text: //===--- Specifiers.h - Declaration and Type Specifiers ---------*- C++ -*-===//
  //
  //                     The LLVM Compiler Infrastructure
  //
  // This file is distributed under the University of Illinois Open Source
  // License. See LICENSE.TXT for details.
  //
  //===----------------------------------------------------------------------===//
  ///
  /// \file
  /// \brief Defines various enumerations that describe declaration and
  /// type specifiers.
  ///
  //===----------------------------------------------------------------------===//
  
  #ifndef LLVM_CLANG_BASIC_SPECIFIERS_H
  #define LLVM_CLANG_BASIC_SPECIFIERS_H
  
  #include "llvm/ADT/StringRef.h"
  #include "llvm/Support/DataTypes.h"
  #include "llvm/Support/ErrorHandling.h"
  
  namespace clang {
    /// \brief Specifies the width of a type, e.g., short, long, or long long.
    enum TypeSpecifierWidth {
      TSW_unspecified,
      TSW_short,
      TSW_long,
      TSW_longlong
    };
    
    /// \brief Specifies the signedness of a type, e.g., signed or unsigned.
    enum TypeSpecifierSign {
      TSS_unspecified,
      TSS_signed,
      TSS_unsigned
    };
    
    enum TypeSpecifiersPipe {
      TSP_unspecified,
      TSP_pipe
    };
  
    /// \brief Specifies the kind of type.
    enum TypeSpecifierType {
      TST_unspecified,
      TST_void,
      TST_char,
      TST_wchar,        // C++ wchar_t
      TST_char8,        // C++20 char8_t (proposed)
      TST_char16,       // C++11 char16_t
      TST_char32,       // C++11 char32_t
      TST_int,
      TST_int128,
      TST_half,         // OpenCL half, ARM NEON __fp16
      TST_Float16,      // C11 extension ISO/IEC TS 18661-3
      TST_float,
      TST_double,
      TST_float128,
      TST_bool,         // _Bool
      TST_decimal32,    // _Decimal32
      TST_decimal64,    // _Decimal64
      TST_decimal128,   // _Decimal128
      TST_enum,
      TST_union,
      TST_struct,
      TST_class,        // C++ class type
      TST_interface,    // C++ (Microsoft-specific) __interface type
      TST_typename,     // Typedef, C++ class-name or enum name, etc.
      TST_typeofType,
      TST_typeofExpr,
      TST_decltype,         // C++11 decltype
      TST_underlyingType,   // __underlying_type for C++11
      TST_auto,             // C++11 auto
      TST_decltype_auto,    // C++1y decltype(auto)
      TST_auto_type,        // __auto_type extension
      TST_unknown_anytype,  // __unknown_anytype extension
      TST_atomic,           // C11 _Atomic
  #define GENERIC_IMAGE_TYPE(ImgType, Id) TST_##ImgType##_t, // OpenCL image types
  #include "clang/Basic/OpenCLImageTypes.def"
      TST_error // erroneous type
    };
  
    /// \brief Structure that packs information about the type specifiers that
    /// were written in a particular type specifier sequence.
    struct WrittenBuiltinSpecs {
      static_assert(TST_error < 1 << 6, "Type bitfield not wide enough for TST");
      /*DeclSpec::TST*/ unsigned Type  : 6;
      /*DeclSpec::TSS*/ unsigned Sign  : 2;
      /*DeclSpec::TSW*/ unsigned Width : 2;
      unsigned ModeAttr : 1;
    };
  
    /// \brief A C++ access specifier (public, private, protected), plus the
    /// special value "none" which means different things in different contexts.
    enum AccessSpecifier {
      AS_public,
      AS_protected,
      AS_private,
      AS_none
    };
  
    /// \brief The categorization of expression values, currently following the
    /// C++11 scheme.
    enum ExprValueKind {
      /// \brief An r-value expression (a pr-value in the C++11 taxonomy)
      /// produces a temporary value.
      VK_RValue,
  
      /// \brief An l-value expression is a reference to an object with
      /// independent storage.
      VK_LValue,
  
      /// \brief An x-value expression is a reference to an object with
      /// independent storage but which can be "moved", i.e.
      /// efficiently cannibalized for its resources.
      VK_XValue
    };
  
    /// \brief A further classification of the kind of object referenced by an
    /// l-value or x-value.
    enum ExprObjectKind {
      /// An ordinary object is located at an address in memory.
      OK_Ordinary,
  
      /// A bitfield object is a bitfield on a C or C++ record.
      OK_BitField,
  
      /// A vector component is an element or range of elements on a vector.
      OK_VectorComponent,
  
      /// An Objective-C property is a logical field of an Objective-C
      /// object which is read and written via Objective-C method calls.
      OK_ObjCProperty,
      
      /// An Objective-C array/dictionary subscripting which reads an
      /// object or writes at the subscripted array/dictionary element via
      /// Objective-C method calls.
      OK_ObjCSubscript
    };
  
    /// \brief Describes the kind of template specialization that a
    /// particular template specialization declaration represents.
    enum TemplateSpecializationKind {
      /// This template specialization was formed from a template-id but
      /// has not yet been declared, defined, or instantiated.
      TSK_Undeclared = 0,
      /// This template specialization was implicitly instantiated from a
      /// template. (C++ [temp.inst]).
      TSK_ImplicitInstantiation,
      /// This template specialization was declared or defined by an
      /// explicit specialization (C++ [temp.expl.spec]) or partial
      /// specialization (C++ [temp.class.spec]).
      TSK_ExplicitSpecialization,
      /// This template specialization was instantiated from a template
      /// due to an explicit instantiation declaration request
      /// (C++11 [temp.explicit]).
      TSK_ExplicitInstantiationDeclaration,
      /// This template specialization was instantiated from a template
      /// due to an explicit instantiation definition request
      /// (C++ [temp.explicit]).
      TSK_ExplicitInstantiationDefinition
    };
  
    /// \brief Determine whether this template specialization kind refers
    /// to an instantiation of an entity (as opposed to a non-template or
    /// an explicit specialization).
    inline bool isTemplateInstantiation(TemplateSpecializationKind Kind) {
      return Kind != TSK_Undeclared && Kind != TSK_ExplicitSpecialization;
    }
  
    /// \brief True if this template specialization kind is an explicit
    /// specialization, explicit instantiation declaration, or explicit
    /// instantiation definition.
    inline bool isTemplateExplicitInstantiationOrSpecialization(
        TemplateSpecializationKind Kind) {
      switch (Kind) {
      case TSK_ExplicitSpecialization:
      case TSK_ExplicitInstantiationDeclaration:
      case TSK_ExplicitInstantiationDefinition:
        return true;
  
      case TSK_Undeclared:
      case TSK_ImplicitInstantiation:
        return false;
      }
      llvm_unreachable("bad template specialization kind");
    }
  
    /// \brief Thread storage-class-specifier.
    enum ThreadStorageClassSpecifier {
      TSCS_unspecified,
      /// GNU __thread.
      TSCS___thread,
      /// C++11 thread_local. Implies 'static' at block scope, but not at
      /// class scope.
      TSCS_thread_local,
      /// C11 _Thread_local. Must be combined with either 'static' or 'extern'
      /// if used at block scope.
      TSCS__Thread_local
    };
  
    /// \brief Storage classes.
    enum StorageClass {
      // These are legal on both functions and variables.
      SC_None,
      SC_Extern,
      SC_Static,
      SC_PrivateExtern,
  
      // These are only legal on variables.
      SC_Auto,
      SC_Register
    };
  
    /// \brief Checks whether the given storage class is legal for functions.
    inline bool isLegalForFunction(StorageClass SC) {
      return SC <= SC_PrivateExtern;
    }
  
    /// \brief Checks whether the given storage class is legal for variables.
    inline bool isLegalForVariable(StorageClass SC) {
      return true;
    }
  
    /// \brief In-class initialization styles for non-static data members.
    enum InClassInitStyle {
      ICIS_NoInit,   ///< No in-class initializer.
      ICIS_CopyInit, ///< Copy initialization.
      ICIS_ListInit  ///< Direct list-initialization.
    };
  
    /// \brief CallingConv - Specifies the calling convention that a function uses.
    enum CallingConv {
      CC_C,           // __attribute__((cdecl))
      CC_X86StdCall,  // __attribute__((stdcall))
      CC_X86FastCall, // __attribute__((fastcall))
      CC_X86ThisCall, // __attribute__((thiscall))
      CC_X86VectorCall, // __attribute__((vectorcall))
      CC_X86Pascal,   // __attribute__((pascal))
      CC_Win64,       // __attribute__((ms_abi))
      CC_X86_64SysV,  // __attribute__((sysv_abi))
      CC_X86RegCall, // __attribute__((regcall))
      CC_AAPCS,       // __attribute__((pcs("aapcs")))
      CC_AAPCS_VFP,   // __attribute__((pcs("aapcs-vfp")))
      CC_IntelOclBicc, // __attribute__((intel_ocl_bicc))
      CC_SpirFunction, // default for OpenCL functions on SPIR target
      CC_OpenCLKernel, // inferred for OpenCL kernels
      CC_Swift,        // __attribute__((swiftcall))
      CC_PreserveMost, // __attribute__((preserve_most))
      CC_PreserveAll,  // __attribute__((preserve_all))
    };
  
    /// \brief Checks whether the given calling convention supports variadic
    /// calls. Unprototyped calls also use the variadic call rules.
    inline bool supportsVariadicCall(CallingConv CC) {
      switch (CC) {
      case CC_X86StdCall:
      case CC_X86FastCall:
      case CC_X86ThisCall:
      case CC_X86RegCall:
      case CC_X86Pascal:
      case CC_X86VectorCall:
      case CC_SpirFunction:
      case CC_OpenCLKernel:
      case CC_Swift:
        return false;
      default:
        return true;
      }
    }
  
    /// \brief The storage duration for an object (per C++ [basic.stc]).
    enum StorageDuration {
      SD_FullExpression, ///< Full-expression storage duration (for temporaries).
      SD_Automatic,      ///< Automatic storage duration (most local variables).
      SD_Thread,         ///< Thread storage duration.
      SD_Static,         ///< Static storage duration.
      SD_Dynamic         ///< Dynamic storage duration.
    };
  
    /// Describes the nullability of a particular type.
    enum class NullabilityKind : uint8_t {
      /// Values of this type can never be null.
      NonNull = 0,
      /// Values of this type can be null.
      Nullable,
      /// Whether values of this type can be null is (explicitly)
      /// unspecified. This captures a (fairly rare) case where we
      /// can't conclude anything about the nullability of the type even
      /// though it has been considered.
      Unspecified
    };
  
    /// Retrieve the spelling of the given nullability kind.
    llvm::StringRef getNullabilitySpelling(NullabilityKind kind,
                                           bool isContextSensitive = false);
  
    /// \brief Kinds of parameter ABI.
    enum class ParameterABI {
      /// This parameter uses ordinary ABI rules for its type.
      Ordinary,
  
      /// This parameter (which must have pointer type) is a Swift
      /// indirect result parameter.
      SwiftIndirectResult,
  
      /// This parameter (which must have pointer-to-pointer type) uses
      /// the special Swift error-result ABI treatment.  There can be at
      /// most one parameter on a given function that uses this treatment.
      SwiftErrorResult,
  
      /// This parameter (which must have pointer type) uses the special
      /// Swift context-pointer ABI treatment.  There can be at
      /// most one parameter on a given function that uses this treatment.
      SwiftContext
    };
  
    llvm::StringRef getParameterABISpelling(ParameterABI kind);
  } // end namespace clang
  
  #endif // LLVM_CLANG_BASIC_SPECIFIERS_H
  