Move macros into separate feature.

It's enabled by default to avoid breakage, but this allows compiling
pyo3 with a lot less dependencies in case the macros are not needed.

.github/workflows/test.yml

@@ -28,7 +28,9 @@ jobs:
           toolchain: nightly
           default: true
       - run: rustup set default-host ${{ matrix.platform.rust-target }}
-      - name: Build
+      - name: Build without default features
+        run: cargo build --no-default-features --verbose
+      - name: Build with default features
         run: cargo build --verbose
       - name: Install test dependencies
         run: |

Cargo.toml

@@ -19,14 +19,14 @@ travis-ci = { repository = "PyO3/pyo3", branch = "master" }
 appveyor = { repository = "fafhrd91/pyo3" }
 
 [dependencies]
-indoc = "0.3.4"
-inventory = "0.1.4"
+indoc = { version = "0.3.4", optional = true }
+inventory = { version = "0.1.4", optional = true }
 libc = "0.2.62"
 num-bigint = { version = "0.2", optional = true }
 num-complex = { version = "0.2", optional = true }
-paste = "0.1.6"
-pyo3cls = { path = "pyo3cls", version = "=0.9.2" }
-unindent = "0.1.4"
+paste = { version = "0.1.6", optional = true }
+pyo3cls = { path = "pyo3cls", version = "=0.9.2", optional = true }
+unindent = { version = "0.1.4", optional = true }
 
 [dev-dependencies]
 assert_approx_eq = "1.1.0"
@@ -36,7 +36,8 @@ trybuild = "1.0.23"
 version_check = "0.9.1"
 
 [features]
-default = []
+default = ["macros"]
+macros = ["indoc", "inventory", "paste", "pyo3cls", "unindent"]
 
 # this is no longer needed internally, but setuptools-rust assumes this feature
 python3 = []

src/class/methods.rs

@@ -138,6 +138,7 @@ impl PySetterDef {
 /// Allows arbitrary pymethod blocks to submit their methods, which are eventually
 /// collected by pyclass.
 #[doc(hidden)]
+#[cfg(feature = "macros")]
 pub trait PyMethodsInventory: inventory::Collect {
     /// Create a new instance
     fn new(methods: &'static [PyMethodDefType]) -> Self;
@@ -149,6 +150,7 @@ pub trait PyMethodsInventory: inventory::Collect {
 /// Implementation detail. Only to be used through the proc macros.
 /// For pyclass derived structs, this trait collects method from all impl blocks using inventory.
 #[doc(hidden)]
+#[cfg(feature = "macros")]
 pub trait PyMethodsImpl {
     /// Normal methods. Mainly defined by `#[pymethod]`.
     type Methods: PyMethodsInventory;
@@ -161,3 +163,11 @@ pub trait PyMethodsImpl {
             .collect()
     }
 }
+
+#[doc(hidden)]
+#[cfg(not(feature = "macros"))]
+pub trait PyMethodsImpl {
+    fn py_methods() -> Vec<&'static PyMethodDefType> {
+        Vec::new()
+    }
+}

src/lib.rs

@@ -150,21 +150,18 @@ pub use crate::type_object::{type_flags, PyTypeInfo};
 // Since PyAny is as important as PyObject, we expose it to the top level.
 pub use crate::types::PyAny;
 
-// Re-exported for wrap_function
+#[cfg(feature = "macros")]
 #[doc(hidden)]
-pub use paste;
-// Re-exported for py_run
-#[doc(hidden)]
-pub use indoc;
-// Re-exported for pymethods
-#[doc(hidden)]
-pub use inventory;
+pub use {
+    indoc,     // Re-exported for py_run
+    inventory, // Re-exported for pymethods
+    paste,     // Re-exported for wrap_function
+    unindent,  // Re-exported for py_run
+};
+
 // Re-exported for the `__wrap` functions
 #[doc(hidden)]
 pub use libc;
-// Re-exported for py_run
-#[doc(hidden)]
-pub use unindent;
 
 pub mod buffer;
 #[doc(hidden)]
@@ -197,6 +194,7 @@ pub mod type_object;
 pub mod types;
 
 /// The proc macros, which are also part of the prelude.
+#[cfg(feature = "macros")]
 pub mod proc_macro {
     pub use pyo3cls::pymodule;
     /// The proc macro attributes
@@ -278,6 +276,7 @@ macro_rules! wrap_pymodule {
 /// If you need to handle failures, please use [Python::run] directly.
 ///
 #[macro_export]
+#[cfg(feature = "macros")]
 macro_rules! py_run {
     ($py:expr, $($val:ident)+, $code:literal) => {{
         pyo3::py_run_impl!($py, $($val)+, pyo3::indoc::indoc!($code))
@@ -289,6 +288,7 @@ macro_rules! py_run {
 
 #[macro_export]
 #[doc(hidden)]
+#[cfg(feature = "macros")]
 macro_rules! py_run_impl {
     ($py:expr, $($val:ident)+, $code:expr) => {{
         use pyo3::types::IntoPyDict;

src/prelude.rs

@@ -20,5 +20,5 @@ pub use crate::python::Python;
 pub use crate::{FromPy, FromPyObject, IntoPy, IntoPyPointer, PyTryFrom, PyTryInto, ToPyObject};
 // PyModule is only part of the prelude because we need it for the pymodule function
 pub use crate::types::{PyAny, PyModule};
-pub use pyo3cls::pymodule;
-pub use pyo3cls::{pyclass, pyfunction, pymethods, pyproto};
+#[cfg(feature = "macros")]
+pub use pyo3cls::{pyclass, pyfunction, pymethods, pymodule, pyproto};