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AaronBallmanAaronBallman
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[C23] Do not diagnose binary literals as an extension (#81658)
We previously would diagnose them as a GNU extension in C mode, but they are now a feature of C23. The -Wgnu-binary-literal warning group no longer controls any diagnostics as this is no longer a GNU extension. The warning group is retained as a noop to help avoid "unknown warning" diagnostics. This also adds the companion compatibility warning which existed for C++ but not for C. Fixes #72017
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‎clang/docs/ReleaseNotes.rst

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@@ -56,6 +56,12 @@ Clang Frontend Potentially Breaking Changes
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``ArrayRef<TemplateArgument>`` reduces AST memory usage by 0.4% when compiling clang, and is
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expected to show similar improvements on other workloads.
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- The ``-Wgnu-binary-literal`` diagnostic group no longer controls any
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diagnostics. Binary literals are no longer a GNU extension, they're now a C23
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extension which is controlled via ``-pedantic`` or ``-Wc23-extensions``. Use
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of ``-Wno-gnu-binary-literal`` will no longer silence this pedantic warning,
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which may break existing uses with ``-Werror``.
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Target OS macros extension
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^^^^^^^^^^^^^^^^^^^^^^^^^^
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A new Clang extension (see :ref:`here <target_os_detail>`) is enabled for
@@ -113,6 +119,8 @@ C Language Changes
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C23 Feature Support
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^^^^^^^^^^^^^^^^^^^
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- No longer diagnose use of binary literals as an extension in C23 mode. Fixes
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`#72017 <https://github.com/llvm/llvm-project/issues/72017>`_.
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Non-comprehensive list of changes in this release
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-------------------------------------------------

‎clang/include/clang/Basic/DiagnosticGroups.td

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@@ -44,10 +44,8 @@ def DeprecatedModuleDotMap : DiagGroup<"deprecated-module-dot-map">;
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def FrameworkHdrAtImport : DiagGroup<"atimport-in-framework-header">;
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def CXX14BinaryLiteral : DiagGroup<"c++14-binary-literal">;
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def CXXPre14CompatBinaryLiteral : DiagGroup<"c++98-c++11-compat-binary-literal">;
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def GNUBinaryLiteral : DiagGroup<"gnu-binary-literal">;
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def BinaryLiteral : DiagGroup<"binary-literal", [CXX14BinaryLiteral,
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CXXPre14CompatBinaryLiteral,
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GNUBinaryLiteral]>;
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CXXPre14CompatBinaryLiteral]>;
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def GNUCompoundLiteralInitializer : DiagGroup<"gnu-compound-literal-initializer">;
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def SingleBitBitFieldConstantConversion :
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DiagGroup<"single-bit-bitfield-constant-conversion">;
@@ -1176,10 +1174,13 @@ def C23 : DiagGroup<"c23-extensions">;
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def : DiagGroup<"c2x-extensions", [C23]>;
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// Previously supported warning group which is no longer pertinent as binary
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// literals are a C++14 and C23 extension now instead of a GNU extension.
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def GNUBinaryLiteral : DiagGroup<"gnu-binary-literal">;
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// A warning group for warnings about GCC extensions.
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def GNU : DiagGroup<"gnu", [GNUAlignofExpression, GNUAnonymousStruct,
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GNUAutoType,
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GNUBinaryLiteral, GNUCaseRange,
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GNUAutoType, GNUBinaryLiteral, GNUCaseRange,
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GNUComplexInteger, GNUCompoundLiteralInitializer,
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GNUConditionalOmittedOperand, GNUDesignator,
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GNUEmptyStruct,

‎clang/include/clang/Basic/DiagnosticLexKinds.td

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@@ -246,7 +246,10 @@ def warn_cxx17_hex_literal : Warning<
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"C++ standards before C++17">,
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InGroup<CXXPre17CompatPedantic>, DefaultIgnore;
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def ext_binary_literal : Extension<
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"binary integer literals are a GNU extension">, InGroup<GNUBinaryLiteral>;
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"binary integer literals are a C23 extension">, InGroup<C23>;
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def warn_c23_compat_binary_literal : Warning<
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"binary integer literals are incompatible with C standards before C23">,
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InGroup<CPre23Compat>, DefaultIgnore;
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def ext_binary_literal_cxx14 : Extension<
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"binary integer literals are a C++14 extension">, InGroup<CXX14BinaryLiteral>;
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def warn_cxx11_compat_binary_literal : Warning<

‎clang/lib/Lex/LiteralSupport.cpp

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@@ -1358,11 +1358,17 @@ void NumericLiteralParser::ParseNumberStartingWithZero(SourceLocation TokLoc) {
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// Handle simple binary numbers 0b01010
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if ((c1 == 'b' || c1 == 'B') && (s[1] == '0' || s[1] == '1')) {
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// 0b101010 is a C++1y / GCC extension.
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Diags.Report(TokLoc, LangOpts.CPlusPlus14
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? diag::warn_cxx11_compat_binary_literal
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: LangOpts.CPlusPlus ? diag::ext_binary_literal_cxx14
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: diag::ext_binary_literal);
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// 0b101010 is a C++14 and C23 extension.
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unsigned DiagId;
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if (LangOpts.CPlusPlus14)
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DiagId = diag::warn_cxx11_compat_binary_literal;
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else if (LangOpts.C23)
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DiagId = diag::warn_c23_compat_binary_literal;
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else if (LangOpts.CPlusPlus)
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DiagId = diag::ext_binary_literal_cxx14;
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else
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DiagId = diag::ext_binary_literal;
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Diags.Report(TokLoc, DiagId);
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++s;
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assert(s < ThisTokEnd && "didn't maximally munch?");
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radix = 2;

‎clang/test/C/C2x/n2549.c

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// RUN: %clang_cc1 -verify -std=c23 %s
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// RUN: %clang_cc1 -verify=pedantic -std=c17 -pedantic %s
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// RUN: %clang_cc1 -verify=compat -std=c23 -Wpre-c23-compat %s
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// expected-no-diagnostics
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/* WG14 N2549: Clang 9
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* Binary literals
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*/
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int i = 0b01; /* pedantic-warning {{binary integer literals are a C23 extension}}
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compat-warning {{binary integer literals are incompatible with C standards before C23}}
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*/
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‎clang/test/Lexer/gnu-flags.c

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// RUN: %clang_cc1 -fsyntax-only -verify %s -DNONE
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// RUN: %clang_cc1 -fsyntax-only -verify %s -DALL -Wgnu
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// RUN: %clang_cc1 -fsyntax-only -verify %s -DALL -Wgnu
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// RUN: %clang_cc1 -fsyntax-only -verify %s -DALL \
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// RUN: -Wgnu-zero-variadic-macro-arguments \
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// RUN: -Wgnu-imaginary-constant -Wgnu-binary-literal -Wgnu-zero-line-directive
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// RUN: -Wgnu-imaginary-constant -Wgnu-zero-line-directive
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// RUN: %clang_cc1 -fsyntax-only -verify %s -DNONE -Wgnu \
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// RUN: -Wno-gnu-zero-variadic-macro-arguments \
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// RUN: -Wno-gnu-imaginary-constant -Wno-gnu-binary-literal -Wno-gnu-zero-line-directive
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// RUN: -Wno-gnu-imaginary-constant -Wno-gnu-zero-line-directive
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// Additional disabled tests:
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// %clang_cc1 -fsyntax-only -verify %s -DZEROARGS -Wgnu-zero-variadic-macro-arguments
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// %clang_cc1 -fsyntax-only -verify %s -DIMAGINARYCONST -Wgnu-imaginary-constant
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// %clang_cc1 -fsyntax-only -verify %s -DBINARYLITERAL -Wgnu-binary-literal
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// %clang_cc1 -fsyntax-only -verify %s -DLINE0 -Wgnu-zero-line-directive
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#if NONE
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float _Complex c = 1.if;
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#if ALL || BINARYLITERAL
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// expected-warning@+3 {{binary integer literals are a GNU extension}}
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#endif
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int b = 0b0101;
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// This case is handled differently because lit has a bug whereby #line 0 is reported to be on line 4294967295
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// http://llvm.org/bugs/show_bug.cgi?id=16952
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#if ALL || LINE0

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