diff options
| -rw-r--r-- | src/libsyntax/ext/deriving/generic/mod.rs | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/src/libsyntax/ext/deriving/generic/mod.rs b/src/libsyntax/ext/deriving/generic/mod.rs index e7d242ab703..8f9e0279b29 100644 --- a/src/libsyntax/ext/deriving/generic/mod.rs +++ b/src/libsyntax/ext/deriving/generic/mod.rs @@ -188,6 +188,7 @@ pub use self::SubstructureFields::*; use self::StructType::*; use std::cell::RefCell; +use std::collections::HashSet; use std::vec; use abi::Abi; @@ -549,10 +550,20 @@ impl<'a> TraitDef<'a> { .map(|ty_param| ty_param.ident.name) .collect(); + let mut processed_field_types = HashSet::new(); for field_ty in field_tys { let tys = find_type_parameters(&*field_ty, &ty_param_names); for ty in tys { + // if we have already handled this type, skip it + if let ast::TyPath(_, ref p) = ty.node { + if p.segments.len() == 1 + && ty_param_names.contains(&p.segments[0].identifier.name) + || processed_field_types.contains(&p.segments) { + continue; + }; + processed_field_types.insert(p.segments.clone()); + } let mut bounds: Vec<_> = self.additional_bounds.iter().map(|p| { cx.typarambound(p.to_path(cx, self.span, type_ident, generics)) }).collect(); |