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Sema: Fix two problems in checkReferencedGenericParams() analysis #67566

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Merged
merged 1 commit into from
Jul 28, 2023
Merged

Sema: Fix two problems in checkReferencedGenericParams() analysis #67566

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19 changes: 19 additions & 0 deletions lib/Sema/TypeCheckGeneric.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -341,6 +341,25 @@ void TypeChecker::checkReferencedGenericParams(GenericContext *dc) {
ReferencedGenericParams.insert(ty->getCanonicalType());
return Action::SkipChildren;
}

// Skip the count type, which is always a generic parameter;
// we don't consider it a reference because it only binds the
// shape and not the metadata.
if (auto *expansionTy = ty->getAs<PackExpansionType>()) {
expansionTy->getPatternType().walk(*this);
return Action::SkipChildren;
}

// Don't walk into generic type alias substitutions. This does
// not constrain `T`:
//
// typealias Foo<T> = Int
// func foo<T>(_: Foo<T>) {}
if (auto *aliasTy = dyn_cast<TypeAliasType>(ty.getPointer())) {
Type(aliasTy->getSinglyDesugaredType()).walk(*this);
return Action::SkipChildren;
}

return Action::Continue;
}

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9 changes: 9 additions & 0 deletions test/type/pack_expansion.swift
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Expand Up @@ -65,6 +65,7 @@ struct Outer<each T> {
func packRef<each T>(_: repeat each T) where repeat each T: P {}

func packMemberRef<each T>(_: repeat (each T).T) where repeat each T: P {}
// expected-error@-1 {{generic parameter 'T' is not used in function signature}}

// expected-error@+1 {{'each' cannot be applied to non-pack type 'Int'}}{{31-35=}}
func invalidPackRefEachInt(_: each Int) {}
Expand Down Expand Up @@ -98,3 +99,11 @@ func golden<Z>(_ z: Z) {}
func hour<each T>(_ t: repeat each T) {
_ = (repeat golden(each t))
}

func unusedParameterPack1<each T: Sequence>(_: repeat (each T).Element) {}
// expected-error@-1 {{generic parameter 'T' is not used in function signature}}

typealias First<T, U> = T

func unusedParameterPack2<each T>(_: repeat First<Int, each T>) {}
// expected-error@-1 {{generic parameter 'T' is not used in function signature}}