pyproto: make deprecated feature opt-in

Architecture.md

@@ -153,8 +153,8 @@ implemented in Python, such as GC support.
 
 ## 5. Procedural macros to simplify usage for users.
 
-[`pyo3-macros`] provides six proc-macro APIs: `pymodule`, `pyproto`, `pyfunction`, `pyclass`,
-`pymethods`, and `#[derive(FromPyObject)]`.
+[`pyo3-macros`] provides five proc-macro APIs: `pymodule`, `pyfunction`, `pyclass`,
+`pymethods`, and `#[derive(FromPyObject)]`. (And a deprecated `pyproto` macro.)
 [`pyo3-macros-backend`] has the actual implementations of these APIs.
 [`src/derive_utils.rs`] contains some utilities used in code generated by these proc-macros,
 such as parsing function arguments.

CHANGELOG.md

@@ -12,6 +12,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - Implement `ToPyObject` for `[T; N]`. [#2313](https://github.com/PyO3/pyo3/pull/2313)
 
+### Changed
+
+- The deprecated `pyproto` feature is now disabled by default. [#2321](https://github.com/PyO3/pyo3/pull/2321)
+
 ## [0.16.4] - 2022-04-14
 
 ### Added

Cargo.toml

@@ -53,7 +53,7 @@ serde_json = "1.0.61"
 pyo3-build-config = { path = "pyo3-build-config", version = "0.16.4", features = ["resolve-config"] }
 
 [features]
-default = ["macros", "pyproto"]
+default = ["macros"]
 
 # Enables macros: #[pyclass], #[pymodule], #[pyfunction] etc.
 macros = ["pyo3-macros", "indoc", "unindent"]

guide/src/class/protocols.md

@@ -4,8 +4,8 @@ Python's object model defines several protocols for different object behavior, s
 
 In the Python C-API which PyO3 is implemented upon, many of these magic methods have to be placed into special "slots" on the class type object, as covered in the previous section. There are two ways in which this can be done:
 
- - [New in PyO3 0.15, recommended in PyO3 0.16] In `#[pymethods]`, if the name of the method is a recognised magic method, PyO3 will place it in the type object automatically.
- - [Deprecated in PyO3 0.16] In special traits combined with the `#[pyproto]` attribute.
+ - In `#[pymethods]`, if the name of the method is a recognised magic method, PyO3 will place it in the type object automatically.
+ - [Deprecated since PyO3 0.16] In special traits combined with the `#[pyproto]` attribute.
 
 (There are also many magic methods which don't have a special slot, such as `__dir__`. These methods can be implemented as normal in `#[pymethods]`.)
 
@@ -404,7 +404,7 @@ impl ClassWithGCSupport {
 
 PyO3 can use the `#[pyproto]` attribute in combination with special traits to implement the magic methods which need slots. The special traits are listed below. See also the [documentation for the `pyo3::class` module]({{#PYO3_DOCS_URL}}/pyo3/class/index.html).
 
-Due to complexity in the implementation and usage, these traits are deprecated in PyO3 0.16 in favour of the `#[pymethods]` solution.
+Due to complexity in the implementation and usage, these traits were deprecated in PyO3 0.16 in favour of the `#[pymethods]` solution.
 
 All `#[pyproto]` methods can return `T` instead of `PyResult<T>` if the method implementation is infallible. In addition, if the return type is `()`, it can be omitted altogether.
 

guide/src/features.md

@@ -59,7 +59,6 @@ This feature enables a dependency on the `pyo3-macros` crate, which provides the
 - `#[pyfunction]`
 - `#[pyclass]`
 - `#[pymethods]`
-- `#[pyproto]`
 - `#[derive(FromPyObject)]`
 
 It also provides the `py_run!` macro.
@@ -78,9 +77,7 @@ See [the `#[pyclass]` implementation details](class.md#implementation-details) f
 
 ### `pyproto`
 
-This feature enables the `#[pyproto]` macro, which is an alternative (older, soon-to-be-deprecated) to `#[pymethods]` for defining magic methods such as `__eq__`.
-
-> This feature is enabled by default. To disable it, set `default-features = false` for the `pyo3` entry in your Cargo.toml.
+This feature enables the `#[pyproto]` macro, which is a deprecated alternative to `#[pymethods]` for defining magic methods such as `__eq__`.
 
 ### `nightly`
 

guide/src/migration.md

@@ -3,6 +3,12 @@
 This guide can help you upgrade code through breaking changes from one PyO3 version to the next.
 For a detailed list of all changes, see the [CHANGELOG](changelog.md).
 
+## from 0.16.* to 0.17
+
+### The `pyproto` feature is now disabled by default
+
+In preparation for removing the deprecated `#[pyproto]` attribute macro in a future PyO3 version, it is now gated behind an opt-in feature flag. This also gives a slight saving to compile times for code which does not use the deprecated macro.
+
 ## from 0.15.* to 0.16
 
 ### Drop support for older technologies