Invalid recursive bound removal

the test:

trait Types {
	type Assoc;
}
#[derive(Encode, Decode)]
struct Assoc<T: Types> {
	a: Vec<<T>::Assoc>,
}

fails because the bound <T>::Assoc is consider as Assoc and thus the code thinks it is a recursive bound and so removes it.

A fix should be something like:

diff --git a/derive/src/trait_bounds.rs b/derive/src/trait_bounds.rs
index c6303f4..8c9d15e 100644
--- a/derive/src/trait_bounds.rs
+++ b/derive/src/trait_bounds.rs
@@ -52,12 +52,14 @@ struct TypePathStartsWithIdent<'a> {
 
 impl<'a, 'ast> Visit<'ast> for TypePathStartsWithIdent<'a> {
        fn visit_type_path(&mut self, i: &'ast TypePath) {
+               if i.qself.is_none() {
                if let Some(segment) = i.path.segments.first() {
                        if &segment.ident == self.ident {
                                self.result = true;
                                return;
                        }
                }
+               }
 
                visit::visit_type_path(self, i);
        }

But we should check that other usage are not broken by this change.

Start in derive/src/trait_bounds.rs and reproduce the Rust example from the issue to inspect how the type-path visitor classifies ::Assoc. Confirm that associated-type paths are not treated as recursive bounds, then check the visitor's other usages and run the existing test suite to ensure they still pass.