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| author | Matthias Krüger <matthias.krueger@famsik.de> | 2023-12-05 16:08:35 +0100 |
|---|---|---|
| committer | GitHub <noreply@github.com> | 2023-12-05 16:08:35 +0100 |
| commit | 81b6263dd03aa9288a03178a4ec556922d5332c4 (patch) | |
| tree | 935ce85c8242e296b4e9c9dd3f862e978e8d6763 /compiler/rustc_feature/src | |
| parent | fddda14ac0345c1d0ab602d6016b976c972aa643 (diff) | |
| parent | 5e470db05cc842593c7d2e59bc5c2e8ae71a7025 (diff) | |
| download | rust-81b6263dd03aa9288a03178a4ec556922d5332c4.tar.gz rust-81b6263dd03aa9288a03178a4ec556922d5332c4.zip | |
Rollup merge of #118598 - Nadrieril:remove_precise_pointer_size_matching, r=davidtwco
Remove the `precise_pointer_size_matching` feature gate
`usize` and `isize` are special for pattern matching because their range might depend on the platform. To make code portable across platforms, the following is never considered exhaustive:
```rust
let x: usize = ...;
match x {
0..=18446744073709551615 => {}
}
```
Because of how rust handles constants, this also unfortunately counts `0..=usize::MAX` as non-exhaustive. The [`precise_pointer_size_matching`](https://github.com/rust-lang/rust/issues/56354) feature gate was introduced both for this convenience and for the possibility that the lang team could decide to allow the above.
Since then, [half-open range patterns](https://github.com/rust-lang/rust/issues/67264) have been implemented, and since #116692 they correctly support `usize`/`isize`:
```rust
match 0usize { // exhaustive!
0..5 => {}
5.. => {}
}
```
I believe this subsumes all the use cases of the feature gate. Moreover no attempt has been made to stabilize it in the 5 years of its existence. I therefore propose we retire this feature gate.
Closes https://github.com/rust-lang/rust/issues/56354
Diffstat (limited to 'compiler/rustc_feature/src')
| -rw-r--r-- | compiler/rustc_feature/src/removed.rs | 3 | ||||
| -rw-r--r-- | compiler/rustc_feature/src/unstable.rs | 2 |
2 files changed, 3 insertions, 2 deletions
diff --git a/compiler/rustc_feature/src/removed.rs b/compiler/rustc_feature/src/removed.rs index 4385e745bac..c0d3fc3fae0 100644 --- a/compiler/rustc_feature/src/removed.rs +++ b/compiler/rustc_feature/src/removed.rs @@ -158,6 +158,9 @@ declare_features! ( /// Allows using `#[plugin_registrar]` on functions. (removed, plugin_registrar, "1.54.0", Some(29597), None, Some("plugins are no longer supported")), + /// Allows exhaustive integer pattern matching with `usize::MAX`/`isize::MIN`/`isize::MAX`. + (removed, precise_pointer_size_matching, "1.32.0", Some(56354), None, + Some("removed in favor of half-open ranges")), (removed, proc_macro_expr, "1.27.0", Some(54727), None, Some("subsumed by `#![feature(proc_macro_hygiene)]`")), (removed, proc_macro_gen, "1.27.0", Some(54727), None, diff --git a/compiler/rustc_feature/src/unstable.rs b/compiler/rustc_feature/src/unstable.rs index dee68bff21d..1d4fa9c75d9 100644 --- a/compiler/rustc_feature/src/unstable.rs +++ b/compiler/rustc_feature/src/unstable.rs @@ -543,8 +543,6 @@ declare_features! ( (unstable, offset_of_enum, "1.75.0", Some(106655), None), /// Allows using `#[optimize(X)]`. (unstable, optimize_attribute, "1.34.0", Some(54882), None), - /// Allows exhaustive integer pattern matching on `usize` and `isize`. - (unstable, precise_pointer_size_matching, "1.32.0", Some(56354), None), /// Allows macro attributes on expressions, statements and non-inline modules. (unstable, proc_macro_hygiene, "1.30.0", Some(54727), None), /// Allows `&raw const $place_expr` and `&raw mut $place_expr` expressions. |