Implement lifetime elision inside of pins

macro/src/expand.rs

@@ -436,7 +436,7 @@ fn expand_cxx_function_shim(efn: &ExternFn, types: &Types) -> TokenStream {
     let receiver = efn.receiver.iter().map(|receiver| {
         let var = receiver.var;
         if receiver.pinned {
-            let ty = receiver.ty();
+            let ty = receiver.ty_self();
             quote!(#var: #ty)
         } else {
             let ampersand = receiver.ampersand;

syntax/tokens.rs

@@ -270,12 +270,18 @@ impl ToTokens for NamedType {
 }
 
 pub struct ReceiverType<'a>(&'a Receiver);
+pub struct ReceiverTypeSelf<'a>(&'a Receiver);
 
 impl Receiver {
     // &TheType
     pub fn ty(&self) -> ReceiverType {
         ReceiverType(self)
     }
+
+    // &Self
+    pub fn ty_self(&self) -> ReceiverTypeSelf {
+        ReceiverTypeSelf(self)
+    }
 }
 
 impl ToTokens for ReceiverType<'_> {
@@ -304,3 +310,30 @@ impl ToTokens for ReceiverType<'_> {
         }
     }
 }
+
+impl ToTokens for ReceiverTypeSelf<'_> {
+    fn to_tokens(&self, tokens: &mut TokenStream) {
+        let Receiver {
+            pinned: _,
+            ampersand,
+            lifetime,
+            mutable: _,
+            var: _,
+            ty,
+            shorthand: _,
+            pin_tokens,
+            mutability,
+        } = &self.0;
+        if let Some((pin, langle, _rangle)) = pin_tokens {
+            tokens.extend(quote_spanned!(pin.span=> ::std::pin::Pin));
+            langle.to_tokens(tokens);
+        }
+        ampersand.to_tokens(tokens);
+        lifetime.to_tokens(tokens);
+        mutability.to_tokens(tokens);
+        Token![Self](ty.rust.span()).to_tokens(tokens);
+        if let Some((_pin, _langle, rangle)) = pin_tokens {
+            rangle.to_tokens(tokens);
+        }
+    }
+}

tests/ffi/lib.rs

@@ -224,6 +224,7 @@ pub mod ffi {
         fn c_return_borrow(s: &CxxString) -> UniquePtr<Borrow>;
 
         fn const_member(self: &Borrow);
+        fn nonconst_member(self: Pin<&mut Borrow>);
     }
 
     #[repr(u32)]

tests/ffi/tests.cc

@@ -211,6 +211,8 @@ Borrow::Borrow(const std::string &s) : s(s) {}
 
 void Borrow::const_member() const {}
 
+void Borrow::nonconst_member() {}
+
 std::unique_ptr<Borrow> c_return_borrow(const std::string &s) {
   return std::unique_ptr<Borrow>(new Borrow(s));
 }

tests/ffi/tests.h

@@ -80,6 +80,7 @@ enum COwnedEnum {
 struct Borrow {
   Borrow(const std::string &s);
   void const_member() const;
+  void nonconst_member();
   const std::string &s;
 };