1 //===--- Linkage.h - Linkage enumeration and utilities ----------*- C++ -*-===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 ///
10 /// \file
11 /// \brief Defines the Linkage enumeration and various utility functions.
12 ///
13 //===----------------------------------------------------------------------===//
14 #ifndef LLVM_CLANG_BASIC_LINKAGE_H
15 #define LLVM_CLANG_BASIC_LINKAGE_H
16
17 namespace clang {
18
19 /// \brief Describes the different kinds of linkage
20 /// (C++ [basic.link], C99 6.2.2) that an entity may have.
21 enum Linkage {
22 /// \brief No linkage, which means that the entity is unique and
23 /// can only be referred to from within its scope.
24 NoLinkage = 0,
25
26 /// \brief Internal linkage, which indicates that the entity can
27 /// be referred to from within the translation unit (but not other
28 /// translation units).
29 InternalLinkage,
30
31 /// \brief External linkage within a unique namespace.
32 ///
33 /// From the language perspective, these entities have external
34 /// linkage. However, since they reside in an anonymous namespace,
35 /// their names are unique to this translation unit, which is
36 /// equivalent to having internal linkage from the code-generation
37 /// point of view.
38 UniqueExternalLinkage,
39
40 /// \brief No linkage according to the standard, but is visible from other
41 /// translation units because of types defined in a inline function.
42 VisibleNoLinkage,
43
44 /// \brief External linkage, which indicates that the entity can
45 /// be referred to from other translation units.
46 ExternalLinkage
47 };
48
49 /// \brief Describes the different kinds of language linkage
50 /// (C++ [dcl.link]) that an entity may have.
51 enum LanguageLinkage {
52 CLanguageLinkage,
53 CXXLanguageLinkage,
54 NoLanguageLinkage
55 };
56
57 /// \brief A more specific kind of linkage than enum Linkage.
58 ///
59 /// This is relevant to CodeGen and AST file reading.
60 enum GVALinkage {
61 GVA_Internal,
62 GVA_C99Inline,
63 GVA_CXXInline,
64 GVA_StrongExternal,
65 GVA_TemplateInstantiation,
66 GVA_ExplicitTemplateInstantiation
67 };
68
isExternallyVisible(Linkage L)69 inline bool isExternallyVisible(Linkage L) {
70 return L == ExternalLinkage || L == VisibleNoLinkage;
71 }
72
getFormalLinkage(Linkage L)73 inline Linkage getFormalLinkage(Linkage L) {
74 if (L == UniqueExternalLinkage)
75 return ExternalLinkage;
76 if (L == VisibleNoLinkage)
77 return NoLinkage;
78 return L;
79 }
80
isExternalFormalLinkage(Linkage L)81 inline bool isExternalFormalLinkage(Linkage L) {
82 return getFormalLinkage(L) == ExternalLinkage;
83 }
84
85 /// \brief Compute the minimum linkage given two linkages.
86 ///
87 /// The linkage can be interpreted as a pair formed by the formal linkage and
88 /// a boolean for external visibility. This is just what getFormalLinkage and
89 /// isExternallyVisible return. We want the minimum of both components. The
90 /// Linkage enum is defined in an order that makes this simple, we just need
91 /// special cases for when VisibleNoLinkage would lose the visible bit and
92 /// become NoLinkage.
minLinkage(Linkage L1,Linkage L2)93 inline Linkage minLinkage(Linkage L1, Linkage L2) {
94 if (L2 == VisibleNoLinkage)
95 std::swap(L1, L2);
96 if (L1 == VisibleNoLinkage) {
97 if (L2 == InternalLinkage)
98 return NoLinkage;
99 if (L2 == UniqueExternalLinkage)
100 return NoLinkage;
101 }
102 return L1 < L2 ? L1 : L2;
103 }
104
105 } // end namespace clang
106
107 #endif // LLVM_CLANG_BASIC_LINKAGE_H
108