Handle `W: X<T = Y>` generics where `Y` is used as `Z<Y>`
[ldk-c-bindings] / c-bindings-gen / src / types.rs
index bd0c9c5ceecc8cfcb4aaa8ce175cda800d73ddab..74db47ccb35054f45943fcbc90d973cc68215d03 100644 (file)
@@ -723,6 +723,14 @@ impl FullLibraryAST {
 fn initial_clonable_types() -> HashSet<String> {
        let mut res = HashSet::new();
        res.insert("crate::c_types::u5".to_owned());
+       res.insert("crate::c_types::ThirtyTwoBytes".to_owned());
+       res.insert("crate::c_types::PublicKey".to_owned());
+       res.insert("crate::c_types::Transaction".to_owned());
+       res.insert("crate::c_types::TxOut".to_owned());
+       res.insert("crate::c_types::Signature".to_owned());
+       res.insert("crate::c_types::RecoverableSignature".to_owned());
+       res.insert("crate::c_types::Secp256k1Error".to_owned());
+       res.insert("crate::c_types::IOError".to_owned());
        res
 }
 
@@ -850,9 +858,6 @@ impl<'a, 'c: 'a> TypeResolver<'a, 'c> {
                if self.is_primitive(ty) { return true; }
                match ty {
                        "()" => true,
-                       "crate::c_types::Signature" => true,
-                       "crate::c_types::RecoverableSignature" => true,
-                       "crate::c_types::TxOut" => true,
                        _ => false,
                }
        }
@@ -885,6 +890,7 @@ impl<'a, 'c: 'a> TypeResolver<'a, 'c> {
                        "std::io::Error" => Some("crate::c_types::IOError"),
 
                        "bech32::u5" => Some("crate::c_types::u5"),
+                       "core::num::NonZeroU8" => Some("u8"),
 
                        "bitcoin::secp256k1::key::PublicKey"|"bitcoin::secp256k1::PublicKey"|"secp256k1::key::PublicKey"
                                => Some("crate::c_types::PublicKey"),
@@ -905,6 +911,11 @@ impl<'a, 'c: 'a> TypeResolver<'a, 'c> {
                        "bitcoin::blockdata::block::BlockHeader" if is_ref  => Some("*const [u8; 80]"),
                        "bitcoin::blockdata::block::Block" if is_ref  => Some("crate::c_types::u8slice"),
 
+                       "bitcoin::hash_types::PubkeyHash"|"bitcoin::hash_types::WPubkeyHash"|"bitcoin::hash_types::ScriptHash"
+                               if is_ref => Some("*const [u8; 20]"),
+                       "bitcoin::hash_types::WScriptHash"
+                               if is_ref => Some("*const [u8; 32]"),
+
                        // Newtypes that we just expose in their original form.
                        "bitcoin::hash_types::Txid"|"bitcoin::hash_types::BlockHash"|"bitcoin_hashes::sha256::Hash"
                                if is_ref  => Some("*const [u8; 32]"),
@@ -950,6 +961,7 @@ impl<'a, 'c: 'a> TypeResolver<'a, 'c> {
 
                        "str" if is_ref => Some(""),
                        "alloc::string::String"|"String" => Some(""),
+                       "std::io::Error" if !is_ref => Some(""),
                        // Note that we'll panic for String if is_ref, as we only have non-owned memory, we
                        // cannot create a &String.
 
@@ -957,6 +969,7 @@ impl<'a, 'c: 'a> TypeResolver<'a, 'c> {
                        "std::time::SystemTime" => Some("(::std::time::SystemTime::UNIX_EPOCH + std::time::Duration::from_secs("),
 
                        "bech32::u5" => Some(""),
+                       "core::num::NonZeroU8" => Some("core::num::NonZeroU8::new("),
 
                        "bitcoin::secp256k1::key::PublicKey"|"bitcoin::secp256k1::PublicKey"|"secp256k1::key::PublicKey"
                                if is_ref => Some("&"),
@@ -978,6 +991,15 @@ impl<'a, 'c: 'a> TypeResolver<'a, 'c> {
                        "bitcoin::blockdata::block::BlockHeader" => Some("&::bitcoin::consensus::encode::deserialize(unsafe { &*"),
                        "bitcoin::blockdata::block::Block" if is_ref => Some("&::bitcoin::consensus::encode::deserialize("),
 
+                       "bitcoin::hash_types::PubkeyHash" if is_ref =>
+                               Some("&bitcoin::hash_types::PubkeyHash::from_hash(bitcoin::hashes::Hash::from_inner(unsafe { *"),
+                       "bitcoin::hash_types::WPubkeyHash" if is_ref =>
+                               Some("&bitcoin::hash_types::WPubkeyHash::from_hash(bitcoin::hashes::Hash::from_inner(unsafe { *"),
+                       "bitcoin::hash_types::ScriptHash" if is_ref =>
+                               Some("&bitcoin::hash_types::ScriptHash::from_hash(bitcoin::hashes::Hash::from_inner(unsafe { *"),
+                       "bitcoin::hash_types::WScriptHash" if is_ref =>
+                               Some("&bitcoin::hash_types::WScriptHash::from_hash(bitcoin::hashes::Hash::from_inner(unsafe { *"),
+
                        // Newtypes that we just expose in their original form.
                        "bitcoin::hash_types::Txid" if is_ref => Some("&::bitcoin::hash_types::Txid::from_slice(&unsafe { &*"),
                        "bitcoin::hash_types::Txid" if !is_ref => Some("::bitcoin::hash_types::Txid::from_slice(&"),
@@ -1016,11 +1038,13 @@ impl<'a, 'c: 'a> TypeResolver<'a, 'c> {
 
                        "str" if is_ref => Some(".into_str()"),
                        "alloc::string::String"|"String" => Some(".into_string()"),
+                       "std::io::Error" if !is_ref => Some(".to_rust()"),
 
                        "std::time::Duration"|"core::time::Duration" => Some(")"),
                        "std::time::SystemTime" => Some("))"),
 
                        "bech32::u5" => Some(".into()"),
+                       "core::num::NonZeroU8" => Some(").expect(\"Value must be non-zero\")"),
 
                        "bitcoin::secp256k1::key::PublicKey"|"bitcoin::secp256k1::PublicKey"|"secp256k1::key::PublicKey"
                                => Some(".into_rust()"),
@@ -1038,6 +1062,10 @@ impl<'a, 'c: 'a> TypeResolver<'a, 'c> {
                        "bitcoin::blockdata::block::BlockHeader" => Some(" }).unwrap()"),
                        "bitcoin::blockdata::block::Block" => Some(".to_slice()).unwrap()"),
 
+                       "bitcoin::hash_types::PubkeyHash"|"bitcoin::hash_types::WPubkeyHash"|
+                       "bitcoin::hash_types::ScriptHash"|"bitcoin::hash_types::WScriptHash"
+                               if is_ref => Some(" }.clone()))"),
+
                        // Newtypes that we just expose in their original form.
                        "bitcoin::hash_types::Txid" if is_ref => Some(" }[..]).unwrap()"),
                        "bitcoin::hash_types::Txid" => Some(".data[..]).unwrap()"),
@@ -1256,7 +1284,7 @@ impl<'a, 'c: 'a> TypeResolver<'a, 'c> {
        }
        /// Returns true if the path is a "transparent" container, ie an Option or a container which does
        /// not require a generated continer class.
-       fn is_path_transparent_container(&self, full_path: &syn::Path, generics: Option<&GenericTypes>, is_ref: bool) -> bool {
+       pub fn is_path_transparent_container(&self, full_path: &syn::Path, generics: Option<&GenericTypes>, is_ref: bool) -> bool {
                let inner_iter = match &full_path.segments.last().unwrap().arguments {
                        syn::PathArguments::None => return false,
                        syn::PathArguments::AngleBracketed(args) => args.args.iter().map(|arg| {
@@ -1283,16 +1311,15 @@ impl<'a, 'c: 'a> TypeResolver<'a, 'c> {
                                                        (").into(), Err(mut e) => crate::c_types::CResultTempl::err(".to_string(), "e".to_string())],
                                                ").into() }", ContainerPrefixLocation::PerConv))
                        },
-                       "Vec" if !is_ref => {
-                               Some(("Vec::new(); for mut item in ", vec![(format!(".drain(..) {{ local_{}.push(", var_name), "item".to_string())], "); }", ContainerPrefixLocation::PerConv))
-                       },
                        "Vec" => {
-                               // We should only get here if the single contained has an inner
-                               assert!(self.c_type_has_inner(single_contained.unwrap()));
-                               Some(("Vec::new(); for mut item in ", vec![(format!(".drain(..) {{ local_{}.push(", var_name), "*item".to_string())], "); }", ContainerPrefixLocation::PerConv))
+                               if is_ref {
+                                       // We should only get here if the single contained has an inner
+                                       assert!(self.c_type_has_inner(single_contained.unwrap()));
+                               }
+                               Some(("Vec::new(); for mut item in ", vec![(format!(".drain(..) {{ local_{}.push(", var_name), "item".to_string())], "); }", ContainerPrefixLocation::PerConv))
                        },
                        "Slice" => {
-                               Some(("Vec::new(); for item in ", vec![(format!(".iter() {{ local_{}.push(", var_name), "*item".to_string())], "); }", ContainerPrefixLocation::PerConv))
+                               Some(("Vec::new(); for item in ", vec![(format!(".iter() {{ local_{}.push(", var_name), "item".to_string())], "); }", ContainerPrefixLocation::PerConv))
                        },
                        "Option" => {
                                let contained_struct = if let Some(syn::Type::Path(p)) = single_contained {
@@ -1312,9 +1339,9 @@ impl<'a, 'c: 'a> TypeResolver<'a, 'c> {
                                                let is_inner_ref = if let Some(syn::Type::Reference(_)) = single_contained { true } else { false };
                                                if is_ref {
                                                        return Some(("if ", vec![
-                                                               (".is_none() { std::ptr::null() } else { ".to_owned(),
+                                                               (".is_none() { std::ptr::null() } else { ObjOps::nonnull_ptr_to_inner(".to_owned(),
                                                                        format!("({}{}.unwrap())", var_access, if is_inner_ref { "" } else { ".as_ref()" }))
-                                                               ], " }", ContainerPrefixLocation::OutsideConv));
+                                                               ], ") }", ContainerPrefixLocation::OutsideConv));
                                                } else {
                                                        return Some(("if ", vec![
                                                                (".is_none() { std::ptr::null_mut() } else { ".to_owned(), format!("({}.unwrap())", var_access))
@@ -1404,6 +1431,49 @@ impl<'a, 'c: 'a> TypeResolver<'a, 'c> {
                }
        }
 
+       /// Constructs a reference to the given type, possibly tweaking the type if relevant to make it
+       /// convertable to C.
+       pub fn create_ownable_reference(&self, t: &syn::Type, generics: Option<&GenericTypes>) -> Option<syn::Type> {
+               let default_value = Some(syn::Type::Reference(syn::TypeReference {
+                       and_token: syn::Token!(&)(Span::call_site()), lifetime: None, mutability: None,
+                       elem: Box::new(t.clone()) }));
+               match generics.resolve_type(t) {
+                       syn::Type::Path(p) => {
+                               if let Some(resolved_path) = self.maybe_resolve_path(&p.path, generics) {
+                                       if resolved_path != "Vec" { return default_value; }
+                                       if p.path.segments.len() != 1 { unimplemented!(); }
+                                       let only_seg = p.path.segments.iter().next().unwrap();
+                                       if let syn::PathArguments::AngleBracketed(args) = &only_seg.arguments {
+                                               if args.args.len() != 1 { unimplemented!(); }
+                                               let inner_arg = args.args.iter().next().unwrap();
+                                               if let syn::GenericArgument::Type(ty) = &inner_arg {
+                                                       let mut can_create = self.c_type_has_inner(&ty);
+                                                       if let syn::Type::Path(inner) = ty {
+                                                               if inner.path.segments.len() == 1 &&
+                                                                               format!("{}", inner.path.segments[0].ident) == "Vec" {
+                                                                       can_create = true;
+                                                               }
+                                                       }
+                                                       if !can_create { return default_value; }
+                                                       if let Some(inner_ty) = self.create_ownable_reference(&ty, generics) {
+                                                               return Some(syn::Type::Reference(syn::TypeReference {
+                                                                       and_token: syn::Token![&](Span::call_site()),
+                                                                       lifetime: None,
+                                                                       mutability: None,
+                                                                       elem: Box::new(syn::Type::Slice(syn::TypeSlice {
+                                                                               bracket_token: syn::token::Bracket { span: Span::call_site() },
+                                                                               elem: Box::new(inner_ty)
+                                                                       }))
+                                                               }));
+                                                       } else { return default_value; }
+                                               } else { unimplemented!(); }
+                                       } else { unimplemented!(); }
+                               } else { return None; }
+                       },
+                       _ => default_value,
+               }
+       }
+
        // *************************************************
        // *** Type definition during main.rs processing ***
        // *************************************************
@@ -1415,12 +1485,14 @@ impl<'a, 'c: 'a> TypeResolver<'a, 'c> {
        pub fn c_type_has_inner_from_path(&self, full_path: &str) -> bool {
                self.crate_types.opaques.get(full_path).is_some()
        }
+
        /// Returns true if the object at the given path is mapped as X { inner: *mut origX, .. }.
        pub fn c_type_has_inner(&self, ty: &syn::Type) -> bool {
                match ty {
                        syn::Type::Path(p) => {
-                               let full_path = self.resolve_path(&p.path, None);
-                               self.c_type_has_inner_from_path(&full_path)
+                               if let Some(full_path) = self.maybe_resolve_path(&p.path, None) {
+                                       self.c_type_has_inner_from_path(&full_path)
+                               } else { false }
                        },
                        syn::Type::Reference(r) => {
                                self.c_type_has_inner(&*r.elem)
@@ -1782,6 +1854,8 @@ impl<'a, 'c: 'a> TypeResolver<'a, 'c> {
                                } else if let syn::Type::Reference(r) = &*s.elem {
                                        if let syn::Type::Path(p) = &*r.elem {
                                                write!(w, "{}", sliceconv(self.c_type_has_inner_from_path(&self.resolve_path(&p.path, generics)), None)).unwrap();
+                                       } else if let syn::Type::Slice(_) = &*r.elem {
+                                               write!(w, "{}", sliceconv(false, None)).unwrap();
                                        } else { unimplemented!(); }
                                } else if let syn::Type::Tuple(t) = &*s.elem {
                                        assert!(!t.elems.is_empty());
@@ -1839,16 +1913,16 @@ impl<'a, 'c: 'a> TypeResolver<'a, 'c> {
                                                DeclType::MirroredEnum => write!(w, "crate::{}::native_into(", decl_path).unwrap(),
                                                DeclType::EnumIgnored|DeclType::StructImported if is_ref && ptr_for_ref && from_ptr =>
                                                        write!(w, "crate::{} {{ inner: unsafe {{ (", decl_path).unwrap(),
-                                               DeclType::EnumIgnored|DeclType::StructImported if is_ref && ptr_for_ref =>
-                                                       write!(w, "crate::{} {{ inner: unsafe {{ ( (&(*", decl_path).unwrap(),
-                                               DeclType::EnumIgnored|DeclType::StructImported if is_ref =>
-                                                       write!(w, "&crate::{} {{ inner: unsafe {{ (", decl_path).unwrap(),
+                                               DeclType::EnumIgnored|DeclType::StructImported if is_ref => {
+                                                       if !ptr_for_ref { write!(w, "&").unwrap(); }
+                                                       write!(w, "crate::{} {{ inner: unsafe {{ ObjOps::nonnull_ptr_to_inner((", decl_path).unwrap()
+                                               },
                                                DeclType::EnumIgnored|DeclType::StructImported if !is_ref && from_ptr =>
                                                        write!(w, "crate::{} {{ inner: ", decl_path).unwrap(),
                                                DeclType::EnumIgnored|DeclType::StructImported if !is_ref =>
-                                                       write!(w, "crate::{} {{ inner: Box::into_raw(Box::new(", decl_path).unwrap(),
+                                                       write!(w, "crate::{} {{ inner: ObjOps::heap_alloc(", decl_path).unwrap(),
                                                DeclType::Trait(_) if is_ref => write!(w, "").unwrap(),
-                                               DeclType::Trait(_) if !is_ref => {},
+                                               DeclType::Trait(_) if !is_ref => write!(w, "Into::into(").unwrap(),
                                                _ => panic!("{:?}", decl_path),
                                        }
                                });
@@ -1863,20 +1937,18 @@ impl<'a, 'c: 'a> TypeResolver<'a, 'c> {
                                        DeclType::MirroredEnum => write!(w, ")").unwrap(),
                                        DeclType::EnumIgnored|DeclType::StructImported if is_ref && ptr_for_ref && from_ptr =>
                                                write!(w, " as *const _) as *mut _ }}, is_owned: false }}").unwrap(),
-                                       DeclType::EnumIgnored|DeclType::StructImported if is_ref && ptr_for_ref =>
-                                               write!(w, ") as *const _) as *mut _) }}, is_owned: false }}").unwrap(),
                                        DeclType::EnumIgnored|DeclType::StructImported if is_ref =>
-                                               write!(w, " as *const _) as *mut _ }}, is_owned: false }}").unwrap(),
+                                               write!(w, " as *const _) as *mut _) }}, is_owned: false }}").unwrap(),
                                        DeclType::EnumIgnored|DeclType::StructImported if !is_ref && from_ptr =>
                                                write!(w, ", is_owned: true }}").unwrap(),
-                                       DeclType::EnumIgnored|DeclType::StructImported if !is_ref => write!(w, ")), is_owned: true }}").unwrap(),
+                                       DeclType::EnumIgnored|DeclType::StructImported if !is_ref => write!(w, "), is_owned: true }}").unwrap(),
                                        DeclType::Trait(_) if is_ref => {},
                                        DeclType::Trait(_) => {
                                                // This is used when we're converting a concrete Rust type into a C trait
                                                // for use when a Rust trait method returns an associated type.
                                                // Because all of our C traits implement From<RustTypesImplementingTraits>
                                                // we can just call .into() here and be done.
-                                               write!(w, ".into()").unwrap()
+                                               write!(w, ")").unwrap()
                                        },
                                        _ => unimplemented!(),
                                });
@@ -1885,13 +1957,11 @@ impl<'a, 'c: 'a> TypeResolver<'a, 'c> {
                self.write_to_c_conversion_inline_suffix_inner(w, t, generics, false, ptr_for_ref, false);
        }
 
-       fn write_from_c_conversion_prefix_inner<W: std::io::Write>(&self, w: &mut W, t: &syn::Type, generics: Option<&GenericTypes>, is_ref: bool, ptr_for_ref: bool) {
+       fn write_from_c_conversion_prefix_inner<W: std::io::Write>(&self, w: &mut W, t: &syn::Type, generics: Option<&GenericTypes>, is_ref: bool, _ptr_for_ref: bool) {
                self.write_conversion_inline_intern(w, t, generics, is_ref, false, false, "() /*", true, |_, _| "&local_".to_owned(),
                                |a, b, _c| self.from_c_conversion_prefix_from_path(a, b),
-                               |w, decl_type, _full_path, is_ref, is_mut| match decl_type {
-                                       DeclType::StructImported if is_ref && ptr_for_ref => write!(w, "unsafe {{ &*(*").unwrap(),
-                                       DeclType::StructImported if is_mut && is_ref => write!(w, "unsafe {{ &mut *").unwrap(),
-                                       DeclType::StructImported if is_ref => write!(w, "unsafe {{ &*").unwrap(),
+                               |w, decl_type, _full_path, is_ref, _is_mut| match decl_type {
+                                       DeclType::StructImported if is_ref => write!(w, "").unwrap(),
                                        DeclType::StructImported if !is_ref => write!(w, "*unsafe {{ Box::from_raw(").unwrap(),
                                        DeclType::MirroredEnum if is_ref => write!(w, "&").unwrap(),
                                        DeclType::MirroredEnum => {},
@@ -1911,9 +1981,10 @@ impl<'a, 'c: 'a> TypeResolver<'a, 'c> {
                                        (true, Some(_)) => unreachable!(),
                                },
                                |a, b, _c| self.from_c_conversion_suffix_from_path(a, b),
-                               |w, decl_type, _full_path, is_ref, _is_mut| match decl_type {
-                                       DeclType::StructImported if is_ref && ptr_for_ref => write!(w, ").inner }}").unwrap(),
-                                       DeclType::StructImported if is_ref => write!(w, ".inner }}").unwrap(),
+                               |w, decl_type, _full_path, is_ref, is_mut| match decl_type {
+                                       DeclType::StructImported if is_ref && ptr_for_ref => write!(w, "XXX unimplemented").unwrap(),
+                                       DeclType::StructImported if is_mut && is_ref => write!(w, ".get_native_mut_ref()").unwrap(),
+                                       DeclType::StructImported if is_ref => write!(w, ".get_native_ref()").unwrap(),
                                        DeclType::StructImported if !is_ref => write!(w, ".take_inner()) }}").unwrap(),
                                        DeclType::MirroredEnum if is_ref => write!(w, ".to_native()").unwrap(),
                                        DeclType::MirroredEnum => write!(w, ".into_native()").unwrap(),
@@ -1934,7 +2005,7 @@ impl<'a, 'c: 'a> TypeResolver<'a, 'c> {
                                        } else { None }
                                },
                                |w, decl_type, _full_path, is_ref, _is_mut| match decl_type {
-                                       DeclType::StructImported if !is_ref => write!(w, "unsafe {{ &*").unwrap(),
+                                       DeclType::StructImported if !is_ref => write!(w, "").unwrap(),
                                        _ => unimplemented!(),
                                });
        }
@@ -1948,7 +2019,7 @@ impl<'a, 'c: 'a> TypeResolver<'a, 'c> {
                                },
                                |a, b, _c| self.from_c_conversion_suffix_from_path(a, b),
                                |w, decl_type, _full_path, is_ref, _is_mut| match decl_type {
-                                       DeclType::StructImported if !is_ref => write!(w, ".inner }}").unwrap(),
+                                       DeclType::StructImported if !is_ref => write!(w, ".get_native_ref()").unwrap(),
                                        _ => unimplemented!(),
                                });
        }
@@ -2037,14 +2108,14 @@ impl<'a, 'c: 'a> TypeResolver<'a, 'c> {
                                                if prefix_location == ContainerPrefixLocation::PerConv {
                                                        var_prefix(w, conv_ty, generics, is_ref && ty_has_inner, ptr_for_ref, false);
                                                } else if !is_ref && !needs_ref_map && to_c && only_contained_has_inner {
-                                                       write!(w, "Box::into_raw(Box::new(").unwrap();
+                                                       write!(w, "ObjOps::heap_alloc(").unwrap();
                                                }
 
                                                write!(w, "{}{}", if contains_slice { "local_" } else { "" }, if new_var { new_var_name } else { var_access }).unwrap();
                                                if prefix_location == ContainerPrefixLocation::PerConv {
                                                        var_suffix(w, conv_ty, generics, is_ref && ty_has_inner, ptr_for_ref, false);
                                                } else if !is_ref && !needs_ref_map && to_c && only_contained_has_inner {
-                                                       write!(w, "))").unwrap();
+                                                       write!(w, ")").unwrap();
                                                }
                                                write!(w, " }}").unwrap();
                                        }
@@ -2085,7 +2156,7 @@ impl<'a, 'c: 'a> TypeResolver<'a, 'c> {
                                        if let syn::PathArguments::AngleBracketed(args) = &p.path.segments.iter().next().unwrap().arguments {
                                                convert_container!(resolved_path, args.args.len(), || args.args.iter().map(|arg| {
                                                        if let syn::GenericArgument::Type(ty) = arg {
-                                                               ty
+                                                               generics.resolve_type(ty)
                                                        } else { unimplemented!(); }
                                                }));
                                        } else { unimplemented!(); }
@@ -2118,7 +2189,7 @@ impl<'a, 'c: 'a> TypeResolver<'a, 'c> {
                                } else if let syn::Type::Reference(ty) = &*s.elem {
                                        let tyref = [&*ty.elem];
                                        is_ref = true;
-                                       convert_container!("Slice", 1, || tyref.iter().map(|t| *t));
+                                       convert_container!("Slice", 1, || tyref.iter().map(|t| generics.resolve_type(*t)));
                                        unimplemented!("convert_container should return true as container_lookup should succeed for slices");
                                } else if let syn::Type::Tuple(t) = &*s.elem {
                                        // When mapping into a temporary new var, we need to own all the underlying objects.
@@ -2393,62 +2464,68 @@ impl<'a, 'c: 'a> TypeResolver<'a, 'c> {
                                        } else { return false; }
                                }
                        }
-                       if let syn::Type::Tuple(tuple) = arg {
-                               if tuple.elems.len() == 0 {
-                                       write!(w, "None").unwrap();
-                                       write!(mangled_type, "None").unwrap();
-                               } else {
-                                       let mut mangled_tuple_type: Vec<u8> = Vec::new();
-
-                                       // Figure out what the mangled type should look like. To disambiguate
-                                       // ((A, B), C) and (A, B, C) we prefix the generic args with a _ and suffix
-                                       // them with a Z. Ideally we wouldn't use Z, but not many special chars are
-                                       // available for use in type names.
-                                       write!(w, "C{}Tuple_", tuple.elems.len()).unwrap();
-                                       write!(mangled_type, "C{}Tuple_", tuple.elems.len()).unwrap();
-                                       write!(mangled_tuple_type, "C{}Tuple_", tuple.elems.len()).unwrap();
-                                       for elem in tuple.elems.iter() {
-                                               if let syn::Type::Path(p) = elem {
-                                                       write_path!(p, Some(&mut mangled_tuple_type));
-                                               } else if let syn::Type::Reference(refelem) = elem {
-                                                       if let syn::Type::Path(p) = &*refelem.elem {
+                       match generics.resolve_type(arg) {
+                               syn::Type::Tuple(tuple) => {
+                                       if tuple.elems.len() == 0 {
+                                               write!(w, "None").unwrap();
+                                               write!(mangled_type, "None").unwrap();
+                                       } else {
+                                               let mut mangled_tuple_type: Vec<u8> = Vec::new();
+
+                                               // Figure out what the mangled type should look like. To disambiguate
+                                               // ((A, B), C) and (A, B, C) we prefix the generic args with a _ and suffix
+                                               // them with a Z. Ideally we wouldn't use Z, but not many special chars are
+                                               // available for use in type names.
+                                               write!(w, "C{}Tuple_", tuple.elems.len()).unwrap();
+                                               write!(mangled_type, "C{}Tuple_", tuple.elems.len()).unwrap();
+                                               write!(mangled_tuple_type, "C{}Tuple_", tuple.elems.len()).unwrap();
+                                               for elem in tuple.elems.iter() {
+                                                       if let syn::Type::Path(p) = elem {
                                                                write_path!(p, Some(&mut mangled_tuple_type));
+                                                       } else if let syn::Type::Reference(refelem) = elem {
+                                                               if let syn::Type::Path(p) = &*refelem.elem {
+                                                                       write_path!(p, Some(&mut mangled_tuple_type));
+                                                               } else { return false; }
                                                        } else { return false; }
-                                               } else { return false; }
-                                       }
-                                       write!(w, "Z").unwrap();
-                                       write!(mangled_type, "Z").unwrap();
-                                       write!(mangled_tuple_type, "Z").unwrap();
-                                       if !self.check_create_container(String::from_utf8(mangled_tuple_type).unwrap(),
-                                                       &format!("{}Tuple", tuple.elems.len()), tuple.elems.iter().collect(), generics, is_ref) {
-                                               return false;
+                                               }
+                                               write!(w, "Z").unwrap();
+                                               write!(mangled_type, "Z").unwrap();
+                                               write!(mangled_tuple_type, "Z").unwrap();
+                                               if !self.check_create_container(String::from_utf8(mangled_tuple_type).unwrap(),
+                                                               &format!("{}Tuple", tuple.elems.len()), tuple.elems.iter().collect(), generics, is_ref) {
+                                                       return false;
+                                               }
                                        }
-                               }
-                       } else if let syn::Type::Path(p_arg) = arg {
-                               write_path!(p_arg, None);
-                       } else if let syn::Type::Reference(refty) = arg {
-                               if let syn::Type::Path(p_arg) = &*refty.elem {
+                               },
+                               syn::Type::Path(p_arg) => {
                                        write_path!(p_arg, None);
-                               } else if let syn::Type::Slice(_) = &*refty.elem {
-                                       // write_c_type will actually do exactly what we want here, we just need to
-                                       // make it a pointer so that its an option. Note that we cannot always convert
-                                       // the Vec-as-slice (ie non-ref types) containers, so sometimes need to be able
-                                       // to edit it, hence we use *mut here instead of *const.
-                                       if args.len() != 1 { return false; }
-                                       write!(w, "*mut ").unwrap();
-                                       self.write_c_type(w, arg, None, true);
-                               } else { return false; }
-                       } else if let syn::Type::Array(a) = arg {
-                               if let syn::Type::Path(p_arg) = &*a.elem {
-                                       let resolved = self.resolve_path(&p_arg.path, generics);
-                                       if !self.is_primitive(&resolved) { return false; }
-                                       if let syn::Expr::Lit(syn::ExprLit { lit: syn::Lit::Int(len), .. }) = &a.len {
-                                               if self.c_type_from_path(&format!("[{}; {}]", resolved, len.base10_digits()), is_ref, ptr_for_ref).is_none() { return false; }
-                                               write!(w, "_{}{}", resolved, len.base10_digits()).unwrap();
-                                               write!(mangled_type, "_{}{}", resolved, len.base10_digits()).unwrap();
+                               },
+                               syn::Type::Reference(refty) => {
+                                       if let syn::Type::Path(p_arg) = &*refty.elem {
+                                               write_path!(p_arg, None);
+                                       } else if let syn::Type::Slice(_) = &*refty.elem {
+                                               // write_c_type will actually do exactly what we want here, we just need to
+                                               // make it a pointer so that its an option. Note that we cannot always convert
+                                               // the Vec-as-slice (ie non-ref types) containers, so sometimes need to be able
+                                               // to edit it, hence we use *mut here instead of *const.
+                                               if args.len() != 1 { return false; }
+                                               write!(w, "*mut ").unwrap();
+                                               self.write_c_type(w, arg, None, true);
                                        } else { return false; }
-                               } else { return false; }
-                       } else { return false; }
+                               },
+                               syn::Type::Array(a) => {
+                                       if let syn::Type::Path(p_arg) = &*a.elem {
+                                               let resolved = self.resolve_path(&p_arg.path, generics);
+                                               if !self.is_primitive(&resolved) { return false; }
+                                               if let syn::Expr::Lit(syn::ExprLit { lit: syn::Lit::Int(len), .. }) = &a.len {
+                                                       if self.c_type_from_path(&format!("[{}; {}]", resolved, len.base10_digits()), is_ref, ptr_for_ref).is_none() { return false; }
+                                                       write!(w, "_{}{}", resolved, len.base10_digits()).unwrap();
+                                                       write!(mangled_type, "_{}{}", resolved, len.base10_digits()).unwrap();
+                                               } else { return false; }
+                                       } else { return false; }
+                               },
+                               _ => { return false; },
+                       }
                }
                if self.is_transparent_container(ident, is_ref, args.iter().map(|a| *a)) { return true; }
                // Push the "end of type" Z
@@ -2574,6 +2651,20 @@ impl<'a, 'c: 'a> TypeResolver<'a, 'c> {
                                                } else { return false; };
                                                write!(w, "{}::{}", Self::generated_container_path(), mangled_container).unwrap();
                                                self.check_create_container(mangled_container, "Vec", vec![&*r.elem], generics, false)
+                                       } else if let syn::Type::Slice(sl2) = &*r.elem {
+                                               if let syn::Type::Reference(r2) = &*sl2.elem {
+                                                       if let syn::Type::Path(p) = &*r2.elem {
+                                                               // Slices with slices with opaque types (with is_owned flags) are mapped as non-ref Vecs
+                                                               let resolved = self.resolve_path(&p.path, generics);
+                                                               let mangled_container = if let Some(ident) = self.crate_types.opaques.get(&resolved) {
+                                                                       format!("CVec_CVec_{}ZZ", ident)
+                                                               } else { return false; };
+                                                               write!(w, "{}::{}", Self::generated_container_path(), mangled_container).unwrap();
+                                                               let inner = &r2.elem;
+                                                               let vec_ty: syn::Type = syn::parse_quote!(Vec<#inner>);
+                                                               self.check_create_container(mangled_container, "Vec", vec![&vec_ty], generics, false)
+                                                       } else { false }
+                                               } else { false }
                                        } else { false }
                                } else if let syn::Type::Tuple(_) = &*s.elem {
                                        let mut args = syn::punctuated::Punctuated::<_, syn::token::Comma>::new();