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Remove Ord from ClosureKind
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Using `Ord` to accomplish a meaning of subset relationship
can be hard to read. The existing uses for that are easily
replaced with a `match`, and in my opinion, more readable
without needing to resorting to comments to explain the
intention.
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fee1-dead committed Mar 9, 2024
1 parent 09bc67b commit 7e1969a
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Showing 4 changed files with 42 additions and 28 deletions.
17 changes: 12 additions & 5 deletions compiler/rustc_hir_typeck/src/closure.rs
Original file line number Diff line number Diff line change
Expand Up @@ -19,7 +19,7 @@ use rustc_target::spec::abi::Abi;
use rustc_trait_selection::traits;
use rustc_trait_selection::traits::error_reporting::ArgKind;
use rustc_trait_selection::traits::error_reporting::InferCtxtExt as _;
use std::cmp;
use rustc_type_ir::ClosureKind;
use std::iter;
use std::ops::ControlFlow;

Expand Down Expand Up @@ -437,10 +437,17 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
};

if let Some(found_kind) = found_kind {
expected_kind = Some(
expected_kind
.map_or_else(|| found_kind, |current| cmp::min(current, found_kind)),
);
// always use the closure kind that is more permissive.
match (expected_kind, found_kind) {
(None, _) => expected_kind = Some(found_kind),
(Some(ClosureKind::FnMut), ClosureKind::Fn) => {
expected_kind = Some(ClosureKind::Fn)
}
(Some(ClosureKind::FnOnce), ClosureKind::Fn | ClosureKind::FnMut) => {
expected_kind = Some(found_kind)
}
_ => {}
}
}
}
}
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2 changes: 1 addition & 1 deletion compiler/rustc_middle/src/ty/instance.rs
Original file line number Diff line number Diff line change
Expand Up @@ -30,7 +30,7 @@ pub struct Instance<'tcx> {
pub args: GenericArgsRef<'tcx>,
}

#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)]
#[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
#[derive(TyEncodable, TyDecodable, HashStable, TypeFoldable, TypeVisitable, Lift)]
pub enum InstanceDef<'tcx> {
/// A user-defined callable item.
Expand Down
37 changes: 20 additions & 17 deletions compiler/rustc_ty_utils/src/instance.rs
Original file line number Diff line number Diff line change
Expand Up @@ -7,6 +7,7 @@ use rustc_middle::ty::GenericArgsRef;
use rustc_middle::ty::{self, Instance, TyCtxt, TypeVisitableExt};
use rustc_span::sym;
use rustc_trait_selection::traits;
use rustc_type_ir::ClosureKind;
use traits::{translate_args, Reveal};

use crate::errors::UnexpectedFnPtrAssociatedItem;
Expand Down Expand Up @@ -296,23 +297,25 @@ fn resolve_associated_item<'tcx>(
{
match *rcvr_args.type_at(0).kind() {
ty::CoroutineClosure(coroutine_closure_def_id, args) => {
// If we're computing `AsyncFnOnce`/`AsyncFnMut` for a by-ref closure,
// or `AsyncFnOnce` for a by-mut closure, then construct a new body that
// has the right return types.
//
// Specifically, `AsyncFnMut` for a by-ref coroutine-closure just needs
// to have its input and output types fixed (`&mut self` and returning
// `i16` coroutine kind).
if target_kind > args.as_coroutine_closure().kind() {
Some(Instance {
def: ty::InstanceDef::ConstructCoroutineInClosureShim {
coroutine_closure_def_id,
target_kind,
},
args,
})
} else {
Some(Instance::new(coroutine_closure_def_id, args))
match (target_kind, args.as_coroutine_closure().kind()) {
(ClosureKind::FnOnce | ClosureKind::FnMut, ClosureKind::Fn)
| (ClosureKind::FnOnce, ClosureKind::FnMut) => {
// If we're computing `AsyncFnOnce`/`AsyncFnMut` for a by-ref closure,
// or `AsyncFnOnce` for a by-mut closure, then construct a new body that
// has the right return types.
//
// Specifically, `AsyncFnMut` for a by-ref coroutine-closure just needs
// to have its input and output types fixed (`&mut self` and returning
// `i16` coroutine kind).
Some(Instance {
def: ty::InstanceDef::ConstructCoroutineInClosureShim {
coroutine_closure_def_id,
target_kind,
},
args,
})
}
_ => Some(Instance::new(coroutine_closure_def_id, args)),
}
}
ty::Closure(closure_def_id, args) => {
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14 changes: 9 additions & 5 deletions compiler/rustc_type_ir/src/lib.rs
Original file line number Diff line number Diff line change
Expand Up @@ -369,12 +369,9 @@ rustc_index::newtype_index! {
///
/// You can get the environment type of a closure using
/// `tcx.closure_env_ty()`.
#[derive(Clone, Copy, PartialOrd, Ord, PartialEq, Eq, Hash, Debug)]
#[derive(Clone, Copy, PartialEq, Eq, Hash, Debug)]
#[cfg_attr(feature = "nightly", derive(Encodable, Decodable, HashStable_NoContext))]
pub enum ClosureKind {
// Warning: Ordering is significant here! The ordering is chosen
// because the trait Fn is a subtrait of FnMut and so in turn, and
// hence we order it so that Fn < FnMut < FnOnce.
Fn,
FnMut,
FnOnce,
Expand All @@ -394,8 +391,15 @@ impl ClosureKind {

/// Returns `true` if a type that impls this closure kind
/// must also implement `other`.
#[rustfmt::skip]
pub fn extends(self, other: ClosureKind) -> bool {
self <= other
use ClosureKind::*;
match (self, other) {
(Fn, Fn | FnMut | FnOnce)
| (FnMut, FnMut | FnOnce)
| (FnOnce, FnOnce) => true,
_ => false,
}
}
}

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