Parse and ignore extended encoding type information

See more details in https://bou.io/ExtendedTypeInfoInObjC.html

crates/objc2-encode/src/encoding.rs

@@ -84,6 +84,14 @@ pub enum Encoding {
     /// A C `char *`. Corresponds to the `"*"` code.
     String,
     /// An Objective-C object (`id`). Corresponds to the `"@"` code.
+    ///
+    /// Some compilers may choose to store the name of the class in instance
+    /// variables and properties as `"@" class_name`, see [Extended Type Info
+    /// in Objective-C][ext] (note that this does not include generics).
+    ///
+    /// Such class names are currently ignored by `objc2-encode`.
+    ///
+    /// [ext]: https://bou.io/ExtendedTypeInfoInObjC.html
     Object,
     /// An Objective-C block. Corresponds to the `"@" "?"` code.
     Block,
@@ -378,6 +386,10 @@ mod tests {
             Encoding::Object;
             !Encoding::Block;
             "@";
+            ~"@\"AnyClassName\"";
+            ~"@\"\""; // Empty class name
+            !"@\"MyClassName";
+            !"@MyClassName\"";
             !"@?";
         }
 

crates/objc2-encode/src/parse.rs

@@ -5,7 +5,7 @@ use alloc::string::{String, ToString};
 use alloc::vec::Vec;
 use core::fmt;
 
-use crate::helper::{ContainerKind, EncodingType, Helper, NestingLevel};
+use crate::helper::{ContainerKind, EncodingType, Helper, NestingLevel, Primitive};
 use crate::{Encoding, EncodingBox};
 
 /// Check whether a struct or union name is a valid identifier
@@ -251,7 +251,16 @@ impl Parser<'_> {
 
     pub(crate) fn expect_encoding(&mut self, enc: &Encoding, level: NestingLevel) -> Option<()> {
         match enc.helper() {
-            Helper::Primitive(primitive) => self.expect_str(primitive.to_str()),
+            Helper::Primitive(primitive) => {
+                self.expect_str(primitive.to_str())?;
+
+                if primitive == Primitive::Object && self.try_peek() == Some(b'"') {
+                    self.advance();
+                    self.consume_while(|b| b != b'"');
+                    self.expect_byte(b'"')?;
+                }
+                Some(())
+            }
             Helper::BitField(size, Some((offset, t))) => {
                 self.expect_byte(b'b')?;
                 self.expect_u64(*offset)?;
@@ -388,6 +397,13 @@ impl Parser<'_> {
                     self.advance();
                     EncodingBox::Block
                 }
+                // Parse class name if present
+                Some(b'"') => {
+                    self.advance();
+                    self.consume_while(|b| b != b'"');
+                    self.expect_byte(b'"').ok_or(ErrorKind::UnexpectedEnd)?;
+                    EncodingBox::Object
+                }
                 _ => EncodingBox::Object,
             },
             b'#' => EncodingBox::Class,

crates/objc2/src/runtime/mod.rs

@@ -917,6 +917,7 @@ impl AnyClass {
         Bool::from_raw(res).as_bool()
     }
 
+    // <https://developer.apple.com/library/archive/documentation/Cocoa/Conceptual/ObjCRuntimeGuide/Articles/ocrtPropertyIntrospection.html>
     // fn property(&self, name: &str) -> Option<&Property>;
     // fn properties(&self) -> Malloc<[&Property]>;
     // unsafe fn replace_method(&self, name: Sel, imp: Imp, types: &str) -> Imp;