1 //===--- Specifiers.h - Declaration and Type Specifiers ---------*- C++ -*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 ///
9 /// \file
10 /// Defines various enumerations that describe declaration and
11 /// type specifiers.
12 ///
13 //===----------------------------------------------------------------------===//
14 
15 #ifndef LLVM_CLANG_BASIC_SPECIFIERS_H
16 #define LLVM_CLANG_BASIC_SPECIFIERS_H
17 
18 #include "llvm/ADT/StringRef.h"
19 #include "llvm/Support/DataTypes.h"
20 #include "llvm/Support/ErrorHandling.h"
21 
22 namespace llvm {
23 class raw_ostream;
24 } // namespace llvm
25 namespace clang {
26 
27   /// Define the meaning of possible values of the kind in ExplicitSpecifier.
28   enum class ExplicitSpecKind : unsigned {
29     ResolvedFalse,
30     ResolvedTrue,
31     Unresolved,
32   };
33 
34   /// Define the kind of constexpr specifier.
35   enum class ConstexprSpecKind { Unspecified, Constexpr, Consteval, Constinit };
36 
37   /// In an if statement, this denotes whether the statement is
38   /// a constexpr or consteval if statement.
39   enum class IfStatementKind : unsigned {
40     Ordinary,
41     Constexpr,
42     ConstevalNonNegated,
43     ConstevalNegated
44   };
45 
46   /// Specifies the width of a type, e.g., short, long, or long long.
47   enum class TypeSpecifierWidth { Unspecified, Short, Long, LongLong };
48 
49   /// Specifies the signedness of a type, e.g., signed or unsigned.
50   enum class TypeSpecifierSign { Unspecified, Signed, Unsigned };
51 
52   enum class TypeSpecifiersPipe { Unspecified, Pipe };
53 
54   /// Specifies the kind of type.
55   enum TypeSpecifierType {
56     TST_unspecified,
57     TST_void,
58     TST_char,
59     TST_wchar,  // C++ wchar_t
60     TST_char8,  // C++20 char8_t (proposed)
61     TST_char16, // C++11 char16_t
62     TST_char32, // C++11 char32_t
63     TST_int,
64     TST_int128,
65     TST_bitint,  // Bit-precise integer types.
66     TST_half,    // OpenCL half, ARM NEON __fp16
67     TST_Float16, // C11 extension ISO/IEC TS 18661-3
68     TST_Accum,   // ISO/IEC JTC1 SC22 WG14 N1169 Extension
69     TST_Fract,
70     TST_BFloat16,
71     TST_float,
72     TST_double,
73     TST_float128,
74     TST_ibm128,
75     TST_bool,       // _Bool
76     TST_decimal32,  // _Decimal32
77     TST_decimal64,  // _Decimal64
78     TST_decimal128, // _Decimal128
79     TST_enum,
80     TST_union,
81     TST_struct,
82     TST_class,     // C++ class type
83     TST_interface, // C++ (Microsoft-specific) __interface type
84     TST_typename,  // Typedef, C++ class-name or enum name, etc.
85     TST_typeofType,        // C2x (and GNU extension) typeof(type-name)
86     TST_typeofExpr,        // C2x (and GNU extension) typeof(expression)
87     TST_typeof_unqualType, // C2x typeof_unqual(type-name)
88     TST_typeof_unqualExpr, // C2x typeof_unqual(expression)
89     TST_decltype, // C++11 decltype
90 #define TRANSFORM_TYPE_TRAIT_DEF(_, Trait) TST_##Trait,
91 #include "clang/Basic/TransformTypeTraits.def"
92     TST_auto,            // C++11 auto
93     TST_decltype_auto,   // C++1y decltype(auto)
94     TST_auto_type,       // __auto_type extension
95     TST_unknown_anytype, // __unknown_anytype extension
96     TST_atomic,          // C11 _Atomic
97 #define GENERIC_IMAGE_TYPE(ImgType, Id) TST_##ImgType##_t, // OpenCL image types
98 #include "clang/Basic/OpenCLImageTypes.def"
99     TST_error // erroneous type
100   };
101 
102   /// Structure that packs information about the type specifiers that
103   /// were written in a particular type specifier sequence.
104   struct WrittenBuiltinSpecs {
105     static_assert(TST_error < 1 << 7, "Type bitfield not wide enough for TST");
106     /*DeclSpec::TST*/ unsigned Type : 7;
107     /*DeclSpec::TSS*/ unsigned Sign  : 2;
108     /*TypeSpecifierWidth*/ unsigned Width : 2;
109     unsigned ModeAttr : 1;
110   };
111 
112   /// A C++ access specifier (public, private, protected), plus the
113   /// special value "none" which means different things in different contexts.
114   enum AccessSpecifier {
115     AS_public,
116     AS_protected,
117     AS_private,
118     AS_none
119   };
120 
121   /// The categorization of expression values, currently following the
122   /// C++11 scheme.
123   enum ExprValueKind {
124     /// A pr-value expression (in the C++11 taxonomy)
125     /// produces a temporary value.
126     VK_PRValue,
127 
128     /// An l-value expression is a reference to an object with
129     /// independent storage.
130     VK_LValue,
131 
132     /// An x-value expression is a reference to an object with
133     /// independent storage but which can be "moved", i.e.
134     /// efficiently cannibalized for its resources.
135     VK_XValue
136   };
137 
138   /// A further classification of the kind of object referenced by an
139   /// l-value or x-value.
140   enum ExprObjectKind {
141     /// An ordinary object is located at an address in memory.
142     OK_Ordinary,
143 
144     /// A bitfield object is a bitfield on a C or C++ record.
145     OK_BitField,
146 
147     /// A vector component is an element or range of elements on a vector.
148     OK_VectorComponent,
149 
150     /// An Objective-C property is a logical field of an Objective-C
151     /// object which is read and written via Objective-C method calls.
152     OK_ObjCProperty,
153 
154     /// An Objective-C array/dictionary subscripting which reads an
155     /// object or writes at the subscripted array/dictionary element via
156     /// Objective-C method calls.
157     OK_ObjCSubscript,
158 
159     /// A matrix component is a single element of a matrix.
160     OK_MatrixComponent
161   };
162 
163   /// The reason why a DeclRefExpr does not constitute an odr-use.
164   enum NonOdrUseReason {
165     /// This is an odr-use.
166     NOUR_None = 0,
167     /// This name appears in an unevaluated operand.
168     NOUR_Unevaluated,
169     /// This name appears as a potential result of an lvalue-to-rvalue
170     /// conversion that is a constant expression.
171     NOUR_Constant,
172     /// This name appears as a potential result of a discarded value
173     /// expression.
174     NOUR_Discarded,
175   };
176 
177   /// Describes the kind of template specialization that a
178   /// particular template specialization declaration represents.
179   enum TemplateSpecializationKind {
180     /// This template specialization was formed from a template-id but
181     /// has not yet been declared, defined, or instantiated.
182     TSK_Undeclared = 0,
183     /// This template specialization was implicitly instantiated from a
184     /// template. (C++ [temp.inst]).
185     TSK_ImplicitInstantiation,
186     /// This template specialization was declared or defined by an
187     /// explicit specialization (C++ [temp.expl.spec]) or partial
188     /// specialization (C++ [temp.class.spec]).
189     TSK_ExplicitSpecialization,
190     /// This template specialization was instantiated from a template
191     /// due to an explicit instantiation declaration request
192     /// (C++11 [temp.explicit]).
193     TSK_ExplicitInstantiationDeclaration,
194     /// This template specialization was instantiated from a template
195     /// due to an explicit instantiation definition request
196     /// (C++ [temp.explicit]).
197     TSK_ExplicitInstantiationDefinition
198   };
199 
200   /// Determine whether this template specialization kind refers
201   /// to an instantiation of an entity (as opposed to a non-template or
202   /// an explicit specialization).
203   inline bool isTemplateInstantiation(TemplateSpecializationKind Kind) {
204     return Kind != TSK_Undeclared && Kind != TSK_ExplicitSpecialization;
205   }
206 
207   /// True if this template specialization kind is an explicit
208   /// specialization, explicit instantiation declaration, or explicit
209   /// instantiation definition.
210   inline bool isTemplateExplicitInstantiationOrSpecialization(
211       TemplateSpecializationKind Kind) {
212     switch (Kind) {
213     case TSK_ExplicitSpecialization:
214     case TSK_ExplicitInstantiationDeclaration:
215     case TSK_ExplicitInstantiationDefinition:
216       return true;
217 
218     case TSK_Undeclared:
219     case TSK_ImplicitInstantiation:
220       return false;
221     }
222     llvm_unreachable("bad template specialization kind");
223   }
224 
225   /// Thread storage-class-specifier.
226   enum ThreadStorageClassSpecifier {
227     TSCS_unspecified,
228     /// GNU __thread.
229     TSCS___thread,
230     /// C++11 thread_local. Implies 'static' at block scope, but not at
231     /// class scope.
232     TSCS_thread_local,
233     /// C11 _Thread_local. Must be combined with either 'static' or 'extern'
234     /// if used at block scope.
235     TSCS__Thread_local
236   };
237 
238   /// Storage classes.
239   enum StorageClass {
240     // These are legal on both functions and variables.
241     SC_None,
242     SC_Extern,
243     SC_Static,
244     SC_PrivateExtern,
245 
246     // These are only legal on variables.
247     SC_Auto,
248     SC_Register
249   };
250 
251   /// Checks whether the given storage class is legal for functions.
252   inline bool isLegalForFunction(StorageClass SC) {
253     return SC <= SC_PrivateExtern;
254   }
255 
256   /// Checks whether the given storage class is legal for variables.
257   inline bool isLegalForVariable(StorageClass SC) {
258     return true;
259   }
260 
261   /// In-class initialization styles for non-static data members.
262   enum InClassInitStyle {
263     ICIS_NoInit,   ///< No in-class initializer.
264     ICIS_CopyInit, ///< Copy initialization.
265     ICIS_ListInit  ///< Direct list-initialization.
266   };
267 
268   /// CallingConv - Specifies the calling convention that a function uses.
269   enum CallingConv {
270     CC_C,           // __attribute__((cdecl))
271     CC_X86StdCall,  // __attribute__((stdcall))
272     CC_X86FastCall, // __attribute__((fastcall))
273     CC_X86ThisCall, // __attribute__((thiscall))
274     CC_X86VectorCall, // __attribute__((vectorcall))
275     CC_X86Pascal,   // __attribute__((pascal))
276     CC_Win64,       // __attribute__((ms_abi))
277     CC_X86_64SysV,  // __attribute__((sysv_abi))
278     CC_X86RegCall, // __attribute__((regcall))
279     CC_AAPCS,       // __attribute__((pcs("aapcs")))
280     CC_AAPCS_VFP,   // __attribute__((pcs("aapcs-vfp")))
281     CC_IntelOclBicc, // __attribute__((intel_ocl_bicc))
282     CC_SpirFunction, // default for OpenCL functions on SPIR target
283     CC_OpenCLKernel, // inferred for OpenCL kernels
284     CC_Swift,        // __attribute__((swiftcall))
285     CC_SwiftAsync,        // __attribute__((swiftasynccall))
286     CC_PreserveMost, // __attribute__((preserve_most))
287     CC_PreserveAll,  // __attribute__((preserve_all))
288     CC_AArch64VectorCall, // __attribute__((aarch64_vector_pcs))
289     CC_AArch64SVEPCS, // __attribute__((aarch64_sve_pcs))
290     CC_AMDGPUKernelCall, // __attribute__((amdgpu_kernel))
291   };
292 
293   /// Checks whether the given calling convention supports variadic
294   /// calls. Unprototyped calls also use the variadic call rules.
295   inline bool supportsVariadicCall(CallingConv CC) {
296     switch (CC) {
297     case CC_X86StdCall:
298     case CC_X86FastCall:
299     case CC_X86ThisCall:
300     case CC_X86RegCall:
301     case CC_X86Pascal:
302     case CC_X86VectorCall:
303     case CC_SpirFunction:
304     case CC_OpenCLKernel:
305     case CC_Swift:
306     case CC_SwiftAsync:
307       return false;
308     default:
309       return true;
310     }
311   }
312 
313   /// The storage duration for an object (per C++ [basic.stc]).
314   enum StorageDuration {
315     SD_FullExpression, ///< Full-expression storage duration (for temporaries).
316     SD_Automatic,      ///< Automatic storage duration (most local variables).
317     SD_Thread,         ///< Thread storage duration.
318     SD_Static,         ///< Static storage duration.
319     SD_Dynamic         ///< Dynamic storage duration.
320   };
321 
322   /// Describes the nullability of a particular type.
323   enum class NullabilityKind : uint8_t {
324     /// Values of this type can never be null.
325     NonNull = 0,
326     /// Values of this type can be null.
327     Nullable,
328     /// Whether values of this type can be null is (explicitly)
329     /// unspecified. This captures a (fairly rare) case where we
330     /// can't conclude anything about the nullability of the type even
331     /// though it has been considered.
332     Unspecified,
333     // Generally behaves like Nullable, except when used in a block parameter
334     // that was imported into a swift async method. There, swift will assume
335     // that the parameter can get null even if no error occurred. _Nullable
336     // parameters are assumed to only get null on error.
337     NullableResult,
338   };
339   /// Prints human-readable debug representation.
340   llvm::raw_ostream &operator<<(llvm::raw_ostream&, NullabilityKind);
341 
342   /// Return true if \p L has a weaker nullability annotation than \p R. The
343   /// ordering is: Unspecified < Nullable < NonNull.
344   inline bool hasWeakerNullability(NullabilityKind L, NullabilityKind R) {
345     return uint8_t(L) > uint8_t(R);
346   }
347 
348   /// Retrieve the spelling of the given nullability kind.
349   llvm::StringRef getNullabilitySpelling(NullabilityKind kind,
350                                          bool isContextSensitive = false);
351 
352   /// Kinds of parameter ABI.
353   enum class ParameterABI {
354     /// This parameter uses ordinary ABI rules for its type.
355     Ordinary,
356 
357     /// This parameter (which must have pointer type) is a Swift
358     /// indirect result parameter.
359     SwiftIndirectResult,
360 
361     /// This parameter (which must have pointer-to-pointer type) uses
362     /// the special Swift error-result ABI treatment.  There can be at
363     /// most one parameter on a given function that uses this treatment.
364     SwiftErrorResult,
365 
366     /// This parameter (which must have pointer type) uses the special
367     /// Swift context-pointer ABI treatment.  There can be at
368     /// most one parameter on a given function that uses this treatment.
369     SwiftContext,
370 
371     /// This parameter (which must have pointer type) uses the special
372     /// Swift asynchronous context-pointer ABI treatment.  There can be at
373     /// most one parameter on a given function that uses this treatment.
374     SwiftAsyncContext,
375   };
376 
377   /// Assigned inheritance model for a class in the MS C++ ABI. Must match order
378   /// of spellings in MSInheritanceAttr.
379   enum class MSInheritanceModel {
380     Single = 0,
381     Multiple = 1,
382     Virtual = 2,
383     Unspecified = 3,
384   };
385 
386   llvm::StringRef getParameterABISpelling(ParameterABI kind);
387 
388   inline llvm::StringRef getAccessSpelling(AccessSpecifier AS) {
389     switch (AS) {
390     case AccessSpecifier::AS_public:
391       return "public";
392     case AccessSpecifier::AS_protected:
393       return "protected";
394     case AccessSpecifier::AS_private:
395       return "private";
396     case AccessSpecifier::AS_none:
397       return {};
398     }
399     llvm_unreachable("Unknown AccessSpecifier");
400   }
401 } // end namespace clang
402 
403 #endif // LLVM_CLANG_BASIC_SPECIFIERS_H
404