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[Sema] Check for already existential type while resolving existential #59015

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Merged
merged 1 commit into from
May 24, 2022
Merged

[Sema] Check for already existential type while resolving existential #59015

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3 changes: 3 additions & 0 deletions include/swift/AST/DiagnosticsSema.def
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Original file line number Diff line number Diff line change
Expand Up @@ -4709,6 +4709,9 @@ ERROR(unchecked_not_inheritance_clause,none,
ERROR(unchecked_not_existential,none,
"'unchecked' attribute cannot apply to non-protocol type %0", (Type))

ERROR(redundant_any_in_existential,none,
"redundant 'any' has no effect on existential type %0",
(Type))
ERROR(any_not_existential,none,
"'any' has no effect on %select{concrete type|type parameter}0 %1",
(bool, Type))
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18 changes: 11 additions & 7 deletions lib/Sema/TypeCheckType.cpp
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Expand Up @@ -3987,7 +3987,7 @@ TypeResolver::resolveExistentialType(ExistentialTypeRepr *repr,
if (constraintType->hasError())
return ErrorType::get(getASTContext());

if (!constraintType->isExistentialType()) {
if (!constraintType->isConstraintType()) {
// Emit a tailored diagnostic for the incorrect optional
// syntax 'any P?' with a fix-it to add parenthesis.
auto wrapped = constraintType->getOptionalObjectType();
Expand All @@ -4001,14 +4001,18 @@ TypeResolver::resolveExistentialType(ExistentialTypeRepr *repr,
.fixItReplace(repr->getSourceRange(), fix);
return constraintType;
}

// Diagnose redundant `any` on an already existential type e.g. any (any P)
// with a fix-it to remove first any.
if (constraintType->is<ExistentialType>()) {
diagnose(repr->getLoc(), diag::redundant_any_in_existential, constraintType)
.fixItRemove(repr->getAnyLoc());
return constraintType;
}

auto anyStart = repr->getAnyLoc();
auto anyEnd = Lexer::getLocForEndOfToken(getASTContext().SourceMgr,
anyStart);
diagnose(repr->getLoc(), diag::any_not_existential,
constraintType->isTypeParameter(),
constraintType)
.fixItRemove({anyStart, anyEnd});
constraintType->isTypeParameter(), constraintType)
.fixItRemove(repr->getAnyLoc());
return constraintType;
}

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12 changes: 12 additions & 0 deletions test/type/explicit_existential.swift
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Expand Up @@ -329,3 +329,15 @@ func testEnumAssociatedValue() {
case c3((P) -> Void)
}
}

// https://github.com/apple/swift/issues/58920
typealias Iterator = any IteratorProtocol
var example: any Iterator = 5 // expected-error{{redundant 'any' has no effect on existential type 'Iterator' (aka 'IteratorProtocol')}} {{14-18=}}
// expected-error@-1{{value of type 'Int' does not conform to specified type 'IteratorProtocol'}}
var example1: any (any IteratorProtocol) = 5 // expected-error{{redundant 'any' has no effect on existential type 'any IteratorProtocol'}} {{15-19=}}
// expected-error@-1{{value of type 'Int' does not conform to specified type 'IteratorProtocol'}}

protocol PP {}
struct A : PP {}
let _: any PP = A() // Ok
let _: any (any PP) = A() // expected-error{{redundant 'any' has no effect on existential type 'any PP'}} {{8-12=}}