disallowed_methods configuration for traits with generics

[asasine]

What's the correct syntax for referring to a trait method with Clippy's disallowed-methods field in clippy.toml?

In this, heapless::index_map::IndexMap::extend is generic over multiple arguments impl<'a, K, V, S, const N: usize> Extend<(&'a K, &'a V)> for IndexMap<K, V, S, N> as well as having a second impl<K, V, S, const N: usize> Extend<(K, V)> for IndexMap<K, V, S, N>.

How do I write the fully qualified path for both of these (or some singular path that refers to both) that Clippy will understand?

---

If I force it to be an invalid path by changing the function name to something garbage, Clippy does not give me a warning that the path is invalid, so I know this syntax isn't correct.

disallowed-methods = [
    { path = "<heapless::index_map::IndexMap as core::iter::Extend>::invalid" }, # note: invalid method name to test whether this path syntax is correct
]

[ShreeChaturvedi]

Use the trait method path. Generics and UFCS are not supported:

disallowed-methods = [
  { path = "core::iter::Extend::extend", reason = "..." },
]

That one path covers every Extend::extend call (owned pairs, ref pairs, any type). Generics never go in the path.

You cannot limit it to only IndexMap today. heapless::index_map::IndexMap::extend only finds inherent methods, and <Type as Trait>::method is not parsed. Tracked here: #8581

Pitfall: a path that starts with < never resolves, and Clippy often skips the invalid-path warning because the first segment looks like an unloaded crate.