Implement derive for IntoArc and IntoRc

cf. <rust-lang/rust#45990>

Author: YOSHIOKA Takuma

opaque_typedef_macros/src/derives.rs

@@ -18,8 +18,10 @@ pub enum Derive {
     DerefMut,
     Display,
     FromInner,
+    IntoArc,
     IntoBox,
     IntoInner,
+    IntoRc,
 }
 
 impl Derive {
@@ -55,7 +57,9 @@ impl Derive {
                         "Display" => &[Derive::Display],
                         "FromInner" => &[Derive::FromInner],
                         "IntoBox" => &[Derive::IntoBox],
+                        "IntoArc" => &[Derive::IntoArc],
                         "IntoInner" => &[Derive::IntoInner],
+                        "IntoRc" => &[Derive::IntoRc],
                         target => panic!(
                             "`#[opaque_typedef({}({}))] is specified but the target `{}` is unknown",
                             names::DERIVE,

opaque_typedef_macros/src/utils.rs

@@ -387,6 +387,15 @@ impl<'a> TypeProperties<'a> {
                         }
                     }
                 },
+                (Derive::IntoArc, Sizedness::Unsized) => quote! {
+                    impl<'a> ::std::convert::From<&'a #ty_outer> for ::std::sync::Arc<#ty_outer> {
+                        fn from(other: &'a #ty_outer) -> Self {
+                            let arc_inner = ::std::sync::Arc::<#ty_inner>::from(&other.#field_inner);
+                            let rw = ::std::sync::Arc::into_raw(arc_inner) as *mut #ty_outer;
+                            unsafe { ::std::sync::Arc::from_raw(rw) }
+                        }
+                    }
+                },
                 (Derive::IntoBox, Sizedness::Unsized) => quote! {
                     impl<'a> ::std::convert::From<&'a #ty_outer> for ::std::boxed::Box<#ty_outer> {
                         fn from(other: &'a #ty_outer) -> Self {
@@ -396,6 +405,15 @@ impl<'a> TypeProperties<'a> {
                         }
                     }
                 },
+                (Derive::IntoRc, Sizedness::Unsized) => quote! {
+                    impl<'a> ::std::convert::From<&'a #ty_outer> for ::std::rc::Rc<#ty_outer> {
+                        fn from(other: &'a #ty_outer) -> Self {
+                            let rc_inner = ::std::rc::Rc::<#ty_inner>::from(&other.#field_inner);
+                            let rw = ::std::rc::Rc::into_raw(rc_inner) as *mut #ty_outer;
+                            unsafe { ::std::rc::Rc::from_raw(rw) }
+                        }
+                    }
+                },
                 (Derive::IntoInner, Sizedness::Sized) => quote! {
                     impl ::std::convert::Into<#ty_inner> for #ty_outer {
                         fn into(self) -> #ty_inner {

opaque_typedef_tests/src/my_str.rs

@@ -4,7 +4,7 @@
 /// My string slice.
 #[derive(Debug, PartialEq, Eq, PartialOrd, Ord, Hash, OpaqueTypedefUnsized)]
 #[opaque_typedef(derive(AsciiExt, AsMutDeref, AsRefDeref, DefaultRef, Deref, DerefMut, Display,
-                        FromInner, IntoBox, IntoInner))]
+                        FromInner, IntoArc, IntoBox, IntoRc, IntoInner))]
 #[opaque_typedef(allow_mut_ref)]
 pub struct MyStr {
     #[opaque_typedef(inner)] inner: str,

opaque_typedef_tests/tests/my_str.rs

@@ -86,6 +86,15 @@ mod my_str {
         let _: &MyStr = <&MyStr as From<&str>>::from(ok_str);
     }
 
+    #[test]
+    fn into_arc() {
+        let ok_str = "foobar";
+        let my_str = MyStr::new(ok_str);
+        let my_str_arc = ::std::sync::Arc::<MyStr>::from(my_str);
+        let inner = <&MyStr as Into<&str>>::into(&*my_str_arc);
+        assert_eq!(ok_str, inner);
+    }
+
     #[test]
     fn into_box() {
         let ok_str = "foobar";
@@ -95,6 +104,15 @@ mod my_str {
         assert_eq!(ok_str, inner);
     }
 
+    #[test]
+    fn into_rc() {
+        let ok_str = "foobar";
+        let my_str = MyStr::new(ok_str);
+        let my_str_rc = ::std::rc::Rc::<MyStr>::from(my_str);
+        let inner = <&MyStr as Into<&str>>::into(&*my_str_rc);
+        assert_eq!(ok_str, inner);
+    }
+
     #[test]
     fn into_inner() {
         let ok_str = "foobar";