Implement an unsafe expression to cover uses of unsafe constructs #78554
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Introduce an `unsafe` expression akin to `try` and `await` that notes
that there are unsafe constructs in the expression to the right-hand
side. Extend the effects checker to also check for unsafety along with
throwing and async operations. This will result in diagnostics like
the following:
10 | func sum() -> Int {
11 | withUnsafeBufferPointer { buffer in
12 | let value = buffer[0]
| | `- note: reference to unsafe subscript 'subscript(_:)'
| |- warning: expression uses unsafe constructs but is not marked with 'unsafe'
| `- note: reference to parameter 'buffer' involves unsafe type 'UnsafeBufferPointer<Int>'
13 | tryWithP(X())
14 | return fastAdd(buffer.baseAddress, buffer.count)
These will come with a Fix-It that inserts `unsafe` into the proper
place. There's also a warning that appears when `unsafe` doesn't cover
any unsafe code, making it easier to clean up extraneous `unsafe`.
This approach requires that `@unsafe` be present on any declaration
that involves unsafe constructs within its signature. Outside of the
signature, the `unsafe` expression is used to identify unsafe code.
With the move to unsafe effects, we no longer model `unsafe` as an availability problem. Remove all of that supporting code.
DougGregor
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Introduce an
unsafeexpression akin totryandawaitthat notes that there are unsafe constructs in the expression to the right-hand side. Extend the effects checker to also check for unsafety along with throwing and async operations. This will result in diagnostics like the following:These will come with a Fix-It that inserts
unsafeinto the proper place. There's also a warning that appears whenunsafedoesn't cover any unsafe code, making it easier to clean up extraneousunsafe.This approach requires that
@unsafebe present on any declaration that involves unsafe constructs within its signature. Outside of the signature, theunsafeexpression is used to identify unsafe code.