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Existential Types Cannot Satisfy Superclass Bounds #58624

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Merged
merged 1 commit into from
May 3, 2022
Merged

Existential Types Cannot Satisfy Superclass Bounds #58624

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7 changes: 5 additions & 2 deletions lib/Sema/CSSimplify.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -3465,8 +3465,11 @@ ConstraintSystem::matchExistentialTypes(Type type1, Type type2,
if (!req)
return getTypeMatchFailure(locator);

if (type1->isPlaceholder() ||
req->getRequirementKind() == RequirementKind::Superclass)
// Superclass constraints are never satisfied by existentials,
// even those that contain the superclass a la `any C & P`.
if (!type1->isExistentialType() &&
(type1->isPlaceholder() ||
req->getRequirementKind() == RequirementKind::Superclass))
return getTypeMatchSuccess();

auto *fix = fixRequirementFailure(*this, type1, type2, locator);
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22 changes: 22 additions & 0 deletions test/Constraints/members.swift
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Expand Up @@ -753,3 +753,25 @@ func fSR14533(_ s: SR14533) {
// expected-error@-1{{value of type 'SR14533' has no member 'ys'}}
}
}

// rdar://92358570
class SomeClassBound {}
protocol ClassBoundProtocol: SomeClassBound {
}

struct RDAR92358570<Element> {}

extension RDAR92358570 where Element : SomeClassBound {
// expected-note@-1 2 {{where 'Element' = 'any ClassBoundProtocol', 'SomeClassBound' = 'AnyObject'}}
// expected-note@-2 2 {{where 'Element' = 'any SomeClassBound & ClassBoundProtocol', 'SomeClassBound' = 'AnyObject'}}
func doSomething() {}
static func doSomethingStatically() {}
}

func rdar92358570(_ x: RDAR92358570<ClassBoundProtocol>, _ y: RDAR92358570<SomeClassBound & ClassBoundProtocol>) {
x.doSomething() // expected-error {{referencing instance method 'doSomething()' on 'RDAR92358570' requires that 'any ClassBoundProtocol' inherit from 'AnyObject'}}
RDAR92358570<ClassBoundProtocol>.doSomethingStatically() // expected-error {{referencing static method 'doSomethingStatically()' on 'RDAR92358570' requires that 'any ClassBoundProtocol' inherit from 'AnyObject'}}

y.doSomething() // expected-error {{referencing instance method 'doSomething()' on 'RDAR92358570' requires that 'any SomeClassBound & ClassBoundProtocol' inherit from 'AnyObject'}}
RDAR92358570<SomeClassBound & ClassBoundProtocol>.doSomethingStatically() // expected-error {{referencing static method 'doSomethingStatically()' on 'RDAR92358570' requires that 'any SomeClassBound & ClassBoundProtocol' inherit from 'AnyObject'}}
}