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Auto merge of #9146 - arieluy:type_params, r=dswij

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Fix `mismatching_type_param_order` false positive

changelog: Don't lint `mismatching_type_param_order` on complicated generic params

fixes #8962
This commit is contained in:
bors 2022-07-18 10:13:39 +00:00
commit f4c9183531
2 changed files with 19 additions and 9 deletions
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24
clippy_lints/src/mismatching_type_param_order.rs
View File

@ -18,6 +18,11 @@
/// Naming type parameters inconsistently may cause you to refer to the
/// wrong type parameter.
///
/// ### Limitations
/// This lint only applies to impl blocks with simple generic params, e.g.
/// `A`. If there is anything more complicated, such as a tuple, it will be
/// ignored.
///
/// ### Example
/// ```rust
/// struct Foo<A, B> {
@ -53,14 +58,15 @@ fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx Item<'tcx>) {
if !generic_args.args.is_empty();
then {
// get the name and span of the generic parameters in the Impl
let impl_params = generic_args.args.iter()
.filter_map(|p|
let mut impl_params = Vec::new();
for p in generic_args.args.iter() {
match p {
GenericArg::Type(Ty {kind: TyKind::Path(QPath::Resolved(_, path)), ..}) =>
Some((path.segments[0].ident.to_string(), path.span)),
_ => None,
}
);
impl_params.push((path.segments[0].ident.to_string(), path.span)),
GenericArg::Type(_) => return,
_ => (),
};
}
// find the type that the Impl is for
// only lint on struct/enum/union for now
@ -83,8 +89,8 @@ fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx Item<'tcx>) {
type_param_names.iter().enumerate().map(|(i, param)| (param, i)).collect();
let type_name = segment.ident;
for (i, (impl_param_name, impl_param_span)) in impl_params.enumerate() {
if mismatch_param_name(i, &impl_param_name, &type_param_names_hashmap) {
for (i, (impl_param_name, impl_param_span)) in impl_params.iter().enumerate() {
if mismatch_param_name(i, impl_param_name, &type_param_names_hashmap) {
let msg = format!("`{}` has a similarly named generic type parameter `{}` in its declaration, but in a different order",
type_name, impl_param_name);
let help = format!("try `{}`, or a name that does not conflict with `{}`'s generic params",
@ -92,7 +98,7 @@ fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx Item<'tcx>) {
span_lint_and_help(
cx,
MISMATCHING_TYPE_PARAM_ORDER,
impl_param_span,
*impl_param_span,
&msg,
None,
&help

4
tests/ui/mismatching_type_param_order.rs
View File

@ -57,4 +57,8 @@ impl<A, B> FooUnion<A, B>
B: Copy,
{
}
// if the types are complicated, do not lint
impl<K, V, B> Foo<(K, V), B> {}
impl<K, V, A> Foo<(K, V), A> {}
}