declare_clippy_lint! {
/// ### What it does
/// Checks for type parameters which are positioned inconsistently between
- /// a type definition and impl block. Specifically, a paramater in an impl
+ /// a type definition and impl block. Specifically, a parameter in an impl
/// block which has the same name as a parameter in the type def, but is in
/// a different place.
///
/// 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> {
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
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",
span_lint_and_help(
cx,
MISMATCHING_TYPE_PARAM_ORDER,
- impl_param_span,
+ *impl_param_span,
&msg,
None,
&help