rust/clippy_lints/src/methods/cloned_instead_of_copied.rs
Nicholas Nethercote 5fa961b951 Overhaul TyS and Ty.
Specifically, change `Ty` from this:
```
pub type Ty<'tcx> = &'tcx TyS<'tcx>;
```
to this
```
pub struct Ty<'tcx>(Interned<'tcx, TyS<'tcx>>);
```
There are two benefits to this.
- It's now a first class type, so we can define methods on it. This
  means we can move a lot of methods away from `TyS`, leaving `TyS` as a
  barely-used type, which is appropriate given that it's not meant to
  be used directly.
- The uniqueness requirement is now explicit, via the `Interned` type.
  E.g. the pointer-based `Eq` and `Hash` comes from `Interned`, rather
  than via `TyS`, which wasn't obvious at all.

Much of this commit is boring churn. The interesting changes are in
these files:
- compiler/rustc_middle/src/arena.rs
- compiler/rustc_middle/src/mir/visit.rs
- compiler/rustc_middle/src/ty/context.rs
- compiler/rustc_middle/src/ty/mod.rs

Specifically:
- Most mentions of `TyS` are removed. It's very much a dumb struct now;
  `Ty` has all the smarts.
- `TyS` now has `crate` visibility instead of `pub`.
- `TyS::make_for_test` is removed in favour of the static `BOOL_TY`,
  which just works better with the new structure.
- The `Eq`/`Ord`/`Hash` impls are removed from `TyS`. `Interned`s impls
  of `Eq`/`Hash` now suffice. `Ord` is now partly on `Interned`
  (pointer-based, for the `Equal` case) and partly on `TyS`
  (contents-based, for the other cases).
- There are many tedious sigil adjustments, i.e. adding or removing `*`
  or `&`. They seem to be unavoidable.
2022-02-15 16:03:24 +11:00

46 lines
1.5 KiB
Rust

use clippy_utils::diagnostics::span_lint_and_sugg;
use clippy_utils::ty::{get_iterator_item_ty, is_copy};
use clippy_utils::{is_trait_method, meets_msrv, msrvs};
use rustc_errors::Applicability;
use rustc_hir::Expr;
use rustc_lint::LateContext;
use rustc_middle::ty;
use rustc_semver::RustcVersion;
use rustc_span::{sym, Span};
use super::CLONED_INSTEAD_OF_COPIED;
pub fn check(cx: &LateContext<'_>, expr: &Expr<'_>, recv: &Expr<'_>, span: Span, msrv: Option<&RustcVersion>) {
let recv_ty = cx.typeck_results().expr_ty_adjusted(recv);
let inner_ty = match recv_ty.kind() {
// `Option<T>` -> `T`
ty::Adt(adt, subst)
if cx.tcx.is_diagnostic_item(sym::Option, adt.did) && meets_msrv(msrv, &msrvs::OPTION_COPIED) =>
{
subst.type_at(0)
},
_ if is_trait_method(cx, expr, sym::Iterator) && meets_msrv(msrv, &msrvs::ITERATOR_COPIED) => {
match get_iterator_item_ty(cx, recv_ty) {
// <T as Iterator>::Item
Some(ty) => ty,
_ => return,
}
},
_ => return,
};
match inner_ty.kind() {
// &T where T: Copy
ty::Ref(_, ty, _) if is_copy(cx, *ty) => {},
_ => return,
};
span_lint_and_sugg(
cx,
CLONED_INSTEAD_OF_COPIED,
span,
"used `cloned` where `copied` could be used instead",
"try",
"copied".into(),
Applicability::MachineApplicable,
);
}