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Using the same feature set logic as experimental features, provide feature names for "future" features, which are changes that will become available with Swift 6. Use the feature check when determining whether to implementation the feature instead of a language version check, and map existing flags for these features (when available) over to the feature set. As an internal implementation detail, this makes it easier to reason about when specific features are enabled (or not). If we decide to go with piecemeal adoption support for features, it can provide an alternative path to enabling features that feeds this mechanism.
69 lines
2.2 KiB
C++
69 lines
2.2 KiB
C++
//===--- Feature.h - Helpers related to Swift features ----------*- 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) 2014 - 2017 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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#ifndef SWIFT_BASIC_FEATURES_H
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#define SWIFT_BASIC_FEATURES_H
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#include "llvm/ADT/Optional.h"
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#include "llvm/ADT/StringRef.h"
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namespace swift {
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class LangOptions;
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/// Enumeration describing all of the named features.
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enum class Feature {
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#define LANGUAGE_FEATURE(FeatureName, SENumber, Description, Option) \
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FeatureName,
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#include "swift/Basic/Features.def"
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};
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constexpr unsigned numFeatures() {
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enum Features {
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#define LANGUAGE_FEATURE(FeatureName, SENumber, Description, Option) \
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FeatureName,
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#include "swift/Basic/Features.def"
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NumFeatures
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};
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return NumFeatures;
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}
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/// Determine whether the given feature is suppressible.
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bool isSuppressibleFeature(Feature feature);
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/// Determine the in-source name of the given feature.
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llvm::StringRef getFeatureName(Feature feature);
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/// Determine whether the first feature is more recent (and thus implies
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/// the existence of) the second feature. Only meaningful for suppressible
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/// features.
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inline bool featureImpliesFeature(Feature feature, Feature implied) {
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// Suppressible features are expected to be listed in order of
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// addition in Features.def.
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return (unsigned) feature < (unsigned) implied;
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}
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/// Get the feature corresponding to this "future" feature, if there is one.
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llvm::Optional<Feature> getFutureFeature(llvm::StringRef name);
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/// Get the feature corresponding to this "experimental" feature, if there is
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/// one.
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llvm::Optional<Feature> getExperimentalFeature(llvm::StringRef name);
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/// Get the major language version in which this feature was introduced, or
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/// \c None if it does not have such a version.
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llvm::Optional<unsigned> getFeatureLanguageVersion(Feature feature);
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}
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#endif // SWIFT_BASIC_FEATURES_H
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