Switch Python to BindingsIr

The new system is to do a `BindingsIr` specialization pass, which means
implementing `VisitMut` and using it to:
  - Rewrite names, docstrings, etc.
  - Derive things like FFI converter names and store them in `lang_data`
  - Generate language-specific things like imports as we walk the tree

Along the way I made a couple changes to the Python bindings:

Changed `_uniffi_rust_call_async` to not lift the return value.  This
makes it fit in with the sync logic better and also enables async
constructors (which store the pointer in `self` rather than lift it).

Added the `CustomTypeConfig::type_name`.  While updating the code I
noticed the current templates handle this in a slightly buggy way where
they assume the type name is the builtin type, even if there's a
`from_custom`/`into_custom` that converts to a different type.

Removed almost all of the macros, `define_callable` is the only one left.

CHANGELOG.md

@@ -20,6 +20,9 @@ We have [detailed upgrade notes](https://mozilla.github.io/uniffi-rs/next/Upgrad
   The `UniffiCustomTypeConverter` trait is no longer used, use the
   [`custom_type!` macro](https://mozilla.github.io/uniffi-rs/next/types/custom_types.html) instead.
 
+- Python: Added the `type_name` field for custom type configs.  This is required when the name of
+  the custom type differs from the Python type name.
+
 - The [UDL syntax for external types](https://mozilla.github.io/uniffi-rs/next/udl/external_types.html) has changed.
   `typedef extern MyEnum;` has been replaced
   with `typedef enum MyEnum;`. Attributes other than `[External = "crate_name"]` have been removed.

docs/manual/src/types/custom_types.md

@@ -219,10 +219,9 @@ lower = "{}.toString()"
 Here's how the configuration works in `uniffi.toml`.
 
 * Create a `[bindings.{language}.custom_types.{CustomTypeName}]` table to enable a custom type on a bindings side.  This has several subkeys:
-  * `type_name` (Optional, Typed languages only): Type/class name for the
-    custom type.  Defaults to the type name used in the UDL.  Note: The UDL
-    type name will still be used in generated function signatures, however it
-    will be defined as a typealias to this type.
+  * `type_name` (Optional): Type/class name for the custom type.
+    Defaults to the type name used in the proc macro.
+    Note: The UDL type name will still be used in generated function signatures for the foreign bindings, however it will be defined as a typealias to this type.
   * `lift`: Expression to convert the UDL type to the custom type.  `{}` will be replaced with the value of the UDL type.
   * `lower`: Expression to convert the custom type to the UDL type.  `{}` will be replaced with the value of the custom type.
   * `imports` (Optional) list of modules to import for your `lift`/`lower` functions.

examples/custom-types/uniffi.toml

@@ -48,8 +48,8 @@ from_custom = "{}.toString()"
 
 [bindings.python.custom_types.Url]
 # We're going to be the urllib.parse.ParseResult class, which is the closest
-# thing Python has to a Url class.  No need to specify `type_name` though,
-# since Python is loosely typed.
+# thing Python has to a Url class.
+type_name = "urllib.parse.ParseResult"
 # modules to import
 imports = ["urllib.parse"]
 # Functions to convert between strings and the ParsedUrl class

fixtures/futures/tests/bindings/test_futures.py

@@ -77,13 +77,13 @@ async def test():
         asyncio.run(test())
 
     def test_async_constructors(self):
-        # Check the default constructor has been disabled.
+        # Async constructor's can't be called directly
         with self.assertRaises(ValueError) as e:
             Megaphone()
-        self.assertTrue(str(e.exception).startswith("async constructors not supported"))
 
         async def test():
-            megaphone = await Megaphone.secondary()
+            # Instead, users should use the `new` classmethod.
+            megaphone = await Megaphone.new()
             result_alice = await megaphone.say_after(0, 'Alice')
             self.assertEqual(result_alice, 'HELLO, ALICE!')
 

uniffi_bindgen/Cargo.toml

@@ -29,6 +29,7 @@ once_cell = "1.12"
 paste = "1.0"
 serde = { version = "1", features = ["derive"] }
 toml = "0.5"
+uniffi_internal_macros = { path = "../uniffi_internal_macros", version = "=0.28.3" }
 uniffi_meta = { path = "../uniffi_meta", version = "=0.28.3" }
 uniffi_testing = { path = "../uniffi_testing", version = "=0.28.3", optional = true }
 uniffi_udl = { path = "../uniffi_udl", version = "=0.28.3" }