[bindings] Always resolve supertrait types during supertrait walks
[rust-lightning] / c-bindings-gen / src / main.rs
index ecbd947baa8fb7dfd72231ee39b73716632842a2..c0c5ecee1e9b0d4522d59c94658a52855b2051bf 100644 (file)
@@ -92,15 +92,18 @@ macro_rules! walk_supertraits { ($t: expr, $types: expr, ($( $pat: pat => $e: ex
                                        if supertrait.paren_token.is_some() || supertrait.lifetimes.is_some() {
                                                unimplemented!();
                                        }
-                                       if let Some(ident) = supertrait.path.get_ident() {
-                                               match (&format!("{}", ident) as &str, &ident) {
+                                       // 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.
+                                       if let Some(path) = $types.maybe_resolve_path(&supertrait.path, None) {
+                                               match (&path as &str, &supertrait.path.segments.iter().last().unwrap().ident) {
                                                        $( $pat => $e, )*
                                                }
-                                       } else {
-                                               let path = $types.resolve_path(&supertrait.path, None);
-                                               match (&path as &str, &supertrait.path.segments.iter().last().unwrap().ident) {
+                                       } else if let Some(ident) = supertrait.path.get_ident() {
+                                               match (&format!("{}", ident) as &str, &ident) {
                                                        $( $pat => $e, )*
                                                }
+                                       } else {
+                                               panic!("Supertrait unresolvable and not single-ident");
                                        }
                                },
                                syn::TypeParamBound::Lifetime(_) => unimplemented!(),
@@ -109,31 +112,6 @@ macro_rules! walk_supertraits { ($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 +126,12 @@ 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 +139,17 @@ 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 +166,7 @@ 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 +178,7 @@ 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
@@ -204,8 +188,10 @@ 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!(),
@@ -218,7 +204,8 @@ fn writeln_trait<'a, 'b, W: std::io::Write>(w: &mut W, t: &'a syn::ItemTrait, ty
                        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", _) => {
@@ -243,21 +230,25 @@ fn writeln_trait<'a, 'b, W: std::io::Write>(w: &mut W, t: &'a syn::ItemTrait, ty
                ("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!(); }
@@ -284,8 +275,10 @@ 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 +302,11 @@ 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 +314,14 @@ 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 +331,27 @@ 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, None)).unwrap();
+                                               writeln!(w, "\ttype {} = crate::{};", t.ident, types.resolve_path(&tr.path, Some(&gen_types))).unwrap();
                                        },
                                        _ => unimplemented!(),
                                }
@@ -439,6 +433,10 @@ fn writeln_opaque<W: std::io::Write>(w: &mut W, ident: &syn::Ident, struct_name:
                                                                        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();
                                                                        break 'attr_loop;
                                                                }
                                                        }
@@ -585,7 +583,7 @@ fn writeln_impl<W: std::io::Write>(w: &mut W, i: &syn::ItemImpl, types: &mut Typ
                                                // 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 {
@@ -605,6 +603,21 @@ fn writeln_impl<W: std::io::Write>(w: &mut W, i: &syn::ItemImpl, types: &mut Typ
                                                        ExportStatus::Export => {},
                                                        ExportStatus::NoExport|ExportStatus::TestOnly => return,
                                                }
+
+                                               // 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: *const {}) -> 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();
@@ -651,8 +664,7 @@ fn writeln_impl<W: std::io::Write>(w: &mut W, i: &syn::ItemImpl, types: &mut Typ
                                                                writeln!(w, "\t\tclone: Some({}_clone_void),", ident).unwrap();
                                                        },
                                                        (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();
@@ -686,7 +698,7 @@ 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, &$m.sig, "", types, Some(&gen_types), false);
                                                                let mut takes_self = false;
@@ -712,7 +724,7 @@ fn writeln_impl<W: std::io::Write>(w: &mut W, i: &syn::ItemImpl, types: &mut Typ
                                                                        },
                                                                        _ => {},
                                                                }
-                                                               write_method_call_params(w, &$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 {
@@ -743,9 +755,8 @@ fn writeln_impl<W: std::io::Write>(w: &mut W, i: &syn::ItemImpl, types: &mut Typ
                                                }
                                                walk_supertraits!(trait_obj, 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) => {
@@ -799,7 +810,7 @@ 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 +828,7 @@ 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();
                                                                }
@@ -980,6 +991,10 @@ 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 +1009,11 @@ 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();
 }