Don't generate #[cfg]s in proc macro

Author: messense

examples/decorator/Cargo.toml

@@ -10,4 +10,7 @@ crate-type = ["cdylib"]
 [dependencies]
 pyo3 = { path = "../../", features = ["extension-module"] }
 
+[features]
+pep489 = ["pyo3/pep489"]
+
 [workspace]

examples/maturin-starter/Cargo.toml

@@ -10,4 +10,7 @@ crate-type = ["cdylib"]
 [dependencies]
 pyo3 = { path = "../../", features = ["extension-module"] }
 
+[features]
+pep489 = ["pyo3/pep489"]
+
 [workspace]

examples/setuptools-rust-starter/Cargo.toml

@@ -10,4 +10,7 @@ crate-type = ["cdylib"]
 [dependencies]
 pyo3 = { path = "../../", features = ["extension-module"] }
 
+[features]
+pep489 = ["pyo3/pep489"]
+
 [workspace]

examples/word-count/Cargo.toml

@@ -11,4 +11,7 @@ crate-type = ["cdylib"]
 pyo3 = { path = "../..", features = ["extension-module"] }
 rayon = "1.0.2"
 
+[features]
+pep489 = ["pyo3/pep489"]
+
 [workspace]

pyo3-macros-backend/Cargo.toml

@@ -16,6 +16,7 @@ edition = "2018"
 [dependencies]
 quote = { version = "1", default-features = false }
 proc-macro2 = { version = "1", default-features = false }
+pyo3-build-config = { path = "../pyo3-build-config", version = "0.16.2", features = ["resolve-config"] }
 
 [dependencies.syn]
 version = "1.0.56"

pyo3-macros-backend/src/module.rs

@@ -76,8 +76,7 @@ pub fn pymodule_impl(
 
     let module_def_name = module_def_ident(fnname);
 
-    quote! {
-        #[cfg(any(not(feature = "pep489"), PyPy))]
+    let single_phase_module = quote! {
         #[no_mangle]
         #[allow(non_snake_case)]
         /// This autogenerated function is called by the python interpreter when importing
@@ -86,13 +85,13 @@ pub fn pymodule_impl(
             unsafe { #module_def_name.module_init() }
         }
 
-        #[cfg(any(not(feature = "pep489"), PyPy))]
         #[doc(hidden)]
         #visibility static #module_def_name: #krate::impl_::pymodule::ModuleDef = unsafe {
             #krate::impl_::pymodule::ModuleDef::new(concat!(stringify!(#name), "\0"), #doc, #krate::impl_::pymodule::ModuleInitializer(#fnname))
         };
+    };
 
-        #[cfg(all(feature = "pep489", not(PyPy)))]
+    let multi_phase_module = quote! {
         #[no_mangle]
         #[allow(non_snake_case)]
         /// This autogenerated function is called by the python interpreter when importing
@@ -101,7 +100,6 @@ pub fn pymodule_impl(
             unsafe { #krate::ffi::PyModuleDef_Init(#module_def_name.module_def()) }
         }
 
-        #[cfg(all(feature = "pep489", not(PyPy)))]
         pub unsafe extern "C" fn #mod_exec_name(module: *mut #krate::ffi::PyObject) -> ::std::os::raw::c_int {
             use #krate::conversion::FromPyPointer;
 
@@ -118,7 +116,6 @@ pub fn pymodule_impl(
         }
 
         // An array of slot definitions for multi-phase initialization, terminated by a {0, NULL} entry.
-        #[cfg(all(feature = "pep489", not(PyPy)))]
         #[doc(hidden)]
         #visibility static #slots_name: [#krate::impl_::pymodule::ModuleDefSlot; 2] = [
             #krate::impl_::pymodule::ModuleDefSlot::new(
@@ -131,7 +128,6 @@ pub fn pymodule_impl(
             ),
         ];
 
-        #[cfg(all(feature = "pep489", not(PyPy)))]
         #[doc(hidden)]
         #visibility static #module_def_name: #krate::impl_::pymodule::ModuleDef = unsafe {
             #krate::impl_::pymodule::ModuleDef::new(
@@ -140,9 +136,22 @@ pub fn pymodule_impl(
                 &#slots_name as *const #krate::impl_::pymodule::ModuleDefSlot as *mut #krate::ffi::PyModuleDef_Slot,
             )
         };
+    };
+
+    if is_pypy() {
+        single_phase_module
+    } else if cfg!(feature = "pep489") {
+        multi_phase_module
+    } else {
+        single_phase_module
     }
 }
 
+fn is_pypy() -> bool {
+    let config = pyo3_build_config::get();
+    config.implementation.is_pypy()
+}
+
 /// Finds and takes care of the #[pyfn(...)] in `#[pymodule]`
 pub fn process_functions_in_module(func: &mut syn::ItemFn) -> syn::Result<()> {
     let mut stmts: Vec<syn::Stmt> = Vec::new();