Support `Option<Trait>` (and `Option<&Trait>`, implemented the same)

diff --git a/c-bindings-gen/src/types.rs b/c-bindings-gen/src/types.rs
index 497556d7d69d4bab3e90870f21c57af7ec50a8e4..bc015f04bd8ecf4ec4add92e3e4c76528b2940be 100644 (file)
--- a/c-bindings-gen/src/types.rs
+++ b/c-bindings-gen/src/types.rs
@@ -2201,7 +2201,7 @@ impl<'a, 'c: 'a> TypeResolver<'a, 'c> {
                                // For slices (and Options), we refuse to directly map them as is_ref when they
                                // aren't opaque types containing an inner pointer. This is due to the fact that,
                                // in both cases, the actual higher-level type is non-is_ref.
-                               let ty_has_inner = if $args_len == 1 {
+                               let (ty_has_inner, ty_is_trait) = if $args_len == 1 {
                                        let ty = $args_iter().next().unwrap();
                                        if $container_type == "Slice" && to_c {
                                                // "To C ptr_for_ref" means "return the regular object with is_owned
@@ -2211,12 +2211,14 @@ impl<'a, 'c: 'a> TypeResolver<'a, 'c> {
                                        }
                                        if let syn::Type::Reference(t) = ty {
                                                if let syn::Type::Path(p) = &*t.elem {
-                                                       self.c_type_has_inner_from_path(&self.resolve_path(&p.path, generics))
-                                               } else { false }
+                                                       let resolved = self.resolve_path(&p.path, generics);
+                                                       (self.c_type_has_inner_from_path(&resolved), self.crate_types.traits.get(&resolved).is_some())
+                                               } else { (false, false) }
                                        } else if let syn::Type::Path(p) = ty {
-                                               self.c_type_has_inner_from_path(&self.resolve_path(&p.path, generics))
-                                       } else { false }
-                               } else { true };
+                                               let resolved = self.resolve_path(&p.path, generics);
+                                               (self.c_type_has_inner_from_path(&resolved), self.crate_types.traits.get(&resolved).is_some())
+                                       } else { (false, false) }
+                               } else { (true, false) };
 
                                // Options get a bunch of special handling, since in general we map Option<>al
                                // types into the same C type as non-Option-wrapped types. This ends up being
@@ -2240,7 +2242,7 @@ impl<'a, 'c: 'a> TypeResolver<'a, 'c> {
                                                // If the inner element contains an inner pointer, we will just use that,
                                                // avoiding the need to map elements to references. Otherwise we'll need to
                                                // do an extra mapping step.
-                                               needs_ref_map = !only_contained_has_inner && $container_type == "Option";
+                                               needs_ref_map = !only_contained_has_inner && !ty_is_trait && $container_type == "Option";
                                        } else {
                                                only_contained_type = Some(arg);
                                                only_contained_type_nonref = Some(arg);
@@ -2488,10 +2490,11 @@ impl<'a, 'c: 'a> TypeResolver<'a, 'c> {
        // ******************************************************
 
        fn write_template_generics<'b, W: std::io::Write>(&self, w: &mut W, args: &mut dyn Iterator<Item=&'b syn::Type>, generics: Option<&GenericTypes>, is_ref: bool) -> bool {
-               for (idx, t) in args.enumerate() {
+               for (idx, orig_t) in args.enumerate() {
                        if idx != 0 {
                                write!(w, ", ").unwrap();
                        }
+                       let t = generics.resolve_type(orig_t);
                        if let syn::Type::Reference(r_arg) = t {
                                assert!(!is_ref); // We don't currently support outer reference types for non-primitive inners
 
@@ -2503,6 +2506,7 @@ impl<'a, 'c: 'a> TypeResolver<'a, 'c> {
                                if let syn::Type::Path(p_arg) = &*r_arg.elem {
                                        let resolved = self.resolve_path(&p_arg.path, generics);
                                        assert!(self.crate_types.opaques.get(&resolved).is_some() ||
+                                                       self.crate_types.traits.get(&resolved).is_some() ||
                                                        self.c_type_from_path(&resolved, true, true).is_some(), "Template generics should be opaque or have a predefined mapping");
                                } else { unimplemented!(); }
                        } else if let syn::Type::Path(p_arg) = t {