Added Bindgen names to objective-c pointer return types

* Took advantage of the repr transparent to use Bindgen return type
  names.
* Updated unit tests and book

Author: simlay

book/src/objc.md

@@ -17,6 +17,15 @@ The objective-c classes will be represented as a `struct Foo(id)` and a trait
 objc::runtime::Object` (the pointer to the objective-c instance). The trait
 `IFoo` is needed to allow for the generated inheritance.
 
+Functions that use or return objective-c pointers of instance `Foo` will return
+`Foo`. The reason this works is beacuse `Foo` represented as `transparent`.
+This will be helpful for a lot of objective-c frameworks however there are some
+cases where functions return `instancetype` which is a type alias for `id` so
+an occasional `foo.0` may be required. An example of this would in the UIKit
+framework should you want to add a `UILabel` to a
+[UIStackView](https://developer.apple.com/documentation/uikit/uistackview/1616227-addarrangedsubview?language=objc)
+you will need to convert the `UILabel` to a `UIView` via `UIView(label.0)`.
+
 Each class (struct) has an `alloc` and a `dealloc` to match that of some of the alloc
 methods found in `NSObject`.
 

src/codegen/mod.rs

@@ -3512,6 +3512,14 @@ impl TryToRustTy for Type {
                     inner.into_resolver().through_type_refs().resolve(ctx);
                 let inner_ty = inner.expect_type();
 
+                let is_objc_pointer =
+                    inner.kind().as_type().map_or(false, |ty| {
+                        match ty.kind() {
+                            TypeKind::ObjCInterface(..) => true,
+                            _ => false,
+                        }
+                    });
+
                 // Regardless if we can properly represent the inner type, we
                 // should always generate a proper pointer here, so use
                 // infallible conversion of the inner type.
@@ -3520,7 +3528,8 @@ impl TryToRustTy for Type {
 
                 // Avoid the first function pointer level, since it's already
                 // represented in Rust.
-                if inner_ty.canonical_type(ctx).is_function() {
+                if inner_ty.canonical_type(ctx).is_function() || is_objc_pointer
+                {
                     Ok(ty)
                 } else {
                     Ok(ty.to_ptr(is_const))
@@ -3539,9 +3548,12 @@ impl TryToRustTy for Type {
             TypeKind::ObjCId => Ok(quote! {
                 id
             }),
-            TypeKind::ObjCInterface(..) => Ok(quote! {
-                objc::runtime::Object
-            }),
+            TypeKind::ObjCInterface(ref interface) => {
+                let name = ctx.rust_ident(interface.name());
+                Ok(quote! {
+                    #name
+                })
+            }
             ref u @ TypeKind::UnresolvedTypeRef(..) => {
                 unreachable!("Should have been resolved after parsing {:?}!", u)
             }
@@ -4395,11 +4407,12 @@ mod utils {
                     TypeKind::Pointer(inner) => {
                         let inner = ctx.resolve_item(inner);
                         let inner_ty = inner.expect_type();
-                        if let TypeKind::ObjCInterface(_) =
+                        if let TypeKind::ObjCInterface(ref interface) =
                             *inner_ty.canonical_type(ctx).kind()
                         {
+                            let name = ctx.rust_ident(interface.name());
                             quote! {
-                                id
+                                #name
                             }
                         } else {
                             arg_item.to_rust_ty_or_opaque(ctx, &())

tests/expectations/tests/objc_class.rs

@@ -11,7 +11,7 @@ extern crate objc;
 #[allow(non_camel_case_types)]
 pub type id = *mut objc::runtime::Object;
 extern "C" {
-    pub static mut fooVar: *mut objc::runtime::Object;
+    pub static mut fooVar: Foo;
 }
 #[repr(transparent)]
 #[derive(Clone, Copy)]

tests/expectations/tests/objc_class_method.rs

@@ -39,7 +39,7 @@ pub trait IFoo: Sized + std::ops::Deref {
     {
         msg_send!(class!(Foo), methodWithInt: foo)
     }
-    unsafe fn methodWithFoo_(foo: id)
+    unsafe fn methodWithFoo_(foo: Foo)
     where
         <Self as std::ops::Deref>::Target: objc::Message + Sized,
     {
@@ -51,7 +51,7 @@ pub trait IFoo: Sized + std::ops::Deref {
     {
         msg_send!(class!(Foo), methodReturningInt)
     }
-    unsafe fn methodReturningFoo() -> *mut objc::runtime::Object
+    unsafe fn methodReturningFoo() -> Foo
     where
         <Self as std::ops::Deref>::Target: objc::Message + Sized,
     {

tests/expectations/tests/objc_interface_type.rs

@@ -30,7 +30,7 @@ pub trait IFoo: Sized + std::ops::Deref {}
 #[repr(C)]
 #[derive(Debug, Copy, Clone)]
 pub struct FooStruct {
-    pub foo: *mut objc::runtime::Object,
+    pub foo: Foo,
 }
 #[test]
 fn bindgen_test_layout_FooStruct() {
@@ -63,8 +63,8 @@ impl Default for FooStruct {
     }
 }
 extern "C" {
-    pub fn fooFunc(foo: id);
+    pub fn fooFunc(foo: Foo);
 }
 extern "C" {
-    pub static mut kFoo: *const objc::runtime::Object;
+    pub static mut kFoo: Foo;
 }

tests/expectations/tests/objc_method.rs

@@ -39,7 +39,7 @@ pub trait IFoo: Sized + std::ops::Deref {
     {
         msg_send!(self, methodWithInt: foo)
     }
-    unsafe fn methodWithFoo_(self, foo: id)
+    unsafe fn methodWithFoo_(self, foo: Foo)
     where
         <Self as std::ops::Deref>::Target: objc::Message + Sized,
     {
@@ -51,7 +51,7 @@ pub trait IFoo: Sized + std::ops::Deref {
     {
         msg_send!(self, methodReturningInt)
     }
-    unsafe fn methodReturningFoo(self) -> *mut objc::runtime::Object
+    unsafe fn methodReturningFoo(self) -> Foo
     where
         <Self as std::ops::Deref>::Target: objc::Message + Sized,
     {

tests/expectations/tests/objc_pointer_return_types.rs

@@ -0,0 +1,59 @@
+#![allow(
+    dead_code,
+    non_snake_case,
+    non_camel_case_types,
+    non_upper_case_globals
+)]
+#![cfg(target_os = "macos")]
+
+#[macro_use]
+extern crate objc;
+#[allow(non_camel_case_types)]
+pub type id = *mut objc::runtime::Object;
+#[repr(transparent)]
+#[derive(Clone, Copy)]
+pub struct Bar(pub id);
+impl std::ops::Deref for Bar {
+    type Target = objc::runtime::Object;
+    fn deref(&self) -> &Self::Target {
+        unsafe { &*self.0 }
+    }
+}
+unsafe impl objc::Message for Bar {}
+impl Bar {
+    pub fn alloc() -> Self {
+        Self(unsafe { msg_send!(objc::class!(Bar), alloc) })
+    }
+}
+impl IBar for Bar {}
+pub trait IBar: Sized + std::ops::Deref {}
+#[repr(transparent)]
+#[derive(Clone, Copy)]
+pub struct Foo(pub id);
+impl std::ops::Deref for Foo {
+    type Target = objc::runtime::Object;
+    fn deref(&self) -> &Self::Target {
+        unsafe { &*self.0 }
+    }
+}
+unsafe impl objc::Message for Foo {}
+impl Foo {
+    pub fn alloc() -> Self {
+        Self(unsafe { msg_send!(objc::class!(Foo), alloc) })
+    }
+}
+impl IFoo for Foo {}
+pub trait IFoo: Sized + std::ops::Deref {
+    unsafe fn methodUsingBar_(self, my_bar: Bar)
+    where
+        <Self as std::ops::Deref>::Target: objc::Message + Sized,
+    {
+        msg_send!(self, methodUsingBar: my_bar)
+    }
+    unsafe fn methodReturningBar() -> Bar
+    where
+        <Self as std::ops::Deref>::Target: objc::Message + Sized,
+    {
+        msg_send!(class!(Foo), methodReturningBar)
+    }
+}

tests/headers/objc_pointer_return_types.h

@@ -0,0 +1,10 @@
+// bindgen-flags: --objc-extern-crate -- -x objective-c
+// bindgen-osx-only
+
+@interface Bar
+@end
+
+@interface Foo
++ (Bar*)methodReturningBar;
+- (void)methodUsingBar:(Bar *)my_bar;
+@end