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| author | bors <bors@rust-lang.org> | 2021-08-18 01:00:17 +0000 |
|---|---|---|
| committer | bors <bors@rust-lang.org> | 2021-08-18 01:00:17 +0000 |
| commit | 02b27f1e70fc60a8f2aa0982e80d7cde5889112e (patch) | |
| tree | 065c73132ec35f5b5bd53d02f0734b81cbf444ed /compiler/rustc_error_codes | |
| parent | adf168844791b213383b18d10515eaee88695f7d (diff) | |
| parent | 7a62f29f3171767090949778ce0f161e930706b9 (diff) | |
| download | rust-02b27f1e70fc60a8f2aa0982e80d7cde5889112e.tar.gz rust-02b27f1e70fc60a8f2aa0982e80d7cde5889112e.zip | |
Auto merge of #86860 - fee1-dead:stabilize, r=LeSeulArtichaut
Stabilize `arbitrary_enum_discriminant`
Closes #60553.
----
## Stabilization Report
_copied from https://github.com/rust-lang/rust/issues/60553#issuecomment-865922311_
### Summary
Enables a user to specify *explicit* discriminants on arbitrary enums.
Previously, this was hard to achieve:
```rust
#[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](https://github.com/rust-lang/rfcs/blob/master/text/2195-really-tagged-unions.md), this feature would provide more flexibility for FFI and unsafe code involving enums.
### Test cases
Most tests are in [`src/test/ui/enum-discriminant`](https://github.com/rust-lang/rust/tree/master/src/test/ui/enum-discriminant), there are two [historical](https://github.com/rust-lang/rust/blob/master/src/test/ui/parser/tag-variant-disr-non-nullary.rs) [tests](https://github.com/rust-lang/rust/blob/master/src/test/ui/parser/issue-17383.rs) 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](https://github.com/rust-lang/rust/issues/70509) was related to another unstable feature named `repr128` and is resolved.
### Previous PRs
The [implementation PR](https://github.com/rust-lang/rust/pull/60732) added documentation to the Unstable Book, https://github.com/rust-lang/reference/pull/1055 was opened as a continuation of https://github.com/rust-lang/reference/pull/639.
### Resolution of unresolved questions
The questions are resolved in https://github.com/rust-lang/rust/issues/60553#issuecomment-511235271.
----
(someone please add `needs-fcp`)
Diffstat (limited to 'compiler/rustc_error_codes')
| -rw-r--r-- | compiler/rustc_error_codes/src/error_codes/E0732.md | 4 |
1 files changed, 0 insertions, 4 deletions
diff --git a/compiler/rustc_error_codes/src/error_codes/E0732.md b/compiler/rustc_error_codes/src/error_codes/E0732.md index 7347e6654c5..9536fdbf0df 100644 --- a/compiler/rustc_error_codes/src/error_codes/E0732.md +++ b/compiler/rustc_error_codes/src/error_codes/E0732.md @@ -3,8 +3,6 @@ An `enum` with a discriminant must specify a `#[repr(inttype)]`. Erroneous code example: ```compile_fail,E0732 -#![feature(arbitrary_enum_discriminant)] - enum Enum { // error! Unit = 1, Tuple() = 2, @@ -20,8 +18,6 @@ is a well-defined way to extract a variant's discriminant from a value; for instance: ``` -#![feature(arbitrary_enum_discriminant)] - #[repr(u8)] enum Enum { Unit = 3, |