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040050a6c7
MSVC did not like the original code and would fail to build as: ``` swift\include\swift/Basic/Located.h(50): error C2995: 'bool swift::operator ==(const swift::Located<T> &,const swift::Located<T> &)': function template has already been defined swift\include\swift/Basic/Located.h(50): note: see declaration of 'swift::operator ==' llvm\include\llvm/Support/TrailingObjects.h(76): note: see reference to class template instantiation 'swift::Located<swift::Identifier>' being compiled llvm\include\llvm/Support/TrailingObjects.h(233): note: see reference to class template instantiation 'llvm::trailing_objects_internal::AlignmentCalcHelper<swift::Located<swift::Identifier>>' being compiled swift\include\swift/AST/Decl.h(1512): note: see reference to class template instantiation 'llvm::TrailingObjects<swift::ImportDecl,swift::Located<swift::Identifier>>' being compiled ``` The original code is odd. There appears to be some unnecessary complexity. First, the member function is marked as a friend of a `struct` type which does not change the member's visibility, thus all the members are `public`, and the function need not be friended. Second, the function is templated over the same parameter type, which means that the original template parameter could be used and the standard member equality operator could be used rather than the free-standing form. It is unclear why the member equality operator is insufficient, and the extraneous template instatiations here seem wasteful. Out-of-line the free-standing form and not mark it as a friend to restore the build. Switching to a member form can be a follow up change.
86 lines
2.8 KiB
C++
86 lines
2.8 KiB
C++
//===--- Located.h - Source Location and Associated Value ----------*- C++ -*-===//
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//
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// This source file is part of the Swift.org open source project
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//
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// Copyright (c) 2019 Apple Inc. and the Swift project authors
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// Licensed under Apache License v2.0 with Runtime Library Exception
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//
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// See https://swift.org/LICENSE.txt for license information
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// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
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//
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//===----------------------------------------------------------------------===//
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//
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// Provides a currency data type Located<T> that should be used instead
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// of std::pair<T, SourceLoc>.
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//
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//===----------------------------------------------------------------------===//
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#ifndef SWIFT_BASIC_LOCATED_H
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#define SWIFT_BASIC_LOCATED_H
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#include "swift/Basic/Debug.h"
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#include "swift/Basic/LLVM.h"
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#include "swift/Basic/SourceLoc.h"
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namespace swift {
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/// A currency type for keeping track of items which were found in the source code.
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/// Several parts of the compiler need to keep track of a `SourceLoc` corresponding
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/// to an item, in case they need to report some diagnostics later. For example,
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/// the ClangImporter needs to keep track of where imports were originally written.
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/// Located makes it easy to do so while making the code more readable, compared to
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/// using `std::pair`.
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template <typename T>
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struct Located {
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/// The main item whose source location is being tracked.
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T Item;
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/// The original source location from which the item was parsed.
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SourceLoc Loc;
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Located() : Item(), Loc() {}
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Located(T Item, SourceLoc loc) : Item(Item), Loc(loc) {}
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SWIFT_DEBUG_DUMP;
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void dump(raw_ostream &os) const;
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};
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template <typename T>
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bool operator ==(const Located<T> &lhs, const Located<T> &rhs) {
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return lhs.Item == rhs.Item && lhs.Loc == rhs.Loc;
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}
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} // end namespace swift
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namespace llvm {
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template <typename T> struct DenseMapInfo;
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template<typename T>
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struct DenseMapInfo<swift::Located<T>> {
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static inline swift::Located<T> getEmptyKey() {
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return swift::Located<T>(DenseMapInfo<T>::getEmptyKey(),
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DenseMapInfo<swift::SourceLoc>::getEmptyKey());
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}
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static inline swift::Located<T> getTombstoneKey() {
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return swift::Located<T>(DenseMapInfo<T>::getTombstoneKey(),
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DenseMapInfo<swift::SourceLoc>::getTombstoneKey());
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}
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static unsigned getHashValue(const swift::Located<T> &LocatedVal) {
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return combineHashValue(DenseMapInfo<T>::getHashValue(LocatedVal.Item),
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DenseMapInfo<swift::SourceLoc>::getHashValue(LocatedVal.Loc));
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}
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static bool isEqual(const swift::Located<T> &LHS, const swift::Located<T> &RHS) {
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return DenseMapInfo<T>::isEqual(LHS.Item, RHS.Item) &&
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DenseMapInfo<T>::isEqual(LHS.Loc, RHS.Loc);
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}
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};
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} // namespace llvm
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#endif // SWIFT_BASIC_LOCATED_H
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