Sema: Variadic parameters are always @escaping and cannot be @autoclo… #4878
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Contributor
slavapestov
commented
Sep 20, 2016
slavapestov
commented
- Description: This fixes some oversights with the new @escaping attribute combined with varargs, as well as a long-standing issue with @autoclosure.
- Scope of the issue: Anyone who defines a variadic function taking closures would have had to previously write @escaping, because the default behavior produced an array of non-escaping closures, which confused the rest of the type checker.
- Risk: Low, just changes type resolution behavior during type checking. This is technically a source breaking change, but only on invalid code, I think.
- Reviewed by: @milseman
…sure A variadic parameter of function type must be @escaping -- we cannot reason about an array of non-escaping closures, so this was a safety hole. Also, attempting to define an @autoclosure variadic did not produce a diagnostic, but would fail later on if you actually tried to do anything with it. Let's ban this completely. Both changes are source breaking, but impact is limited to code that was already only marginally valid.
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@swift-ci Please test |
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@milseman Are you OK with taking this in? |
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I agree, LGTM |
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This did turn out to be source-breaking after all, SR-2907. |
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Yeah, we knew it was source breaking all along, but we also thought the old behavior was just wrong. |
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Ah, I thought we decided the old behavior was wrong for non-escaping closures, not for escaping closures. That is, there's no way to write the code in 3.0 that would do the "right" thing that 3.0.1 does. |
aaditya-chandrasekhar
pushed a commit
to val-verde/swift
that referenced
this pull request
Sep 30, 2022
[pull] swiftwasm-release/5.7 from release/5.7
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