Merge pull request #555 from dtolnay/impl

Limit instantiation of Vec and Box shims to local element type

Author: dtolnay

macro/src/expand.rs

@@ -960,6 +960,8 @@ fn expand_rust_box(ident: &RustName, types: &Types) -> TokenStream {
 
     let span = ident.span();
     quote_spanned! {span=>
+        #[doc(hidden)]
+        unsafe impl ::cxx::private::ImplBox for #ident {}
         #[doc(hidden)]
         #[export_name = #link_uninit]
         unsafe extern "C" fn #local_uninit(
@@ -999,6 +1001,8 @@ fn expand_rust_vec(elem: &RustName, types: &Types) -> TokenStream {
 
     let span = elem.span();
     quote_spanned! {span=>
+        #[doc(hidden)]
+        unsafe impl ::cxx::private::ImplVec for #elem {}
         #[doc(hidden)]
         #[export_name = #link_new]
         unsafe extern "C" fn #local_new(this: *mut ::cxx::private::RustVec<#elem>) {

src/lib.rs

@@ -448,7 +448,7 @@ pub mod private {
     pub use crate::rust_slice::RustSlice;
     pub use crate::rust_str::RustStr;
     pub use crate::rust_string::RustString;
-    pub use crate::rust_type::RustType;
+    pub use crate::rust_type::{ImplBox, ImplVec, RustType};
     pub use crate::rust_vec::RustVec;
     pub use crate::shared_ptr::SharedPtrTarget;
     pub use crate::unique_ptr::UniquePtrTarget;

src/rust_type.rs

@@ -1 +1,3 @@
 pub unsafe trait RustType {}
+pub unsafe trait ImplBox {}
+pub unsafe trait ImplVec {}