From 955064b6aaa5c24e980328f9d9fbe731cc29636c Mon Sep 17 00:00:00 2001
From: Jonas Schievink <jonasschievink@gmail.com>
Date: Tue, 1 Jun 2021 21:33:14 +0200
Subject: [PATCH] Implement `#[rustc_skip_array_during_method_dispatch]`
---
crates/hir_def/src/data.rs | 14 +++++-
crates/hir_ty/src/method_resolution.rs | 16 ++++++-
crates/hir_ty/src/tests/method_resolution.rs | 49 ++++++++++++++++++++
3 files changed, 77 insertions(+), 2 deletions(-)
diff --git a/crates/hir_def/src/data.rs b/crates/hir_def/src/data.rs
index d2bb381be02..2f06a6e29ac 100644
--- a/crates/hir_def/src/data.rs
+++ b/crates/hir_def/src/data.rs
@@ -143,6 +143,7 @@ pub struct TraitData {
pub is_auto: bool,
pub is_unsafe: bool,
pub visibility: RawVisibility,
+ pub skip_array_during_method_dispatch: bool,
}
impl TraitData {
@@ -157,6 +158,10 @@ impl TraitData {
let container = AssocContainerId::TraitId(tr);
let visibility = item_tree[tr_def.visibility].clone();
let mut expander = Expander::new(db, tr_loc.id.file_id(), module_id);
+ let skip_array_during_method_dispatch = item_tree
+ .attrs(db, tr_loc.container.krate(), ModItem::from(tr_loc.id.value).into())
+ .by_key("rustc_skip_array_during_method_dispatch")
+ .exists();
let items = collect_items(
db,
@@ -168,7 +173,14 @@ impl TraitData {
100,
);
- Arc::new(TraitData { name, items, is_auto, is_unsafe, visibility })
+ Arc::new(TraitData {
+ name,
+ items,
+ is_auto,
+ is_unsafe,
+ visibility,
+ skip_array_during_method_dispatch,
+ })
}
pub fn associated_types(&self) -> impl Iterator<Item = TypeAliasId> + '_ {
diff --git a/crates/hir_ty/src/method_resolution.rs b/crates/hir_ty/src/method_resolution.rs
index af6b6cda709..a23527f7df2 100644
--- a/crates/hir_ty/src/method_resolution.rs
+++ b/crates/hir_ty/src/method_resolution.rs
@@ -5,7 +5,7 @@
use std::{iter, sync::Arc};
use arrayvec::ArrayVec;
-use base_db::CrateId;
+use base_db::{CrateId, Edition};
use chalk_ir::{cast::Cast, Mutability, UniverseIndex};
use hir_def::{
lang_item::LangItemTarget, nameres::DefMap, AssocContainerId, AssocItemId, FunctionId,
@@ -639,6 +639,7 @@ fn iterate_trait_method_candidates(
receiver_ty: Option<&Canonical<Ty>>,
callback: &mut dyn FnMut(&Ty, AssocItemId) -> bool,
) -> bool {
+ let receiver_is_array = matches!(self_ty.value.kind(&Interner), chalk_ir::TyKind::Array(..));
// if ty is `dyn Trait`, the trait doesn't need to be in scope
let inherent_trait =
self_ty.value.dyn_trait().into_iter().flat_map(|t| all_super_traits(db.upcast(), t));
@@ -655,6 +656,19 @@ fn iterate_trait_method_candidates(
'traits: for t in traits {
let data = db.trait_data(t);
+ // Traits annotated with `#[rustc_skip_array_during_method_dispatch]` are skipped during
+ // method resolution, if the receiver is an array, and we're compiling for editions before
+ // 2021.
+ // This is to make `[a].into_iter()` not break code with the new `IntoIterator` impl for
+ // arrays.
+ if data.skip_array_during_method_dispatch && receiver_is_array {
+ // FIXME: this should really be using the edition of the method name's span, in case it
+ // comes from a macro
+ if db.crate_graph()[krate].edition < Edition::Edition2021 {
+ continue;
+ }
+ }
+
// we'll be lazy about checking whether the type implements the
// trait, but if we find out it doesn't, we'll skip the rest of the
// iteration
diff --git a/crates/hir_ty/src/tests/method_resolution.rs b/crates/hir_ty/src/tests/method_resolution.rs
index 058eb91299d..f26b2c8a79c 100644
--- a/crates/hir_ty/src/tests/method_resolution.rs
+++ b/crates/hir_ty/src/tests/method_resolution.rs
@@ -1349,3 +1349,52 @@ fn f() {
"#,
);
}
+
+#[test]
+fn skip_array_during_method_dispatch() {
+ check_types(
+ r#"
+//- /main2018.rs crate:main2018 deps:core
+use core::IntoIterator;
+
+fn f() {
+ let v = [4].into_iter();
+ v;
+ //^ &i32
+
+ let a = [0, 1].into_iter();
+ a;
+ //^ &i32
+}
+
+//- /main2021.rs crate:main2021 deps:core edition:2021
+use core::IntoIterator;
+
+fn f() {
+ let v = [4].into_iter();
+ v;
+ //^ i32
+
+ let a = [0, 1].into_iter();
+ a;
+ //^ &i32
+}
+
+//- /core.rs crate:core
+#[rustc_skip_array_during_method_dispatch]
+pub trait IntoIterator {
+ type Out;
+ fn into_iter(self) -> Self::Out;
+}
+
+impl<T> IntoIterator for [T; 1] {
+ type Out = T;
+ fn into_iter(self) -> Self::Out {}
+}
+impl<'a, T> IntoIterator for &'a [T] {
+ type Out = &'a T;
+ fn into_iter(self) -> Self::Out {}
+}
+ "#,
+ );
+}