https://github.com/MitalAshok updated https://github.com/llvm/llvm-project/pull/78112
>From 92f8720e3d21521b589d5291f086a2f32b87bfe0 Mon Sep 17 00:00:00 2001 From: Mital Ashok <mi...@mitalashok.co.uk> Date: Sun, 14 Jan 2024 19:52:31 +0000 Subject: [PATCH] [clang] [SemaCXX] Implement CWG2627 Bit-fields and narrowing conversions --- clang/docs/ReleaseNotes.rst | 5 + .../clang/Basic/DiagnosticSemaKinds.td | 3 + clang/include/clang/Sema/Overload.h | 7 +- clang/lib/Sema/SemaExpr.cpp | 10 +- clang/lib/Sema/SemaInit.cpp | 20 ++- clang/lib/Sema/SemaOverload.cpp | 119 +++++++++------ .../dcl.decl/dcl.init/dcl.init.list/p7-0x.cpp | 24 ++++ clang/test/CXX/drs/dr26xx.cpp | 136 ++++++++++++++++++ clang/www/cxx_dr_status.html | 2 +- 9 files changed, 278 insertions(+), 48 deletions(-) diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst index 92563262cc6737..28202fc604e298 100644 --- a/clang/docs/ReleaseNotes.rst +++ b/clang/docs/ReleaseNotes.rst @@ -157,6 +157,11 @@ Resolutions to C++ Defect Reports - Clang now diagnoses declarative nested-name-specifiers with pack-index-specifiers. (`CWG2858: Declarative nested-name-specifiers and pack-index-specifiers <https://cplusplus.github.io/CWG/issues/2858.html>`_). +- Casts from a bit-field to an integral type is now not considered narrowing if the + width of the bit-field means that all potential values are in the range + of the target type, even if the type of the bit-field is larger. + (`CWG2627. Bit-fields and narrowing conversions <https://cplusplus.github.io/CWG/issues/2627.html>`_). + C Language Changes ------------------ diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td index fdca82934cb4dc..6cdb439be30ae5 100644 --- a/clang/include/clang/Basic/DiagnosticSemaKinds.td +++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td @@ -6253,6 +6253,9 @@ def ext_init_list_variable_narrowing_const_reference : ExtWarn< def ext_init_list_constant_narrowing : ExtWarn< "constant expression evaluates to %0 which cannot be narrowed to type %1">, InGroup<CXX11Narrowing>, DefaultError, SFINAEFailure; +def ext_bit_field_narrowing : Extension< + "narrowing non-constant-expression from %0 bit-field of width %2 to %1 is a C++23 extension">, + InGroup<CXX20CompatPedantic>, SFINAEFailure; def ext_init_list_constant_narrowing_const_reference : ExtWarn< ext_init_list_constant_narrowing.Summary>, InGroup<CXX11NarrowingConstReference>, DefaultError, SFINAEFailure; diff --git a/clang/include/clang/Sema/Overload.h b/clang/include/clang/Sema/Overload.h index 76311b00d2fc58..0d94045cc13f79 100644 --- a/clang/include/clang/Sema/Overload.h +++ b/clang/include/clang/Sema/Overload.h @@ -244,7 +244,11 @@ class Sema; /// Not a narrowing conversion. NK_Not_Narrowing, - /// A narrowing conversion by virtue of the source and destination types. + /// Not a narrowing conversion in C++23 because the source is a bit-field + /// whose range can fit in the target type + NK_BitField_Not_Narrowing, + + /// A narrowing conversion by virtue of the source and target types. NK_Type_Narrowing, /// A narrowing conversion, because a constant expression got narrowed. @@ -387,6 +391,7 @@ class Sema; NarrowingKind getNarrowingKind(ASTContext &Context, const Expr *Converted, APValue &ConstantValue, QualType &ConstantType, + unsigned &BitFieldWidth, bool IgnoreFloatToIntegralConversion = false) const; bool isPointerConversionToBool() const; bool isPointerConversionToVoidPointer(ASTContext& Context) const; diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp index 50f92c496a539a..4c16fcc60fc771 100644 --- a/clang/lib/Sema/SemaExpr.cpp +++ b/clang/lib/Sema/SemaExpr.cpp @@ -12361,8 +12361,9 @@ static bool checkThreeWayNarrowingConversion(Sema &S, QualType ToType, Expr *E, APValue PreNarrowingValue; QualType PreNarrowingType; + unsigned BitFieldWidth; switch (SCS.getNarrowingKind(S.Context, E, PreNarrowingValue, - PreNarrowingType, + PreNarrowingType, BitFieldWidth, /*IgnoreFloatToIntegralConversion*/ true)) { case NK_Dependent_Narrowing: // Implicit conversion to a narrower type, but the expression is @@ -12370,6 +12371,13 @@ static bool checkThreeWayNarrowingConversion(Sema &S, QualType ToType, Expr *E, case NK_Not_Narrowing: return false; + case NK_BitField_Not_Narrowing: + if (!S.getLangOpts().CPlusPlus23) { + return S.Diag(E->getBeginLoc(), diag::ext_bit_field_narrowing) + << FromType << ToType << BitFieldWidth; + } + return false; + case NK_Constant_Narrowing: // Implicit conversion to a narrower type, and the value is not a constant // expression. diff --git a/clang/lib/Sema/SemaInit.cpp b/clang/lib/Sema/SemaInit.cpp index 003a157990d307..778fe53967bc54 100644 --- a/clang/lib/Sema/SemaInit.cpp +++ b/clang/lib/Sema/SemaInit.cpp @@ -10509,13 +10509,27 @@ static void DiagnoseNarrowingInInitList(Sema &S, // C++11 [dcl.init.list]p7: Check whether this is a narrowing conversion. APValue ConstantValue; QualType ConstantType; + unsigned BitFieldWidth; switch (SCS->getNarrowingKind(S.Context, PostInit, ConstantValue, - ConstantType)) { + ConstantType, BitFieldWidth)) { case NK_Not_Narrowing: case NK_Dependent_Narrowing: // No narrowing occurred. return; + case NK_BitField_Not_Narrowing: + // A bit-field was "narrowed" to an integer type which is wider than the + // bit-field but the declared type of the bit-field is wider than the target + // type. This is not considered narrowing in C++23. + if (S.getLangOpts().CPlusPlus23) + return; + if (!(S.Diag(PostInit->getBeginLoc(), diag::ext_bit_field_narrowing) + << PreNarrowingType + << EntityType.getNonReferenceType().getLocalUnqualifiedType() + << BitFieldWidth)) + return; + break; + case NK_Type_Narrowing: { // This was a floating-to-integer conversion, which is always considered a // narrowing conversion even if the value is a constant and can be @@ -10592,9 +10606,10 @@ static void CheckC23ConstexprInitConversion(Sema &S, QualType FromType, APValue Value; QualType PreNarrowingType; + unsigned BitFieldWidth; // Reuse C++ narrowing check. switch (ICS.Standard.getNarrowingKind( - S.Context, Init, Value, PreNarrowingType, + S.Context, Init, Value, PreNarrowingType, BitFieldWidth, /*IgnoreFloatToIntegralConversion*/ false)) { // The value doesn't fit. case NK_Constant_Narrowing: @@ -10610,6 +10625,7 @@ static void CheckC23ConstexprInitConversion(Sema &S, QualType FromType, // Since we only reuse narrowing check for C23 constexpr variables here, we're // not really interested in these cases. + case NK_BitField_Not_Narrowing: case NK_Dependent_Narrowing: case NK_Variable_Narrowing: case NK_Not_Narrowing: diff --git a/clang/lib/Sema/SemaOverload.cpp b/clang/lib/Sema/SemaOverload.cpp index 04cd9e78739d20..8bf42a4b1dfa4b 100644 --- a/clang/lib/Sema/SemaOverload.cpp +++ b/clang/lib/Sema/SemaOverload.cpp @@ -331,11 +331,14 @@ static const Expr *IgnoreNarrowingConversion(ASTContext &Ctx, /// value of the expression prior to the narrowing conversion. /// \param ConstantType If this is an NK_Constant_Narrowing conversion, the /// type of the expression prior to the narrowing conversion. +/// \param BitFieldWidth If this is an NK_BitField_Not_Narrowing conversion, +/// the width of the source bit-field. /// \param IgnoreFloatToIntegralConversion If true type-narrowing conversions /// from floating point types to integral types should be ignored. NarrowingKind StandardConversionSequence::getNarrowingKind( ASTContext &Ctx, const Expr *Converted, APValue &ConstantValue, - QualType &ConstantType, bool IgnoreFloatToIntegralConversion) const { + QualType &ConstantType, unsigned &BitFieldWidth, + bool IgnoreFloatToIntegralConversion) const { assert((Ctx.getLangOpts().CPlusPlus || Ctx.getLangOpts().C23) && "narrowing check outside C++"); @@ -463,7 +466,12 @@ NarrowingKind StandardConversionSequence::getNarrowingKind( // -- from an integer type or unscoped enumeration type to an integer type // that cannot represent all the values of the original type, except where - // the source is a constant expression and the actual value after + // (C++23) -- the source is a bit-field whose width w is less than that of + // its type (or, for an enumeration type, its underlying type) and the + // target type can represent all the values of a hypothetical extended + // integer type with width w and with the same signedness as the original + // type or + // -- the source is a constant expression and the actual value after // conversion will fit into the target type and will produce the original // value when converted back to the original type. case ICK_Integral_Conversion: @@ -475,49 +483,70 @@ NarrowingKind StandardConversionSequence::getNarrowingKind( const bool ToSigned = ToType->isSignedIntegerOrEnumerationType(); const unsigned ToWidth = Ctx.getIntWidth(ToType); - if (FromWidth > ToWidth || - (FromWidth == ToWidth && FromSigned != ToSigned) || - (FromSigned && !ToSigned)) { - // Not all values of FromType can be represented in ToType. - const Expr *Initializer = IgnoreNarrowingConversion(Ctx, Converted); - - // If it's value-dependent, we can't tell whether it's narrowing. - if (Initializer->isValueDependent()) - return NK_Dependent_Narrowing; + constexpr auto CanRepresentAll = [](bool FromSigned, unsigned FromWidth, + bool ToSigned, unsigned ToWidth) { + return (FromWidth < ToWidth + (FromSigned == ToSigned)) && + (FromSigned <= ToSigned); + }; - std::optional<llvm::APSInt> OptInitializerValue; - if (!(OptInitializerValue = Initializer->getIntegerConstantExpr(Ctx))) { - // Such conversions on variables are always narrowing. - return NK_Variable_Narrowing; - } - llvm::APSInt &InitializerValue = *OptInitializerValue; - bool Narrowing = false; - if (FromWidth < ToWidth) { - // Negative -> unsigned is narrowing. Otherwise, more bits is never - // narrowing. - if (InitializerValue.isSigned() && InitializerValue.isNegative()) - Narrowing = true; - } else { - // Add a bit to the InitializerValue so we don't have to worry about - // signed vs. unsigned comparisons. - InitializerValue = InitializerValue.extend( - InitializerValue.getBitWidth() + 1); - // Convert the initializer to and from the target width and signed-ness. - llvm::APSInt ConvertedValue = InitializerValue; - ConvertedValue = ConvertedValue.trunc(ToWidth); - ConvertedValue.setIsSigned(ToSigned); - ConvertedValue = ConvertedValue.extend(InitializerValue.getBitWidth()); - ConvertedValue.setIsSigned(InitializerValue.isSigned()); - // If the result is different, this was a narrowing conversion. - if (ConvertedValue != InitializerValue) - Narrowing = true; - } - if (Narrowing) { - ConstantType = Initializer->getType(); - ConstantValue = APValue(InitializerValue); - return NK_Constant_Narrowing; + if (CanRepresentAll(FromSigned, FromWidth, ToSigned, ToWidth)) + return NK_Not_Narrowing; + + // Not all values of FromType can be represented in ToType. + const Expr *Initializer = IgnoreNarrowingConversion(Ctx, Converted); + + // If it's value-dependent, we can't tell whether it's narrowing. + if (Initializer->isValueDependent()) + return NK_Dependent_Narrowing; + + std::optional<llvm::APSInt> OptInitializerValue; + if (!(OptInitializerValue = Initializer->getIntegerConstantExpr(Ctx))) { + // Check for bit-field whose width means that this would not be narrowing + // (This check is after checking for constant expressions because + // a constant expression that fits is never narrowing but a non-constant + // expression that comes from a bit-field is only not narrowing before + // C++23 as an extension) + if (const FieldDecl *BitField = Initializer->getSourceBitField()) { + if (BitField->getBitWidth()->isValueDependent()) { + return NK_Dependent_Narrowing; + } + BitFieldWidth = BitField->getBitWidthValue(Ctx); + if (CanRepresentAll(FromSigned, BitFieldWidth, ToSigned, ToWidth)) { + return NK_BitField_Not_Narrowing; + } } + + // Otherwise, such a conversion is always narrowing + return NK_Variable_Narrowing; + } + llvm::APSInt &InitializerValue = *OptInitializerValue; + bool Narrowing = false; + if (FromWidth < ToWidth) { + // Negative -> unsigned is narrowing. Otherwise, more bits is never + // narrowing. + if (InitializerValue.isSigned() && InitializerValue.isNegative()) + Narrowing = true; + } else { + // Add a bit to the InitializerValue so we don't have to worry about + // signed vs. unsigned comparisons. + InitializerValue = + InitializerValue.extend(InitializerValue.getBitWidth() + 1); + // Convert the initializer to and from the target width and signed-ness. + llvm::APSInt ConvertedValue = InitializerValue; + ConvertedValue = ConvertedValue.trunc(ToWidth); + ConvertedValue.setIsSigned(ToSigned); + ConvertedValue = ConvertedValue.extend(InitializerValue.getBitWidth()); + ConvertedValue.setIsSigned(InitializerValue.isSigned()); + // If the result is different, this was a narrowing conversion. + if (ConvertedValue != InitializerValue) + Narrowing = true; + } + if (Narrowing) { + ConstantType = Initializer->getType(); + ConstantValue = APValue(InitializerValue); + return NK_Constant_Narrowing; } + return NK_Not_Narrowing; } case ICK_Complex_Real: @@ -6232,14 +6261,18 @@ static ExprResult BuildConvertedConstantExpression(Sema &S, Expr *From, // Check for a narrowing implicit conversion. bool ReturnPreNarrowingValue = false; QualType PreNarrowingType; + unsigned BitFieldWidth; switch (SCS->getNarrowingKind(S.Context, Result.get(), PreNarrowingValue, - PreNarrowingType)) { + PreNarrowingType, BitFieldWidth)) { case NK_Dependent_Narrowing: // Implicit conversion to a narrower type, but the expression is // value-dependent so we can't tell whether it's actually narrowing. case NK_Variable_Narrowing: // Implicit conversion to a narrower type, and the value is not a constant // expression. We'll diagnose this in a moment. + case NK_BitField_Not_Narrowing: + // Implicit conversion where the source is a bit-field and not a constant + // expression. case NK_Not_Narrowing: break; diff --git a/clang/test/CXX/dcl.decl/dcl.init/dcl.init.list/p7-0x.cpp b/clang/test/CXX/dcl.decl/dcl.init/dcl.init.list/p7-0x.cpp index 2bceb3e267790d..a3049dc57d9fac 100644 --- a/clang/test/CXX/dcl.decl/dcl.init/dcl.init.list/p7-0x.cpp +++ b/clang/test/CXX/dcl.decl/dcl.init/dcl.init.list/p7-0x.cpp @@ -203,6 +203,30 @@ void shrink_int() { unsigned short usc1 = { c }; // expected-error {{non-constant-expression cannot be narrowed from type 'signed char'}} expected-note {{silence}} unsigned short usc2 = { (signed char)'x' }; // OK unsigned short usc3 = { (signed char)-1 }; // expected-error {{ -1 which cannot be narrowed}} expected-note {{silence}} + +#if __BITINT_MAXWIDTH__ >= 3 + _BitInt(2) S2 = 0; + unsigned _BitInt(2) U2 = 0; + _BitInt(3) S3 = 0; + unsigned _BitInt(3) U3 = 0; + + _BitInt(2) bi0 = { S2 }; + _BitInt(2) bi1 = { U2 }; // expected-error {{cannot be narrowed from type 'unsigned _BitInt(2)'}} + _BitInt(2) bi2 = { S3 }; // expected-error {{cannot be narrowed from type '_BitInt(3)'}} + _BitInt(2) bi3 = { U3 }; // expected-error {{cannot be narrowed from type 'unsigned _BitInt(3)'}} + unsigned _BitInt(2) bi4 = { S2 }; // expected-error {{cannot be narrowed from type '_BitInt(2)'}} + unsigned _BitInt(2) bi5 = { U2 }; + unsigned _BitInt(2) bi6 = { S3 }; // expected-error {{cannot be narrowed from type '_BitInt(3)'}} + unsigned _BitInt(2) bi7 = { U3 }; // expected-error {{cannot be narrowed from type 'unsigned _BitInt(3)'}} + _BitInt(3) bi8 = { S2 }; + _BitInt(3) bi9 = { U2 }; + _BitInt(3) bia = { S3 }; + _BitInt(3) bib = { U3 }; // expected-error {{cannot be narrowed from type 'unsigned _BitInt(3)'}} + unsigned _BitInt(3) bic = { S2 }; // expected-error {{cannot be narrowed from type '_BitInt(2)'}} + unsigned _BitInt(3) bid = { U2 }; + unsigned _BitInt(3) bie = { S3 }; // expected-error {{cannot be narrowed from type '_BitInt(3)'}} + unsigned _BitInt(3) bif = { U3 }; +#endif } // Be sure that type- and value-dependent expressions in templates get the error diff --git a/clang/test/CXX/drs/dr26xx.cpp b/clang/test/CXX/drs/dr26xx.cpp index f7a05b9827a235..3834325d69c4b5 100644 --- a/clang/test/CXX/drs/dr26xx.cpp +++ b/clang/test/CXX/drs/dr26xx.cpp @@ -1,11 +1,37 @@ // RUN: %clang_cc1 -std=c++98 -triple x86_64-unknown-unknown %s -verify=expected // RUN: %clang_cc1 -std=c++11 -triple x86_64-unknown-unknown %s -verify=expected,since-cxx11,cxx11 +// RUN: %clang_cc1 -std=c++11 -pedantic -triple x86_64-unknown-unknown %s -verify=expected,since-cxx11,cxx11,until-cxx23-pedantic // RUN: %clang_cc1 -std=c++14 -triple x86_64-unknown-unknown %s -verify=expected,since-cxx11 +// RUN: %clang_cc1 -std=c++14 -pedantic -triple x86_64-unknown-unknown %s -verify=expected,since-cxx11,until-cxx23-pedantic // RUN: %clang_cc1 -std=c++17 -triple x86_64-unknown-unknown %s -verify=expected,since-cxx11 +// RUN: %clang_cc1 -std=c++17 -pedantic -triple x86_64-unknown-unknown %s -verify=expected,since-cxx11,until-cxx23-pedantic // RUN: %clang_cc1 -std=c++20 -triple x86_64-unknown-unknown %s -verify=expected,since-cxx11,since-cxx20 +// RUN: %clang_cc1 -std=c++20 -pedantic -triple x86_64-unknown-unknown %s -verify=expected,since-cxx11,since-cxx20,until-cxx23-pedantic // RUN: %clang_cc1 -std=c++23 -triple x86_64-unknown-unknown %s -verify=expected,since-cxx11,since-cxx20,since-cxx23 +// RUN: %clang_cc1 -std=c++23 -pedantic -triple x86_64-unknown-unknown %s -verify=expected,since-cxx11,since-cxx20,since-cxx23 // RUN: %clang_cc1 -std=c++2c -triple x86_64-unknown-unknown %s -verify=expected,since-cxx11,since-cxx20,since-cxx23 +// RUN: %clang_cc1 -std=c++2c -pedantic -triple x86_64-unknown-unknown %s -verify=expected,since-cxx11,since-cxx20,since-cxx23 +namespace std { +#if __cplusplus >= 202002L + struct strong_ordering { + int n; + constexpr operator int() const { return n; } + static const strong_ordering less, equal, greater; + }; + constexpr strong_ordering strong_ordering::less{-1}, + strong_ordering::equal{0}, strong_ordering::greater{1}; +#endif + + typedef __INT16_TYPE__ int16_t; + typedef __UINT16_TYPE__ uint16_t; + typedef __INT32_TYPE__ int32_t; + typedef __UINT32_TYPE__ uint32_t; + typedef __INT64_TYPE__ int64_t; + typedef __UINT64_TYPE__ uint64_t; + + template<typename T> T declval(); +} namespace cwg2621 { // cwg2621: 16 #if __cplusplus >= 202002L @@ -24,6 +50,116 @@ using enum E; #endif } +namespace cwg2627 { // cwg2627: 19 +#if __cplusplus >= 202002L +struct C { + long long i : 8; + friend auto operator<=>(C, C) = default; // #cwg2627-3way-def +}; + +void f() { + C x{1}, y{2}; + static_cast<void>(x <=> y); +// until-cxx23-pedantic-warning@#cwg2627-3way-def 2 {{narrowing non-constant-expression from 'long long' bit-field of width 8 to 'int' is a C++23 extension}} +// until-cxx23-pedantic-note@-2 {{in defaulted three-way comparison operator for 'C' first required here}} + static_cast<void>(x.i <=> y.i); +// until-cxx23-pedantic-warning@-1 2 {{narrowing non-constant-expression from 'long long' bit-field of width 8 to 'int' is a C++23 extension}} +} + +template<typename T> +struct CDependent { + T i : 8; + friend auto operator<=>(CDependent, CDependent) = default; +}; + +template<typename T> +concept three_way_comparable = requires(T t) { { t <=> t }; }; +template<typename T> +concept bf_three_way_comparable = requires(T t) { { t.i <=> t.i }; }; +static_assert(three_way_comparable<CDependent<long long>> == (__cplusplus >= 202302L)); +static_assert(bf_three_way_comparable<CDependent<long long>> == (__cplusplus >= 202302L)); +#endif + +#if __cplusplus >= 201103L +template<int W> +struct D { + __int128 i : W; +}; + +template<int W> +std::int64_t f(D<W> d) { + return std::int64_t{ d.i }; // #cwg2627-f +} + +template std::int64_t f(D<63>); +// until-cxx23-pedantic-warning-re@#cwg2627-f {{narrowing non-constant-expression from '__int128' bit-field of width 63 to 'std::int64_t' (aka '{{.+}}') is a C++23 extension}} +// until-cxx23-pedantic-note@-2 {{in instantiation of function template specialization 'cwg2627::f<63>' requested here}} +// until-cxx23-pedantic-note@#cwg2627-f {{insert an explicit cast to silence this issue}} +template std::int64_t f(D<64>); +// until-cxx23-pedantic-warning-re@#cwg2627-f {{narrowing non-constant-expression from '__int128' bit-field of width 64 to 'std::int64_t' (aka '{{.+}}') is a C++23 extension}} +// until-cxx23-pedantic-note@-2 {{in instantiation of function template specialization 'cwg2627::f<64>' requested here}} +// until-cxx23-pedantic-note@#cwg2627-f {{insert an explicit cast to silence this issue}} +template std::int64_t f(D<65>); +// since-cxx11-error-re@#cwg2627-f {{non-constant-expression cannot be narrowed from type '__int128' to 'std::int64_t' (aka '{{.+}}') in initializer list}} +// since-cxx11-note@-2 {{in instantiation of function template specialization 'cwg2627::f<65>' requested here}} +// since-cxx11-note@#cwg2627-f {{insert an explicit cast to silence this issue}} + +template<typename Target, typename Source> +Target g(Source x) { + return Target{ x.i }; // #cwg2627-g +} + +template<typename T, int N> +struct E { + T i : N; +}; + +template std::int16_t g(E<int, 16>); +// until-cxx23-pedantic-warning-re@#cwg2627-g {{narrowing non-constant-expression from 'int' bit-field of width 16 to '{{.+}}' is a C++23 extension}} +// until-cxx23-pedantic-note-re@-2 {{in instantiation of function template specialization 'cwg2627::g<{{.+}}, cwg2627::E<int, 16>>' requested here}} +// until-cxx23-pedantic-note@#cwg2627-g {{insert an explicit cast to silence this issue}} +template std::int16_t g(E<unsigned, 15>); +// until-cxx23-pedantic-warning-re@#cwg2627-g {{narrowing non-constant-expression from 'unsigned int' bit-field of width 15 to '{{.+}}' is a C++23 extension}} +// until-cxx23-pedantic-note-re@-2 {{in instantiation of function template specialization 'cwg2627::g<{{.+}}, cwg2627::E<unsigned int, 15>>' requested here}} +// until-cxx23-pedantic-note@#cwg2627-g {{insert an explicit cast to silence this issue}} +template std::int16_t g(E<unsigned, 16>); +// since-cxx11-error-re@#cwg2627-g {{non-constant-expression cannot be narrowed from type 'unsigned int' to '{{.+}}' in initializer list}} +// since-cxx11-note-re@-2 {{in instantiation of function template specialization 'cwg2627::g<{{.+}}, cwg2627::E<unsigned int, 16>>' requested here}} +// since-cxx11-note@#cwg2627-g {{insert an explicit cast to silence this issue}} +template std::uint16_t g(E<unsigned, 16>); +// until-cxx23-pedantic-warning-re@#cwg2627-g {{narrowing non-constant-expression from 'unsigned int' bit-field of width 16 to '{{.+}}' is a C++23 extension}} +// until-cxx23-pedantic-note-re@-2 {{in instantiation of function template specialization 'cwg2627::g<{{.+}}, cwg2627::E<unsigned int, 16>>' requested here}} +// until-cxx23-pedantic-note@#cwg2627-g {{insert an explicit cast to silence this issue}} +template std::uint16_t g(E<int, 1>); +// since-cxx11-error-re@#cwg2627-g {{non-constant-expression cannot be narrowed from type 'int' to '{{.+}}' in initializer list}} +// since-cxx11-note-re@-2 {{in instantiation of function template specialization 'cwg2627::g<{{.+}}, cwg2627::E<int, 1>>' requested here}} +// since-cxx11-note@#cwg2627-g {{insert an explicit cast to silence this issue}} + +template bool g(E<unsigned, 1>); +// until-cxx23-pedantic-warning@#cwg2627-g {{narrowing non-constant-expression from 'unsigned int' bit-field of width 1 to 'bool' is a C++23 extension}} +// until-cxx23-pedantic-note@-2 {{in instantiation of function template specialization 'cwg2627::g<bool, cwg2627::E<unsigned int, 1>>' requested here}} +// until-cxx23-pedantic-note@#cwg2627-g {{insert an explicit cast to silence this issue}} +template bool g(E<int, 1>); +// since-cxx11-error@#cwg2627-g {{non-constant-expression cannot be narrowed from type 'int' to 'bool' in initializer list}} +// since-cxx11-note@-2 {{in instantiation of function template specialization 'cwg2627::g<bool, cwg2627::E<int, 1>>' requested here}} +// since-cxx11-note@#cwg2627-g {{insert an explicit cast to silence this issue}} + +template<typename Target, typename Source> +constexpr decltype(Target{ std::declval<Source>().i }, false) is_narrowing(int) { return false; } +template<typename Target, typename Source> +constexpr bool is_narrowing(long) { return true; } + +constexpr bool is_cxx23 = __cplusplus >= 202302L; +static_assert(is_narrowing<std::int16_t, E<int, 16>>(0) == !is_cxx23, ""); +static_assert(is_narrowing<std::int16_t, E<unsigned, 15>>(0) == !is_cxx23, ""); +static_assert(is_narrowing<std::int16_t, E<unsigned, 16>>(0), ""); +static_assert(is_narrowing<std::uint16_t, E<unsigned, 16>>(0) == !is_cxx23, ""); +static_assert(is_narrowing<std::uint16_t, E<int, 1>>(0), ""); +static_assert(is_narrowing<bool, E<unsigned, 1>>(0) == !is_cxx23, ""); +static_assert(is_narrowing<bool, E<int, 1>>(0), ""); +#endif +} + namespace cwg2628 { // cwg2628: no // this was reverted for the 16.x release // due to regressions, see the issue for more details: diff --git a/clang/www/cxx_dr_status.html b/clang/www/cxx_dr_status.html index ea8872c91be604..d1f28bad642796 100755 --- a/clang/www/cxx_dr_status.html +++ b/clang/www/cxx_dr_status.html @@ -15570,7 +15570,7 @@ <h2 id="cxxdr">C++ defect report implementation status</h2> <td><a href="https://cplusplus.github.io/CWG/issues/2627.html";>2627</a></td> <td>C++23</td> <td>Bit-fields and narrowing conversions</td> - <td class="unknown" align="center">Unknown</td> + <td class="unreleased" align="center">Clang 19</td> </tr> <tr id="2628"> <td><a href="https://cplusplus.github.io/CWG/issues/2628.html";>2628</a></td> _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
