[bindings] Move to manual write-out for Vec, too
[rust-lightning] / c-bindings-gen / src / main.rs
index 52ee3b05f16e887a09c272606d95394f7c90a15f..d927d2ae71c816af9f92ee824861103715117d0f 100644 (file)
@@ -10,7 +10,7 @@
 //! It also generates relevant memory-management functions and free-standing functions with
 //! parameters mapped.
 
-use std::collections::HashMap;
+use std::collections::{HashMap, HashSet};
 use std::env;
 use std::fs::File;
 use std::io::{Read, Write};
@@ -38,10 +38,14 @@ fn convert_macro<W: std::io::Write>(w: &mut W, macro_path: &syn::Path, stream: &
                        if let Some(s) = types.maybe_resolve_ident(&struct_for) {
                                if !types.crate_types.opaques.get(&s).is_some() { return; }
                                writeln!(w, "#[no_mangle]").unwrap();
-                               writeln!(w, "pub extern \"C\" fn {}_write(obj: *const {}) -> crate::c_types::derived::CVec_u8Z {{", struct_for, struct_for).unwrap();
+                               writeln!(w, "pub extern \"C\" fn {}_write(obj: &{}) -> crate::c_types::derived::CVec_u8Z {{", struct_for, struct_for).unwrap();
                                writeln!(w, "\tcrate::c_types::serialize_obj(unsafe {{ &(*(*obj).inner) }})").unwrap();
                                writeln!(w, "}}").unwrap();
                                writeln!(w, "#[no_mangle]").unwrap();
+                               writeln!(w, "pub(crate) extern \"C\" fn {}_write_void(obj: *const c_void) -> crate::c_types::derived::CVec_u8Z {{", struct_for).unwrap();
+                               writeln!(w, "\tcrate::c_types::serialize_obj(unsafe {{ &*(obj as *const native{}) }})", struct_for).unwrap();
+                               writeln!(w, "}}").unwrap();
+                               writeln!(w, "#[no_mangle]").unwrap();
                                writeln!(w, "pub extern \"C\" fn {}_read(ser: crate::c_types::u8slice) -> {} {{", struct_for, struct_for).unwrap();
                                writeln!(w, "\tif let Ok(res) = crate::c_types::deserialize_obj(ser) {{").unwrap();
                                writeln!(w, "\t\t{} {{ inner: Box::into_raw(Box::new(res)), is_owned: true }}", struct_for).unwrap();
@@ -54,32 +58,167 @@ fn convert_macro<W: std::io::Write>(w: &mut W, macro_path: &syn::Path, stream: &
        }
 }
 
-/// Convert "impl trait_path for for_obj { .. }" for manually-mapped types (ie (de)serialization)
-fn maybe_convert_trait_impl<W: std::io::Write>(w: &mut W, trait_path: &syn::Path, for_obj: &syn::Ident, types: &TypeResolver) {
-       if let Some(t) = types.maybe_resolve_path(&trait_path) {
-               let s = types.maybe_resolve_ident(for_obj).unwrap();
-               if !types.crate_types.opaques.get(&s).is_some() { return; }
+/// Convert "impl trait_path for for_ty { .. }" for manually-mapped types (ie (de)serialization)
+fn maybe_convert_trait_impl<W: std::io::Write>(w: &mut W, trait_path: &syn::Path, for_ty: &syn::Type, types: &mut TypeResolver, generics: &GenericTypes) {
+       if let Some(t) = types.maybe_resolve_path(&trait_path, Some(generics)) {
+               let for_obj;
+               let full_obj_path;
+               let mut has_inner = false;
+               if let syn::Type::Path(ref p) = for_ty {
+                       if let Some(ident) = single_ident_generic_path_to_ident(&p.path) {
+                               for_obj = format!("{}", ident);
+                               full_obj_path = for_obj.clone();
+                               has_inner = types.c_type_has_inner_from_path(&types.resolve_path(&p.path, Some(generics)));
+                       } else { return; }
+               } else {
+                       // We assume that anything that isn't a Path is somehow a generic that ends up in our
+                       // derived-types module.
+                       let mut for_obj_vec = Vec::new();
+                       types.write_c_type(&mut for_obj_vec, for_ty, Some(generics), false);
+                       full_obj_path = String::from_utf8(for_obj_vec).unwrap();
+                       assert!(full_obj_path.starts_with(TypeResolver::generated_container_path()));
+                       for_obj = full_obj_path[TypeResolver::generated_container_path().len() + 2..].into();
+               }
+
                match &t as &str {
                        "util::ser::Writeable" => {
                                writeln!(w, "#[no_mangle]").unwrap();
-                               writeln!(w, "pub extern \"C\" fn {}_write(obj: *const {}) -> crate::c_types::derived::CVec_u8Z {{", for_obj, for_obj).unwrap();
-                               writeln!(w, "\tcrate::c_types::serialize_obj(unsafe {{ &(*(*obj).inner) }})").unwrap();
+                               writeln!(w, "pub extern \"C\" fn {}_write(obj: &{}) -> crate::c_types::derived::CVec_u8Z {{", for_obj, full_obj_path).unwrap();
+
+                               let ref_type = syn::Type::Reference(syn::TypeReference {
+                                       and_token: syn::Token!(&)(Span::call_site()), lifetime: None, mutability: None,
+                                       elem: Box::new(for_ty.clone()) });
+                               assert!(!types.write_from_c_conversion_new_var(w, &syn::Ident::new("obj", Span::call_site()), &ref_type, Some(generics)));
+
+                               write!(w, "\tcrate::c_types::serialize_obj(").unwrap();
+                               types.write_from_c_conversion_prefix(w, &ref_type, Some(generics));
+                               write!(w, "unsafe {{ &*obj }}").unwrap();
+                               types.write_from_c_conversion_suffix(w, &ref_type, Some(generics));
+                               writeln!(w, ")").unwrap();
+
                                writeln!(w, "}}").unwrap();
+                               if has_inner {
+                                       writeln!(w, "#[no_mangle]").unwrap();
+                                       writeln!(w, "pub(crate) extern \"C\" fn {}_write_void(obj: *const c_void) -> crate::c_types::derived::CVec_u8Z {{", for_obj).unwrap();
+                                       writeln!(w, "\tcrate::c_types::serialize_obj(unsafe {{ &*(obj as *const native{}) }})", for_obj).unwrap();
+                                       writeln!(w, "}}").unwrap();
+                               }
                        },
-                       "util::ser::Readable" => {
+                       "util::ser::Readable"|"util::ser::ReadableArgs" => {
+                               // Create the Result<Object, DecodeError> syn::Type
+                               let mut err_segs = syn::punctuated::Punctuated::new();
+                               err_segs.push(syn::PathSegment { ident: syn::Ident::new("ln", Span::call_site()), arguments: syn::PathArguments::None });
+                               err_segs.push(syn::PathSegment { ident: syn::Ident::new("msgs", Span::call_site()), arguments: syn::PathArguments::None });
+                               err_segs.push(syn::PathSegment { ident: syn::Ident::new("DecodeError", Span::call_site()), arguments: syn::PathArguments::None });
+                               let mut args = syn::punctuated::Punctuated::new();
+                               args.push(syn::GenericArgument::Type(for_ty.clone()));
+                               args.push(syn::GenericArgument::Type(syn::Type::Path(syn::TypePath {
+                                       qself: None, path: syn::Path {
+                                               leading_colon: Some(syn::Token![::](Span::call_site())), segments: err_segs,
+                                       }
+                               })));
+                               let mut res_segs = syn::punctuated::Punctuated::new();
+                               res_segs.push(syn::PathSegment {
+                                       ident: syn::Ident::new("Result", Span::call_site()),
+                                       arguments: syn::PathArguments::AngleBracketed(syn::AngleBracketedGenericArguments {
+                                               colon2_token: None, lt_token: syn::Token![<](Span::call_site()), args, gt_token: syn::Token![>](Span::call_site()),
+                                       })
+                               });
+                               let res_ty = syn::Type::Path(syn::TypePath { qself: None, path: syn::Path {
+                                       leading_colon: None, segments: res_segs } });
+
                                writeln!(w, "#[no_mangle]").unwrap();
-                               writeln!(w, "pub extern \"C\" fn {}_read(ser: crate::c_types::u8slice) -> {} {{", for_obj, for_obj).unwrap();
-                               writeln!(w, "\tif let Ok(res) = crate::c_types::deserialize_obj(ser) {{").unwrap();
-                               writeln!(w, "\t\t{} {{ inner: Box::into_raw(Box::new(res)), is_owned: true }}", for_obj).unwrap();
-                               writeln!(w, "\t}} else {{").unwrap();
-                               writeln!(w, "\t\t{} {{ inner: std::ptr::null_mut(), is_owned: true }}", for_obj).unwrap();
-                               writeln!(w, "\t}}\n}}").unwrap();
+                               write!(w, "pub extern \"C\" fn {}_read(ser: crate::c_types::u8slice", for_obj).unwrap();
+
+                               let mut arg_conv = Vec::new();
+                               if t == "util::ser::ReadableArgs" {
+                                       write!(w, ", arg: ").unwrap();
+                                       assert!(trait_path.leading_colon.is_none());
+                                       let args_seg = trait_path.segments.iter().last().unwrap();
+                                       assert_eq!(format!("{}", args_seg.ident), "ReadableArgs");
+                                       if let syn::PathArguments::AngleBracketed(args) = &args_seg.arguments {
+                                               assert_eq!(args.args.len(), 1);
+                                               if let syn::GenericArgument::Type(args_ty) = args.args.iter().next().unwrap() {
+                                                       types.write_c_type(w, args_ty, Some(generics), false);
+
+                                                       assert!(!types.write_from_c_conversion_new_var(&mut arg_conv, &syn::Ident::new("arg", Span::call_site()), &args_ty, Some(generics)));
+
+                                                       write!(&mut arg_conv, "\tlet arg_conv = ").unwrap();
+                                                       types.write_from_c_conversion_prefix(&mut arg_conv, &args_ty, Some(generics));
+                                                       write!(&mut arg_conv, "arg").unwrap();
+                                                       types.write_from_c_conversion_suffix(&mut arg_conv, &args_ty, Some(generics));
+                                               } else { unreachable!(); }
+                                       } else { unreachable!(); }
+                               }
+                               write!(w, ") -> ").unwrap();
+                               types.write_c_type(w, &res_ty, Some(generics), false);
+                               writeln!(w, " {{").unwrap();
+
+                               if t == "util::ser::ReadableArgs" {
+                                       w.write(&arg_conv).unwrap();
+                                       write!(w, ";\n\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);
+                                       writeln!(w, " = crate::c_types::deserialize_obj_arg(ser, arg_conv);").unwrap();
+                               } else {
+                                       writeln!(w, "\tlet res = crate::c_types::deserialize_obj(ser);").unwrap();
+                               }
+                               write!(w, "\t").unwrap();
+                               if types.write_to_c_conversion_new_var(w, &syn::Ident::new("res", Span::call_site()), &res_ty, Some(generics), false) {
+                                       write!(w, "\n\t").unwrap();
+                               }
+                               types.write_to_c_conversion_inline_prefix(w, &res_ty, Some(generics), false);
+                               write!(w, "res").unwrap();
+                               types.write_to_c_conversion_inline_suffix(w, &res_ty, Some(generics), false);
+                               writeln!(w, "\n}}").unwrap();
                        },
                        _ => {},
                }
        }
 }
 
+/// Convert "TraitA : TraitB" to a single function name and return type.
+///
+/// This is (obviously) somewhat over-specialized and only useful for TraitB's that only require a
+/// single function (eg for serialization).
+fn convert_trait_impl_field(trait_path: &str) -> (String, &'static str) {
+       match trait_path {
+               "util::ser::Writeable" => ("write".to_owned(), "crate::c_types::derived::CVec_u8Z"),
+               _ => unimplemented!(),
+       }
+}
+
+/// Companion to convert_trait_impl_field, write an assignment for the function defined by it for
+/// `for_obj` which implements the the trait at `trait_path`.
+fn write_trait_impl_field_assign<W: std::io::Write>(w: &mut W, trait_path: &str, for_obj: &syn::Ident) {
+       match trait_path {
+               "util::ser::Writeable" => {
+                       writeln!(w, "\t\twrite: {}_write_void,", for_obj).unwrap();
+               },
+               _ => unimplemented!(),
+       }
+}
+
+/// Write out the impl block for a defined trait struct which has a supertrait
+fn do_write_impl_trait<W: std::io::Write>(w: &mut W, trait_path: &str, trait_name: &syn::Ident, for_obj: &str) {
+       match trait_path {
+               "util::events::MessageSendEventsProvider" => {
+                       writeln!(w, "impl lightning::{} for {} {{", trait_path, for_obj).unwrap();
+                       writeln!(w, "\tfn get_and_clear_pending_msg_events(&self) -> Vec<lightning::util::events::MessageSendEvent> {{").unwrap();
+                       writeln!(w, "\t\t<crate::{} as lightning::{}>::get_and_clear_pending_msg_events(&self.{})", trait_path, trait_path, trait_name).unwrap();
+                       writeln!(w, "\t}}\n}}").unwrap();
+               },
+               "util::ser::Writeable" => {
+                       writeln!(w, "impl lightning::{} for {} {{", trait_path, for_obj).unwrap();
+                       writeln!(w, "\tfn write<W: lightning::util::ser::Writer>(&self, w: &mut W) -> Result<(), ::std::io::Error> {{").unwrap();
+                       writeln!(w, "\t\tlet vec = (self.write)(self.this_arg);").unwrap();
+                       writeln!(w, "\t\tw.write_all(vec.as_slice())").unwrap();
+                       writeln!(w, "\t}}\n}}").unwrap();
+               },
+               _ => panic!(),
+       }
+}
+
 // *******************************
 // *** Per-Type Printing Logic ***
 // *******************************
@@ -92,15 +231,23 @@ macro_rules! walk_supertraits { ($t: expr, $types: expr, ($( $pat: pat => $e: ex
                                        if supertrait.paren_token.is_some() || supertrait.lifetimes.is_some() {
                                                unimplemented!();
                                        }
+                                       // First try to resolve path to find in-crate traits, but if that doesn't work
+                                       // assume its a prelude trait (eg Clone, etc) and just use the single ident.
+                                       let types_opt: Option<&TypeResolver> = $types;
+                                       if let Some(types) = types_opt {
+                                               if let Some(path) = types.maybe_resolve_path(&supertrait.path, None) {
+                                                       match (&path as &str, &supertrait.path.segments.iter().last().unwrap().ident) {
+                                                               $( $pat => $e, )*
+                                                       }
+                                                       continue;
+                                               }
+                                       }
                                        if let Some(ident) = supertrait.path.get_ident() {
                                                match (&format!("{}", ident) as &str, &ident) {
                                                        $( $pat => $e, )*
                                                }
-                                       } else {
-                                               let path = $types.resolve_path(&supertrait.path);
-                                               match (&path as &str, &supertrait.path.segments.iter().last().unwrap().ident) {
-                                                       $( $pat => $e, )*
-                                               }
+                                       } else if types_opt.is_some() {
+                                               panic!("Supertrait unresolvable and not single-ident");
                                        }
                                },
                                syn::TypeParamBound::Lifetime(_) => unimplemented!(),
@@ -109,31 +256,6 @@ macro_rules! walk_supertraits { ($t: expr, $types: expr, ($( $pat: pat => $e: ex
        }
 } } }
 
-/// Gets a HashMap from name idents to the bounding trait for associated types.
-/// eg if a native trait has a "type T = TraitA", this will return a HashMap containing a mapping
-/// from "T" to "TraitA".
-fn learn_associated_types<'a>(t: &'a syn::ItemTrait) -> HashMap<&'a syn::Ident, &'a syn::Ident> {
-       let mut associated_types = HashMap::new();
-       for item in t.items.iter() {
-               match item {
-                       &syn::TraitItem::Type(ref t) => {
-                               if t.default.is_some() || t.generics.lt_token.is_some() { unimplemented!(); }
-                               let mut bounds_iter = t.bounds.iter();
-                               match bounds_iter.next().unwrap() {
-                                       syn::TypeParamBound::Trait(tr) => {
-                                               assert_simple_bound(&tr);
-                                               associated_types.insert(&t.ident, assert_single_path_seg(&tr.path));
-                                       },
-                                       _ => unimplemented!(),
-                               }
-                               if bounds_iter.next().is_some() { unimplemented!(); }
-                       },
-                       _ => {},
-               }
-       }
-       associated_types
-}
-
 /// Prints a C-mapped trait object containing a void pointer and a jump table for each function in
 /// the original trait.
 /// Implements the native Rust trait and relevant parent traits for the new C-mapped trait.
@@ -148,9 +270,12 @@ fn writeln_trait<'a, 'b, W: std::io::Write>(w: &mut W, t: &'a syn::ItemTrait, ty
        }
        writeln_docs(w, &t.attrs, "");
 
+       let mut gen_types = GenericTypes::new();
+       assert!(gen_types.learn_generics(&t.generics, types));
+       gen_types.learn_associated_types(&t, types);
+
        writeln!(w, "#[repr(C)]\npub struct {} {{", trait_name).unwrap();
        writeln!(w, "\tpub this_arg: *mut c_void,").unwrap();
-       let associated_types = learn_associated_types(t);
        let mut generated_fields = Vec::new(); // Every field's name except this_arg, used in Clone generation
        for item in t.items.iter() {
                match item {
@@ -158,15 +283,17 @@ fn writeln_trait<'a, 'b, W: std::io::Write>(w: &mut W, t: &'a syn::ItemTrait, ty
                                match export_status(&m.attrs) {
                                        ExportStatus::NoExport => {
                                                // NoExport in this context means we'll hit an unimplemented!() at runtime,
-                                               // so add a comment noting that this needs to change in the output.
-                                               writeln!(w, "\t//XXX: Need to export {}", m.sig.ident).unwrap();
-                                               continue;
+                                               // so bail out.
+                                               unimplemented!();
                                        },
                                        ExportStatus::Export => {},
                                        ExportStatus::TestOnly => continue,
                                }
                                if m.default.is_some() { unimplemented!(); }
 
+                               gen_types.push_ctx();
+                               assert!(gen_types.learn_generics(&m.sig.generics, types));
+
                                writeln_docs(w, &m.attrs, "\t");
 
                                if let syn::ReturnType::Type(_, rtype) = &m.sig.output {
@@ -183,7 +310,7 @@ fn writeln_trait<'a, 'b, W: std::io::Write>(w: &mut W, t: &'a syn::ItemTrait, ty
                                                // called when the trait method is called which allows updating on the fly.
                                                write!(w, "\tpub {}: ", m.sig.ident).unwrap();
                                                generated_fields.push(format!("{}", m.sig.ident));
-                                               types.write_c_type(w, &*r.elem, None, false);
+                                               types.write_c_type(w, &*r.elem, Some(&gen_types), false);
                                                writeln!(w, ",").unwrap();
                                                writeln!(w, "\t/// Fill in the {} field as a reference to it will be given to Rust after this returns", m.sig.ident).unwrap();
                                                writeln!(w, "\t/// Note that this takes a pointer to this object, not the this_ptr like other methods do").unwrap();
@@ -195,6 +322,7 @@ fn writeln_trait<'a, 'b, W: std::io::Write>(w: &mut W, t: &'a syn::ItemTrait, ty
                                                // which does not compile since Thing is not defined before it is used.
                                                writeln!(extra_headers, "struct LDK{};", trait_name).unwrap();
                                                writeln!(extra_headers, "typedef struct LDK{} LDK{};", trait_name, trait_name).unwrap();
+                                               gen_types.pop_ctx();
                                                continue;
                                        }
                                        // Sadly, this currently doesn't do what we want, but it should be easy to get
@@ -204,21 +332,24 @@ fn writeln_trait<'a, 'b, W: std::io::Write>(w: &mut W, t: &'a syn::ItemTrait, ty
 
                                write!(w, "\tpub {}: extern \"C\" fn (", m.sig.ident).unwrap();
                                generated_fields.push(format!("{}", m.sig.ident));
-                               write_method_params(w, &m.sig, &associated_types, "c_void", types, None, true, false);
+                               write_method_params(w, &m.sig, "c_void", types, Some(&gen_types), true, false);
                                writeln!(w, ",").unwrap();
+
+                               gen_types.pop_ctx();
                        },
                        &syn::TraitItem::Type(_) => {},
                        _ => unimplemented!(),
                }
        }
        // Add functions which may be required for supertrait implementations.
-       walk_supertraits!(t, types, (
+       walk_supertraits!(t, Some(&types), (
                ("Clone", _) => {
                        writeln!(w, "\tpub clone: Option<extern \"C\" fn (this_arg: *const c_void) -> *mut c_void>,").unwrap();
                        generated_fields.push("clone".to_owned());
                },
                ("std::cmp::Eq", _) => {
-                       writeln!(w, "\tpub eq: extern \"C\" fn (this_arg: *const c_void, other_arg: *const c_void) -> bool,").unwrap();
+                       writeln!(w, "\tpub eq: extern \"C\" fn (this_arg: *const c_void, other_arg: &{}) -> bool,", trait_name).unwrap();
+                       writeln!(extra_headers, "typedef struct LDK{} LDK{};", trait_name, trait_name).unwrap();
                        generated_fields.push("eq".to_owned());
                },
                ("std::hash::Hash", _) => {
@@ -227,46 +358,49 @@ fn writeln_trait<'a, 'b, W: std::io::Write>(w: &mut W, t: &'a syn::ItemTrait, ty
                },
                ("Send", _) => {}, ("Sync", _) => {},
                (s, i) => {
-                       // For in-crate supertraits, just store a C-mapped copy of the supertrait as a member.
-                       if types.crate_types.traits.get(s).is_none() { unimplemented!(); }
-                       writeln!(w, "\tpub {}: crate::{},", i, s).unwrap();
-                       generated_fields.push(format!("{}", i));
+                       generated_fields.push(if types.crate_types.traits.get(s).is_none() {
+                               let (name, ret) = convert_trait_impl_field(s);
+                               writeln!(w, "\tpub {}: extern \"C\" fn (this_arg: *const c_void) -> {},", name, ret).unwrap();
+                               name
+                       } else {
+                               // For in-crate supertraits, just store a C-mapped copy of the supertrait as a member.
+                               writeln!(w, "\tpub {}: crate::{},", i, s).unwrap();
+                               format!("{}", i)
+                       });
                }
        ) );
        writeln!(w, "\tpub free: Option<extern \"C\" fn(this_arg: *mut c_void)>,").unwrap();
        generated_fields.push("free".to_owned());
        writeln!(w, "}}").unwrap();
        // Implement supertraits for the C-mapped struct.
-       walk_supertraits!(t, types, (
+       walk_supertraits!(t, Some(&types), (
                ("Send", _) => writeln!(w, "unsafe impl Send for {} {{}}", trait_name).unwrap(),
                ("Sync", _) => writeln!(w, "unsafe impl Sync for {} {{}}", trait_name).unwrap(),
                ("std::cmp::Eq", _) => {
                        writeln!(w, "impl std::cmp::Eq for {} {{}}", trait_name).unwrap();
                        writeln!(w, "impl std::cmp::PartialEq for {} {{", trait_name).unwrap();
-                       writeln!(w, "\tfn eq(&self, o: &Self) -> bool {{ (self.eq)(self.this_arg, o.this_arg) }}\n}}").unwrap();
+                       writeln!(w, "\tfn eq(&self, o: &Self) -> bool {{ (self.eq)(self.this_arg, o) }}\n}}").unwrap();
                },
                ("std::hash::Hash", _) => {
                        writeln!(w, "impl std::hash::Hash for {} {{", trait_name).unwrap();
                        writeln!(w, "\tfn hash<H: std::hash::Hasher>(&self, hasher: &mut H) {{ hasher.write_u64((self.hash)(self.this_arg)) }}\n}}").unwrap();
                },
                ("Clone", _) => {
-                       writeln!(w, "impl Clone for {} {{", trait_name).unwrap();
-                       writeln!(w, "\tfn clone(&self) -> Self {{").unwrap();
-                       writeln!(w, "\t\tSelf {{").unwrap();
-                       writeln!(w, "\t\tthis_arg: if let Some(f) = self.clone {{ (f)(self.this_arg) }} else {{ self.this_arg }},").unwrap();
+                       writeln!(w, "#[no_mangle]").unwrap();
+                       writeln!(w, "pub extern \"C\" fn {}_clone(orig: &{}) -> {} {{", trait_name, trait_name, trait_name).unwrap();
+                       writeln!(w, "\t{} {{", trait_name).unwrap();
+                       writeln!(w, "\t\tthis_arg: if let Some(f) = orig.clone {{ (f)(orig.this_arg) }} else {{ orig.this_arg }},").unwrap();
                        for field in generated_fields.iter() {
-                               writeln!(w, "\t\t\t{}: self.{}.clone(),", field, field).unwrap();
+                               writeln!(w, "\t\t{}: orig.{}.clone(),", field, field).unwrap();
                        }
-                       writeln!(w, "\t\t}}\n\t}}\n}}").unwrap();
+                       writeln!(w, "\t}}\n}}").unwrap();
+                       writeln!(w, "impl Clone for {} {{", trait_name).unwrap();
+                       writeln!(w, "\tfn clone(&self) -> Self {{").unwrap();
+                       writeln!(w, "\t\t{}_clone(self)", trait_name).unwrap();
+                       writeln!(w, "\t}}\n}}").unwrap();
                },
                (s, i) => {
-                       if s != "util::events::MessageSendEventsProvider" { unimplemented!(); }
-                       // XXX: We straight-up cheat here - instead of bothering to get the trait object we
-                       // just print what we need since this is only used in one place.
-                       writeln!(w, "impl lightning::{} for {} {{", s, trait_name).unwrap();
-                       writeln!(w, "\tfn get_and_clear_pending_msg_events(&self) -> Vec<lightning::util::events::MessageSendEvent> {{").unwrap();
-                       writeln!(w, "\t\t<crate::{} as lightning::{}>::get_and_clear_pending_msg_events(&self.{})", s, s, i).unwrap();
-                       writeln!(w, "\t}}\n}}").unwrap();
+                       do_write_impl_trait(w, s, i, &trait_name);
                }
        ) );
 
@@ -284,8 +418,10 @@ fn writeln_trait<'a, 'b, W: std::io::Write>(w: &mut W, t: &'a syn::ItemTrait, ty
                                                m.sig.abi.is_some() || m.sig.variadic.is_some() {
                                        unimplemented!();
                                }
+                               gen_types.push_ctx();
+                               assert!(gen_types.learn_generics(&m.sig.generics, types));
                                write!(w, "\tfn {}", m.sig.ident).unwrap();
-                               types.write_rust_generic_param(w, m.sig.generics.params.iter());
+                               types.write_rust_generic_param(w, Some(&gen_types), m.sig.generics.params.iter());
                                write!(w, "(").unwrap();
                                for inp in m.sig.inputs.iter() {
                                        match inp {
@@ -309,11 +445,11 @@ fn writeln_trait<'a, 'b, W: std::io::Write>(w: &mut W, t: &'a syn::ItemTrait, ty
                                                                                        ident.mutability.is_some() || ident.subpat.is_some() {
                                                                                unimplemented!();
                                                                        }
-                                                                       write!(w, ", {}{}: ", if types.skip_arg(&*arg.ty, None) { "_" } else { "" }, ident.ident).unwrap();
+                                                                       write!(w, ", {}{}: ", if types.skip_arg(&*arg.ty, Some(&gen_types)) { "_" } else { "" }, ident.ident).unwrap();
                                                                }
                                                                _ => unimplemented!(),
                                                        }
-                                                       types.write_rust_type(w, &*arg.ty);
+                                                       types.write_rust_type(w, Some(&gen_types), &*arg.ty);
                                                }
                                        }
                                }
@@ -321,15 +457,14 @@ 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();
-                                               types.write_rust_type(w, &*rtype)
+                                               types.write_rust_type(w, Some(&gen_types), &*rtype)
                                        },
                                        _ => {},
                                }
                                write!(w, " {{\n\t\t").unwrap();
                                match export_status(&m.attrs) {
                                        ExportStatus::NoExport => {
-                                               writeln!(w, "unimplemented!();\n\t}}").unwrap();
-                                               continue;
+                                               unimplemented!();
                                        },
                                        _ => {},
                                }
@@ -339,25 +474,27 @@ fn writeln_trait<'a, 'b, W: std::io::Write>(w: &mut W, t: &'a syn::ItemTrait, ty
                                                writeln!(w, "if let Some(f) = self.set_{} {{", m.sig.ident).unwrap();
                                                writeln!(w, "\t\t\t(f)(self);").unwrap();
                                                write!(w, "\t\t}}\n\t\t").unwrap();
-                                               types.write_from_c_conversion_to_ref_prefix(w, &*r.elem, None);
+                                               types.write_from_c_conversion_to_ref_prefix(w, &*r.elem, Some(&gen_types));
                                                write!(w, "self.{}", m.sig.ident).unwrap();
-                                               types.write_from_c_conversion_to_ref_suffix(w, &*r.elem, None);
+                                               types.write_from_c_conversion_to_ref_suffix(w, &*r.elem, Some(&gen_types));
                                                writeln!(w, "\n\t}}").unwrap();
+                                               gen_types.pop_ctx();
                                                continue;
                                        }
                                }
-                               write_method_var_decl_body(w, &m.sig, "\t", types, None, true);
+                               write_method_var_decl_body(w, &m.sig, "\t", types, Some(&gen_types), true);
                                write!(w, "(self.{})(", m.sig.ident).unwrap();
-                               write_method_call_params(w, &m.sig, &associated_types, "\t", types, None, "", true);
+                               write_method_call_params(w, &m.sig, "\t", types, Some(&gen_types), "", true);
 
                                writeln!(w, "\n\t}}").unwrap();
+                               gen_types.pop_ctx();
                        },
                        &syn::TraitItem::Type(ref t) => {
                                if t.default.is_some() || t.generics.lt_token.is_some() { unimplemented!(); }
                                let mut bounds_iter = t.bounds.iter();
                                match bounds_iter.next().unwrap() {
                                        syn::TypeParamBound::Trait(tr) => {
-                                               writeln!(w, "\ttype {} = crate::{};", t.ident, types.resolve_path(&tr.path)).unwrap();
+                                               writeln!(w, "\ttype {} = crate::{};", t.ident, types.resolve_path(&tr.path, Some(&gen_types))).unwrap();
                                        },
                                        _ => unimplemented!(),
                                }
@@ -397,7 +534,7 @@ fn writeln_opaque<W: std::io::Write>(w: &mut W, ident: &syn::Ident, struct_name:
        writeln!(w, ";\n").unwrap();
        writeln!(extra_headers, "struct native{}Opaque;\ntypedef struct native{}Opaque LDKnative{};", ident, ident, ident).unwrap();
        writeln_docs(w, &attrs, "");
-       writeln!(w, "#[must_use]\n#[repr(C)]\npub struct {} {{\n\t/// Nearly everyhwere, inner must be non-null, however in places where", struct_name).unwrap();
+       writeln!(w, "#[must_use]\n#[repr(C)]\npub struct {} {{\n\t/// Nearly everywhere, inner must be non-null, however in places where", struct_name).unwrap();
        writeln!(w, "\t/// the Rust equivalent takes an Option, it may be set to null to indicate None.").unwrap();
        writeln!(w, "\tpub inner: *mut native{},\n\tpub is_owned: bool,\n}}\n", ident).unwrap();
        writeln!(w, "impl Drop for {} {{\n\tfn drop(&mut self) {{", struct_name).unwrap();
@@ -411,63 +548,56 @@ fn writeln_opaque<W: std::io::Write>(w: &mut W, ident: &syn::Ident, struct_name:
        writeln!(w, "#[allow(unused)]").unwrap();
        writeln!(w, "/// When moving out of the pointer, we have to ensure we aren't a reference, this makes that easy").unwrap();
        writeln!(w, "impl {} {{", struct_name).unwrap();
-       writeln!(w, "\tpub(crate) fn take_ptr(mut self) -> *mut native{} {{", struct_name).unwrap();
+       writeln!(w, "\tpub(crate) fn take_inner(mut self) -> *mut native{} {{", struct_name).unwrap();
        writeln!(w, "\t\tassert!(self.is_owned);").unwrap();
        writeln!(w, "\t\tlet ret = self.inner;").unwrap();
        writeln!(w, "\t\tself.inner = std::ptr::null_mut();").unwrap();
        writeln!(w, "\t\tret").unwrap();
        writeln!(w, "\t}}\n}}").unwrap();
 
-       'attr_loop: for attr in attrs.iter() {
-               let tokens_clone = attr.tokens.clone();
-               let mut token_iter = tokens_clone.into_iter();
-               if let Some(token) = token_iter.next() {
-                       match token {
-                               TokenTree::Group(g) => {
-                                       if format!("{}", single_ident_generic_path_to_ident(&attr.path).unwrap()) == "derive" {
-                                               for id in g.stream().into_iter() {
-                                                       if let TokenTree::Ident(i) = id {
-                                                               if i == "Clone" {
-                                                                       writeln!(w, "impl Clone for {} {{", struct_name).unwrap();
-                                                                       writeln!(w, "\tfn clone(&self) -> Self {{").unwrap();
-                                                                       writeln!(w, "\t\tSelf {{").unwrap();
-                                                                       writeln!(w, "\t\t\tinner: Box::into_raw(Box::new(unsafe {{ &*self.inner }}.clone())),").unwrap();
-                                                                       writeln!(w, "\t\t\tis_owned: true,").unwrap();
-                                                                       writeln!(w, "\t\t}}\n\t}}\n}}").unwrap();
-                                                                       writeln!(w, "#[allow(unused)]").unwrap();
-                                                                       writeln!(w, "/// Used only if an object of this type is returned as a trait impl by a method").unwrap();
-                                                                       writeln!(w, "pub(crate) extern \"C\" fn {}_clone_void(this_ptr: *const c_void) -> *mut c_void {{", struct_name).unwrap();
-                                                                       writeln!(w, "\tBox::into_raw(Box::new(unsafe {{ (*(this_ptr as *mut native{})).clone() }})) as *mut c_void", struct_name).unwrap();
-                                                                       writeln!(w, "}}").unwrap();
-                                                                       break 'attr_loop;
-                                                               }
-                                                       }
-                                               }
-                                       }
-                               },
-                               _ => {},
-                       }
-               }
+       if attrs_derives_clone(attrs) {
+               writeln!(w, "impl Clone for {} {{", struct_name).unwrap();
+               writeln!(w, "\tfn clone(&self) -> Self {{").unwrap();
+               writeln!(w, "\t\tSelf {{").unwrap();
+               writeln!(w, "\t\t\tinner: Box::into_raw(Box::new(unsafe {{ &*self.inner }}.clone())),").unwrap();
+               writeln!(w, "\t\t\tis_owned: true,").unwrap();
+               writeln!(w, "\t\t}}\n\t}}\n}}").unwrap();
+               writeln!(w, "#[allow(unused)]").unwrap();
+               writeln!(w, "/// Used only if an object of this type is returned as a trait impl by a method").unwrap();
+               writeln!(w, "pub(crate) extern \"C\" fn {}_clone_void(this_ptr: *const c_void) -> *mut c_void {{", struct_name).unwrap();
+               writeln!(w, "\tBox::into_raw(Box::new(unsafe {{ (*(this_ptr as *mut native{})).clone() }})) as *mut c_void", struct_name).unwrap();
+               writeln!(w, "}}").unwrap();
+               writeln!(w, "#[no_mangle]").unwrap();
+               writeln!(w, "pub extern \"C\" fn {}_clone(orig: &{}) -> {} {{", struct_name, struct_name, struct_name).unwrap();
+               writeln!(w, "\t{} {{ inner: Box::into_raw(Box::new(unsafe {{ &*orig.inner }}.clone())), is_owned: true }}", struct_name).unwrap();
+               writeln!(w, "}}").unwrap();
        }
 
        write_cpp_wrapper(cpp_headers, &format!("{}", ident), true);
 }
 
-/// Writes out all the relevant mappings for a Rust struct, deferring to writeln_opaque to generate
-/// the struct itself, and then writing getters and setters for public, understood-type fields and
-/// a constructor if every field is public.
-fn writeln_struct<'a, 'b, W: std::io::Write>(w: &mut W, s: &'a syn::ItemStruct, types: &mut TypeResolver<'b, 'a>, extra_headers: &mut File, cpp_headers: &mut File) {
-       let struct_name = &format!("{}", s.ident);
+fn declare_struct<'a, 'b>(s: &'a syn::ItemStruct, types: &mut TypeResolver<'b, 'a>) -> bool {
        let export = export_status(&s.attrs);
        match export {
                ExportStatus::Export => {},
-               ExportStatus::TestOnly => return,
+               ExportStatus::TestOnly => return false,
                ExportStatus::NoExport => {
                        types.struct_ignored(&s.ident);
-                       return;
+                       return false;
                }
        }
 
+       types.struct_imported(&s.ident, format!("{}", s.ident));
+       true
+}
+
+/// Writes out all the relevant mappings for a Rust struct, deferring to writeln_opaque to generate
+/// the struct itself, and then writing getters and setters for public, understood-type fields and
+/// a constructor if every field is public.
+fn writeln_struct<'a, 'b, W: std::io::Write>(w: &mut W, s: &'a syn::ItemStruct, types: &mut TypeResolver<'b, 'a>, extra_headers: &mut File, cpp_headers: &mut File) {
+       if !declare_struct(s, types) { return; }
+
+       let struct_name = &format!("{}", s.ident);
        writeln_opaque(w, &s.ident, struct_name, &s.generics, &s.attrs, types, extra_headers, cpp_headers);
 
        eprintln!("exporting fields for {}", struct_name);
@@ -551,8 +681,6 @@ fn writeln_struct<'a, 'b, W: std::io::Write>(w: &mut W, s: &'a syn::ItemStruct,
                        writeln!(w, "\t}})), is_owned: true }}\n}}").unwrap();
                }
        }
-
-       types.struct_imported(&s.ident, struct_name.clone());
 }
 
 /// Prints a relevant conversion for impl *
@@ -565,6 +693,36 @@ fn writeln_struct<'a, 'b, W: std::io::Write>(w: &mut W, s: &'a syn::ItemStruct,
 ///
 /// A few non-crate Traits are hard-coded including Default.
 fn writeln_impl<W: std::io::Write>(w: &mut W, i: &syn::ItemImpl, types: &mut TypeResolver) {
+       match export_status(&i.attrs) {
+               ExportStatus::Export => {},
+               ExportStatus::NoExport|ExportStatus::TestOnly => return,
+       }
+
+       if let syn::Type::Tuple(_) = &*i.self_ty {
+               if types.understood_c_type(&*i.self_ty, None) {
+                       let mut gen_types = GenericTypes::new();
+                       if !gen_types.learn_generics(&i.generics, types) {
+                               eprintln!("Not implementing anything for `impl (..)` due to not understood generics");
+                               return;
+                       }
+
+                       if i.defaultness.is_some() || i.unsafety.is_some() { unimplemented!(); }
+                       if let Some(trait_path) = i.trait_.as_ref() {
+                               if trait_path.0.is_some() { unimplemented!(); }
+                               if types.understood_c_path(&trait_path.1) {
+                                       eprintln!("Not implementing anything for `impl Trait for (..)` - we only support manual defines");
+                                       return;
+                               } else {
+                                       // Just do a manual implementation:
+                                       maybe_convert_trait_impl(w, &trait_path.1, &*i.self_ty, types, &gen_types);
+                               }
+                       } else {
+                               eprintln!("Not implementing anything for plain `impl (..)` block - we only support `impl Trait for (..)` blocks");
+                               return;
+                       }
+               }
+               return;
+       }
        if let &syn::Type::Path(ref p) = &*i.self_ty {
                if p.qself.is_some() { unimplemented!(); }
                if let Some(ident) = single_ident_generic_path_to_ident(&p.path) {
@@ -579,13 +737,13 @@ fn writeln_impl<W: std::io::Write>(w: &mut W, i: &syn::ItemImpl, types: &mut Typ
                                if let Some(trait_path) = i.trait_.as_ref() {
                                        if trait_path.0.is_some() { unimplemented!(); }
                                        if types.understood_c_path(&trait_path.1) {
-                                               let full_trait_path = types.resolve_path(&trait_path.1);
+                                               let full_trait_path = types.resolve_path(&trait_path.1, None);
                                                let trait_obj = *types.crate_types.traits.get(&full_trait_path).unwrap();
                                                // We learn the associated types maping from the original trait object.
                                                // That's great, except that they are unresolved idents, so if we learn
                                                // mappings from a trai defined in a different file, we may mis-resolve or
                                                // fail to resolve the mapped types.
-                                               let trait_associated_types = learn_associated_types(trait_obj);
+                                               gen_types.learn_associated_types(trait_obj, types);
                                                let mut impl_associated_types = HashMap::new();
                                                for item in i.items.iter() {
                                                        match item {
@@ -605,7 +763,22 @@ fn writeln_impl<W: std::io::Write>(w: &mut W, i: &syn::ItemImpl, types: &mut Typ
                                                        ExportStatus::Export => {},
                                                        ExportStatus::NoExport|ExportStatus::TestOnly => return,
                                                }
-                                               write!(w, "#[no_mangle]\npub extern \"C\" fn {}_as_{}(this_arg: *const {}) -> crate::{} {{\n", ident, trait_obj.ident, ident, full_trait_path).unwrap();
+
+                                               // For cases where we have a concrete native object which implements a
+                                               // trait and need to return the C-mapped version of the trait, provide a
+                                               // From<> implementation which does all the work to ensure free is handled
+                                               // properly. This way we can call this method from deep in the
+                                               // type-conversion logic without actually knowing the concrete native type.
+                                               writeln!(w, "impl From<native{}> for crate::{} {{", ident, full_trait_path).unwrap();
+                                               writeln!(w, "\tfn from(obj: native{}) -> Self {{", ident).unwrap();
+                                               writeln!(w, "\t\tlet mut rust_obj = {} {{ inner: Box::into_raw(Box::new(obj)), is_owned: true }};", ident).unwrap();
+                                               writeln!(w, "\t\tlet mut ret = {}_as_{}(&rust_obj);", ident, trait_obj.ident).unwrap();
+                                               writeln!(w, "\t\t// We want to free rust_obj when ret gets drop()'d, not rust_obj, so wipe rust_obj's pointer and set ret's free() fn").unwrap();
+                                               writeln!(w, "\t\trust_obj.inner = std::ptr::null_mut();").unwrap();
+                                               writeln!(w, "\t\tret.free = Some({}_free_void);", ident).unwrap();
+                                               writeln!(w, "\t\tret\n\t}}\n}}").unwrap();
+
+                                               write!(w, "#[no_mangle]\npub extern \"C\" fn {}_as_{}(this_arg: &{}) -> crate::{} {{\n", ident, trait_obj.ident, ident, full_trait_path).unwrap();
                                                writeln!(w, "\tcrate::{} {{", full_trait_path).unwrap();
                                                writeln!(w, "\t\tthis_arg: unsafe {{ (*this_arg).inner as *mut c_void }},").unwrap();
                                                writeln!(w, "\t\tfree: None,").unwrap();
@@ -628,7 +801,7 @@ fn writeln_impl<W: std::io::Write>(w: &mut W, i: &syn::ItemImpl, types: &mut Typ
                                                                if let syn::ReturnType::Type(_, rtype) = &$m.sig.output {
                                                                        if let syn::Type::Reference(r) = &**rtype {
                                                                                write!(w, "\n\t\t{}{}: ", $indent, $m.sig.ident).unwrap();
-                                                                               types.write_empty_rust_val(w, &*r.elem);
+                                                                               types.write_empty_rust_val(Some(&gen_types), w, &*r.elem);
                                                                                writeln!(w, ",\n{}\t\tset_{}: Some({}_{}_set_{}),", $indent, $m.sig.ident, ident, trait_obj.ident, $m.sig.ident).unwrap();
                                                                                printed = true;
                                                                        }
@@ -646,13 +819,14 @@ fn writeln_impl<W: std::io::Write>(w: &mut W, i: &syn::ItemImpl, types: &mut Typ
                                                                _ => {},
                                                        }
                                                }
-                                               walk_supertraits!(trait_obj, types, (
+                                               walk_supertraits!(trait_obj, Some(&types), (
                                                        ("Clone", _) => {
                                                                writeln!(w, "\t\tclone: Some({}_clone_void),", ident).unwrap();
                                                        },
+                                                       ("Sync", _) => {}, ("Send", _) => {},
+                                                       ("std::marker::Sync", _) => {}, ("std::marker::Send", _) => {},
                                                        (s, t) => {
-                                                               if s.starts_with("util::") {
-                                                                       let supertrait_obj = types.crate_types.traits.get(s).unwrap();
+                                                               if let Some(supertrait_obj) = types.crate_types.traits.get(s) {
                                                                        writeln!(w, "\t\t{}: crate::{} {{", t, s).unwrap();
                                                                        writeln!(w, "\t\t\tthis_arg: unsafe {{ (*this_arg).inner as *mut c_void }},").unwrap();
                                                                        writeln!(w, "\t\t\tfree: None,").unwrap();
@@ -665,6 +839,8 @@ fn writeln_impl<W: std::io::Write>(w: &mut W, i: &syn::ItemImpl, types: &mut Typ
                                                                                }
                                                                        }
                                                                        write!(w, "\t\t}},\n").unwrap();
+                                                               } else {
+                                                                       write_trait_impl_field_assign(w, s, ident);
                                                                }
                                                        }
                                                ) );
@@ -686,7 +862,7 @@ fn writeln_impl<W: std::io::Write>(w: &mut W, i: &syn::ItemImpl, types: &mut Typ
                                                                write!(w, "extern \"C\" fn {}_{}_{}(", ident, trait_obj.ident, $m.sig.ident).unwrap();
                                                                gen_types.push_ctx();
                                                                assert!(gen_types.learn_generics(&$m.sig.generics, types));
-                                                               write_method_params(w, &$m.sig, &trait_associated_types, "c_void", types, Some(&gen_types), true, true);
+                                                               write_method_params(w, &$m.sig, "c_void", types, Some(&gen_types), true, true);
                                                                write!(w, " {{\n\t").unwrap();
                                                                write_method_var_decl_body(w, &$m.sig, "", types, Some(&gen_types), false);
                                                                let mut takes_self = false;
@@ -712,7 +888,7 @@ fn writeln_impl<W: std::io::Write>(w: &mut W, i: &syn::ItemImpl, types: &mut Typ
                                                                        },
                                                                        _ => {},
                                                                }
-                                                               write_method_call_params(w, &$m.sig, &trait_associated_types, "", types, Some(&gen_types), &real_type, false);
+                                                               write_method_call_params(w, &$m.sig, "", types, Some(&gen_types), &real_type, false);
                                                                gen_types.pop_ctx();
                                                                write!(w, "\n}}\n").unwrap();
                                                                if let syn::ReturnType::Type(_, rtype) = &$m.sig.output {
@@ -722,7 +898,7 @@ 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(w, &*r.elem, &format!("trait_self_arg.{}", $m.sig.ident));
+                                                                               types.write_empty_rust_val_check(Some(&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_obj.ident, trait_obj.ident, $m.sig.ident, ident, trait_obj.ident, $m.sig.ident).unwrap();
                                                                                writeln!(w, "\t}}").unwrap();
@@ -741,11 +917,10 @@ fn writeln_impl<W: std::io::Write>(w: &mut W, i: &syn::ItemImpl, types: &mut Typ
                                                                _ => unimplemented!(),
                                                        }
                                                }
-                                               walk_supertraits!(trait_obj, types, (
+                                               walk_supertraits!(trait_obj, Some(&types), (
                                                        (s, t) => {
-                                                               if s.starts_with("util::") {
+                                                               if let Some(supertrait_obj) = types.crate_types.traits.get(s).cloned() {
                                                                        writeln!(w, "use {}::{} as native{}Trait;", types.orig_crate, s, t).unwrap();
-                                                                       let supertrait_obj = *types.crate_types.traits.get(s).unwrap();
                                                                        for item in supertrait_obj.items.iter() {
                                                                                match item {
                                                                                        syn::TraitItem::Method(m) => {
@@ -769,12 +944,11 @@ fn writeln_impl<W: std::io::Write>(w: &mut W, i: &syn::ItemImpl, types: &mut Typ
                                                        },
                                                        "PartialEq" => {},
                                                        // If we have no generics, try a manual implementation:
-                                                       _ if p.path.get_ident().is_some() => maybe_convert_trait_impl(w, &trait_path.1, &ident, types),
-                                                       _ => {},
+                                                       _ => maybe_convert_trait_impl(w, &trait_path.1, &*i.self_ty, types, &gen_types),
                                                }
-                                       } else if p.path.get_ident().is_some() {
+                                       } else {
                                                // If we have no generics, try a manual implementation:
-                                               maybe_convert_trait_impl(w, &trait_path.1, &ident, types);
+                                               maybe_convert_trait_impl(w, &trait_path.1, &*i.self_ty, types, &gen_types);
                                        }
                                } else {
                                        let declared_type = (*types.get_declared_type(&ident).unwrap()).clone();
@@ -799,7 +973,7 @@ fn writeln_impl<W: std::io::Write>(w: &mut W, i: &syn::ItemImpl, types: &mut Typ
                                                                        };
                                                                        gen_types.push_ctx();
                                                                        assert!(gen_types.learn_generics(&m.sig.generics, types));
-                                                                       write_method_params(w, &m.sig, &HashMap::new(), &ret_type, types, Some(&gen_types), false, true);
+                                                                       write_method_params(w, &m.sig, &ret_type, types, Some(&gen_types), false, true);
                                                                        write!(w, " {{\n\t").unwrap();
                                                                        write_method_var_decl_body(w, &m.sig, "", types, Some(&gen_types), false);
                                                                        let mut takes_self = false;
@@ -817,7 +991,7 @@ fn writeln_impl<W: std::io::Write>(w: &mut W, i: &syn::ItemImpl, types: &mut Typ
                                                                        } else {
                                                                                write!(w, "{}::{}::{}(", types.orig_crate, resolved_path, m.sig.ident).unwrap();
                                                                        }
-                                                                       write_method_call_params(w, &m.sig, &HashMap::new(), "", types, Some(&gen_types), &ret_type, false);
+                                                                       write_method_call_params(w, &m.sig, "", types, Some(&gen_types), &ret_type, false);
                                                                        gen_types.pop_ctx();
                                                                        writeln!(w, "\n}}\n").unwrap();
                                                                }
@@ -852,6 +1026,19 @@ fn is_enum_opaque(e: &syn::ItemEnum) -> bool {
        false
 }
 
+fn declare_enum<'a, 'b>(e: &'a syn::ItemEnum, types: &mut TypeResolver<'b, 'a>) {
+       match export_status(&e.attrs) {
+               ExportStatus::Export => {},
+               ExportStatus::NoExport|ExportStatus::TestOnly => return,
+       }
+
+       if is_enum_opaque(e) {
+               types.enum_ignored(&e.ident);
+       } else {
+               types.mirrored_enum_declared(&e.ident);
+       }
+}
+
 /// Print a mapping of an enum. If all of the enum's fields are C-mapped in some form (or the enum
 /// is unitary), we generate an equivalent enum with all types replaced with their C mapped
 /// versions followed by conversion functions which map between the Rust version and the C mapped
@@ -865,7 +1052,6 @@ fn writeln_enum<'a, 'b, W: std::io::Write>(w: &mut W, e: &'a syn::ItemEnum, type
        if is_enum_opaque(e) {
                eprintln!("Skipping enum {} as it contains non-unit fields", e.ident);
                writeln_opaque(w, &e.ident, &format!("{}", e.ident), &e.generics, &e.attrs, types, extra_headers, cpp_headers);
-               types.enum_ignored(&e.ident);
                return;
        }
        writeln_docs(w, &e.attrs, "");
@@ -873,7 +1059,6 @@ fn writeln_enum<'a, 'b, W: std::io::Write>(w: &mut W, e: &'a syn::ItemEnum, type
        if e.generics.lt_token.is_some() {
                unimplemented!();
        }
-       types.mirrored_enum_declared(&e.ident);
 
        let mut needs_free = false;
 
@@ -980,6 +1165,10 @@ fn writeln_enum<'a, 'b, W: std::io::Write>(w: &mut W, e: &'a syn::ItemEnum, type
        if needs_free {
                writeln!(w, "#[no_mangle]\npub extern \"C\" fn {}_free(this_ptr: {}) {{ }}", e.ident, 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();
        write_cpp_wrapper(cpp_headers, &format!("{}", e.ident), needs_free);
 }
 
@@ -994,11 +1183,11 @@ fn writeln_fn<'a, 'b, W: std::io::Write>(w: &mut W, f: &'a syn::ItemFn, types: &
        if !gen_types.learn_generics(&f.sig.generics, types) { return; }
 
        write!(w, "#[no_mangle]\npub extern \"C\" fn {}(", f.sig.ident).unwrap();
-       write_method_params(w, &f.sig, &HashMap::new(), "", types, Some(&gen_types), false, true);
+       write_method_params(w, &f.sig, "", types, Some(&gen_types), false, true);
        write!(w, " {{\n\t").unwrap();
        write_method_var_decl_body(w, &f.sig, "", types, Some(&gen_types), false);
        write!(w, "{}::{}::{}(", types.orig_crate, types.module_path, f.sig.ident).unwrap();
-       write_method_call_params(w, &f.sig, &HashMap::new(), "", types, Some(&gen_types), "", false);
+       write_method_call_params(w, &f.sig, "", types, Some(&gen_types), "", false);
        writeln!(w, "\n}}\n").unwrap();
 }
 
@@ -1057,8 +1246,6 @@ struct FullLibraryAST {
 /// `out_path` and fills it with wrapper structs/functions to allow calling the things in the AST
 /// at `module` from C.
 fn convert_file<'a, 'b>(libast: &'a FullLibraryAST, crate_types: &mut CrateTypes<'a>, in_dir: &str, out_dir: &str, path: &str, orig_crate: &str, module: &str, header_file: &mut File, cpp_header_file: &mut File) {
-       eprintln!("Converting {}...", path);
-
        let syntax = if let Some(ast) = libast.files.get(module) { ast } else { return };
 
        assert!(syntax.shebang.is_none()); // Not sure what this is, hope we dont have one
@@ -1096,11 +1283,31 @@ fn convert_file<'a, 'b>(libast: &'a FullLibraryAST, crate_types: &mut CrateTypes
                        orig_crate, &new_mod, header_file, cpp_header_file);
        }
 
+       eprintln!("Converting {} entries...", path);
+
        let mut type_resolver = TypeResolver::new(orig_crate, module, crate_types);
 
+       // First pass over the items and fill in imports and file-declared objects in the type resolver
        for item in syntax.items.iter() {
                match item {
                        syn::Item::Use(u) => type_resolver.process_use(&mut out, &u),
+                       syn::Item::Struct(s) => {
+                               if let syn::Visibility::Public(_) = s.vis {
+                                       declare_struct(&s, &mut type_resolver);
+                               }
+                       },
+                       syn::Item::Enum(e) => {
+                               if let syn::Visibility::Public(_) = e.vis {
+                                       declare_enum(&e, &mut type_resolver);
+                               }
+                       },
+                       _ => {},
+               }
+       }
+
+       for item in syntax.items.iter() {
+               match item {
+                       syn::Item::Use(_) => {}, // Handled above
                        syn::Item::Static(_) => {},
                        syn::Item::Enum(e) => {
                                if let syn::Visibility::Public(_) = e.vis {
@@ -1125,7 +1332,7 @@ fn convert_file<'a, 'b>(libast: &'a FullLibraryAST, crate_types: &mut CrateTypes
                                // Re-export any primitive-type constants.
                                if let syn::Visibility::Public(_) = c.vis {
                                        if let syn::Type::Path(p) = &*c.ty {
-                                               let resolved_path = type_resolver.resolve_path(&p.path);
+                                               let resolved_path = type_resolver.resolve_path(&p.path, None);
                                                if type_resolver.is_primitive(&resolved_path) {
                                                        writeln!(out, "\n#[no_mangle]").unwrap();
                                                        writeln!(out, "pub static {}: {} = {}::{}::{};", c.ident, resolved_path, orig_crate, module, c.ident).unwrap();
@@ -1139,8 +1346,18 @@ fn convert_file<'a, 'b>(libast: &'a FullLibraryAST, crate_types: &mut CrateTypes
                                                ExportStatus::Export => {},
                                                ExportStatus::NoExport|ExportStatus::TestOnly => continue,
                                        }
-                                       if t.generics.lt_token.is_none() {
-                                               writeln_opaque(&mut out, &t.ident, &format!("{}", t.ident), &t.generics, &t.attrs, &type_resolver, header_file, cpp_header_file);
+
+                                       let mut process_alias = true;
+                                       for tok in t.generics.params.iter() {
+                                               if let syn::GenericParam::Lifetime(_) = tok {}
+                                               else { process_alias = false; }
+                                       }
+                                       if process_alias {
+                                               match &*t.ty {
+                                                       syn::Type::Path(_) =>
+                                                               writeln_opaque(&mut out, &t.ident, &format!("{}", t.ident), &t.generics, &t.attrs, &type_resolver, header_file, cpp_header_file),
+                                                       _ => {}
+                                               }
                                        }
                                }
                        },
@@ -1180,6 +1397,52 @@ fn load_ast(in_dir: &str, path: &str, module: String, ast_storage: &mut FullLibr
        ast_storage.files.insert(module, syntax);
 }
 
+/// Insert ident -> absolute Path resolutions into imports from the given UseTree and path-prefix.
+fn process_use_intern<'a>(u: &'a syn::UseTree, mut path: syn::punctuated::Punctuated<syn::PathSegment, syn::token::Colon2>, imports: &mut HashMap<&'a syn::Ident, syn::Path>) {
+       match u {
+               syn::UseTree::Path(p) => {
+                       path.push(syn::PathSegment { ident: p.ident.clone(), arguments: syn::PathArguments::None });
+                       process_use_intern(&p.tree, path, imports);
+               },
+               syn::UseTree::Name(n) => {
+                       path.push(syn::PathSegment { ident: n.ident.clone(), arguments: syn::PathArguments::None });
+                       imports.insert(&n.ident, syn::Path { leading_colon: Some(syn::Token![::](Span::call_site())), segments: path });
+               },
+               syn::UseTree::Group(g) => {
+                       for i in g.items.iter() {
+                               process_use_intern(i, path.clone(), imports);
+                       }
+               },
+               _ => {}
+       }
+}
+
+/// Map all the Paths in a Type into absolute paths given a set of imports (generated via process_use_intern)
+fn resolve_imported_refs(imports: &HashMap<&syn::Ident, syn::Path>, mut ty: syn::Type) -> syn::Type {
+       match &mut ty {
+               syn::Type::Path(p) => {
+                       if let Some(ident) = p.path.get_ident() {
+                               if let Some(newpath) = imports.get(ident) {
+                                       p.path = newpath.clone();
+                               }
+                       } else { unimplemented!(); }
+               },
+               syn::Type::Reference(r) => {
+                       r.elem = Box::new(resolve_imported_refs(imports, (*r.elem).clone()));
+               },
+               syn::Type::Slice(s) => {
+                       s.elem = Box::new(resolve_imported_refs(imports, (*s.elem).clone()));
+               },
+               syn::Type::Tuple(t) => {
+                       for e in t.elems.iter_mut() {
+                               *e = resolve_imported_refs(imports, e.clone());
+                       }
+               },
+               _ => unimplemented!(),
+       }
+       ty
+}
+
 /// Walk the FullLibraryAST, deciding how things will be mapped and adding tracking to CrateTypes.
 fn walk_ast<'a>(in_dir: &str, path: &str, module: String, ast_storage: &'a FullLibraryAST, crate_types: &mut CrateTypes<'a>) {
        let syntax = if let Some(ast) = ast_storage.files.get(&module) { ast } else { return };
@@ -1189,8 +1452,13 @@ fn walk_ast<'a>(in_dir: &str, path: &str, module: String, ast_storage: &'a FullL
                walk_ast(in_dir, &path, new_mod, ast_storage, crate_types);
        }
 
+       let mut import_maps = HashMap::new();
+
        for item in syntax.items.iter() {
                match item {
+                       syn::Item::Use(u) => {
+                               process_use_intern(&u.tree, syn::punctuated::Punctuated::new(), &mut import_maps);
+                       },
                        syn::Item::Struct(s) => {
                                if let syn::Visibility::Public(_) = s.vis {
                                        match export_status(&s.attrs) {
@@ -1198,6 +1466,10 @@ fn walk_ast<'a>(in_dir: &str, path: &str, module: String, ast_storage: &'a FullL
                                                ExportStatus::NoExport|ExportStatus::TestOnly => continue,
                                        }
                                        let struct_path = format!("{}::{}", module, s.ident);
+                                       if attrs_derives_clone(&s.attrs) {
+                                               crate_types.clonable_types.insert("crate::".to_owned() + &struct_path);
+                                       }
+
                                        crate_types.opaques.insert(struct_path, &s.ident);
                                }
                        },
@@ -1208,9 +1480,40 @@ fn walk_ast<'a>(in_dir: &str, path: &str, module: String, ast_storage: &'a FullL
                                                ExportStatus::NoExport|ExportStatus::TestOnly => continue,
                                        }
                                        let trait_path = format!("{}::{}", module, t.ident);
+                                       walk_supertraits!(t, None, (
+                                               ("Clone", _) => {
+                                                       crate_types.clonable_types.insert("crate::".to_owned() + &trait_path);
+                                               },
+                                               (_, _) => {}
+                                       ) );
                                        crate_types.traits.insert(trait_path, &t);
                                }
                        },
+                       syn::Item::Type(t) => {
+                               if let syn::Visibility::Public(_) = t.vis {
+                                       match export_status(&t.attrs) {
+                                               ExportStatus::Export => {},
+                                               ExportStatus::NoExport|ExportStatus::TestOnly => continue,
+                                       }
+                                       let type_path = format!("{}::{}", module, t.ident);
+                                       let mut process_alias = true;
+                                       for tok in t.generics.params.iter() {
+                                               if let syn::GenericParam::Lifetime(_) = tok {}
+                                               else { process_alias = false; }
+                                       }
+                                       if process_alias {
+                                               match &*t.ty {
+                                                       syn::Type::Path(_) => {
+                                                               // If its a path with no generics, assume we don't map the aliased type and map it opaque
+                                                               crate_types.opaques.insert(type_path, &t.ident);
+                                                       },
+                                                       _ => {
+                                                               crate_types.type_aliases.insert(type_path, resolve_imported_refs(&import_maps, (*t.ty).clone()));
+                                                       }
+                                               }
+                                       }
+                               }
+                       },
                        syn::Item::Enum(e) if is_enum_opaque(e) => {
                                if let syn::Visibility::Public(_) = e.vis {
                                        match export_status(&e.attrs) {
@@ -1218,6 +1521,9 @@ fn walk_ast<'a>(in_dir: &str, path: &str, module: String, ast_storage: &'a FullL
                                                ExportStatus::NoExport|ExportStatus::TestOnly => continue,
                                        }
                                        let enum_path = format!("{}::{}", module, e.ident);
+                                       if attrs_derives_clone(&e.attrs) {
+                                               crate_types.clonable_types.insert("crate::".to_owned() + &enum_path);
+                                       }
                                        crate_types.opaques.insert(enum_path, &e.ident);
                                }
                        },
@@ -1228,6 +1534,9 @@ fn walk_ast<'a>(in_dir: &str, path: &str, module: String, ast_storage: &'a FullL
                                                ExportStatus::NoExport|ExportStatus::TestOnly => continue,
                                        }
                                        let enum_path = format!("{}::{}", module, e.ident);
+                                       if attrs_derives_clone(&e.attrs) {
+                                               crate_types.clonable_types.insert("crate::".to_owned() + &enum_path);
+                                       }
                                        crate_types.mirrored_enums.insert(enum_path, &e);
                                }
                        },
@@ -1250,10 +1559,18 @@ fn main() {
        let mut cpp_header_file = std::fs::OpenOptions::new().write(true).create(true).truncate(true)
                .open(&args[6]).expect("Unable to open new header file");
 
-       writeln!(header_file, "#if defined(__GNUC__)\n#define MUST_USE_STRUCT __attribute__((warn_unused))").unwrap();
-       writeln!(header_file, "#else\n#define MUST_USE_STRUCT\n#endif").unwrap();
-       writeln!(header_file, "#if defined(__GNUC__)\n#define MUST_USE_RES __attribute__((warn_unused_result))").unwrap();
-       writeln!(header_file, "#else\n#define MUST_USE_RES\n#endif").unwrap();
+       writeln!(header_file, "#if defined(__GNUC__)").unwrap();
+       writeln!(header_file, "#define MUST_USE_STRUCT __attribute__((warn_unused))").unwrap();
+       writeln!(header_file, "#define MUST_USE_RES __attribute__((warn_unused_result))").unwrap();
+       writeln!(header_file, "#else").unwrap();
+       writeln!(header_file, "#define MUST_USE_STRUCT").unwrap();
+       writeln!(header_file, "#define MUST_USE_RES").unwrap();
+       writeln!(header_file, "#endif").unwrap();
+       writeln!(header_file, "#if defined(__clang__)").unwrap();
+       writeln!(header_file, "#define NONNULL_PTR _Nonnull").unwrap();
+       writeln!(header_file, "#else").unwrap();
+       writeln!(header_file, "#define NONNULL_PTR").unwrap();
+       writeln!(header_file, "#endif").unwrap();
        writeln!(cpp_header_file, "#include <string.h>\nnamespace LDK {{").unwrap();
 
        // First parse the full crate's ASTs, caching them so that we can hold references to the AST
@@ -1264,7 +1581,8 @@ 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 { traits: HashMap::new(), opaques: HashMap::new(), mirrored_enums: HashMap::new(),
-               templates_defined: HashMap::new(), template_file: &mut derived_templates };
+               type_aliases: HashMap::new(), templates_defined: HashMap::default(), template_file: &mut derived_templates,
+               clonable_types: HashSet::new() };
        walk_ast(&args[1], "/lib.rs", "".to_string(), &libast, &mut libtypes);
 
        // ... finally, do the actual file conversion/mapping, writing out types as we go.