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Lint iter_not_returning_iterator on the trait definition rather than the implementation

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This commit is contained in:
Jason Newcomb 2022-01-05 13:46:35 -05:00
parent 92048f4826
commit 2cc38a2322
3 changed files with 60 additions and 21 deletions
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61
clippy_lints/src/iter_not_returning_iterator.rs
View file

@ -1,8 +1,7 @@
use clippy_utils::{diagnostics::span_lint, return_ty, ty::implements_trait};
use rustc_hir::{ImplItem, ImplItemKind};
use clippy_utils::{diagnostics::span_lint, get_parent_node, ty::implements_trait};
use rustc_hir::{def_id::LocalDefId, FnSig, ImplItem, ImplItemKind, Item, ItemKind, Node, TraitItem, TraitItemKind};
use rustc_lint::{LateContext, LateLintPass};
use rustc_session::{declare_lint_pass, declare_tool_lint};
use rustc_span::symbol::kw;
use rustc_span::symbol::sym;
declare_clippy_lint! {
@ -41,25 +40,47 @@ declare_clippy_lint! {
declare_lint_pass!(IterNotReturningIterator => [ITER_NOT_RETURNING_ITERATOR]);
impl LateLintPass<'_> for IterNotReturningIterator {
fn check_impl_item(&mut self, cx: &LateContext<'tcx>, impl_item: &'tcx ImplItem<'tcx>) {
let name = impl_item.ident.name.as_str();
if_chain! {
if let ImplItemKind::Fn(fn_sig, _) = &impl_item.kind;
let ret_ty = return_ty(cx, impl_item.hir_id());
if matches!(name, "iter" | "iter_mut");
if let [param] = cx.tcx.fn_arg_names(impl_item.def_id);
if param.name == kw::SelfLower;
if let Some(iter_trait_id) = cx.tcx.get_diagnostic_item(sym::Iterator);
if !implements_trait(cx, ret_ty, iter_trait_id, &[]);
fn check_trait_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx TraitItem<'_>) {
let name = item.ident.name.as_str();
if matches!(name, "iter" | "iter_mut") {
if let TraitItemKind::Fn(fn_sig, _) = &item.kind {
check_sig(cx, name, fn_sig, item.def_id);
}
}
}
then {
span_lint(
cx,
ITER_NOT_RETURNING_ITERATOR,
fn_sig.span,
&format!("this method is named `{}` but its return type does not implement `Iterator`", name),
);
fn check_impl_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx ImplItem<'tcx>) {
let name = item.ident.name.as_str();
if matches!(name, "iter" | "iter_mut")
&& !matches!(
get_parent_node(cx.tcx, item.hir_id()),
Some(Node::Item(Item { kind: ItemKind::Impl(i), .. })) if i.of_trait.is_some()
)
{
if let ImplItemKind::Fn(fn_sig, _) = &item.kind {
check_sig(cx, name, fn_sig, item.def_id);
}
}
}
}
fn check_sig(cx: &LateContext<'_>, name: &str, sig: &FnSig<'_>, fn_id: LocalDefId) {
if sig.decl.implicit_self.has_implicit_self() {
let ret_ty = cx.tcx.fn_sig(fn_id).skip_binder().output();
if cx
.tcx
.get_diagnostic_item(sym::Iterator)
.map_or(false, |iter_id| !implements_trait(cx, ret_ty, iter_id, &[]))
{
span_lint(
cx,
ITER_NOT_RETURNING_ITERATOR,
sig.span,
&format!(
"this method is named `{}` but its return type does not implement `Iterator`",
name
),
);
}
}
}

12
tests/ui/iter_not_returning_iterator.rs
View file

@ -44,4 +44,16 @@ impl Iterator for Counter {
}
}
trait Iter {
type I;
fn iter(&self) -> Self::I;
}
impl Iter for () {
type I = core::slice::Iter<'static, ()>;
fn iter(&self) -> Self::I {
[].iter()
}
}
fn main() {}

8
tests/ui/iter_not_returning_iterator.stderr
View file

@ -12,5 +12,11 @@ error: this method is named `iter_mut` but its return type does not implement `I
LL | fn iter_mut(&self) -> Counter2 {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: aborting due to 2 previous errors
error: this method is named `iter` but its return type does not implement `Iterator`
--> $DIR/iter_not_returning_iterator.rs:49:5
|
LL | fn iter(&self) -> Self::I;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^
error: aborting due to 3 previous errors