latest``)
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Parse and format using the latest supported language version.
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* ``LS_Auto`` (in configuration: ``Auto``)
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Automatic detection based on the input.
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* ``Cpp03``: deprecated alias for ``c++03``
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2322+
* ``Cpp11``: deprecated alias for ``Latest``
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**StatementMacros** (``std::vector<std::string>``)
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A vector of macros that should be interpreted as complete

‎clang/include/clang/Format/Format.h

+23-6
Original file line numberDiff line numberDiff line change
@@ -1945,15 +1945,32 @@ struct FormatStyle {
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/// \endcode
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bool SpacesInSquareBrackets;
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/// Supported language standards.
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/// Supported language standards for parsing and formatting C++ constructs.
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/// \code
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/// Latest: vector<set<int>>
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/// c++03 vs. vector<set<int> >
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/// \endcode
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///
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/// The correct way to spell a specific language version is e.g. ``c++11``.
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/// The historical aliases ``Cpp03`` and ``Cpp11`` are deprecated.
19491956
enum LanguageStandard {
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/// Use C++03-compatible syntax.
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/// c++03: Parse and format as C++03.
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LS_Cpp03,
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/// Use features of C++11, C++14 and C++1z (e.g. ``A<A<int>>`` instead of
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/// ``A<A<int> >``).
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/// c++11: Parse and format as C++11.
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LS_Cpp11,
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/// Automatic detection based on the input.
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LS_Auto
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/// c++14: Parse and format as C++14.
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LS_Cpp14,
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/// c++17: Parse and format as C++17.
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LS_Cpp17,
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/// c++20: Parse and format as C++20.
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LS_Cpp20,
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/// Latest: Parse and format using the latest supported language version.
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/// 'Cpp11' is an alias for LS_Latest for historical reasons.
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LS_Latest,
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/// Auto: Automatic detection based on the input.
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/// Parse using the latest language version. Format based on detected input.
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LS_Auto,
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};
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/// Format compatible with this standard, e.g. use ``A<A<int> >``

‎clang/lib/Format/Format.cpp

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Original file line numberDiff line numberDiff line change
@@ -67,10 +67,19 @@ template <> struct ScalarEnumerationTraits<FormatStyle::LanguageKind> {
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template <> struct ScalarEnumerationTraits<FormatStyle::LanguageStandard> {
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static void enumeration(IO &IO, FormatStyle::LanguageStandard &Value) {
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IO.enumCase(Value, "Cpp03", FormatStyle::LS_Cpp03);
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IO.enumCase(Value, "C++03", FormatStyle::LS_Cpp03);
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IO.enumCase(Value, "Cpp11", FormatStyle::LS_Cpp11);
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IO.enumCase(Value, "C++11", FormatStyle::LS_Cpp11);
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IO.enumCase(Value, "c++03", FormatStyle::LS_Cpp03);
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IO.enumCase(Value, "C++03", FormatStyle::LS_Cpp03); // Legacy alias
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IO.enumCase(Value, "Cpp03", FormatStyle::LS_Cpp03); // Legacy alias
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IO.enumCase(Value, "c++11", FormatStyle::LS_Cpp11);
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IO.enumCase(Value, "C++11", FormatStyle::LS_Cpp11); // Legacy alias
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IO.enumCase(Value, "c++14", FormatStyle::LS_Cpp14);
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IO.enumCase(Value, "c++17", FormatStyle::LS_Cpp17);
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IO.enumCase(Value, "c++20", FormatStyle::LS_Cpp20);
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IO.enumCase(Value, "Latest", FormatStyle::LS_Latest);
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IO.enumCase(Value, "Cpp11", FormatStyle::LS_Latest); // Legacy alias
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IO.enumCase(Value, "Auto", FormatStyle::LS_Auto);
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}
7685
};
@@ -756,7 +765,7 @@ FormatStyle getLLVMStyle(FormatStyle::LanguageKind Language) {
756765
LLVMStyle.ObjCSpaceBeforeProtocolList = true;
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LLVMStyle.PointerAlignment = FormatStyle::PAS_Right;
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LLVMStyle.SpacesBeforeTrailingComments = 1;
759-
LLVMStyle.Standard = FormatStyle::LS_Cpp11;
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LLVMStyle.Standard = FormatStyle::LS_Latest;
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LLVMStyle.UseTab = FormatStyle::UT_Never;
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LLVMStyle.ReflowComments = true;
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LLVMStyle.SpacesInParentheses = false;
@@ -1399,7 +1408,7 @@ class Formatter : public TokenAnalyzer {
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: FormatStyle::PAS_Right;
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if (Style.Standard == FormatStyle::LS_Auto)
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Style.Standard = hasCpp03IncompatibleFormat(AnnotatedLines)
1402-
? FormatStyle::LS_Cpp11
1411+
? FormatStyle::LS_Latest
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: FormatStyle::LS_Cpp03;
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BinPackInconclusiveFunctions =
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HasBinPackedFunction || !HasOnePerLineFunction;
@@ -2455,14 +2464,18 @@ tooling::Replacements sortUsingDeclarations(const FormatStyle &Style,
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LangOptions getFormattingLangOpts(const FormatStyle &Style) {
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LangOptions LangOpts;
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FormatStyle::LanguageStandard LexingStd =
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Style.Standard == FormatStyle::LS_Auto ? FormatStyle::LS_Cpp11
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: Style.Standard;
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2468+
FormatStyle::LanguageStandard LexingStd = Style.Standard;
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if (LexingStd == FormatStyle::LS_Auto)
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LexingStd = FormatStyle::LS_Latest;
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if (LexingStd == FormatStyle::LS_Latest)
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LexingStd = FormatStyle::LS_Cpp20;
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LangOpts.CPlusPlus = 1;
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LangOpts.CPlusPlus11 = LexingStd >= FormatStyle::LS_Cpp11;
2463-
LangOpts.CPlusPlus14 = LexingStd >= FormatStyle::LS_Cpp11;
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LangOpts.CPlusPlus17 = LexingStd >= FormatStyle::LS_Cpp11;
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LangOpts.CPlusPlus2a = LexingStd >= FormatStyle::LS_Cpp11;
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LangOpts.CPlusPlus14 = LexingStd >= FormatStyle::LS_Cpp14;
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LangOpts.CPlusPlus17 = LexingStd >= FormatStyle::LS_Cpp17;
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LangOpts.CPlusPlus2a = LexingStd >= FormatStyle::LS_Cpp20;
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24662479
LangOpts.LineComment = 1;
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bool AlternativeOperators = Style.isCpp();
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LangOpts.CXXOperatorNames = AlternativeOperators ? 1 : 0;

‎clang/unittests/Format/FormatTest.cpp

+22-2
Original file line numberDiff line numberDiff line change
@@ -9388,6 +9388,19 @@ TEST_F(FormatTest, DoesNotTryToParseUDLiteralsInPreCpp11Code) {
93889388
format("#define x(_a) printf(\"foo\"_a);", Style));
93899389
}
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9391+
TEST_F(FormatTest, CppLexVersion) {
9392+
FormatStyle Style = getLLVMStyle();
9393+
// Formatting of x * y differs if x is a type.
9394+
verifyFormat("void foo() { MACRO(a * b); }", Style);
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verifyFormat("void foo() { MACRO(int *b); }", Style);
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// LLVM style uses latest lexer.
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verifyFormat("void foo() { MACRO(char8_t *b); }", Style);
9399+
Style.Standard = FormatStyle::LS_Cpp17;
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// But in c++17, char8_t isn't a keyword.
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verifyFormat("void foo() { MACRO(char8_t * b); }", Style);
9402+
}
9403+
93919404
TEST_F(FormatTest, UnderstandsCpp1y) { verifyFormat("int bi{1'000'000};"); }
93929405

93939406
TEST_F(FormatTest, BreakStringLiteralsBeforeUnbreakableTokenSequence) {
@@ -12305,11 +12318,18 @@ TEST_F(FormatTest, ParsesConfiguration) {
1230512318
FormatStyle::PAS_Middle);
1230612319

1230712320
Style.Standard = FormatStyle::LS_Auto;
12321+
CHECK_PARSE("Standard: c++03", Standard, FormatStyle::LS_Cpp03);
12322+
CHECK_PARSE("Standard: c++11", Standard, FormatStyle::LS_Cpp11);
12323+
CHECK_PARSE("Standard: c++14", Standard, FormatStyle::LS_Cpp14);
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CHECK_PARSE("Standard: c++17", Standard, FormatStyle::LS_Cpp17);
12325+
CHECK_PARSE("Standard: c++20", Standard, FormatStyle::LS_Cpp20);
12326+
CHECK_PARSE("Standard: Auto", Standard, FormatStyle::LS_Auto);
12327+
CHECK_PARSE("Standard: Latest", Standard, FormatStyle::LS_Latest);
12328+
// Legacy aliases:
1230812329
CHECK_PARSE("Standard: Cpp03", Standard, FormatStyle::LS_Cpp03);
12309-
CHECK_PARSE("Standard: Cpp11", Standard, FormatStyle::LS_Cpp11);
12330+
CHECK_PARSE("Standard: Cpp11", Standard, FormatStyle::LS_Latest);
1231012331
CHECK_PARSE("Standard: C++03", Standard, FormatStyle::LS_Cpp03);
1231112332
CHECK_PARSE("Standard: C++11", Standard, FormatStyle::LS_Cpp11);
12312-
CHECK_PARSE("Standard: Auto", Standard, FormatStyle::LS_Auto);
1231312333

1231412334
Style.BreakBeforeBinaryOperators = FormatStyle::BOS_All;
1231512335
CHECK_PARSE("BreakBeforeBinaryOperators: NonAssignment",

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