diff --git a/crates/fayalite-proc-macros-impl/src/hdl_bundle.rs b/crates/fayalite-proc-macros-impl/src/hdl_bundle.rs
index 30cf90f..f3a589a 100644
--- a/crates/fayalite-proc-macros-impl/src/hdl_bundle.rs
+++ b/crates/fayalite-proc-macros-impl/src/hdl_bundle.rs
@@ -431,6 +431,7 @@ impl ToTokens for ParsedBundle {
             builder_ident,
             mask_type_builder_ident,
         } = self;
+        let span = ident.span();
         let ItemOptions {
             outline_generated: _,
             target,
@@ -440,7 +441,7 @@ impl ToTokens for ParsedBundle {
         } = &options.body;
         let target = get_target(target, ident);
         let mut item_attrs = attrs.clone();
-        item_attrs.push(common_derives(ident.span()));
+        item_attrs.push(common_derives(span));
         ItemStruct {
             attrs: item_attrs,
             vis: vis.clone(),
@@ -462,19 +463,19 @@ impl ToTokens for ParsedBundle {
                     .map(|ParsedField { ident, ty, .. }| {
                         let ident = ident.as_ref().unwrap();
                         let expr = ty.make_hdl_type_expr(context);
-                        quote_spanned! {ident.span()=>
+                        quote_spanned! {span=>
                             #ident: #expr,
                         }
                     })
                     .collect();
-                parse_quote_spanned! {ident.span()=>
+                parse_quote_spanned! {span=>
                     #target {
                         #(#fields)*
                     }
                 }
             })
         }
-        let mut wrapped_in_const = WrappedInConst::new(tokens, ident.span());
+        let mut wrapped_in_const = WrappedInConst::new(tokens, span);
         let tokens = wrapped_in_const.inner();
         let builder = Builder {
             vis: vis.clone(),
@@ -488,9 +489,8 @@ impl ToTokens for ParsedBundle {
         let unfilled_builder_ty = builder.builder_struct_ty(|_| BuilderFieldState::Unfilled);
         let filled_builder_ty = builder.builder_struct_ty(|_| BuilderFieldState::Filled);
         let mut mask_type_fields = FieldsNamed::from(fields.clone());
-        for Field { ident, ty, .. } in &mut mask_type_fields.named {
-            let ident = ident.as_ref().unwrap();
-            *ty = parse_quote_spanned! {ident.span()=>
+        for Field { ty, .. } in &mut mask_type_fields.named {
+            *ty = parse_quote_spanned! {span=>
                 <#ty as ::fayalite::ty::Type>::MaskType
             };
         }
@@ -509,8 +509,8 @@ impl ToTokens for ParsedBundle {
             mask_type_builder.builder_struct_ty(|_| BuilderFieldState::Filled);
         ItemStruct {
             attrs: vec![
-                common_derives(ident.span()),
-                parse_quote_spanned! {ident.span()=>
+                common_derives(span),
+                parse_quote_spanned! {span=>
                     #[allow(non_camel_case_types, dead_code)]
                 },
             ],
@@ -523,16 +523,15 @@ impl ToTokens for ParsedBundle {
         }
         .to_tokens(tokens);
         let mut mask_type_match_variant_fields = mask_type_fields;
-        for Field { ident, ty, .. } in &mut mask_type_match_variant_fields.named {
-            let ident = ident.as_ref().unwrap();
-            *ty = parse_quote_spanned! {ident.span()=>
+        for Field { ty, .. } in &mut mask_type_match_variant_fields.named {
+            *ty = parse_quote_spanned! {span=>
                 ::fayalite::expr::Expr<#ty>
             };
         }
         ItemStruct {
             attrs: vec![
-                common_derives(ident.span()),
-                parse_quote_spanned! {ident.span()=>
+                common_derives(span),
+                parse_quote_spanned! {span=>
                     #[allow(non_camel_case_types, dead_code)]
                 },
             ],
@@ -545,16 +544,15 @@ impl ToTokens for ParsedBundle {
         }
         .to_tokens(tokens);
         let mut match_variant_fields = FieldsNamed::from(fields.clone());
-        for Field { ident, ty, .. } in &mut match_variant_fields.named {
-            let ident = ident.as_ref().unwrap();
-            *ty = parse_quote_spanned! {ident.span()=>
+        for Field { ty, .. } in &mut match_variant_fields.named {
+            *ty = parse_quote_spanned! {span=>
                 ::fayalite::expr::Expr<#ty>
             };
         }
         ItemStruct {
             attrs: vec![
-                common_derives(ident.span()),
-                parse_quote_spanned! {ident.span()=>
+                common_derives(span),
+                parse_quote_spanned! {span=>
                     #[allow(non_camel_case_types, dead_code)]
                 },
             ],
@@ -566,17 +564,20 @@ impl ToTokens for ParsedBundle {
             semi_token: None,
         }
         .to_tokens(tokens);
+        let this_token = Ident::new("__this", span);
+        let fields_token = Ident::new("__fields", span);
+        let self_token = Token![self](span);
         let match_variant_body_fields = Vec::from_iter(fields.named().into_iter().map(|field| {
             let ident: &Ident = field.ident().as_ref().unwrap();
             let ident_str = ident.to_string();
-            quote_spanned! {ident.span()=>
-                #ident: ::fayalite::expr::Expr::field(__this, #ident_str),
+            quote_spanned! {span=>
+                #ident: ::fayalite::expr::Expr::field(#this_token, #ident_str),
             }
         }));
         let mask_type_body_fields = Vec::from_iter(fields.named().into_iter().map(|field| {
             let ident: &Ident = field.ident().as_ref().unwrap();
-            quote_spanned! {ident.span()=>
-                #ident: ::fayalite::ty::Type::mask_type(&self.#ident),
+            quote_spanned! {span=>
+                #ident: ::fayalite::ty::Type::mask_type(&#self_token.#ident),
             }
         }));
         let from_canonical_body_fields =
@@ -585,13 +586,13 @@ impl ToTokens for ParsedBundle {
                     let ident: &Ident = field.ident().as_ref().unwrap();
                     let ident_str = ident.to_string();
                     let flipped = flip.is_some();
-                    quote_spanned! {ident.span()=>
+                    quote_spanned! {span=>
                         #ident: {
                             let ::fayalite::bundle::BundleField {
                                 name: __name,
                                 flipped: __flipped,
                                 ty: __ty,
-                            } = __fields[#index];
+                            } = #fields_token[#index];
                             ::fayalite::__std::assert_eq!(&*__name, #ident_str);
                             ::fayalite::__std::assert_eq!(__flipped, #flipped);
                             ::fayalite::ty::Type::from_canonical(__ty)
@@ -604,17 +605,17 @@ impl ToTokens for ParsedBundle {
                 let ident: &Ident = field.ident().as_ref().unwrap();
                 let ident_str = ident.to_string();
                 let flipped = flip.is_some();
-                quote_spanned! {ident.span()=>
+                quote_spanned! {span=>
                     ::fayalite::bundle::BundleField {
                         name: ::fayalite::intern::Intern::intern(#ident_str),
                         flipped: #flipped,
-                        ty: ::fayalite::ty::Type::canonical(&self.#ident),
+                        ty: ::fayalite::ty::Type::canonical(&#self_token.#ident),
                     },
                 }
             },
         ));
         let fields_len = fields.named().into_iter().len();
-        quote_spanned! {ident.span()=>
+        quote_spanned! {span=>
             #[automatically_derived]
             impl #impl_generics ::fayalite::ty::Type for #mask_type_ident #type_generics
             #where_clause
@@ -630,7 +631,7 @@ impl ToTokens for ParsedBundle {
                     <Self as ::fayalite::ty::Type>::MatchVariantAndInactiveScope,
                 >;
                 fn match_variants(
-                    __this: ::fayalite::expr::Expr<Self>,
+                    #this_token: ::fayalite::expr::Expr<Self>,
                     __source_location: ::fayalite::source_location::SourceLocation,
                 ) -> <Self as ::fayalite::ty::Type>::MatchVariantsIter {
                     let __retval = #mask_type_match_variant_ident {
@@ -638,19 +639,19 @@ impl ToTokens for ParsedBundle {
                     };
                     ::fayalite::__std::iter::once(::fayalite::ty::MatchVariantWithoutScope(__retval))
                 }
-                fn mask_type(&self) -> <Self as ::fayalite::ty::Type>::MaskType {
-                    *self
+                fn mask_type(&#self_token) -> <Self as ::fayalite::ty::Type>::MaskType {
+                    *#self_token
                 }
-                fn canonical(&self) -> ::fayalite::ty::CanonicalType {
-                    ::fayalite::ty::Type::canonical(&::fayalite::bundle::Bundle::new(::fayalite::bundle::BundleType::fields(self)))
+                fn canonical(&#self_token) -> ::fayalite::ty::CanonicalType {
+                    ::fayalite::ty::Type::canonical(&::fayalite::bundle::Bundle::new(::fayalite::bundle::BundleType::fields(#self_token)))
                 }
                 #[track_caller]
                 fn from_canonical(__canonical_type: ::fayalite::ty::CanonicalType) -> Self {
                     let ::fayalite::ty::CanonicalType::Bundle(__bundle) = __canonical_type else {
                         ::fayalite::__std::panic!("expected bundle");
                     };
-                    let __fields = ::fayalite::bundle::BundleType::fields(&__bundle);
-                    ::fayalite::__std::assert_eq!(__fields.len(), #fields_len, "bundle has wrong number of fields");
+                    let #fields_token = ::fayalite::bundle::BundleType::fields(&__bundle);
+                    ::fayalite::__std::assert_eq!(#fields_token.len(), #fields_len, "bundle has wrong number of fields");
                     Self {
                         #(#from_canonical_body_fields)*
                     }
@@ -665,7 +666,7 @@ impl ToTokens for ParsedBundle {
             {
                 type Builder = #unfilled_mask_type_builder_ty;
                 type FilledBuilder = #filled_mask_type_builder_ty;
-                fn fields(&self) -> ::fayalite::intern::Interned<[::fayalite::bundle::BundleField]> {
+                fn fields(&#self_token) -> ::fayalite::intern::Interned<[::fayalite::bundle::BundleField]> {
                     ::fayalite::intern::Intern::intern(&[#(#fields_body_fields)*][..])
                 }
             }
@@ -680,8 +681,8 @@ impl ToTokens for ParsedBundle {
             impl #impl_generics ::fayalite::ty::TypeWithDeref for #mask_type_ident #type_generics
             #where_clause
             {
-                fn expr_deref(__this: &::fayalite::expr::Expr<Self>) -> &<Self as ::fayalite::ty::Type>::MatchVariant {
-                    let __this = *__this;
+                fn expr_deref(#this_token: &::fayalite::expr::Expr<Self>) -> &<Self as ::fayalite::ty::Type>::MatchVariant {
+                    let #this_token = *#this_token;
                     let __retval = #mask_type_match_variant_ident {
                         #(#match_variant_body_fields)*
                     };
@@ -703,7 +704,7 @@ impl ToTokens for ParsedBundle {
                     <Self as ::fayalite::ty::Type>::MatchVariantAndInactiveScope,
                 >;
                 fn match_variants(
-                    __this: ::fayalite::expr::Expr<Self>,
+                    #this_token: ::fayalite::expr::Expr<Self>,
                     __source_location: ::fayalite::source_location::SourceLocation,
                 ) -> <Self as ::fayalite::ty::Type>::MatchVariantsIter {
                     let __retval = #match_variant_ident {
@@ -711,21 +712,21 @@ impl ToTokens for ParsedBundle {
                     };
                     ::fayalite::__std::iter::once(::fayalite::ty::MatchVariantWithoutScope(__retval))
                 }
-                fn mask_type(&self) -> <Self as ::fayalite::ty::Type>::MaskType {
+                fn mask_type(&#self_token) -> <Self as ::fayalite::ty::Type>::MaskType {
                     #mask_type_ident {
                         #(#mask_type_body_fields)*
                     }
                 }
-                fn canonical(&self) -> ::fayalite::ty::CanonicalType {
-                    ::fayalite::ty::Type::canonical(&::fayalite::bundle::Bundle::new(::fayalite::bundle::BundleType::fields(self)))
+                fn canonical(&#self_token) -> ::fayalite::ty::CanonicalType {
+                    ::fayalite::ty::Type::canonical(&::fayalite::bundle::Bundle::new(::fayalite::bundle::BundleType::fields(#self_token)))
                 }
                 #[track_caller]
                 fn from_canonical(__canonical_type: ::fayalite::ty::CanonicalType) -> Self {
                     let ::fayalite::ty::CanonicalType::Bundle(__bundle) = __canonical_type else {
                         ::fayalite::__std::panic!("expected bundle");
                     };
-                    let __fields = ::fayalite::bundle::BundleType::fields(&__bundle);
-                    ::fayalite::__std::assert_eq!(__fields.len(), #fields_len, "bundle has wrong number of fields");
+                    let #fields_token = ::fayalite::bundle::BundleType::fields(&__bundle);
+                    ::fayalite::__std::assert_eq!(#fields_token.len(), #fields_len, "bundle has wrong number of fields");
                     Self {
                         #(#from_canonical_body_fields)*
                     }
@@ -740,7 +741,7 @@ impl ToTokens for ParsedBundle {
             {
                 type Builder = #unfilled_builder_ty;
                 type FilledBuilder = #filled_builder_ty;
-                fn fields(&self) -> ::fayalite::intern::Interned<[::fayalite::bundle::BundleField]> {
+                fn fields(&#self_token) -> ::fayalite::intern::Interned<[::fayalite::bundle::BundleField]> {
                     ::fayalite::intern::Intern::intern(&[#(#fields_body_fields)*][..])
                 }
             }
@@ -755,8 +756,8 @@ impl ToTokens for ParsedBundle {
             impl #impl_generics ::fayalite::ty::TypeWithDeref for #target #type_generics
             #where_clause
             {
-                fn expr_deref(__this: &::fayalite::expr::Expr<Self>) -> &<Self as ::fayalite::ty::Type>::MatchVariant {
-                    let __this = *__this;
+                fn expr_deref(#this_token: &::fayalite::expr::Expr<Self>) -> &<Self as ::fayalite::ty::Type>::MatchVariant {
+                    let #this_token = *#this_token;
                     let __retval = #match_variant_ident {
                         #(#match_variant_body_fields)*
                     };
@@ -772,7 +773,7 @@ impl ToTokens for ParsedBundle {
             let static_type_body_fields = Vec::from_iter(fields.named().into_iter().map(|field| {
                 let ident: &Ident = field.ident().as_ref().unwrap();
                 let ty = field.ty();
-                quote_spanned! {ident.span()=>
+                quote_spanned! {span=>
                     #ident: <#ty as ::fayalite::ty::StaticType>::TYPE,
                 }
             }));
@@ -780,28 +781,26 @@ impl ToTokens for ParsedBundle {
                 Vec::from_iter(fields.named().into_iter().map(|field| {
                     let ident: &Ident = field.ident().as_ref().unwrap();
                     let ty = field.ty();
-                    quote_spanned! {ident.span()=>
+                    quote_spanned! {span=>
                         #ident: <#ty as ::fayalite::ty::StaticType>::MASK_TYPE,
                     }
                 }));
-            let type_properties = format_ident!("__type_properties", span = ident.span());
+            let type_properties = format_ident!("__type_properties", span = span);
             let type_properties_fields = Vec::from_iter(fields.named().into_iter().zip(field_flips).map(|(field, field_flip)| {
-                let ident: &Ident = field.ident().as_ref().unwrap();
                 let flipped = field_flip.is_some();
                 let ty = field.ty();
-                quote_spanned! {ident.span()=>
+                quote_spanned! {span=>
                     let #type_properties = #type_properties.field(#flipped, <#ty as ::fayalite::ty::StaticType>::TYPE_PROPERTIES);
                 }
             }));
             let type_properties_mask_fields = Vec::from_iter(fields.named().into_iter().zip(field_flips).map(|(field, field_flip)| {
-                let ident: &Ident = field.ident().as_ref().unwrap();
                 let flipped = field_flip.is_some();
                 let ty = field.ty();
-                quote_spanned! {ident.span()=>
+                quote_spanned! {span=>
                     let #type_properties = #type_properties.field(#flipped, <#ty as ::fayalite::ty::StaticType>::MASK_TYPE_PROPERTIES);
                 }
             }));
-            quote_spanned! {ident.span()=>
+            quote_spanned! {span=>
                 #[automatically_derived]
                 impl #static_impl_generics ::fayalite::ty::StaticType for #mask_type_ident #static_type_generics
                 #static_where_clause
diff --git a/crates/fayalite-proc-macros-impl/src/hdl_enum.rs b/crates/fayalite-proc-macros-impl/src/hdl_enum.rs
index 50fb138..adddd74 100644
--- a/crates/fayalite-proc-macros-impl/src/hdl_enum.rs
+++ b/crates/fayalite-proc-macros-impl/src/hdl_enum.rs
@@ -204,6 +204,7 @@ impl ToTokens for ParsedEnum {
             variants,
             match_variant_ident,
         } = self;
+        let span = ident.span();
         let ItemOptions {
             outline_generated: _,
             target,
@@ -213,8 +214,8 @@ impl ToTokens for ParsedEnum {
         } = &options.body;
         let target = get_target(target, ident);
         let mut struct_attrs = attrs.clone();
-        struct_attrs.push(common_derives(ident.span()));
-        struct_attrs.push(parse_quote_spanned! {ident.span()=>
+        struct_attrs.push(common_derives(span));
+        struct_attrs.push(parse_quote_spanned! {span=>
             #[allow(non_snake_case)]
         });
         let struct_fields = Punctuated::from_iter(variants.pairs().map_pair_value_ref(
@@ -238,8 +239,8 @@ impl ToTokens for ParsedEnum {
                     colon_token = Token![:](paren_token.span.open());
                     ty.clone().into()
                 } else {
-                    colon_token = Token![:](ident.span());
-                    parse_quote_spanned! {ident.span()=>
+                    colon_token = Token![:](span);
+                    parse_quote_spanned! {span=>
                         ()
                     }
                 };
@@ -282,30 +283,30 @@ impl ToTokens for ParsedEnum {
                         }) = field
                         {
                             let expr = ty.make_hdl_type_expr(context);
-                            quote_spanned! {ident.span()=>
+                            quote_spanned! {span=>
                                 #ident: #expr,
                             }
                         } else {
-                            quote_spanned! {ident.span()=>
+                            quote_spanned! {span=>
                                 #ident: (),
                             }
                         }
                     })
                     .collect();
-                parse_quote_spanned! {ident.span()=>
+                parse_quote_spanned! {span=>
                     #target {
                         #(#fields)*
                     }
                 }
             })
         }
-        let mut wrapped_in_const = WrappedInConst::new(tokens, ident.span());
+        let mut wrapped_in_const = WrappedInConst::new(tokens, span);
         let tokens = wrapped_in_const.inner();
         {
-            let mut wrapped_in_const = WrappedInConst::new(tokens, ident.span());
+            let mut wrapped_in_const = WrappedInConst::new(tokens, span);
             let tokens = wrapped_in_const.inner();
             let mut enum_attrs = attrs.clone();
-            enum_attrs.push(parse_quote_spanned! {ident.span()=>
+            enum_attrs.push(parse_quote_spanned! {span=>
                 #[allow(dead_code)]
             });
             ItemEnum {
@@ -354,7 +355,7 @@ impl ToTokens for ParsedEnum {
             .to_tokens(tokens);
         }
         let mut enum_attrs = attrs.clone();
-        enum_attrs.push(parse_quote_spanned! {ident.span()=>
+        enum_attrs.push(parse_quote_spanned! {span=>
             #[allow(dead_code, non_camel_case_types)]
         });
         ItemEnum {
@@ -389,7 +390,7 @@ impl ToTokens for ParsedEnum {
                                     mutability: FieldMutability::None,
                                     ident: None,
                                     colon_token: None,
-                                    ty: parse_quote_spanned! {ident.span()=>
+                                    ty: parse_quote_spanned! {span=>
                                         ::fayalite::expr::Expr<#ty>
                                     },
                                 },
@@ -403,21 +404,22 @@ impl ToTokens for ParsedEnum {
             )),
         }
         .to_tokens(tokens);
+        let self_token = Token![self](span);
         for (index, ParsedVariant { ident, field, .. }) in variants.iter().enumerate() {
             if let Some(ParsedVariantField { ty, .. }) = field {
-                quote_spanned! {ident.span()=>
+                quote_spanned! {span=>
                     #[automatically_derived]
                     impl #impl_generics #target #type_generics
                     #where_clause
                     {
                         #[allow(non_snake_case, dead_code)]
                         #vis fn #ident<__V: ::fayalite::expr::ToExpr<Type = #ty>>(
-                            self,
+                            #self_token,
                             v: __V,
                         ) -> ::fayalite::expr::Expr<Self> {
                             ::fayalite::expr::ToExpr::to_expr(
                                 &::fayalite::expr::ops::EnumLiteral::new_by_index(
-                                    self,
+                                    #self_token,
                                     #index,
                                     ::fayalite::__std::option::Option::Some(
                                         ::fayalite::expr::Expr::canonical(
@@ -430,16 +432,16 @@ impl ToTokens for ParsedEnum {
                     }
                 }
             } else {
-                quote_spanned! {ident.span()=>
+                quote_spanned! {span=>
                     #[automatically_derived]
                     impl #impl_generics #target #type_generics
                     #where_clause
                     {
                         #[allow(non_snake_case, dead_code)]
-                        #vis fn #ident(self) -> ::fayalite::expr::Expr<Self> {
+                        #vis fn #ident(#self_token) -> ::fayalite::expr::Expr<Self> {
                             ::fayalite::expr::ToExpr::to_expr(
                                 &::fayalite::expr::ops::EnumLiteral::new_by_index(
-                                    self,
+                                    #self_token,
                                     #index,
                                     ::fayalite::__std::option::Option::None,
                                 ),
@@ -450,46 +452,48 @@ impl ToTokens for ParsedEnum {
             }
             .to_tokens(tokens);
         }
+        let variants_token = Ident::new("variants", span);
         let from_canonical_body_fields = Vec::from_iter(variants.iter().enumerate().map(
             |(index, ParsedVariant { ident, field, .. })| {
                 let ident_str = ident.to_string();
                 let val = if field.is_some() {
                     let missing_value_msg = format!("expected variant {ident} to have a field");
-                    quote_spanned! {ident.span()=>
+                    quote_spanned! {span=>
                         ::fayalite::ty::Type::from_canonical(ty.expect(#missing_value_msg))
                     }
                 } else {
-                    quote_spanned! {ident.span()=>
+                    quote_spanned! {span=>
                         ::fayalite::__std::assert!(ty.is_none());
                     }
                 };
-                quote_spanned! {ident.span()=>
+                quote_spanned! {span=>
                     #ident: {
                         let ::fayalite::enum_::EnumVariant {
                             name,
                             ty,
-                        } = variants[#index];
+                        } = #variants_token[#index];
                         ::fayalite::__std::assert_eq!(&*name, #ident_str);
                         #val
                     },
                 }
             },
         ));
+        let variant_access_token = Ident::new("variant_access", span);
         let match_active_scope_match_arms = Vec::from_iter(variants.iter().enumerate().map(
             |(index, ParsedVariant { ident, field, .. })| {
                 if field.is_some() {
-                    quote_spanned! {ident.span()=>
+                    quote_spanned! {span=>
                         #index => #match_variant_ident::#ident(
                             ::fayalite::expr::ToExpr::to_expr(
                                 &::fayalite::expr::ops::VariantAccess::new_by_index(
-                                    variant_access.base(),
-                                    variant_access.variant_index(),
+                                    #variant_access_token.base(),
+                                    #variant_access_token.variant_index(),
                                 ),
                             ),
                         ),
                     }
                 } else {
-                    quote_spanned! {ident.span()=>
+                    quote_spanned! {span=>
                         #index => #match_variant_ident::#ident,
                     }
                 }
@@ -507,16 +511,16 @@ impl ToTokens for ParsedEnum {
                 match field {
                     Some(ParsedVariantField { options, .. }) => {
                         let FieldOptions {} = options.body;
-                        quote_spanned! {ident.span()=>
+                        quote_spanned! {span=>
                             ::fayalite::enum_::EnumVariant {
                                 name: ::fayalite::intern::Intern::intern(#ident_str),
                                 ty: ::fayalite::__std::option::Option::Some(
-                                    ::fayalite::ty::Type::canonical(&self.#ident),
+                                    ::fayalite::ty::Type::canonical(&#self_token.#ident),
                                 ),
                             },
                         }
                     }
-                    None => quote_spanned! {ident.span()=>
+                    None => quote_spanned! {span=>
                         ::fayalite::enum_::EnumVariant {
                             name: ::fayalite::intern::Intern::intern(#ident_str),
                             ty: ::fayalite::__std::option::Option::None,
@@ -526,7 +530,7 @@ impl ToTokens for ParsedEnum {
             },
         ));
         let variants_len = variants.len();
-        quote_spanned! {ident.span()=>
+        quote_spanned! {span=>
             #[automatically_derived]
             impl #impl_generics ::fayalite::ty::Type for #target #type_generics
             #where_clause
@@ -544,11 +548,11 @@ impl ToTokens for ParsedEnum {
                 ) -> <Self as ::fayalite::ty::Type>::MatchVariantsIter {
                     ::fayalite::module::enum_match_variants_helper(this, source_location)
                 }
-                fn mask_type(&self) -> <Self as ::fayalite::ty::Type>::MaskType {
+                fn mask_type(&#self_token) -> <Self as ::fayalite::ty::Type>::MaskType {
                     ::fayalite::int::Bool
                 }
-                fn canonical(&self) -> ::fayalite::ty::CanonicalType {
-                    ::fayalite::ty::CanonicalType::Enum(::fayalite::enum_::Enum::new(::fayalite::enum_::EnumType::variants(self)))
+                fn canonical(&#self_token) -> ::fayalite::ty::CanonicalType {
+                    ::fayalite::ty::CanonicalType::Enum(::fayalite::enum_::Enum::new(::fayalite::enum_::EnumType::variants(#self_token)))
                 }
                 #[track_caller]
                 #[allow(non_snake_case)]
@@ -556,8 +560,8 @@ impl ToTokens for ParsedEnum {
                     let ::fayalite::ty::CanonicalType::Enum(enum_) = canonical_type else {
                         ::fayalite::__std::panic!("expected enum");
                     };
-                    let variants = ::fayalite::enum_::EnumType::variants(&enum_);
-                    ::fayalite::__std::assert_eq!(variants.len(), #variants_len, "enum has wrong number of variants");
+                    let #variants_token = ::fayalite::enum_::EnumType::variants(&enum_);
+                    ::fayalite::__std::assert_eq!(#variants_token.len(), #variants_len, "enum has wrong number of variants");
                     Self {
                         #(#from_canonical_body_fields)*
                     }
@@ -573,16 +577,16 @@ impl ToTokens for ParsedEnum {
                 fn match_activate_scope(
                     v: <Self as ::fayalite::ty::Type>::MatchVariantAndInactiveScope,
                 ) -> (<Self as ::fayalite::ty::Type>::MatchVariant, <Self as ::fayalite::ty::Type>::MatchActiveScope) {
-                    let (variant_access, scope) = v.activate();
+                    let (#variant_access_token, scope) = v.activate();
                     (
-                        match variant_access.variant_index() {
+                        match #variant_access_token.variant_index() {
                             #(#match_active_scope_match_arms)*
                             #variants_len.. => ::fayalite::__std::panic!("invalid variant index"),
                         },
                         scope,
                     )
                 }
-                fn variants(&self) -> ::fayalite::intern::Interned<[::fayalite::enum_::EnumVariant]> {
+                fn variants(&#self_token) -> ::fayalite::intern::Interned<[::fayalite::enum_::EnumVariant]> {
                     ::fayalite::intern::Intern::intern(&[
                         #(#variants_body_variants)*
                     ][..])
@@ -597,34 +601,34 @@ impl ToTokens for ParsedEnum {
             let static_type_body_variants =
                 Vec::from_iter(variants.iter().map(|ParsedVariant { ident, field, .. }| {
                     if let Some(_) = field {
-                        quote_spanned! {ident.span()=>
+                        quote_spanned! {span=>
                             #ident: ::fayalite::ty::StaticType::TYPE,
                         }
                     } else {
-                        quote_spanned! {ident.span()=>
+                        quote_spanned! {span=>
                             #ident: (),
                         }
                     }
                 }));
-            let type_properties = format_ident!("__type_properties", span = ident.span());
+            let type_properties = format_ident!("__type_properties", span = span);
             let type_properties_variants =
-                Vec::from_iter(variants.iter().map(|ParsedVariant { ident, field, .. }| {
+                Vec::from_iter(variants.iter().map(|ParsedVariant { field, .. }| {
                     let variant = if let Some(ParsedVariantField { ty, .. }) = field {
-                        quote_spanned! {ident.span()=>
+                        quote_spanned! {span=>
                             ::fayalite::__std::option::Option::Some(
                                 <#ty as ::fayalite::ty::StaticType>::TYPE_PROPERTIES,
                             )
                         }
                     } else {
-                        quote_spanned! {ident.span()=>
+                        quote_spanned! {span=>
                             ::fayalite::__std::option::Option::None
                         }
                     };
-                    quote_spanned! {ident.span()=>
+                    quote_spanned! {span=>
                         let #type_properties = #type_properties.variant(#variant);
                     }
                 }));
-            quote_spanned! {ident.span()=>
+            quote_spanned! {span=>
                 #[automatically_derived]
                 impl #static_impl_generics ::fayalite::ty::StaticType
                 for #target #static_type_generics
diff --git a/crates/fayalite-proc-macros-impl/src/hdl_type_common.rs b/crates/fayalite-proc-macros-impl/src/hdl_type_common.rs
index efbe7f3..e7561fe 100644
--- a/crates/fayalite-proc-macros-impl/src/hdl_type_common.rs
+++ b/crates/fayalite-proc-macros-impl/src/hdl_type_common.rs
@@ -1896,6 +1896,7 @@ pub(crate) mod known_items {
     impl_known_item!(::fayalite::array::ArrayType);
     impl_known_item!(::fayalite::bundle::BundleType);
     impl_known_item!(::fayalite::enum_::EnumType);
+    impl_known_item!(::fayalite::int::BoolOrIntType);
     impl_known_item!(::fayalite::int::DynSize);
     impl_known_item!(::fayalite::int::IntType);
     impl_known_item!(::fayalite::int::KnownSize);
@@ -2085,6 +2086,7 @@ macro_rules! impl_bounds {
 impl_bounds! {
     #[struct = ParsedBounds]
     pub(crate) enum ParsedBound {
+        BoolOrIntType,
         BundleType,
         EnumType,
         IntType,
@@ -2098,6 +2100,7 @@ impl_bounds! {
 impl_bounds! {
     #[struct = ParsedTypeBounds]
     pub(crate) enum ParsedTypeBound {
+        BoolOrIntType,
         BundleType,
         EnumType,
         IntType,
@@ -2109,6 +2112,7 @@ impl_bounds! {
 impl From<ParsedTypeBound> for ParsedBound {
     fn from(value: ParsedTypeBound) -> Self {
         match value {
+            ParsedTypeBound::BoolOrIntType(v) => ParsedBound::BoolOrIntType(v),
             ParsedTypeBound::BundleType(v) => ParsedBound::BundleType(v),
             ParsedTypeBound::EnumType(v) => ParsedBound::EnumType(v),
             ParsedTypeBound::IntType(v) => ParsedBound::IntType(v),
@@ -2121,6 +2125,7 @@ impl From<ParsedTypeBound> for ParsedBound {
 impl From<ParsedTypeBounds> for ParsedBounds {
     fn from(value: ParsedTypeBounds) -> Self {
         let ParsedTypeBounds {
+            BoolOrIntType,
             BundleType,
             EnumType,
             IntType,
@@ -2128,6 +2133,7 @@ impl From<ParsedTypeBounds> for ParsedBounds {
             Type,
         } = value;
         Self {
+            BoolOrIntType,
             BundleType,
             EnumType,
             IntType,
@@ -2143,6 +2149,10 @@ impl ParsedTypeBound {
     fn implied_bounds(self) -> ParsedTypeBounds {
         let span = self.span();
         match self {
+            Self::BoolOrIntType(v) => ParsedTypeBounds::from_iter([
+                ParsedTypeBound::from(v),
+                ParsedTypeBound::Type(known_items::Type(span)),
+            ]),
             Self::BundleType(v) => ParsedTypeBounds::from_iter([
                 ParsedTypeBound::from(v),
                 ParsedTypeBound::Type(known_items::Type(span)),
@@ -2153,6 +2163,7 @@ impl ParsedTypeBound {
             ]),
             Self::IntType(v) => ParsedTypeBounds::from_iter([
                 ParsedTypeBound::from(v),
+                ParsedTypeBound::BoolOrIntType(known_items::BoolOrIntType(span)),
                 ParsedTypeBound::Type(known_items::Type(span)),
             ]),
             Self::StaticType(v) => ParsedTypeBounds::from_iter([
@@ -2185,6 +2196,7 @@ impl From<ParsedSizeTypeBounds> for ParsedBounds {
     fn from(value: ParsedSizeTypeBounds) -> Self {
         let ParsedSizeTypeBounds { KnownSize, Size } = value;
         Self {
+            BoolOrIntType: None,
             BundleType: None,
             EnumType: None,
             IntType: None,
@@ -2260,6 +2272,7 @@ pub(crate) enum ParsedBoundCategory {
 impl ParsedBound {
     fn categorize(self) -> ParsedBoundCategory {
         match self {
+            Self::BoolOrIntType(v) => ParsedBoundCategory::Type(ParsedTypeBound::BoolOrIntType(v)),
             Self::BundleType(v) => ParsedBoundCategory::Type(ParsedTypeBound::BundleType(v)),
             Self::EnumType(v) => ParsedBoundCategory::Type(ParsedTypeBound::EnumType(v)),
             Self::IntType(v) => ParsedBoundCategory::Type(ParsedTypeBound::IntType(v)),
@@ -2575,6 +2588,7 @@ impl ParsedGenerics {
                 }
             })
             .collect();
+        let param_token = Ident::new("__param", ident.span());
         for (param_count, (generics_accumulation_type, next_param)) in generics_accumulation_types
             .iter()
             .zip(&self.params)
@@ -2623,7 +2637,7 @@ impl ParsedGenerics {
                         next_generics.split_for_impl();
                     let next_turbofish = next_type_generics.as_turbofish();
                     let mut param: Expr = parse_quote_spanned! {ident.span()=>
-                        __param
+                        #param_token
                     };
                     let mut generics = next_generics.clone();
                     let mut index_type = param_ident.clone();
@@ -2638,7 +2652,7 @@ impl ParsedGenerics {
                             is_const: false,
                         });
                         param = parse_quote_spanned! {ident.span()=>
-                            ::fayalite::ty::TypeOrDefault::get(__param, || #default_expr)
+                            ::fayalite::ty::TypeOrDefault::get(#param_token, || #default_expr)
                         };
                         let context = MakeHdlTypeExprContext {
                             named_param_values: self_members[..param_count]
@@ -2703,7 +2717,7 @@ impl ParsedGenerics {
                         {
                             type Output = #next_target #next_type_generics;
 
-                            fn index(&self, __param: #index_type) -> &Self::Output {
+                            fn index(&self, #param_token: #index_type) -> &Self::Output {
                                 ::fayalite::intern::Interned::<_>::into_inner(
                                     ::fayalite::intern::Intern::intern_sized(#output_expr),
                                 )
@@ -2724,7 +2738,7 @@ impl ParsedGenerics {
                                 .iter()
                                 .cloned()
                                 .chain([parse_quote_spanned! {ident.span()=>
-                                    __param
+                                    #param_token
                                 }])
                                 .collect(),
                             is_const: false,
@@ -2763,7 +2777,7 @@ impl ParsedGenerics {
                             {
                                 type Output = #next_target #next_target_args;
 
-                                fn index(&self, __param: #param_ident) -> &Self::Output {
+                                fn index(&self, #param_token: #param_ident) -> &Self::Output {
                                     ::fayalite::intern::Interned::<_>::into_inner(
                                         ::fayalite::intern::Intern::intern_sized(#output_expr),
                                     )
@@ -2791,7 +2805,7 @@ impl ParsedGenerics {
                             .iter()
                             .cloned()
                             .chain([parse_quote_spanned! {ident.span()=>
-                                __param
+                                #param_token
                             }])
                             .collect(),
                         is_const: false,
@@ -2833,7 +2847,7 @@ impl ParsedGenerics {
                         {
                             type Output = #next_target #next_target_args;
 
-                            fn index(&self, __param: __Param) -> &Self::Output {
+                            fn index(&self, #param_token: __Param) -> &Self::Output {
                                 ::fayalite::intern::Interned::<_>::into_inner(
                                     ::fayalite::intern::Intern::intern_sized(#output_expr),
                                 )
@@ -3145,16 +3159,21 @@ impl ParsedGenerics {
                                 .Type
                                 .get_or_insert_with(|| known_items::Type(bound.span()));
                             match bound {
-                                ParsedTypeBound::BundleType(_)
+                                ParsedTypeBound::BoolOrIntType(_)
+                                | ParsedTypeBound::BundleType(_)
                                 | ParsedTypeBound::EnumType(_)
                                 | ParsedTypeBound::IntType(_) => {
                                     errors.error(bound, "bound on mask type not implemented");
                                 }
                                 ParsedTypeBound::StaticType(bound) => {
                                     if bounds.StaticType.is_none() {
-                                        errors.error(bound, "StaticType bound on mask type without corresponding StaticType bound on original type is not implemented");
+                                        errors.error(
+                                            bound,
+                                            "StaticType bound on mask type without corresponding \
+                                            StaticType bound on original type is not implemented",
+                                        );
                                     }
-                                },
+                                }
                                 ParsedTypeBound::Type(_) => {}
                             }
                         }
diff --git a/crates/fayalite/src/ty.rs b/crates/fayalite/src/ty.rs
index c7081eb..380d2e6 100644
--- a/crates/fayalite/src/ty.rs
+++ b/crates/fayalite/src/ty.rs
@@ -210,7 +210,9 @@ impl sealed::BaseTypeSealed for CanonicalType {}
 
 impl BaseType for CanonicalType {}
 
-pub trait TypeOrDefault<D: Type>: sealed::TypeOrDefaultSealed {
+pub trait TypeOrDefault<D: Type>:
+    sealed::TypeOrDefaultSealed + Copy + Eq + Hash + fmt::Debug
+{
     type Type: Type;
     fn get<F: FnOnce() -> D>(self, default: F) -> Self::Type;
 }
diff --git a/crates/fayalite/tests/hdl_types.rs b/crates/fayalite/tests/hdl_types.rs
index d043013..3f11de3 100644
--- a/crates/fayalite/tests/hdl_types.rs
+++ b/crates/fayalite/tests/hdl_types.rs
@@ -29,3 +29,69 @@ pub enum E<T> {
 pub struct S2<T = ()> {
     pub v: E<T>,
 }
+
+// check that #[hdl] properly handles hygiene
+macro_rules! types_in_macros {
+    ($a:ident, $b:ident, $c:ident, $d:ident, $e:ident, $f:ident, $A:ident, $B:ident, $C:ident, $D:ident, $E:ident, $F:ident) => {
+        #[hdl]
+        struct $F {}
+        #[hdl]
+        struct $A<$B, $C: Size, const $D: usize, $E = $F> {
+            $a: $B,
+            $b: UIntType<$C>,
+            $c: SInt<$D>,
+            $d: HdlOption<$E>,
+            $e: $E,
+            $f: $F,
+        }
+        #[allow(non_camel_case_types)]
+        #[hdl]
+        enum $B<$C: Size, const $D: usize, $E = $F> {
+            $a($A<(), $C, $D, $E>),
+            $b(UIntType<$C>),
+            $c(SInt<$D>),
+            $d,
+            $e($E),
+            $f($F),
+        }
+    };
+    // ensure every identifier has different hygiene
+    () => {
+        types_in_macros!(a);
+    };
+    ($a:ident) => {
+        types_in_macros!($a, b);
+    };
+    ($a:ident, $b:ident) => {
+        types_in_macros!($a, $b, c);
+    };
+    ($a:ident, $b:ident, $c:ident) => {
+        types_in_macros!($a, $b, $c, d);
+    };
+    ($a:ident, $b:ident, $c:ident, $d:ident) => {
+        types_in_macros!($a, $b, $c, $d, e);
+    };
+    ($a:ident, $b:ident, $c:ident, $d:ident, $e:ident) => {
+        types_in_macros!($a, $b, $c, $d, $e, f);
+    };
+    ($a:ident, $b:ident, $c:ident, $d:ident, $e:ident, $f:ident) => {
+        types_in_macros!($a, $b, $c, $d, $e, $f, A);
+    };
+    ($a:ident, $b:ident, $c:ident, $d:ident, $e:ident, $f:ident, $A:ident) => {
+        types_in_macros!($a, $b, $c, $d, $e, $f, $A, B);
+    };
+    ($a:ident, $b:ident, $c:ident, $d:ident, $e:ident, $f:ident, $A:ident, $B:ident) => {
+        types_in_macros!($a, $b, $c, $d, $e, $f, $A, $B, C);
+    };
+    ($a:ident, $b:ident, $c:ident, $d:ident, $e:ident, $f:ident, $A:ident, $B:ident, $C:ident) => {
+        types_in_macros!($a, $b, $c, $d, $e, $f, $A, $B, $C, D);
+    };
+    ($a:ident, $b:ident, $c:ident, $d:ident, $e:ident, $f:ident, $A:ident, $B:ident, $C:ident, $D:ident) => {
+        types_in_macros!($a, $b, $c, $d, $e, $f, $A, $B, $C, $D, E);
+    };
+    ($a:ident, $b:ident, $c:ident, $d:ident, $e:ident, $f:ident, $A:ident, $B:ident, $C:ident, $D:ident, $E:ident) => {
+        types_in_macros!($a, $b, $c, $d, $e, $f, $A, $B, $C, $D, $E, F);
+    };
+}
+
+types_in_macros!();