1 //===- ParsedAttrInfo.h - Info needed to parse an attribute -----*- 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 // This file defines the ParsedAttrInfo class, which dictates how to
10 // parse an attribute. This class is the one that plugins derive to
11 // define a new attribute.
12 //
13 //===----------------------------------------------------------------------===//
14 
15 #ifndef LLVM_CLANG_BASIC_PARSEDATTRINFO_H
16 #define LLVM_CLANG_BASIC_PARSEDATTRINFO_H
17 
18 #include "clang/Basic/AttrSubjectMatchRules.h"
19 #include "clang/Basic/AttributeCommonInfo.h"
20 #include "llvm/ADT/ArrayRef.h"
21 #include "llvm/Support/Registry.h"
22 #include <climits>
23 #include <list>
24 
25 namespace clang {
26 
27 class Decl;
28 class LangOptions;
29 class ParsedAttr;
30 class Sema;
31 class Stmt;
32 class TargetInfo;
33 
34 struct ParsedAttrInfo {
35   /// Corresponds to the Kind enum.
36   unsigned AttrKind : 16;
37   /// The number of required arguments of this attribute.
38   unsigned NumArgs : 4;
39   /// The number of optional arguments of this attributes.
40   unsigned OptArgs : 4;
41   /// The number of non-fake arguments specified in the attribute definition.
42   unsigned NumArgMembers : 4;
43   /// True if the parsing does not match the semantic content.
44   unsigned HasCustomParsing : 1;
45   // True if this attribute accepts expression parameter pack expansions.
46   unsigned AcceptsExprPack : 1;
47   /// True if this attribute is only available for certain targets.
48   unsigned IsTargetSpecific : 1;
49   /// True if this attribute applies to types.
50   unsigned IsType : 1;
51   /// True if this attribute applies to statements.
52   unsigned IsStmt : 1;
53   /// True if this attribute has any spellings that are known to gcc.
54   unsigned IsKnownToGCC : 1;
55   /// True if this attribute is supported by #pragma clang attribute.
56   unsigned IsSupportedByPragmaAttribute : 1;
57   /// The syntaxes supported by this attribute and how they're spelled.
58   struct Spelling {
59     AttributeCommonInfo::Syntax Syntax;
60     const char *NormalizedFullName;
61   };
62   ArrayRef<Spelling> Spellings;
63   // The names of the known arguments of this attribute.
64   ArrayRef<const char *> ArgNames;
65 
66 protected:
67   constexpr ParsedAttrInfo(AttributeCommonInfo::Kind AttrKind =
68                                AttributeCommonInfo::NoSemaHandlerAttribute)
69       : AttrKind(AttrKind), NumArgs(0), OptArgs(0), NumArgMembers(0),
70         HasCustomParsing(0), AcceptsExprPack(0), IsTargetSpecific(0), IsType(0),
71         IsStmt(0), IsKnownToGCC(0), IsSupportedByPragmaAttribute(0) {}
72 
73   constexpr ParsedAttrInfo(AttributeCommonInfo::Kind AttrKind, unsigned NumArgs,
74                            unsigned OptArgs, unsigned NumArgMembers,
75                            unsigned HasCustomParsing, unsigned AcceptsExprPack,
76                            unsigned IsTargetSpecific, unsigned IsType,
77                            unsigned IsStmt, unsigned IsKnownToGCC,
78                            unsigned IsSupportedByPragmaAttribute,
79                            ArrayRef<Spelling> Spellings,
80                            ArrayRef<const char *> ArgNames)
81       : AttrKind(AttrKind), NumArgs(NumArgs), OptArgs(OptArgs),
82         NumArgMembers(NumArgMembers), HasCustomParsing(HasCustomParsing),
83         AcceptsExprPack(AcceptsExprPack), IsTargetSpecific(IsTargetSpecific),
84         IsType(IsType), IsStmt(IsStmt), IsKnownToGCC(IsKnownToGCC),
85         IsSupportedByPragmaAttribute(IsSupportedByPragmaAttribute),
86         Spellings(Spellings), ArgNames(ArgNames) {}
87 
88 public:
89   virtual ~ParsedAttrInfo() = default;
90 
91   /// Check if this attribute has specified spelling.
92   bool hasSpelling(AttributeCommonInfo::Syntax Syntax, StringRef Name) const {
93     return llvm::any_of(Spellings, [&](const Spelling &S) {
94       return (S.Syntax == Syntax && S.NormalizedFullName == Name);
95     });
96   }
97 
98   /// Check if this attribute appertains to D, and issue a diagnostic if not.
99   virtual bool diagAppertainsToDecl(Sema &S, const ParsedAttr &Attr,
100                                     const Decl *D) const {
101     return true;
102   }
103   /// Check if this attribute appertains to St, and issue a diagnostic if not.
104   virtual bool diagAppertainsToStmt(Sema &S, const ParsedAttr &Attr,
105                                     const Stmt *St) const {
106     return true;
107   }
108   /// Check if the given attribute is mutually exclusive with other attributes
109   /// already applied to the given declaration.
110   virtual bool diagMutualExclusion(Sema &S, const ParsedAttr &A,
111                                    const Decl *D) const {
112     return true;
113   }
114   /// Check if this attribute is allowed by the language we are compiling.
115   virtual bool acceptsLangOpts(const LangOptions &LO) const { return true; }
116 
117   /// Check if this attribute is allowed when compiling for the given target.
118   virtual bool existsInTarget(const TargetInfo &Target) const { return true; }
119   /// Convert the spelling index of Attr to a semantic spelling enum value.
120   virtual unsigned
121   spellingIndexToSemanticSpelling(const ParsedAttr &Attr) const {
122     return UINT_MAX;
123   }
124   /// Returns true if the specified parameter index for this attribute in
125   /// Attr.td is an ExprArgument or VariadicExprArgument, or a subclass thereof;
126   /// returns false otherwise.
127   virtual bool isParamExpr(size_t N) const { return false; }
128   /// Populate Rules with the match rules of this attribute.
129   virtual void getPragmaAttributeMatchRules(
130       llvm::SmallVectorImpl<std::pair<attr::SubjectMatchRule, bool>> &Rules,
131       const LangOptions &LangOpts) const {}
132 
133   enum AttrHandling { NotHandled, AttributeApplied, AttributeNotApplied };
134   /// If this ParsedAttrInfo knows how to handle this ParsedAttr applied to this
135   /// Decl then do so and return either AttributeApplied if it was applied or
136   /// AttributeNotApplied if it wasn't. Otherwise return NotHandled.
137   virtual AttrHandling handleDeclAttribute(Sema &S, Decl *D,
138                                            const ParsedAttr &Attr) const {
139     return NotHandled;
140   }
141 
142   static const ParsedAttrInfo &get(const AttributeCommonInfo &A);
143   static ArrayRef<const ParsedAttrInfo *> getAllBuiltin();
144 };
145 
146 typedef llvm::Registry<ParsedAttrInfo> ParsedAttrInfoRegistry;
147 
148 const std::list<std::unique_ptr<ParsedAttrInfo>> &getAttributePluginInstances();
149 
150 } // namespace clang
151 
152 #endif // LLVM_CLANG_BASIC_PARSEDATTRINFO_H
153