Restore compatibility with Rust 1.41(.1).

This version is currently supported by Debian stable and Alpine Linux.

Fixes PyO3#1420

Cargo.toml

@@ -17,13 +17,15 @@ edition = "2018"
 [dependencies]
 cfg-if = { version = "1.0" }
 ctor = { version = "0.1", optional = true }
-indoc = { version = "1.0.3", optional = true }
+# must stay at 0.3.x for Rust 1.41 compatibility
+indoc = { version = "0.3.6", optional = true }
 inventory = { version = "0.1.4", optional = true }
 libc = "0.2.62"
 parking_lot = "0.11.0"
 num-bigint = { version = "0.3", optional = true }
 num-complex = { version = "0.3", optional = true }
-paste = { version = "1.0.3", optional = true }
+# must stay at 0.1.x for Rust 1.41 compatibility
+paste = { version = "0.1.18", optional = true }
 pyo3-macros = { path = "pyo3-macros", version = "=0.13.1", optional = true }
 unindent = { version = "0.1.4", optional = true }
 hashbrown = { version = "0.9", optional = true }

README.md

@@ -3,7 +3,7 @@
 [![Actions Status](https://github.com/PyO3/pyo3/workflows/Test/badge.svg)](https://github.com/PyO3/pyo3/actions)
 [![codecov](https://codecov.io/gh/PyO3/pyo3/branch/master/graph/badge.svg)](https://codecov.io/gh/PyO3/pyo3)
 [![crates.io](http://meritbadge.herokuapp.com/pyo3)](https://crates.io/crates/pyo3)
-[![minimum rustc 1.45](https://img.shields.io/badge/rustc-1.45+-blue.svg)](https://rust-lang.github.io/rfcs/2495-min-rust-version.html)
+[![minimum rustc 1.41](https://img.shields.io/badge/rustc-1.41+-blue.svg)](https://rust-lang.github.io/rfcs/2495-min-rust-version.html)
 [![Join the dev chat](https://img.shields.io/gitter/room/nwjs/nw.js.svg)](https://gitter.im/PyO3/Lobby)
 
 [Rust](http://www.rust-lang.org/) bindings for [Python](https://www.python.org/). This includes running and interacting with Python code from a Rust binary, as well as writing native Python modules.
@@ -18,7 +18,7 @@ A comparison with rust-cpython can be found [in the guide](https://pyo3.rs/maste
 
 ## Usage
 
-PyO3 supports Python 3.6 and up. The minimum required Rust version is 1.45.0.
+PyO3 supports Python 3.6 and up. The minimum required Rust version is 1.41.1.
 
 Building with PyPy is also possible (via cpyext) for Python 3.6, targeted PyPy version is 7.3+.
 Please refer to the [pypy section in the guide](https://pyo3.rs/master/pypy.html).

pyo3-macros-backend/src/method.rs

@@ -139,10 +139,12 @@ impl<'a> FnSpec<'a> {
 
  // strip get_ or set_
  let strip_fn_name = |prefix: &'static str| {
- name.unraw()
- .to_string()
- .strip_prefix(prefix)
- .map(|rest| syn::Ident::new(rest, name.span()))
+ let ident = name.unraw().to_string();
+ if ident.starts_with(prefix) {
+ Some(syn::Ident::new(&ident[prefix.len()..], ident.span()))
+ } else {
+ None
+ }
  };
 
  // Parse receiver & function type for various method types

pyo3-macros-backend/src/pyfunction.rs

@@ -174,8 +174,8 @@ pub fn parse_name_attribute(attrs: &mut Vec<syn::Attribute>) -> syn::Result<Opti
  Ok(Some(ident))
  }
  [(_, span)] => bail_spanned!(*span => "expected string literal for #[name] argument"),
- [_first_attr, second_attr, ..] => bail_spanned!(
- second_attr.1 => "#[name] can not be specified multiple times"
+ slice => bail_spanned!(
+ slice[1].1 => "#[name] can not be specified multiple times"
  ),
  }
 }

pyo3-macros-backend/src/pymethod.rs

@@ -703,8 +703,13 @@ pub(crate) fn impl_py_getter_def(
 
 /// Split an argument of pyo3::Python from the front of the arg list, if present
 fn split_off_python_arg<'a>(args: &'a [FnArg<'a>]) -> (Option<&FnArg>, &[FnArg]) {
- match args {
- [py, args @ ..] if utils::is_python(&py.ty) => (Some(py), args),
- args => (None, args),
+ if args
+ .get(0)
+ .map(|py| utils::is_python(&py.ty))
+ .unwrap_or(false)
+ {
+ (Some(&args[0]), &args[1..])
+ } else {
+ (None, args)
  }
 }

pyo3-macros/src/lib.rs

@@ -2,6 +2,8 @@
 //! This crate declares only the proc macro attributes, as a crate defining proc macro attributes
 //! must not contain any other public items.
 
+extern crate proc_macro;
+
 use proc_macro::TokenStream;
 use pyo3_macros_backend::{
  build_derive_from_pyobject, build_py_class, build_py_function, build_py_methods,

src/buffer.rs

@@ -48,7 +48,7 @@ impl ElementType {
  pub fn from_format(format: &CStr) -> ElementType {
  match format.to_bytes() {
  [char] | [b'@', char] => native_element_type_from_type_char(*char),
- [modifier, char] if matches!(modifier, b'=' | b'<' | b'>' | b'!') => {
+ [modifier, char] if (*modifier == b'=' || *modifier == b'<' || *modifier == b'>' || *modifier == b'!') => {
  standard_element_type_from_type_char(*char)
  }
  _ => ElementType::Unknown,

src/err/mod.rs

@@ -594,11 +594,8 @@ mod tests {
  assert!(debug_str.starts_with("PyErr { "));
  assert!(debug_str.ends_with(" }"));
 
- let mut fields = debug_str
- .strip_prefix("PyErr { ")
- .unwrap()
- .strip_suffix(" }")
- .unwrap()
+ // strip "PyErr { " and " }"
+ let mut fields = debug_str["PyErr { ".len()..debug_str.len()-2]
  .split(", ");
 
  assert_eq!(fields.next().unwrap(), "type: <class 'Exception'>");

src/freelist.rs

@@ -93,9 +93,10 @@ where
  let free = get_type_free(ty).unwrap_or_else(|| tp_free_fallback(ty));
  free(obj as *mut c_void);
 
- #[cfg(Py_3_8)]
- if ffi::PyType_HasFeature(ty, ffi::Py_TPFLAGS_HEAPTYPE) != 0 {
- ffi::Py_DECREF(ty as *mut ffi::PyObject);
+ if cfg!(Py_3_8) {
+ if ffi::PyType_HasFeature(ty, ffi::Py_TPFLAGS_HEAPTYPE) != 0 {
+ ffi::Py_DECREF(ty as *mut ffi::PyObject);
+ }
  }
  }
  }

src/gil.rs

@@ -86,9 +86,10 @@ pub fn prepare_freethreaded_python() {
 
  // Changed in version 3.7: This function is now called by Py_Initialize(), so you don’t
  // have to call it yourself anymore.
- #[cfg(not(Py_3_7))]
- if ffi::PyEval_ThreadsInitialized() == 0 {
- ffi::PyEval_InitThreads();
+ if cfg!(not(Py_3_7)) {
+ if ffi::PyEval_ThreadsInitialized() == 0 {
+ ffi::PyEval_InitThreads();
+ }
  }
 
  // Release the GIL.
@@ -150,9 +151,10 @@ where
 
  // Changed in version 3.7: This function is now called by Py_Initialize(), so you don’t have to
  // call it yourself anymore.
- #[cfg(not(Py_3_7))]
- if ffi::PyEval_ThreadsInitialized() == 0 {
- ffi::PyEval_InitThreads();
+ if cfg!(not(Py_3_7)) {
+ if ffi::PyEval_ThreadsInitialized() == 0 {
+ ffi::PyEval_InitThreads();
+ }
  }
 
  // Safe: the GIL is already held because of the Py_IntializeEx call.

src/lib.rs

@@ -224,7 +224,7 @@ pub mod proc_macro {
 #[macro_export]
 macro_rules! wrap_pyfunction {
  ($function_name: ident) => {{
- &pyo3::paste::paste! { [<__pyo3_get_function_ $function_name>] }
+ &pyo3::paste::expr! { [<__pyo3_get_function_ $function_name>] }
  }};
 
  ($function_name: ident, $arg: expr) => {
@@ -257,7 +257,7 @@ macro_rules! wrap_pyfunction {
 #[macro_export]
 macro_rules! raw_pycfunction {
  ($function_name: ident) => {{
- pyo3::paste::paste! { [<__pyo3_raw_ $function_name>] }
+ pyo3::paste::expr! { [<__pyo3_raw_ $function_name>] }
  }};
 }
 
@@ -267,7 +267,7 @@ macro_rules! raw_pycfunction {
 #[macro_export]
 macro_rules! wrap_pymodule {
  ($module_name:ident) => {{
- pyo3::paste::paste! {
+ pyo3::paste::expr! {
  &|py| unsafe { pyo3::PyObject::from_owned_ptr(py, [<PyInit_ $module_name>]()) }
  }
  }};

src/pyclass.rs

@@ -93,9 +93,10 @@ pub trait PyClassAlloc: PyTypeInfo + Sized {
  let free = get_type_free(ty).unwrap_or_else(|| tp_free_fallback(ty));
  free(obj as *mut c_void);
 
- #[cfg(Py_3_8)]
- if ffi::PyType_HasFeature(ty, ffi::Py_TPFLAGS_HEAPTYPE) != 0 {
- ffi::Py_DECREF(ty as *mut ffi::PyObject);
+ if cfg!(Py_3_8) {
+ if ffi::PyType_HasFeature(ty, ffi::Py_TPFLAGS_HEAPTYPE) != 0 {
+ ffi::Py_DECREF(ty as *mut ffi::PyObject);
+ }
  }
  }
 }
@@ -194,8 +195,7 @@ where
  slots.maybe_push(ffi::Py_tp_new, new.map(|v| v as _));
  slots.maybe_push(ffi::Py_tp_call, call.map(|v| v as _));
 
- #[cfg(Py_3_9)]
- {
+ if cfg!(Py_3_9) {
  let members = py_class_members::<T>();
  if !members.is_empty() {
  slots.push(ffi::Py_tp_members, into_raw(members))
@@ -265,18 +265,18 @@ fn tp_init_additional<T: PyClass>(type_object: *mut ffi::PyTypeObject) {
 
  // Setting buffer protocols via slots doesn't work until Python 3.9, so on older versions we
  // must manually fixup the type object.
- #[cfg(not(Py_3_9))]
- if let Some(buffer) = T::get_buffer() {
- unsafe {
- (*(*type_object).tp_as_buffer).bf_getbuffer = buffer.bf_getbuffer;
- (*(*type_object).tp_as_buffer).bf_releasebuffer = buffer.bf_releasebuffer;
+ if cfg!(not(Py_3_9)) {
+ if let Some(buffer) = T::get_buffer() {
+ unsafe {
+ (*(*type_object).tp_as_buffer).bf_getbuffer = buffer.bf_getbuffer;
+ (*(*type_object).tp_as_buffer).bf_releasebuffer = buffer.bf_releasebuffer;
+ }
  }
  }
 
  // Setting tp_dictoffset and tp_weaklistoffset via slots doesn't work until Python 3.9, so on
  // older versions again we must fixup the type object.
- #[cfg(not(Py_3_9))]
- {
+ if cfg!(not(Py_3_9)) {
  // __dict__ support
  if let Some(dict_offset) = PyCell::<T>::dict_offset() {
  unsafe {
@@ -368,7 +368,7 @@ fn py_class_method_defs<T: PyMethods>() -> (
 /// tp_weaklistoffset.
 ///
 /// Only works on Python 3.9 and up.
-#[cfg(Py_3_9)]
+// #[cfg(Py_3_9)] -- we need it for code currently using if cfg!(Py_3_9)
 fn py_class_members<T: PyClass>() -> Vec<ffi::structmember::PyMemberDef> {
  #[inline(always)]
  fn offset_def(name: &'static str, offset: usize) -> ffi::structmember::PyMemberDef {
@@ -429,15 +429,16 @@ fn py_class_properties<T: PyClass>() -> Vec<ffi::PyGetSetDef> {
 
  // PyPy doesn't automatically adds __dict__ getter / setter.
  // PyObject_GenericGetDict not in the limited API until Python 3.10.
- #[cfg(not(any(PyPy, all(Py_LIMITED_API, not(Py_3_10)))))]
- if !T::Dict::IS_DUMMY {
- props.push(ffi::PyGetSetDef {
- name: "__dict__\0".as_ptr() as *mut c_char,
- get: Some(ffi::PyObject_GenericGetDict),
- set: Some(ffi::PyObject_GenericSetDict),
- doc: ptr::null_mut(),
- closure: ptr::null_mut(),
- });
+ if cfg!(not(any(PyPy, all(Py_LIMITED_API, not(Py_3_10))))) {
+ if !T::Dict::IS_DUMMY {
+ props.push(ffi::PyGetSetDef {
+ name: "__dict__\0".as_ptr() as *mut c_char,
+ get: Some(ffi::PyObject_GenericGetDict),
+ set: Some(ffi::PyObject_GenericSetDict),
+ doc: ptr::null_mut(),
+ closure: ptr::null_mut(),
+ });
+ }
  }
  if !props.is_empty() {
  props.push(unsafe { std::mem::zeroed() });

tests/test_datetime.rs

@@ -38,7 +38,7 @@ macro_rules! assert_check_exact {
  unsafe {
  use pyo3::{AsPyPointer, ffi::*};
  assert!($check_func(($obj).as_ptr()) != 0);
- assert!(pyo3::paste::paste!([<$check_func Exact>])(($obj).as_ptr()) != 0);
+ assert!(pyo3::paste::expr!([<$check_func Exact>])(($obj).as_ptr()) != 0);
  }
  };
 }
@@ -48,7 +48,7 @@ macro_rules! assert_check_only {
  unsafe {
  use pyo3::{AsPyPointer, ffi::*};
  assert!($check_func(($obj).as_ptr()) != 0);
- assert!(pyo3::paste::paste!([<$check_func Exact>])(($obj).as_ptr()) == 0);
+ assert!(pyo3::paste::expr!([<$check_func Exact>])(($obj).as_ptr()) == 0);
  }
  };
 }

tests/ui/static_ref.stderr

@@ -8,4 +8,4 @@ error[E0597]: `pool` does not live long enough
  | `pool` dropped here while still borrowed
  | cast requires that `pool` is borrowed for `'static`
  |
- = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
+ = note: this error originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)