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[Sema] Check for extra optionals injected on checked cast subexprs when recording extraneous cast warnings #38800

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Merged
merged 1 commit into from
Aug 10, 2021
Merged

[Sema] Check for extra optionals injected on checked cast subexprs when recording extraneous cast warnings #38800

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8 changes: 6 additions & 2 deletions lib/Sema/CSSimplify.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -6636,8 +6636,12 @@ static ConstraintFix *maybeWarnAboutExtraneousCast(
}

// Except for forced cast expressions, if optionals are more than a single
// level difference, we don't need to record any fix.
if (!isExpr<ForcedCheckedCastExpr>(anchor) && extraOptionals > 1)
// level difference or there is a single level between the types but an extra
// level of optional is added to subexpr via OptionalEvaluationExpr, we don't
// need to record any fix.
if (!isExpr<ForcedCheckedCastExpr>(anchor) &&
(extraOptionals > 1 ||
isExpr<OptionalEvaluationExpr>(castExpr->getSubExpr())))
return nullptr;

// Always succeed
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14 changes: 14 additions & 0 deletions test/Constraints/casts.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -535,3 +535,17 @@ protocol PP2: PP1 { }
extension Optional: PP1 where Wrapped == PP2 { }

nil is PP1 // expected-error {{'nil' requires a contextual type}}

// SR-15039
enum ChangeType<T> {
case initial(T)
case delta(previous: T, next: T)
case unset

var delta: (previous: T?, next: T)? { nil }
}

extension ChangeType where T == String? {
var foo: String? { return self.delta?.previous as? String } // OK
var bar: String? { self.delta?.next }
}