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Sema: Relax associated conformance availability checking #76053

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Merged
merged 1 commit into from
Aug 23, 2024
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Sema: Relax associated conformance availability checking #76053

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7 changes: 7 additions & 0 deletions lib/Sema/TypeCheckAvailability.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -295,6 +295,13 @@ ExportContext ExportContext::withExported(bool exported) const {
return copy;
}

ExportContext ExportContext::withRefinedAvailability(
const AvailabilityContext &availability) const {
auto copy = *this;
copy.RunningOSVersion.intersectWith(availability);
return copy;
}

std::optional<PlatformKind> ExportContext::getUnavailablePlatformKind() const {
if (Unavailable)
return PlatformKind(Platform);
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5 changes: 5 additions & 0 deletions lib/Sema/TypeCheckAvailability.h
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Expand Up @@ -153,6 +153,11 @@ class ExportContext {
/// That is, this will perform a 'bitwise and' on the 'exported' bit.
ExportContext withExported(bool exported) const;

/// Produce a new context with the same properties as this one, except the
/// availability context is constrained by \p availability if necessary.
ExportContext
withRefinedAvailability(const AvailabilityContext &availability) const;

DeclContext *getDeclContext() const { return DC; }

AvailabilityContext getAvailabilityContext() const {
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18 changes: 15 additions & 3 deletions lib/Sema/TypeCheckProtocol.cpp
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Expand Up @@ -4987,9 +4987,21 @@ static void ensureRequirementsAreSatisfied(ASTContext &ctx,
if (assocConf.isConcrete()) {
auto *concrete = assocConf.getConcrete();
auto replacementTy = dc->mapTypeIntoContext(concrete->getType());
diagnoseConformanceAvailability(conformance->getLoc(),
assocConf, where,
depTy, replacementTy);

// If this requirement has a dependent member type, only require the
// associated conformance to be as available as the requirement's
// associated type.
auto availability = AvailabilityContext::alwaysAvailable();
if (auto depMemberType = depTy->getAs<DependentMemberType>()) {
auto assocType = depMemberType->getAssocType();
availability.intersectWith(
TypeChecker::overApproximateAvailabilityAtLocation(
assocType->getLoc(), assocType->getDeclContext()));
}

diagnoseConformanceAvailability(
conformance->getLoc(), assocConf,
where.withRefinedAvailability(availability), depTy, replacementTy);
}

return false;
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61 changes: 61 additions & 0 deletions test/Sema/conformance_availability.swift
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Expand Up @@ -279,6 +279,15 @@ func passAvailableConformance1a(x: HasAvailableConformance1) {
_ = UsesHorse<HasAvailableConformance1>.self
}

// Always available conformance
struct HasAvailableConformance2: Horse {}

// Conformance available in macOS 200
struct HasAvailableConformance3 {}

@available(macOS 200, *)
extension HasAvailableConformance3: Horse {}

// Associated conformance with unavailability
protocol Rider {
associatedtype H : Horse
Expand Down Expand Up @@ -326,6 +335,58 @@ extension AssocConformanceAvailable4 : Rider {
typealias H = HasAvailableConformance1
}

@available(macOS 100, *)
protocol Saddle {
associatedtype H : Horse = HasAvailableConformance1
}

struct ConformsToSaddle1 : Saddle {}

struct ConformsToSaddle2 : Saddle {
typealias H = HasAvailableConformance2
}

struct ConformsToSaddle3 : Saddle {
// expected-error@-1 {{conformance of 'HasAvailableConformance3' to 'Horse' is only available in macOS 200 or newer}}
// expected-note@-2 {{add @available attribute to enclosing struct}}
// expected-note@-3 {{in associated type 'Self.H' (inferred as 'HasAvailableConformance3'}}
typealias H = HasAvailableConformance3
}

struct ConformsToSaddle4 : Saddle {
// expected-error@-1 {{conformance of 'HasAvailableConformance3' to 'Horse' is only available in macOS 200 or newer}}
// expected-note@-2 {{add @available attribute to enclosing struct}}
// expected-note@-3 {{in associated type 'Self.H' (inferred as 'HasAvailableConformance3'}}
@available(macOS 200, *)
typealias H = HasAvailableConformance3
}

protocol Barn {
@available(macOS 100, *)
associatedtype H : Horse = HasAvailableConformance1
}

struct ConformsToBarn1 : Barn {}

struct ConformsToBarn2 : Barn {
typealias H = HasAvailableConformance2
}

struct ConformsToBarn3 : Barn {
// expected-error@-1 {{conformance of 'HasAvailableConformance3' to 'Horse' is only available in macOS 200 or newer}}
// expected-note@-2 {{add @available attribute to enclosing struct}}
// expected-note@-3 {{in associated type 'Self.H' (inferred as 'HasAvailableConformance3'}}
typealias H = HasAvailableConformance3
}

struct ConformsToBarn4 : Barn {
// expected-error@-1 {{conformance of 'HasAvailableConformance3' to 'Horse' is only available in macOS 200 or newer}}
// expected-note@-2 {{add @available attribute to enclosing struct}}
// expected-note@-3 {{in associated type 'Self.H' (inferred as 'HasAvailableConformance3'}}
@available(macOS 200, *)
typealias H = HasAvailableConformance3
}

// Solution ranking should down-rank solutions involving unavailable conformances
protocol First {}
extension First {
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