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[Type checker] The superclass of a superclass constraint can have type parameters #8293

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Merged
merged 1 commit into from
Mar 23, 2017
Merged

[Type checker] The superclass of a superclass constraint can have type parameters #8293

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21 changes: 10 additions & 11 deletions lib/Sema/TypeCheckGeneric.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -631,17 +631,16 @@ static void checkReferencedGenericParams(GenericContext *dc,

auto requirements = sig->getRequirements();
for (auto req : requirements) {
if (req.getKind() == RequirementKind::SameType) {
// Same type requirements may allow for generic
// inference, even if this generic parameter
// is not mentioned in the function signature.
// TODO: Make the test more precise.
auto left = req.getFirstType();
auto right = req.getSecondType();
// For now consider any references inside requirements
// as a possibility to infer the generic type.
left.visit(visitorFn);
right.visit(visitorFn);
switch (req.getKind()) {
case RequirementKind::SameType:
case RequirementKind::Superclass:
req.getSecondType().visit(visitorFn);
LLVM_FALLTHROUGH;

case RequirementKind::Conformance:
case RequirementKind::Layout:
req.getFirstType().visit(visitorFn);
break;
}
}

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5 changes: 5 additions & 0 deletions test/Generics/unbound.swift
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Expand Up @@ -67,3 +67,8 @@ func callfoor20792596<T>(x: T) -> T {
return foor20792596(x) // expected-error {{generic parameter 'T' could not be inferred}}
}

// <rdar://problem/31181895> parameter "not used in function signature" when part of a superclass constraint
struct X1<T> {
func bar<U>() where T: X2<U> {}
}
class X2<T> {}