Disallow @_lifetime(borrow) for trivial 'inout' arguments #82189
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To avoid diff/merge confusion.
@_lifetime(borrow holder) // ERROR
func test(holder: inout Holder) -> NE
Fixes rdar://153040843 ([nonescapable] disallow @_lifetime(borrow)
for trivial 'inout' arguments)
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@swift-ci test |
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@swift-ci test |
meg-gupta
reviewed
Jun 12, 2025
| // An owned/consumed BitwiseCopyable value can be effectively borrowed | ||
| // because its lifetime can be indefinitely extended. | ||
| if (loweredOwnership == ValueOwnership::Owned | ||
| && isBitwiseCopyable(type, ctx)) { |
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Shouldn't the same rule apply for @_lifetime(&) ? In which case we will need a similar check when kind == ParsedLifetimeDependenceKind::Inout
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struct C {}
struct NE : ~Escapable {
@_lifetime(immortal)
init() {}
}
@_lifetime(&c)
func foo(_ c: consuming C) -> NE {
NE()
}
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I don't think this should be legal:
@_lifetime(&c)
func foo(_ c: consuming C) -> NE {
We have a special case for BitwiseCopyable because they are frequently used in initializers where the ownership defaults to consuming but the only legal way to express the dependency is
@_lifetime(borrow c)
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I left a minor comment on inout lifetime dependencies. These changes itself lgtm. |
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[NFC] LifetimeDependence: fix indentation
To avoid diff/merge confusion.
Disallow @_lifetime(borrow) for trivial 'inout' arguments
@_lifetime(borrow holder) // ERROR
func test(holder: inout Holder) -> NE
Fixes rdar://153040843 ([nonescapable] disallow @_lifetime(borrow)
for trivial 'inout' arguments)