Merge pull request #81 from TheBlueMatt/main
[ldk-c-bindings] / c-bindings-gen / src / main.rs
index 3814d57b3c335d984c60bd0ed31fe393ae8851cf..42fd470da778207a5dcd039c56dc869e670b3c1d 100644 (file)
@@ -22,6 +22,7 @@ use std::collections::{HashMap, hash_map};
 use std::env;
 use std::fs::File;
 use std::io::{Read, Write};
+use std::iter::FromIterator;
 use std::process;
 
 use proc_macro2::Span;
@@ -162,7 +163,7 @@ fn maybe_convert_trait_impl<W: std::io::Write>(w: &mut W, trait_path: &syn::Path
 
                                write!(w, "\tlet res: ").unwrap();
                                // At least in one case we need type annotations here, so provide them.
-                               types.write_rust_type(w, Some(generics), &res_ty);
+                               types.write_rust_type(w, Some(generics), &res_ty, false);
 
                                if t == "lightning::util::ser::ReadableArgs" {
                                        writeln!(w, " = crate::c_types::deserialize_obj_arg(ser, arg_conv);").unwrap();
@@ -331,7 +332,6 @@ fn writeln_trait<'a, 'b, W: std::io::Write>(w: &mut W, t: &'a syn::ItemTrait, ty
                                        ExportStatus::TestOnly => continue,
                                        ExportStatus::NotImplementable => panic!("(C-not implementable) must only appear on traits"),
                                }
-                               if m.default.is_some() { unimplemented!(); }
 
                                let mut meth_gen_types = gen_types.push_ctx();
                                assert!(meth_gen_types.learn_generics(&m.sig.generics, types));
@@ -446,10 +446,9 @@ fn writeln_trait<'a, 'b, W: std::io::Write>(w: &mut W, t: &'a syn::ItemTrait, ty
                                match item {
                                        syn::TraitItem::Method(m) => {
                                                if let ExportStatus::TestOnly = export_status(&m.attrs) { continue; }
-                                               if m.default.is_some() { unimplemented!(); }
                                                if m.sig.constness.is_some() || m.sig.asyncness.is_some() || m.sig.unsafety.is_some() ||
                                                                m.sig.abi.is_some() || m.sig.variadic.is_some() {
-                                                       unimplemented!();
+                                                       panic!("1");
                                                }
                                                let mut meth_gen_types = gen_types.push_ctx();
                                                assert!(meth_gen_types.learn_generics(&m.sig.generics, $type_resolver));
@@ -462,7 +461,7 @@ fn writeln_trait<'a, 'b, W: std::io::Write>(w: &mut W, t: &'a syn::ItemTrait, ty
                                                for inp in m.sig.inputs.iter() {
                                                        match inp {
                                                                syn::FnArg::Receiver(recv) => {
-                                                                       if !recv.attrs.is_empty() || recv.reference.is_none() { unimplemented!(); }
+                                                                       if !recv.attrs.is_empty() || recv.reference.is_none() { panic!("2"); }
                                                                        write!(w, "&").unwrap();
                                                                        if let Some(lft) = &recv.reference.as_ref().unwrap().1 {
                                                                                write!(w, "'{} ", lft.ident).unwrap();
@@ -474,18 +473,18 @@ fn writeln_trait<'a, 'b, W: std::io::Write>(w: &mut W, t: &'a syn::ItemTrait, ty
                                                                        }
                                                                },
                                                                syn::FnArg::Typed(arg) => {
-                                                                       if !arg.attrs.is_empty() { unimplemented!(); }
+                                                                       if !arg.attrs.is_empty() { panic!("3"); }
                                                                        match &*arg.pat {
                                                                                syn::Pat::Ident(ident) => {
                                                                                        if !ident.attrs.is_empty() || ident.by_ref.is_some() ||
                                                                                                        ident.mutability.is_some() || ident.subpat.is_some() {
-                                                                                               unimplemented!();
+                                                                                               panic!("4");
                                                                                        }
                                                                                        write!(w, ", mut {}{}: ", if $type_resolver.skip_arg(&*arg.ty, Some(&meth_gen_types)) { "_" } else { "" }, ident.ident).unwrap();
                                                                                }
-                                                                               _ => unimplemented!(),
+                                                                               _ => panic!("5"),
                                                                        }
-                                                                       $type_resolver.write_rust_type(w, Some(&gen_types), &*arg.ty);
+                                                                       $type_resolver.write_rust_type(w, Some(&gen_types), &*arg.ty, false);
                                                                }
                                                        }
                                                }
@@ -493,14 +492,14 @@ fn writeln_trait<'a, 'b, W: std::io::Write>(w: &mut W, t: &'a syn::ItemTrait, ty
                                                match &m.sig.output {
                                                        syn::ReturnType::Type(_, rtype) => {
                                                                write!(w, " -> ").unwrap();
-                                                               $type_resolver.write_rust_type(w, Some(&gen_types), &*rtype)
+                                                               $type_resolver.write_rust_type(w, Some(&gen_types), &*rtype, false)
                                                        },
                                                        _ => {},
                                                }
                                                write!(w, " {{\n\t\t").unwrap();
                                                match export_status(&m.attrs) {
                                                        ExportStatus::NoExport => {
-                                                               unimplemented!();
+                                                               panic!("6");
                                                        },
                                                        _ => {},
                                                }
@@ -526,14 +525,14 @@ fn writeln_trait<'a, 'b, W: std::io::Write>(w: &mut W, t: &'a syn::ItemTrait, ty
                                                writeln!(w, "\n\t}}").unwrap();
                                        },
                                        &syn::TraitItem::Type(ref t) => {
-                                               if t.default.is_some() || t.generics.lt_token.is_some() { unimplemented!(); }
+                                               if t.default.is_some() || t.generics.lt_token.is_some() { panic!("10"); }
                                                let mut bounds_iter = t.bounds.iter();
                                                loop {
                                                        match bounds_iter.next().unwrap() {
                                                                syn::TypeParamBound::Trait(tr) => {
                                                                        writeln!(w, "\ttype {} = crate::{};", t.ident, $type_resolver.resolve_path(&tr.path, Some(&gen_types))).unwrap();
                                                                        for bound in bounds_iter {
-                                                                               if let syn::TypeParamBound::Trait(_) = bound { unimplemented!(); }
+                                                                               if let syn::TypeParamBound::Trait(_) = bound { panic!("11"); }
                                                                        }
                                                                        break;
                                                                },
@@ -541,7 +540,7 @@ fn writeln_trait<'a, 'b, W: std::io::Write>(w: &mut W, t: &'a syn::ItemTrait, ty
                                                        }
                                                }
                                        },
-                                       _ => unimplemented!(),
+                                       _ => panic!("12"),
                                }
                        }
                }
@@ -598,7 +597,16 @@ fn writeln_trait<'a, 'b, W: std::io::Write>(w: &mut W, t: &'a syn::ItemTrait, ty
                (s, i) => {
                        if let Some(supertrait) = types.crate_types.traits.get(s) {
                                let resolver = get_module_type_resolver!(s, types.crate_libs, types.crate_types);
-                               writeln!(w, "impl {} for {} {{", s, trait_name).unwrap();
+
+                               // Blindly assume that the same imports where `supertrait` is defined are also
+                               // imported here. This will almost certainly break at some point, but it should be
+                               // a compilation failure when it does so.
+                               write!(w, "impl").unwrap();
+                               maybe_write_lifetime_generics(w, &supertrait.generics, types);
+                               write!(w, " {}", s).unwrap();
+                               maybe_write_generics(w, &supertrait.generics, types, false);
+                               writeln!(w, " for {} {{", trait_name).unwrap();
+
                                impl_trait_for_c!(supertrait, format!(".{}", i), &resolver);
                                writeln!(w, "}}").unwrap();
                        } else {
@@ -1050,7 +1058,7 @@ fn writeln_impl<W: std::io::Write>(w: &mut W, i: &syn::ItemImpl, types: &mut Typ
                                                writeln!(w, "\t}}\n}}\n").unwrap();
 
                                                macro_rules! impl_meth {
-                                                       ($m: expr, $trait_meth: expr, $trait_path: expr, $trait: expr, $indent: expr) => {
+                                                       ($m: expr, $trait_meth: expr, $trait_path: expr, $trait: expr, $indent: expr, $types: expr) => {
                                                                let trait_method = $trait.items.iter().filter_map(|item| {
                                                                        if let syn::TraitItem::Method(t_m) = item { Some(t_m) } else { None }
                                                                }).find(|trait_meth| trait_meth.sig.ident == $m.sig.ident).unwrap();
@@ -1065,14 +1073,14 @@ fn writeln_impl<W: std::io::Write>(w: &mut W, i: &syn::ItemImpl, types: &mut Typ
                                                                }
                                                                write!(w, "extern \"C\" fn {}_{}_{}(", ident, $trait.ident, $m.sig.ident).unwrap();
                                                                let mut meth_gen_types = gen_types.push_ctx();
-                                                               assert!(meth_gen_types.learn_generics(&$m.sig.generics, types));
+                                                               assert!(meth_gen_types.learn_generics(&$m.sig.generics, $types));
                                                                let mut uncallable_function = false;
                                                                for inp in $m.sig.inputs.iter() {
                                                                        match inp {
                                                                                syn::FnArg::Typed(arg) => {
-                                                                                       if types.skip_arg(&*arg.ty, Some(&meth_gen_types)) { continue; }
+                                                                                       if $types.skip_arg(&*arg.ty, Some(&meth_gen_types)) { continue; }
                                                                                        let mut c_type = Vec::new();
-                                                                                       types.write_c_type(&mut c_type, &*arg.ty, Some(&meth_gen_types), false);
+                                                                                       $types.write_c_type(&mut c_type, &*arg.ty, Some(&meth_gen_types), false);
                                                                                        if is_type_unconstructable(&String::from_utf8(c_type).unwrap()) {
                                                                                                uncallable_function = true;
                                                                                        }
@@ -1081,16 +1089,16 @@ fn writeln_impl<W: std::io::Write>(w: &mut W, i: &syn::ItemImpl, types: &mut Typ
                                                                        }
                                                                }
                                                                if uncallable_function {
-                                                                       let mut trait_resolver = get_module_type_resolver!(full_trait_path, types.crate_libs, types.crate_types);
+                                                                       let mut trait_resolver = get_module_type_resolver!(full_trait_path, $types.crate_libs, $types.crate_types);
                                                                        write_method_params(w, &$trait_meth.sig, "c_void", &mut trait_resolver, Some(&meth_gen_types), true, true);
                                                                } else {
-                                                                       write_method_params(w, &$m.sig, "c_void", types, Some(&meth_gen_types), true, true);
+                                                                       write_method_params(w, &$m.sig, "c_void", $types, Some(&meth_gen_types), true, true);
                                                                }
                                                                write!(w, " {{\n\t").unwrap();
                                                                if uncallable_function {
                                                                        write!(w, "unreachable!();").unwrap();
                                                                } else {
-                                                                       write_method_var_decl_body(w, &$m.sig, "", types, Some(&meth_gen_types), false);
+                                                                       write_method_var_decl_body(w, &$m.sig, "", $types, Some(&meth_gen_types), false);
                                                                        let mut takes_self = false;
                                                                        for inp in $m.sig.inputs.iter() {
                                                                                if let syn::FnArg::Receiver(_) = inp {
@@ -1120,7 +1128,7 @@ fn writeln_impl<W: std::io::Write>(w: &mut W, i: &syn::ItemImpl, types: &mut Typ
                                                                                },
                                                                                _ => {},
                                                                        }
-                                                                       write_method_call_params(w, &$m.sig, "", types, Some(&meth_gen_types), &real_type, false);
+                                                                       write_method_call_params(w, &$m.sig, "", $types, Some(&meth_gen_types), &real_type, false);
                                                                }
                                                                write!(w, "\n}}\n").unwrap();
                                                                if let syn::ReturnType::Type(_, rtype) = &$m.sig.output {
@@ -1130,7 +1138,7 @@ fn writeln_impl<W: std::io::Write>(w: &mut W, i: &syn::ItemImpl, types: &mut Typ
                                                                                writeln!(w, "\t// This is a bit race-y in the general case, but for our specific use-cases today, we're safe").unwrap();
                                                                                writeln!(w, "\t// Specifically, we must ensure that the first time we're called it can never be in parallel").unwrap();
                                                                                write!(w, "\tif ").unwrap();
-                                                                               types.write_empty_rust_val_check(Some(&meth_gen_types), w, &*r.elem, &format!("trait_self_arg.{}", $m.sig.ident));
+                                                                               $types.write_empty_rust_val_check(Some(&meth_gen_types), w, &*r.elem, &format!("trait_self_arg.{}", $m.sig.ident));
                                                                                writeln!(w, " {{").unwrap();
                                                                                writeln!(w, "\t\tunsafe {{ &mut *(trait_self_arg as *const {}  as *mut {}) }}.{} = {}_{}_{}(trait_self_arg.this_arg);", $trait.ident, $trait.ident, $m.sig.ident, ident, $trait.ident, $m.sig.ident).unwrap();
                                                                                writeln!(w, "\t}}").unwrap();
@@ -1140,24 +1148,29 @@ fn writeln_impl<W: std::io::Write>(w: &mut W, i: &syn::ItemImpl, types: &mut Typ
                                                        }
                                                }
 
-                                               'impl_item_loop: for item in i.items.iter() {
-                                                       match item {
-                                                               syn::ImplItem::Method(m) => {
-                                                                       for trait_item in trait_obj.items.iter() {
-                                                                               match trait_item {
-                                                                                       syn::TraitItem::Method(meth) => {
+                                               'impl_item_loop: for trait_item in trait_obj.items.iter() {
+                                                       match trait_item {
+                                                               syn::TraitItem::Method(meth) => {
+                                                                       for item in i.items.iter() {
+                                                                               match item {
+                                                                                       syn::ImplItem::Method(m) => {
                                                                                                if meth.sig.ident == m.sig.ident {
-                                                                                                       impl_meth!(m, meth, full_trait_path, trait_obj, "");
+                                                                                                       impl_meth!(m, meth, full_trait_path, trait_obj, "", types);
                                                                                                        continue 'impl_item_loop;
                                                                                                }
                                                                                        },
-                                                                                       _ => {},
+                                                                                       syn::ImplItem::Type(_) => {},
+                                                                                       _ => unimplemented!(),
                                                                                }
                                                                        }
-                                                                       unreachable!();
+                                                                       assert!(meth.default.is_some());
+                                                                       let old_gen_types = gen_types;
+                                                                       gen_types = GenericTypes::new(Some(resolved_path.clone()));
+                                                                       let mut trait_resolver = get_module_type_resolver!(full_trait_path, types.crate_libs, types.crate_types);
+                                                                       impl_meth!(meth, meth, full_trait_path, trait_obj, "", &mut trait_resolver);
+                                                                       gen_types = old_gen_types;
                                                                },
-                                                               syn::ImplItem::Type(_) => {},
-                                                               _ => unimplemented!(),
+                                                               _ => {},
                                                        }
                                                }
                                                if requires_clone {
@@ -1370,119 +1383,7 @@ fn writeln_impl<W: std::io::Write>(w: &mut W, i: &syn::ItemImpl, types: &mut Typ
                                        }
                                }
                        } else if let Some(resolved_path) = types.maybe_resolve_ident(&ident) {
-                               if let Some(aliases) = types.crate_types.reverse_alias_map.get(&resolved_path).cloned() {
-                                       let mut gen_types = Some(GenericTypes::new(Some(resolved_path.clone())));
-                                       if !gen_types.as_mut().unwrap().learn_generics(&i.generics, types) {
-                                               gen_types = None;
-                                       }
-                                       let alias_module = rsplit_once(&resolved_path, "::").unwrap().0;
-
-                                       'alias_impls: for (alias_resolved, arguments) in aliases {
-                                               let mut new_ty_generics = Vec::new();
-                                               let mut need_generics = false;
-
-                                               let alias_resolver_override;
-                                               let alias_resolver = if alias_module != types.module_path {
-                                                       alias_resolver_override = ImportResolver::new(types.types.crate_name, &types.crate_types.lib_ast.dependencies,
-                                                               alias_module, &types.crate_types.lib_ast.modules.get(alias_module).unwrap().items);
-                                                       &alias_resolver_override
-                                               } else { &types.types };/*.maybe_resolve_path(&alias, None).unwrap();*/
-                                               for (idx, gen) in i.generics.params.iter().enumerate() {
-                                                       match gen {
-                                                               syn::GenericParam::Type(type_param) => {
-                                                                       'bounds_check: for bound in type_param.bounds.iter() {
-                                                                               if let syn::TypeParamBound::Trait(trait_bound) = bound {
-                                                                                       if let syn::PathArguments::AngleBracketed(ref t) = &arguments {
-                                                                                               assert!(idx < t.args.len());
-                                                                                               if let syn::GenericArgument::Type(syn::Type::Path(p)) = &t.args[idx] {
-                                                                                                       if let Some(generic_arg) = alias_resolver.maybe_resolve_path(&p.path, None) {
-
-                                                                                                               new_ty_generics.push((type_param.ident.clone(), syn::Type::Path(p.clone())));
-                                                                                                               let generic_bound = types.maybe_resolve_path(&trait_bound.path, None)
-                                                                                                                       .unwrap_or_else(|| format!("{}::{}", types.module_path, single_ident_generic_path_to_ident(&trait_bound.path).unwrap()));
-                                                                                                               if let Some(traits_impld) = types.crate_types.trait_impls.get(&generic_arg) {
-                                                                                                                       for trait_impld in traits_impld {
-                                                                                                                               if *trait_impld == generic_bound { continue 'bounds_check; }
-                                                                                                                       }
-                                                                                                                       eprintln!("struct {}'s generic arg {} didn't match bound {}", alias_resolved, generic_arg, generic_bound);
-                                                                                                                       continue 'alias_impls;
-                                                                                                               } else {
-                                                                                                                       eprintln!("struct {}'s generic arg {} didn't match bound {}", alias_resolved, generic_arg, generic_bound);
-                                                                                                                       continue 'alias_impls;
-                                                                                                               }
-                                                                                                       } else if gen_types.is_some() {
-                                                                                                               new_ty_generics.push((type_param.ident.clone(),
-                                                                                                                       gen_types.as_ref().resolve_type(&syn::Type::Path(p.clone())).clone()));
-                                                                                                               need_generics = true;
-                                                                                                       } else {
-                                                                                                               unimplemented!();
-                                                                                                       }
-                                                                                               } else { unimplemented!(); }
-                                                                                       } else { unimplemented!(); }
-                                                                               } else { unimplemented!(); }
-                                                                       }
-                                                               },
-                                                               syn::GenericParam::Lifetime(_) => {},
-                                                               syn::GenericParam::Const(_) => unimplemented!(),
-                                                       }
-                                               }
-                                               let mut params = syn::punctuated::Punctuated::new();
-                                               let alias = string_path_to_syn_path(&alias_resolved);
-                                               let real_aliased =
-                                                       if need_generics {
-                                                               let alias_generics = types.crate_types.opaques.get(&alias_resolved).unwrap().1;
-
-                                                               // If we need generics on the alias, create impl generic bounds...
-                                                               assert_eq!(new_ty_generics.len(), i.generics.params.len());
-                                                               let mut args = syn::punctuated::Punctuated::new();
-                                                               for (ident, param) in new_ty_generics.drain(..) {
-                                                                       // TODO: We blindly assume that generics in the type alias and
-                                                                       // the aliased type have the same names, which we really shouldn't.
-                                                                       if alias_generics.params.iter().any(|generic|
-                                                                               if let syn::GenericParam::Type(t) = generic { t.ident == ident } else { false })
-                                                                       {
-                                                                               args.push(parse_quote!(#ident));
-                                                                       }
-                                                                       params.push(syn::GenericParam::Type(syn::TypeParam {
-                                                                               attrs: Vec::new(),
-                                                                               ident,
-                                                                               colon_token: None,
-                                                                               bounds: syn::punctuated::Punctuated::new(),
-                                                                               eq_token: Some(syn::token::Eq(Span::call_site())),
-                                                                               default: Some(param),
-                                                                       }));
-                                                               }
-                                                               // ... and swap the last segment of the impl self_ty to use the generic bounds.
-                                                               let mut res = alias.clone();
-                                                               res.segments.last_mut().unwrap().arguments = syn::PathArguments::AngleBracketed(syn::AngleBracketedGenericArguments {
-                                                                       colon2_token: None,
-                                                                       lt_token: syn::token::Lt(Span::call_site()),
-                                                                       args,
-                                                                       gt_token: syn::token::Gt(Span::call_site()),
-                                                               });
-                                                               res
-                                                       } else { alias.clone() };
-                                               let aliased_impl = syn::ItemImpl {
-                                                       attrs: i.attrs.clone(),
-                                                       brace_token: syn::token::Brace(Span::call_site()),
-                                                       defaultness: None,
-                                                       generics: syn::Generics {
-                                                               lt_token: None,
-                                                               params,
-                                                               gt_token: None,
-                                                               where_clause: None,
-                                                       },
-                                                       impl_token: syn::Token![impl](Span::call_site()),
-                                                       items: i.items.clone(),
-                                                       self_ty: Box::new(syn::Type::Path(syn::TypePath { qself: None, path: real_aliased })),
-                                                       trait_: i.trait_.clone(),
-                                                       unsafety: None,
-                                               };
-                                               writeln_impl(w, &aliased_impl, types);
-                                       }
-                               } else {
-                                       eprintln!("Not implementing anything for {} due to it being marked not exported", ident);
-                               }
+                               create_alias_for_impl(resolved_path, i, types, move |aliased_impl, types| writeln_impl(w, &aliased_impl, types));
                        } else {
                                eprintln!("Not implementing anything for {} due to no-resolve (probably the type isn't pub)", ident);
                        }
@@ -1490,6 +1391,168 @@ fn writeln_impl<W: std::io::Write>(w: &mut W, i: &syn::ItemImpl, types: &mut Typ
        }
 }
 
+fn create_alias_for_impl<F: FnMut(syn::ItemImpl, &mut TypeResolver)>(resolved_path: String, i: &syn::ItemImpl, types: &mut TypeResolver, mut callback: F) {
+       if let Some(aliases) = types.crate_types.reverse_alias_map.get(&resolved_path).cloned() {
+               let mut gen_types = Some(GenericTypes::new(Some(resolved_path.clone())));
+               if !gen_types.as_mut().unwrap().learn_generics(&i.generics, types) {
+                       gen_types = None;
+               }
+               let alias_module = rsplit_once(&resolved_path, "::").unwrap().0;
+
+               'alias_impls: for (alias_resolved, arguments) in aliases {
+                       let mut new_ty_generics = Vec::new();
+                       let mut new_ty_bounds = Vec::new();
+                       let mut need_generics = false;
+
+                       let alias_resolver_override;
+                       let alias_resolver = if alias_module != types.module_path {
+                               alias_resolver_override = ImportResolver::new(types.types.crate_name, &types.crate_types.lib_ast.dependencies,
+                                       alias_module, &types.crate_types.lib_ast.modules.get(alias_module).unwrap().items);
+                               &alias_resolver_override
+                       } else { &types.types };
+                       let mut where_clause = syn::WhereClause { where_token: syn::Token![where](Span::call_site()),
+                               predicates: syn::punctuated::Punctuated::new()
+                       };
+                       for (idx, gen) in i.generics.params.iter().enumerate() {
+                               match gen {
+                                       syn::GenericParam::Type(type_param) => {
+                                               'bounds_check: for bound in type_param.bounds.iter() {
+                                                       if let syn::TypeParamBound::Trait(trait_bound) = bound {
+                                                               if let syn::PathArguments::AngleBracketed(ref t) = &arguments {
+                                                                       assert!(idx < t.args.len());
+                                                                       if let syn::GenericArgument::Type(syn::Type::Path(p)) = &t.args[idx] {
+                                                                               let generic_bound = types.maybe_resolve_path(&trait_bound.path, None)
+                                                                                       .unwrap_or_else(|| format!("{}::{}", types.module_path, single_ident_generic_path_to_ident(&trait_bound.path).unwrap()));
+
+                                                                               if let Some(generic_arg) = alias_resolver.maybe_resolve_path(&p.path, None) {
+                                                                                       new_ty_generics.push((type_param.ident.clone(), syn::Type::Path(p.clone())));
+                                                                                       if let Some(traits_impld) = types.crate_types.trait_impls.get(&generic_arg) {
+                                                                                               for trait_impld in traits_impld {
+                                                                                                       if *trait_impld == generic_bound { continue 'bounds_check; }
+                                                                                               }
+                                                                                               eprintln!("struct {}'s generic arg {} didn't match bound {}", alias_resolved, generic_arg, generic_bound);
+                                                                                               continue 'alias_impls;
+                                                                                       } else {
+                                                                                               eprintln!("struct {}'s generic arg {} didn't match bound {}", alias_resolved, generic_arg, generic_bound);
+                                                                                               continue 'alias_impls;
+                                                                                       }
+                                                                               } else if gen_types.is_some() {
+                                                                                       let resp =  types.maybe_resolve_path(&p.path, gen_types.as_ref());
+                                                                                       if generic_bound == "core::ops::Deref" && resp.is_some() {
+                                                                                               new_ty_bounds.push((type_param.ident.clone(),
+                                                                                                       string_path_to_syn_path("core::ops::Deref")));
+                                                                                               let mut bounds = syn::punctuated::Punctuated::new();
+                                                                                               bounds.push(syn::TypeParamBound::Trait(syn::TraitBound {
+                                                                                                       paren_token: None,
+                                                                                                       modifier: syn::TraitBoundModifier::None,
+                                                                                                       lifetimes: None,
+                                                                                                       path: string_path_to_syn_path(&types.resolve_path(&p.path, gen_types.as_ref())),
+                                                                                               }));
+                                                                                               let mut path = string_path_to_syn_path(&format!("{}::Target", type_param.ident));
+                                                                                               path.leading_colon = None;
+                                                                                               where_clause.predicates.push(syn::WherePredicate::Type(syn::PredicateType {
+                                                                                                       lifetimes: None,
+                                                                                                       bounded_ty: syn::Type::Path(syn::TypePath { qself: None, path }),
+                                                                                                       colon_token: syn::Token![:](Span::call_site()),
+                                                                                                       bounds,
+                                                                                               }));
+                                                                                       } else {
+                                                                                               new_ty_generics.push((type_param.ident.clone(),
+                                                                                                       gen_types.as_ref().resolve_type(&syn::Type::Path(p.clone())).clone()));
+                                                                                       }
+                                                                                       need_generics = true;
+                                                                               } else {
+                                                                                       unimplemented!();
+                                                                               }
+                                                                       } else { unimplemented!(); }
+                                                               } else { unimplemented!(); }
+                                                       } else { unimplemented!(); }
+                                               }
+                                       },
+                                       syn::GenericParam::Lifetime(_) => {},
+                                       syn::GenericParam::Const(_) => unimplemented!(),
+                               }
+                       }
+                       let mut params = syn::punctuated::Punctuated::new();
+                       let alias = string_path_to_syn_path(&alias_resolved);
+                       let real_aliased =
+                               if need_generics {
+                                       let alias_generics = types.crate_types.opaques.get(&alias_resolved).unwrap().1;
+
+                                       // If we need generics on the alias, create impl generic bounds...
+                                       assert_eq!(new_ty_generics.len() + new_ty_bounds.len(), i.generics.params.len());
+                                       let mut args = syn::punctuated::Punctuated::new();
+                                       for (ident, param) in new_ty_generics.drain(..) {
+                                               // TODO: We blindly assume that generics in the type alias and
+                                               // the aliased type have the same names, which we really shouldn't.
+                                               if alias_generics.params.iter().any(|generic|
+                                                       if let syn::GenericParam::Type(t) = generic { t.ident == ident } else { false })
+                                               {
+                                                       args.push(parse_quote!(#ident));
+                                               }
+                                               params.push(syn::GenericParam::Type(syn::TypeParam {
+                                                       attrs: Vec::new(),
+                                                       ident,
+                                                       colon_token: None,
+                                                       bounds: syn::punctuated::Punctuated::new(),
+                                                       eq_token: Some(syn::token::Eq(Span::call_site())),
+                                                       default: Some(param),
+                                               }));
+                                       }
+                                       for (ident, param) in new_ty_bounds.drain(..) {
+                                               // TODO: We blindly assume that generics in the type alias and
+                                               // the aliased type have the same names, which we really shouldn't.
+                                               if alias_generics.params.iter().any(|generic|
+                                                       if let syn::GenericParam::Type(t) = generic { t.ident == ident } else { false })
+                                               {
+                                                       args.push(parse_quote!(#ident));
+                                               }
+                                               params.push(syn::GenericParam::Type(syn::TypeParam {
+                                                       attrs: Vec::new(),
+                                                       ident,
+                                                       colon_token: Some(syn::token::Colon(Span::call_site())),
+                                                       bounds: syn::punctuated::Punctuated::from_iter(
+                                                               Some(syn::TypeParamBound::Trait(syn::TraitBound {
+                                                                       path: param, paren_token: None, lifetimes: None,
+                                                                       modifier: syn::TraitBoundModifier::None,
+                                                               }))
+                                                       ),
+                                                       eq_token: None,
+                                                       default: None,
+                                               }));
+                                       }
+                                       // ... and swap the last segment of the impl self_ty to use the generic bounds.
+                                       let mut res = alias.clone();
+                                       res.segments.last_mut().unwrap().arguments = syn::PathArguments::AngleBracketed(syn::AngleBracketedGenericArguments {
+                                               colon2_token: None,
+                                               lt_token: syn::token::Lt(Span::call_site()),
+                                               args,
+                                               gt_token: syn::token::Gt(Span::call_site()),
+                                       });
+                                       res
+                               } else { alias.clone() };
+                       callback(syn::ItemImpl {
+                               attrs: i.attrs.clone(),
+                               brace_token: syn::token::Brace(Span::call_site()),
+                               defaultness: None,
+                               generics: syn::Generics {
+                                       lt_token: None,
+                                       params,
+                                       gt_token: None,
+                                       where_clause: Some(where_clause),
+                               },
+                               impl_token: syn::Token![impl](Span::call_site()),
+                               items: i.items.clone(),
+                               self_ty: Box::new(syn::Type::Path(syn::TypePath { qself: None, path: real_aliased })),
+                               trait_: i.trait_.clone(),
+                               unsafety: None,
+                       }, types);
+               }
+       } else {
+               eprintln!("Not implementing anything for {} due to it being marked not exported", resolved_path);
+       }
+}
+
 /// Replaces upper case charachters with underscore followed by lower case except the first
 /// charachter and repeated upper case characthers (which are only made lower case).
 fn camel_to_snake_case(camel: &str) -> String {
@@ -1531,8 +1594,37 @@ fn writeln_enum<'a, 'b, W: std::io::Write>(w: &mut W, e: &'a syn::ItemEnum, type
 
        let mut needs_free = false;
        let mut constr = Vec::new();
+       let mut is_clonable = true;
+
+       for var in e.variants.iter() {
+               if let syn::Fields::Named(fields) = &var.fields {
+                       needs_free = true;
+                       for field in fields.named.iter() {
+                               if export_status(&field.attrs) == ExportStatus::TestOnly { continue; }
 
-       writeln!(w, "#[must_use]\n#[derive(Clone)]\n#[repr(C)]\npub enum {} {{", e.ident).unwrap();
+                               let mut ty_checks = Vec::new();
+                               types.write_c_type(&mut ty_checks, &field.ty, Some(&gen_types), false);
+                               if !types.is_clonable(&String::from_utf8(ty_checks).unwrap()) {
+                                       is_clonable = false;
+                               }
+                       }
+               } else if let syn::Fields::Unnamed(fields) = &var.fields {
+                       for field in fields.unnamed.iter() {
+                               let mut ty_checks = Vec::new();
+                               types.write_c_type(&mut ty_checks, &field.ty, Some(&gen_types), false);
+                               let ty = String::from_utf8(ty_checks).unwrap();
+                               if ty != "" && !types.is_clonable(&ty) {
+                                       is_clonable = false;
+                               }
+                       }
+               }
+       }
+
+       if is_clonable {
+               writeln!(w, "#[derive(Clone)]").unwrap();
+               types.crate_types.set_clonable(format!("{}::{}", types.module_path, e.ident));
+       }
+       writeln!(w, "#[must_use]\n#[repr(C)]\npub enum {} {{", e.ident).unwrap();
        for var in e.variants.iter() {
                assert_eq!(export_status(&var.attrs), ExportStatus::Export); // We can't partially-export a mirrored enum
                writeln_docs(w, &var.attrs, "\t");
@@ -1549,29 +1641,32 @@ fn writeln_enum<'a, 'b, W: std::io::Write>(w: &mut W, e: &'a syn::ItemEnum, type
                                writeln_field_docs(w, &field.attrs, "\t\t", types, Some(&gen_types), &field.ty);
                                write!(w, "\t\t{}: ", field.ident.as_ref().unwrap()).unwrap();
                                write!(&mut constr, "{}{}: ", if idx != 0 { ", " } else { "" }, field.ident.as_ref().unwrap()).unwrap();
-                               types.write_c_type(w, &field.ty, Some(&gen_types), false);
-                               types.write_c_type(&mut constr, &field.ty, Some(&gen_types), false);
+                               types.write_c_type(w, &field.ty, Some(&gen_types), true);
+                               types.write_c_type(&mut constr, &field.ty, Some(&gen_types), true);
                                writeln!(w, ",").unwrap();
                        }
                        write!(w, "\t}}").unwrap();
                } else if let syn::Fields::Unnamed(fields) = &var.fields {
                        if fields.unnamed.len() == 1 {
                                let mut empty_check = Vec::new();
-                               types.write_c_type(&mut empty_check, &fields.unnamed[0].ty, Some(&gen_types), false);
+                               types.write_c_type(&mut empty_check, &fields.unnamed[0].ty, Some(&gen_types), true);
                                if empty_check.is_empty() {
                                        empty_tuple_variant = true;
                                }
                        }
                        if !empty_tuple_variant {
                                needs_free = true;
-                               write!(w, "(").unwrap();
+                               writeln!(w, "(").unwrap();
                                for (idx, field) in fields.unnamed.iter().enumerate() {
                                        if export_status(&field.attrs) == ExportStatus::TestOnly { continue; }
+                                       writeln_field_docs(w, &field.attrs, "\t\t", types, Some(&gen_types), &field.ty);
+                                       write!(w, "\t\t").unwrap();
+                                       types.write_c_type(w, &field.ty, Some(&gen_types), true);
+
                                        write!(&mut constr, "{}: ", ('a' as u8 + idx as u8) as char).unwrap();
-                                       types.write_c_type(w, &field.ty, Some(&gen_types), false);
                                        types.write_c_type(&mut constr, &field.ty, Some(&gen_types), false);
                                        if idx != fields.unnamed.len() - 1 {
-                                               write!(w, ",").unwrap();
+                                               writeln!(w, ",").unwrap();
                                                write!(&mut constr, ",").unwrap();
                                        }
                                }
@@ -1589,8 +1684,19 @@ fn writeln_enum<'a, 'b, W: std::io::Write>(w: &mut W, e: &'a syn::ItemEnum, type
                } else if let syn::Fields::Unnamed(fields) = &var.fields {
                        if !empty_tuple_variant {
                                write!(&mut constr, "(").unwrap();
-                               for idx in 0..fields.unnamed.len() {
-                                       write!(&mut constr, "{}, ", ('a' as u8 + idx as u8) as char).unwrap();
+                               for (idx, field) in fields.unnamed.iter().enumerate() {
+                                       let mut ref_c_ty = Vec::new();
+                                       let mut nonref_c_ty = Vec::new();
+                                       types.write_c_type(&mut ref_c_ty, &field.ty, Some(&gen_types), false);
+                                       types.write_c_type(&mut nonref_c_ty, &field.ty, Some(&gen_types), true);
+
+                                       if ref_c_ty != nonref_c_ty {
+                                               // We blindly assume references in field types are always opaque types, and
+                                               // print out an opaque reference -> owned reference conversion here.
+                                               write!(&mut constr, "{} {{ inner: {}.inner, is_owned: false }}, ", String::from_utf8(nonref_c_ty).unwrap(), ('a' as u8 + idx as u8) as char).unwrap();
+                                       } else {
+                                               write!(&mut constr, "{}, ", ('a' as u8 + idx as u8) as char).unwrap();
+                                       }
                                }
                                writeln!(&mut constr, ")").unwrap();
                        } else {
@@ -1600,7 +1706,10 @@ fn writeln_enum<'a, 'b, W: std::io::Write>(w: &mut W, e: &'a syn::ItemEnum, type
                writeln!(&mut constr, "}}").unwrap();
                writeln!(w, ",").unwrap();
        }
-       writeln!(w, "}}\nuse {}::{} as native{};\nimpl {} {{", types.module_path, e.ident, e.ident, e.ident).unwrap();
+       writeln!(w, "}}\nuse {}::{} as {}Import;", types.module_path, e.ident, e.ident).unwrap();
+       write!(w, "pub(crate) type native{} = {}Import", e.ident, e.ident).unwrap();
+       maybe_write_generics(w, &e.generics, &types, true);
+       writeln!(w, ";\n\nimpl {} {{", e.ident).unwrap();
 
        macro_rules! write_conv {
                ($fn_sig: expr, $to_c: expr, $ref: expr) => {
@@ -1618,7 +1727,7 @@ fn writeln_enum<'a, 'b, W: std::io::Write>(w: &mut W, e: &'a syn::ItemEnum, type
                                } else if let syn::Fields::Unnamed(fields) = &var.fields {
                                        if fields.unnamed.len() == 1 {
                                                let mut empty_check = Vec::new();
-                                               types.write_c_type(&mut empty_check, &fields.unnamed[0].ty, Some(&gen_types), false);
+                                               types.write_c_type(&mut empty_check, &fields.unnamed[0].ty, Some(&gen_types), true);
                                                if empty_check.is_empty() {
                                                        empty_tuple_variant = true;
                                                }
@@ -1640,7 +1749,7 @@ fn writeln_enum<'a, 'b, W: std::io::Write>(w: &mut W, e: &'a syn::ItemEnum, type
                                                let mut sink = ::std::io::sink();
                                                let mut out: &mut dyn std::io::Write = if $ref { &mut sink } else { w };
                                                let new_var = if $to_c {
-                                                       types.write_to_c_conversion_new_var(&mut out, $field_ident, &$field.ty, Some(&gen_types), false)
+                                                       types.write_to_c_conversion_new_var(&mut out, $field_ident, &$field.ty, Some(&gen_types), true)
                                                } else {
                                                        types.write_from_c_conversion_new_var(&mut out, $field_ident, &$field.ty, Some(&gen_types))
                                                };
@@ -1650,7 +1759,7 @@ fn writeln_enum<'a, 'b, W: std::io::Write>(w: &mut W, e: &'a syn::ItemEnum, type
                                                                if new_var {
                                                                        let nonref_ident = format_ident!("{}_nonref", $field_ident);
                                                                        if $to_c {
-                                                                               types.write_to_c_conversion_new_var(w, &nonref_ident, &$field.ty, Some(&gen_types), false);
+                                                                               types.write_to_c_conversion_new_var(w, &nonref_ident, &$field.ty, Some(&gen_types), true);
                                                                        } else {
                                                                                types.write_from_c_conversion_new_var(w, &nonref_ident, &$field.ty, Some(&gen_types));
                                                                        }
@@ -1682,14 +1791,14 @@ fn writeln_enum<'a, 'b, W: std::io::Write>(w: &mut W, e: &'a syn::ItemEnum, type
                                        ($field: expr, $field_ident: expr) => { {
                                                if export_status(&$field.attrs) == ExportStatus::TestOnly { continue; }
                                                if $to_c {
-                                                       types.write_to_c_conversion_inline_prefix(w, &$field.ty, Some(&gen_types), false);
+                                                       types.write_to_c_conversion_inline_prefix(w, &$field.ty, Some(&gen_types), true);
                                                } else {
                                                        types.write_from_c_conversion_prefix(w, &$field.ty, Some(&gen_types));
                                                }
                                                write!(w, "{}{}", $field_ident,
                                                        if $ref { "_nonref" } else { "" }).unwrap();
                                                if $to_c {
-                                                       types.write_to_c_conversion_inline_suffix(w, &$field.ty, Some(&gen_types), false);
+                                                       types.write_to_c_conversion_inline_suffix(w, &$field.ty, Some(&gen_types), true);
                                                } else {
                                                        types.write_from_c_conversion_suffix(w, &$field.ty, Some(&gen_types));
                                                }
@@ -1723,9 +1832,13 @@ fn writeln_enum<'a, 'b, W: std::io::Write>(w: &mut W, e: &'a syn::ItemEnum, type
                }
        }
 
-       write_conv!(format!("to_native(&self) -> native{}", e.ident), false, true);
+       if is_clonable {
+               write_conv!(format!("to_native(&self) -> native{}", e.ident), false, true);
+       }
        write_conv!(format!("into_native(self) -> native{}", e.ident), false, false);
-       write_conv!(format!("from_native(native: &native{}) -> Self", e.ident), true, true);
+       if is_clonable {
+               write_conv!(format!("from_native(native: &native{}) -> Self", e.ident), true, true);
+       }
        write_conv!(format!("native_into(native: native{}) -> Self", e.ident), true, false);
        writeln!(w, "}}").unwrap();
 
@@ -1733,11 +1846,13 @@ fn writeln_enum<'a, 'b, W: std::io::Write>(w: &mut W, e: &'a syn::ItemEnum, type
                writeln!(w, "/// Frees any resources used by the {}", e.ident).unwrap();
                writeln!(w, "#[no_mangle]\npub extern \"C\" fn {}_free(this_ptr: {}) {{ }}", e.ident, e.ident).unwrap();
        }
-       writeln!(w, "/// Creates a copy of the {}", e.ident).unwrap();
-       writeln!(w, "#[no_mangle]").unwrap();
-       writeln!(w, "pub extern \"C\" fn {}_clone(orig: &{}) -> {} {{", e.ident, e.ident, e.ident).unwrap();
-       writeln!(w, "\torig.clone()").unwrap();
-       writeln!(w, "}}").unwrap();
+       if is_clonable {
+               writeln!(w, "/// Creates a copy of the {}", e.ident).unwrap();
+               writeln!(w, "#[no_mangle]").unwrap();
+               writeln!(w, "pub extern \"C\" fn {}_clone(orig: &{}) -> {} {{", e.ident, e.ident, e.ident).unwrap();
+               writeln!(w, "\torig.clone()").unwrap();
+               writeln!(w, "}}").unwrap();
+       }
        w.write_all(&constr).unwrap();
        write_cpp_wrapper(cpp_headers, &format!("{}", e.ident), needs_free, None);
 }
@@ -1922,6 +2037,11 @@ fn convert_file<'a, 'b>(libast: &'a FullLibraryAST, crate_types: &CrateTypes<'a>
                                                                        type_resolver.crate_types.priv_structs.get(&real_ty).map(|r| *r)).unwrap();
                                                                let mut resolved_generics = t.generics.clone();
 
+                                                               // Assume blindly that the bounds in the struct definition where
+                                                               // clause matches any equivalent bounds on the type alias.
+                                                               assert!(resolved_generics.where_clause.is_none());
+                                                               resolved_generics.where_clause = real_generic_bounds.where_clause.clone();
+
                                                                if let syn::PathArguments::AngleBracketed(real_generics) = &p.path.segments.last().unwrap().arguments {
                                                                        for (real_idx, real_param) in real_generics.args.iter().enumerate() {
                                                                                if let syn::GenericArgument::Type(syn::Type::Path(real_param_path)) = real_param {
@@ -1961,6 +2081,49 @@ fn convert_file<'a, 'b>(libast: &'a FullLibraryAST, crate_types: &CrateTypes<'a>
        }
 }
 
+
+/// Walk the FullLibraryAST, determining if impl aliases need to be marked cloneable.
+fn walk_ast_second_pass<'a>(ast_storage: &'a FullLibraryAST, crate_types: &CrateTypes<'a>) {
+       for (module, astmod) in ast_storage.modules.iter() {
+               let orig_crate = module.splitn(2, "::").next().unwrap();
+               let ASTModule { ref attrs, ref items, .. } = astmod;
+               assert_eq!(export_status(&attrs), ExportStatus::Export);
+
+               let import_resolver = ImportResolver::new(orig_crate, &ast_storage.dependencies, module, items);
+               let mut types = TypeResolver::new(module, import_resolver, crate_types);
+
+               for item in items.iter() {
+                       match item {
+                               syn::Item::Impl(i) => {
+                                       match export_status(&i.attrs) {
+                                               ExportStatus::Export => {},
+                                               ExportStatus::NoExport|ExportStatus::TestOnly => continue,
+                                               ExportStatus::NotImplementable => panic!("(C-not implementable) must only appear on traits"),
+                                       }
+                                       if let Some(trait_path) = i.trait_.as_ref() {
+                                               if path_matches_nongeneric(&trait_path.1, &["core", "clone", "Clone"]) ||
+                                                  path_matches_nongeneric(&trait_path.1, &["Clone"])
+                                               {
+                                                       if let &syn::Type::Path(ref p) = &*i.self_ty {
+                                                               if let Some(resolved_path) = types.maybe_resolve_path(&p.path, None) {
+                                                                       create_alias_for_impl(resolved_path, i, &mut types, |aliased_impl, types| {
+                                                                               if let &syn::Type::Path(ref p) = &*aliased_impl.self_ty {
+                                                                                       if let Some(resolved_aliased_path) = types.maybe_resolve_path(&p.path, None) {
+                                                                                               crate_types.set_clonable("crate::".to_owned() + &resolved_aliased_path);
+                                                                                       }
+                                                                               }
+                                                                       });
+                                                               }
+                                                       }
+                                               }
+                                       }
+                               }
+                               _ => {}
+                       }
+               }
+       }
+}
+
 fn walk_private_mod<'a>(ast_storage: &'a FullLibraryAST, orig_crate: &str, module: String, items: &'a syn::ItemMod, crate_types: &mut CrateTypes<'a>) {
        let import_resolver = ImportResolver::new(orig_crate, &ast_storage.dependencies, &module, &items.content.as_ref().unwrap().1);
        for item in items.content.as_ref().unwrap().1.iter() {
@@ -1986,7 +2149,7 @@ fn walk_private_mod<'a>(ast_storage: &'a FullLibraryAST, orig_crate: &str, modul
 }
 
 /// Walk the FullLibraryAST, deciding how things will be mapped and adding tracking to CrateTypes.
-fn walk_ast<'a>(ast_storage: &'a FullLibraryAST, crate_types: &mut CrateTypes<'a>) {
+fn walk_ast_first_pass<'a>(ast_storage: &'a FullLibraryAST, crate_types: &mut CrateTypes<'a>) {
        for (module, astmod) in ast_storage.modules.iter() {
                let ASTModule { ref attrs, ref items, submods: _ } = astmod;
                assert_eq!(export_status(&attrs), ExportStatus::Export);
@@ -2141,7 +2304,11 @@ fn main() {
        // ...then walk the ASTs tracking what types we will map, and how, so that we can resolve them
        // when parsing other file ASTs...
        let mut libtypes = CrateTypes::new(&mut derived_templates, &libast);
-       walk_ast(&libast, &mut libtypes);
+       walk_ast_first_pass(&libast, &mut libtypes);
+
+       // ... using the generated data, determine a few additional fields, specifically which type
+       // aliases are to be clone-able...
+       walk_ast_second_pass(&libast, &libtypes);
 
        // ... finally, do the actual file conversion/mapping, writing out types as we go.
        convert_file(&libast, &libtypes, &args[1], &mut header_file, &mut cpp_header_file);