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| //===- Linkage.h - Linkage enumeration and utilities ------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
/// \file
/// Defines the Linkage enumeration and various utility functions.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_CLANG_BASIC_LINKAGE_H
#define LLVM_CLANG_BASIC_LINKAGE_H
#include <utility>
namespace clang {
/// Describes the different kinds of linkage
/// (C++ [basic.link], C99 6.2.2) that an entity may have.
enum Linkage : unsigned char {
/// No linkage, which means that the entity is unique and
/// can only be referred to from within its scope.
NoLinkage = 0,
/// Internal linkage, which indicates that the entity can
/// be referred to from within the translation unit (but not other
/// translation units).
InternalLinkage,
/// External linkage within a unique namespace.
///
/// From the language perspective, these entities have external
/// linkage. However, since they reside in an anonymous namespace,
/// their names are unique to this translation unit, which is
/// equivalent to having internal linkage from the code-generation
/// point of view.
UniqueExternalLinkage,
/// No linkage according to the standard, but is visible from other
/// translation units because of types defined in a inline function.
VisibleNoLinkage,
/// Internal linkage according to the Modules TS, but can be referred
/// to from other translation units indirectly through inline functions and
/// templates in the module interface.
ModuleInternalLinkage,
/// Module linkage, which indicates that the entity can be referred
/// to from other translation units within the same module, and indirectly
/// from arbitrary other translation units through inline functions and
/// templates in the module interface.
ModuleLinkage,
/// External linkage, which indicates that the entity can
/// be referred to from other translation units.
ExternalLinkage
};
/// Describes the different kinds of language linkage
/// (C++ [dcl.link]) that an entity may have.
enum LanguageLinkage {
CLanguageLinkage,
CXXLanguageLinkage,
NoLanguageLinkage
};
/// A more specific kind of linkage than enum Linkage.
///
/// This is relevant to CodeGen and AST file reading.
enum GVALinkage {
GVA_Internal,
GVA_AvailableExternally,
GVA_DiscardableODR,
GVA_StrongExternal,
GVA_StrongODR
};
inline bool isDiscardableGVALinkage(GVALinkage L) {
return L <= GVA_DiscardableODR;
}
/// Do we know that this will be the only definition of this symbol (excluding
/// inlining-only definitions)?
inline bool isUniqueGVALinkage(GVALinkage L) {
return L == GVA_Internal || L == GVA_StrongExternal;
}
inline bool isExternallyVisible(Linkage L) {
return L >= VisibleNoLinkage;
}
inline Linkage getFormalLinkage(Linkage L) {
switch (L) {
case UniqueExternalLinkage:
return ExternalLinkage;
case VisibleNoLinkage:
return NoLinkage;
case ModuleInternalLinkage:
return InternalLinkage;
default:
return L;
}
}
inline bool isExternalFormalLinkage(Linkage L) {
return getFormalLinkage(L) == ExternalLinkage;
}
/// Compute the minimum linkage given two linkages.
///
/// The linkage can be interpreted as a pair formed by the formal linkage and
/// a boolean for external visibility. This is just what getFormalLinkage and
/// isExternallyVisible return. We want the minimum of both components. The
/// Linkage enum is defined in an order that makes this simple, we just need
/// special cases for when VisibleNoLinkage would lose the visible bit and
/// become NoLinkage.
inline Linkage minLinkage(Linkage L1, Linkage L2) {
if (L2 == VisibleNoLinkage)
std::swap(L1, L2);
if (L1 == VisibleNoLinkage) {
if (L2 == InternalLinkage)
return NoLinkage;
if (L2 == UniqueExternalLinkage)
return NoLinkage;
}
return L1 < L2 ? L1 : L2;
}
} // namespace clang
#endif // LLVM_CLANG_BASIC_LINKAGE_H
|