PyO3 · davidhewitt · Jun 20, 2025 · May 30, 2025 · May 30, 2025 · May 30, 2025
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
@@ -45,7 +45,7 @@ jobs:
           python-version: "3.13"
       - name: resolve MSRV
         id: resolve-msrv
-        run: echo MSRV=`python -c 'import tomllib; print(tomllib.load(open("Cargo.toml", "rb"))["package"]["rust-version"])'` >> $GITHUB_OUTPUT
+        run: echo MSRV=`python -c 'import tomllib; print(tomllib.load(open("Cargo.toml", "rb"))["workspace"]["package"]["rust-version"])'` >> $GITHUB_OUTPUT
 
   semver-checks:
     if: github.ref != 'refs/heads/main'

diff --git a/Cargo.toml b/Cargo.toml
@@ -10,14 +10,23 @@ repository = "https://github.com/pyo3/pyo3"
 documentation = "https://docs.rs/crate/pyo3/"
 categories = ["api-bindings", "development-tools::ffi"]
 license = "MIT OR Apache-2.0"
-exclude = ["/.gitignore", ".cargo/config", "/codecov.yml", "/Makefile", "/pyproject.toml", "/noxfile.py", "/.github", "/tests/test_compile_error.rs", "/tests/ui"]
+exclude = [
+    "/.gitignore",
+    ".cargo/config",
+    "/codecov.yml",
+    "/Makefile",
+    "/pyproject.toml",
+    "/noxfile.py",
+    "/.github",
+    "/tests/test_compile_error.rs",
+    "/tests/ui",
+]
 edition = "2021"
-rust-version = "1.63"
+rust-version.workspace = true
 
 [dependencies]
 libc = "0.2.62"
 memoffset = "0.9"
-once_cell = "1.13"
 
 # ffi bindings to the python interpreter, split into a separate crate so they can be used independently
 pyo3-ffi = { path = "pyo3-ffi", version = "=0.25.0" }
@@ -140,6 +149,7 @@ full = [
     "eyre",
     "hashbrown",
     "indexmap",
+    "jiff-02",
     "lock_api",
     "num-bigint",
     "num-complex",
@@ -150,6 +160,7 @@ full = [
     "rust_decimal",
     "serde",
     "smallvec",
+    "time",
     "uuid",
 ]
 
@@ -163,6 +174,7 @@ members = [
     "pytests",
     "examples",
 ]
+package.rust-version = "1.74"
 
 [package.metadata.docs.rs]
 no-default-features = true

diff --git a/build.rs b/build.rs
@@ -41,7 +41,6 @@ fn configure_pyo3() -> Result<()> {
         println!("{cfg}")
     }
 
-    // Emit cfgs like `invalid_from_utf8_lint`
     print_feature_cfgs();
 
     // Make `cargo test` etc work on macOS with Xcode bundled Python

diff --git a/examples/Cargo.toml b/examples/Cargo.toml
@@ -3,7 +3,7 @@ name = "pyo3-examples"
 version = "0.0.0"
 publish = false
 edition = "2021"
-rust-version = "1.63"
+rust-version = "1.74"
 
 [dev-dependencies]
 pyo3 = { path = "..", features = ["auto-initialize", "extension-module"] }

diff --git a/examples/decorator/Cargo.toml b/examples/decorator/Cargo.toml
@@ -2,7 +2,7 @@
 name = "decorator"
 version = "0.1.0"
 edition = "2021"
-rust-version = "1.63"
+rust-version = "1.74"
 
 [lib]
 name = "decorator"

diff --git a/examples/getitem/Cargo.toml b/examples/getitem/Cargo.toml
@@ -2,7 +2,7 @@
 name = "getitem"
 version = "0.1.0"
 edition = "2021"
-rust-version = "1.63"
+rust-version = "1.74"
 
 [lib]
 name = "getitem"

diff --git a/examples/maturin-starter/Cargo.toml b/examples/maturin-starter/Cargo.toml
@@ -2,7 +2,7 @@
 name = "maturin-starter"
 version = "0.1.0"
 edition = "2021"
-rust-version = "1.63"
+rust-version = "1.74"
 
 [lib]
 name = "maturin_starter"

diff --git a/examples/plugin/Cargo.toml b/examples/plugin/Cargo.toml
@@ -2,11 +2,11 @@
 name = "plugin_example"
 version = "0.1.0"
 edition = "2021"
-rust-version = "1.63"
+rust-version = "1.74"
 
 [dependencies]
-pyo3={path="../../", features=["macros"]}
-plugin_api={path="plugin_api"}
+pyo3 = { path = "../../", features = ["macros"] }
+plugin_api = { path = "plugin_api" }
 
 
 [workspace]
diff --git a/examples/setuptools-rust-starter/Cargo.toml b/examples/setuptools-rust-starter/Cargo.toml
@@ -2,7 +2,7 @@
 name = "setuptools-rust-starter"
 version = "0.1.0"
 edition = "2021"
-rust-version = "1.63"
+rust-version = "1.74"
 
 [lib]
 name = "setuptools_rust_starter"

diff --git a/examples/word-count/Cargo.toml b/examples/word-count/Cargo.toml
@@ -2,7 +2,7 @@
 name = "word-count"
 version = "0.1.0"
 edition = "2021"
-rust-version = "1.63"
+rust-version = "1.74"
 
 [lib]
 name = "word_count"

diff --git a/newsfragments/5171.packaging.md b/newsfragments/5171.packaging.md
@@ -0,0 +1,2 @@
+Update MSRV to 1.74.
+Drop `once_cell` dependency.
diff --git a/noxfile.py b/noxfile.py
@@ -1,4 +1,3 @@
-from contextlib import contextmanager
 import json
 import os
 import re
@@ -7,6 +6,7 @@
 import sys
 import sysconfig
 import tempfile
+from contextlib import contextmanager
 from functools import lru_cache
 from glob import glob
 from pathlib import Path
@@ -21,7 +21,6 @@
     Tuple,
 )
 
-import nox
 import nox.command
 
 try:
@@ -460,14 +459,6 @@ def docs(session: nox.Session) -> None:
 
     features = "full"
 
-    if get_rust_version()[:2] >= (1, 67):
-        # time needs MSRC 1.67+
-        features += ",time"
-
-    if get_rust_version()[:2] >= (1, 70):
-        # jiff needs MSRC 1.70+
-        features += ",jiff-02"
-
     shutil.rmtree(PYO3_DOCS_TARGET, ignore_errors=True)
     _run_cargo(
         session,
@@ -670,10 +661,7 @@ def set_msrv_package_versions(session: nox.Session):
         *(Path(p).parent for p in glob("examples/*/Cargo.toml")),
         *(Path(p).parent for p in glob("pyo3-ffi/examples/*/Cargo.toml")),
     )
-    min_pkg_versions = {
-        "trybuild": "1.0.89",
-        "allocator-api2": "0.2.10",
-    }
+    min_pkg_versions = {}
 
     # run cargo update first to ensure that everything is at highest
     # possible version, so that this matches what CI will resolve to.
@@ -854,8 +842,8 @@ def update_ui_tests(session: nox.Session):
     env["TRYBUILD"] = "overwrite"
     command = ["test", "--test", "test_compile_error"]
     _run_cargo(session, *command, env=env)
-    _run_cargo(session, *command, "--features=full,jiff-02,time", env=env)
-    _run_cargo(session, *command, "--features=abi3,full,jiff-02,time", env=env)
+    _run_cargo(session, *command, "--features=full", env=env)
+    _run_cargo(session, *command, "--features=abi3,full", env=env)
 
 
 @nox.session(name="test-introspection")
@@ -925,14 +913,6 @@ def _get_feature_sets() -> Tuple[Optional[str], ...]:
         # multiple-pymethods not supported on wasm
         features += ",multiple-pymethods"
 
-    if get_rust_version()[:2] >= (1, 67):
-        # time needs MSRC 1.67+
-        features += ",time"
-
-    if get_rust_version()[:2] >= (1, 70):
-        # jiff needs MSRC 1.70+
-        features += ",jiff-02"
-
     if is_rust_nightly():
         features += ",nightly"
 

diff --git a/pyo3-build-config/Cargo.toml b/pyo3-build-config/Cargo.toml
@@ -9,10 +9,9 @@ repository = "https://github.com/pyo3/pyo3"
 categories = ["api-bindings", "development-tools::ffi"]
 license = "MIT OR Apache-2.0"
 edition = "2021"
-rust-version = "1.63"
+rust-version.workspace = true
 
 [dependencies]
-once_cell = "1"
 python3-dll-a = { version = "0.2.12", optional = true }
 target-lexicon = "0.13"
 

diff --git a/pyo3-build-config/src/impl_.rs b/pyo3-build-config/src/impl_.rs
@@ -845,7 +845,7 @@ fn have_python_interpreter() -> bool {
 /// Must be called from a PyO3 crate build script.
 fn is_abi3() -> bool {
     cargo_env_var("CARGO_FEATURE_ABI3").is_some()
-        || env_var("PYO3_USE_ABI3_FORWARD_COMPATIBILITY").map_or(false, |os_str| os_str == "1")
+        || env_var("PYO3_USE_ABI3_FORWARD_COMPATIBILITY").is_some_and(|os_str| os_str == "1")
 }
 
 /// Gets the minimum supported Python version from PyO3 `abi3-py*` features.
@@ -1464,7 +1464,7 @@ fn search_lib_dir(path: impl AsRef<Path>, cross: &CrossCompileConfig) -> Result<
         sysconfig_paths.extend(match &f {
             // Python 3.7+ sysconfigdata with platform specifics
             Ok(f) if starts_with(f, "_sysconfigdata_") && ends_with(f, "py") => vec![f.path()],
-            Ok(f) if f.metadata().map_or(false, |metadata| metadata.is_dir()) => {
+            Ok(f) if f.metadata().is_ok_and(|metadata| metadata.is_dir()) => {
                 let file_name = f.file_name();
                 let file_name = file_name.to_string_lossy();
                 if file_name == "build" || file_name == "lib" {

diff --git a/pyo3-build-config/src/lib.rs b/pyo3-build-config/src/lib.rs
@@ -16,9 +16,7 @@ use std::{
     path::{Path, PathBuf},
 };
 
-use std::{env, process::Command, str::FromStr};
-
-use once_cell::sync::OnceCell;
+use std::{env, process::Command, str::FromStr, sync::OnceLock};
 
 pub use impl_::{
     cross_compiling_from_to, find_all_sysconfigdata, parse_sysconfigdata, BuildFlag, BuildFlags,
@@ -109,10 +107,10 @@ fn _add_python_framework_link_args(
 
 /// Loads the configuration determined from the build environment.
 ///
-/// Because this will never change in a given compilation run, this is cached in a `once_cell`.
+/// Because this will never change in a given compilation run, this is cached in a `OnceLock`.
 #[cfg(feature = "resolve-config")]
 pub fn get() -> &'static InterpreterConfig {
-    static CONFIG: OnceCell<InterpreterConfig> = OnceCell::new();
+    static CONFIG: OnceLock<InterpreterConfig> = OnceLock::new();
     CONFIG.get_or_init(|| {
         // Check if we are in a build script and cross compiling to a different target.
         let cross_compile_config_path = resolve_cross_compile_config_path();
@@ -183,10 +181,6 @@ fn print_feature_cfg(minor_version_required: u32, cfg: &str) {
 /// so this function is unstable.
 #[doc(hidden)]
 pub fn print_feature_cfgs() {
-    print_feature_cfg(70, "rustc_has_once_lock");
-    print_feature_cfg(70, "cargo_toml_lints");
-    print_feature_cfg(71, "rustc_has_extern_c_unwind");
-    print_feature_cfg(74, "invalid_from_utf8_lint");
     print_feature_cfg(79, "c_str_lit");
     // Actually this is available on 1.78, but we should avoid
     // https://github.com/rust-lang/rust/issues/124651 just in case
@@ -201,7 +195,7 @@ pub fn print_feature_cfgs() {
 /// - <https://doc.rust-lang.org/nightly/cargo/reference/build-scripts.html#rustc-check-cfg>
 #[doc(hidden)]
 pub fn print_expected_cfgs() {
-    if rustc_minor_version().map_or(false, |version| version < 80) {
+    if rustc_minor_version().is_some_and(|version| version < 80) {
         // rustc 1.80.0 stabilized `rustc-check-cfg` feature, don't emit before
         return;
     }
@@ -280,7 +274,7 @@ pub mod pyo3_build_script_impl {
 }
 
 fn rustc_minor_version() -> Option<u32> {
-    static RUSTC_MINOR_VERSION: OnceCell<Option<u32>> = OnceCell::new();
+    static RUSTC_MINOR_VERSION: OnceLock<Option<u32>> = OnceLock::new();
     *RUSTC_MINOR_VERSION.get_or_init(|| {
         let rustc = env::var_os("RUSTC")?;
         let output = Command::new(rustc).arg("--version").output().ok()?;

diff --git a/pyo3-ffi/Cargo.toml b/pyo3-ffi/Cargo.toml
@@ -10,7 +10,7 @@ categories = ["api-bindings", "development-tools::ffi"]
 license = "MIT OR Apache-2.0"
 edition = "2021"
 links = "python"
-rust-version = "1.63"
+rust-version.workspace = true
 
 [dependencies]
 libc = "0.2.62"
@@ -51,8 +51,8 @@ workspace = true
 
 [package.metadata.cpython]
 min-version = "3.7"
-max-version = "3.14"  # inclusive
+max-version = "3.14" # inclusive
 
 [package.metadata.pypy]
 min-version = "3.9"
-max-version = "3.11"  # inclusive
+max-version = "3.11" # inclusive
diff --git a/pyo3-ffi/build.rs b/pyo3-ffi/build.rs
@@ -63,7 +63,7 @@ fn ensure_python_version(interpreter_config: &InterpreterConfig) -> Result<()> {
                          = help: The free-threaded build of CPython does not support the limited API so this check cannot be suppressed.",
                         interpreter_config.version, versions.max, std::env::var("CARGO_PKG_VERSION").unwrap()
                 );
-                ensure!(env_var("PYO3_USE_ABI3_FORWARD_COMPATIBILITY").map_or(false, |os_str| os_str == "1"),
+                ensure!(env_var("PYO3_USE_ABI3_FORWARD_COMPATIBILITY").is_some_and(|os_str| os_str == "1"),
                         "the configured Python interpreter version ({}) is newer than PyO3's maximum supported version ({})\n\
                          = help: please check if an updated version of PyO3 is available. Current version: {}\n\
                          = help: set PYO3_USE_ABI3_FORWARD_COMPATIBILITY=1 to suppress this check and build anyway using the stable ABI",
@@ -192,7 +192,7 @@ fn emit_link_config(interpreter_config: &InterpreterConfig) -> Result<()> {
 fn configure_pyo3() -> Result<()> {
     let interpreter_config = resolve_interpreter_config()?;
 
-    if env_var("PYO3_PRINT_CONFIG").map_or(false, |os_str| os_str == "1") {
+    if env_var("PYO3_PRINT_CONFIG").is_some_and(|os_str| os_str == "1") {
         print_config_and_exit(&interpreter_config);
     }
 
@@ -215,7 +215,6 @@ fn configure_pyo3() -> Result<()> {
         println!("{line}");
     }
 
-    // Emit cfgs like `invalid_from_utf8_lint`
     print_feature_cfgs();
 
     Ok(())

diff --git a/pyo3-ffi/examples/sequential/Cargo.toml b/pyo3-ffi/examples/sequential/Cargo.toml
@@ -2,7 +2,7 @@
 name = "sequential"
 version = "0.1.0"
 edition = "2021"
-rust-version = "1.63"
+rust-version = "1.74"
 
 [lib]
 name = "sequential"

diff --git a/pyo3-ffi/examples/string-sum/Cargo.toml b/pyo3-ffi/examples/string-sum/Cargo.toml
@@ -2,7 +2,7 @@
 name = "string_sum"
 version = "0.1.0"
 edition = "2021"
-rust-version = "1.63"
+rust-version = "1.74"
 
 [lib]
 name = "string_sum"

diff --git a/pyo3-ffi/src/cpython/genobject.rs b/pyo3-ffi/src/cpython/genobject.rs
@@ -18,6 +18,7 @@ pub struct PyGenObject {
     pub gi_weakreflist: *mut PyObject,
     pub gi_name: *mut PyObject,
     pub gi_qualname: *mut PyObject,
+    #[allow(private_interfaces)]
     pub gi_exc_state: crate::cpython::pystate::_PyErr_StackItem,
     #[cfg(Py_3_11)]
     pub gi_origin_or_finalizer: *mut PyObject,

diff --git a/pyo3-ffi/src/cpython/pystate.rs b/pyo3-ffi/src/cpython/pystate.rs
@@ -31,8 +31,7 @@ pub const PyTrace_OPCODE: c_int = 7;
 #[cfg(not(PyPy))]
 #[repr(C)]
 #[derive(Clone, Copy)]
-#[doc(hidden)] // TODO should be able to make pub(crate) after MSRV 1.74
-pub struct _PyErr_StackItem {
+pub(crate) struct _PyErr_StackItem {
     #[cfg(not(Py_3_11))]
     exc_type: *mut PyObject,
     exc_value: *mut PyObject,
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1,2 @@
		Update MSRV to 1.74.
		Drop `once_cell` dependency.