Stabilize `arbitrary_enum_discriminant` by fee1-dead · Pull Request #86860 · rus...
source link: https://github.com/rust-lang/rust/pull/86860
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Closes #60553.
Stabilization Report
copied from #60553 (comment)
Summary
Enables a user to specify explicit discriminants on arbitrary enums.
Previously, this was hard to achieve:
#[repr(u8)]
enum Foo {
A(u8) = 0,
B(i8) = 1,
C(bool) = 42,
}Someone would need to add 41 hidden variants in between as a workaround with implicit discriminants.
In conjunction with RFC 2195, this feature would provide more flexibility for FFI and unsafe code involving enums.
Test cases
Most tests are in src/test/ui/enum-discriminant, there are two historical tests that are now covered by the feature (removed by this pr due to them being obsolete).
Edge cases
The feature is well defined and does not have many edge cases.
One edge case was related to another unstable feature named repr128 and is resolved.
Previous PRs
The implementation PR added documentation to the Unstable Book, rust-lang/reference#1055 was opened as a continuation of rust-lang/reference#639.
Resolution of unresolved questions
The questions are resolved in #60553 (comment).
(someone please add needs-fcp)
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