RustPython · youknowone · Feb 11, 2026 · Feb 11, 2026 · Feb 11, 2026
diff --git a/Cargo.lock b/Cargo.lock
diff --git a/Cargo.toml b/Cargo.toml
@@ -184,7 +184,6 @@ num-integer = "0.1.46"
 num-traits = "0.2"
 num_enum = { version = "0.7", default-features = false }
 optional = "0.5"
-once_cell = "1.20.3"
 parking_lot = "0.12.3"
 paste = "1.0.15"
 proc-macro2 = "1.0.105"

diff --git a/crates/common/Cargo.toml b/crates/common/Cargo.toml
@@ -28,7 +28,6 @@ malachite-bigint = { workspace = true }
 malachite-q = { workspace = true }
 malachite-base = { workspace = true }
 num-traits = { workspace = true }
-once_cell = { workspace = true }
 parking_lot = { workspace = true, optional = true }
 unicode_names2 = { workspace = true }
 radium = { workspace = true }

diff --git a/crates/common/src/lock.rs b/crates/common/src/lock.rs
@@ -10,12 +10,12 @@ cfg_if::cfg_if! {
     if #[cfg(feature = "threading")] {
         pub use parking_lot::{RawMutex, RawRwLock, RawThreadId};
 
-        pub use once_cell::sync::{Lazy, OnceCell};
+        pub use std::sync::{LazyLock as Lazy, OnceLock as OnceCell};
     } else {
         mod cell_lock;
         pub use cell_lock::{RawCellMutex as RawMutex, RawCellRwLock as RawRwLock, SingleThreadId as RawThreadId};
 
-        pub use once_cell::unsync::{Lazy, OnceCell};
+        pub use core::cell::{LazyCell as Lazy, OnceCell};
     }
 }
 

diff --git a/crates/common/src/static_cell.rs b/crates/common/src/static_cell.rs
@@ -31,7 +31,12 @@ mod threading {
         where
             F: FnOnce() -> Result<T, E>,
         {
-            self.inner.get_or_try_init(f)
+            if let Some(val) = self.inner.get() {
+                return Ok(val);
+            }
+            let val = f()?;
+            let _ = self.inner.set(val);
+            Ok(self.inner.get().unwrap())
         }
     }
 
@@ -92,8 +97,15 @@ mod non_threading {
         where
             F: FnOnce() -> Result<T, E>,
         {
-            self.inner
-                .with(|x| x.get_or_try_init(|| f().map(leak)).copied())
+            self.inner.with(|x| {
+                if let Some(val) = x.get() {
+                    Ok(*val)
+                } else {
+                    let val = leak(f()?);
+                    let _ = x.set(val);
+                    Ok(val)
+                }
+            })
         }
     }
 
@@ -156,7 +168,12 @@ mod no_std {
         where
             F: FnOnce() -> Result<T, E>,
         {
-            self.inner.0.get_or_try_init(f)
+            if let Some(val) = self.inner.0.get() {
+                return Ok(val);
+            }
+            let val = f()?;
+            let _ = self.inner.0.set(val);
+            Ok(self.inner.0.get().unwrap())
         }
     }
 

diff --git a/crates/vm/Cargo.toml b/crates/vm/Cargo.toml
@@ -63,7 +63,6 @@ num-complex = { workspace = true }
 num-integer = { workspace = true }
 num-traits = { workspace = true }
 num_enum = { workspace = true }
-once_cell = { workspace = true }
 parking_lot = { workspace = true }
 paste = { workspace = true }
 scoped-tls = { workspace = true }

diff --git a/crates/vm/src/builtins/function.rs b/crates/vm/src/builtins/function.rs
@@ -816,15 +816,16 @@ impl PyFunction {
     #[cfg(feature = "jit")]
     #[pymethod]
     fn __jit__(zelf: PyRef<Self>, vm: &VirtualMachine) -> PyResult<()> {
-        zelf.jitted_code
-            .get_or_try_init(|| {
-                let arg_types = jit::get_jit_arg_types(&zelf, vm)?;
-                let ret_type = jit::jit_ret_type(&zelf, vm)?;
-                let code = zelf.code.lock();
-                rustpython_jit::compile(&code.code, &arg_types, ret_type)
-                    .map_err(|err| jit::new_jit_error(err.to_string(), vm))
-            })
-            .map(drop)
+        if zelf.jitted_code.get().is_some() {
+            return Ok(());
+        }
+        let arg_types = jit::get_jit_arg_types(&zelf, vm)?;
+        let ret_type = jit::jit_ret_type(&zelf, vm)?;
+        let code = zelf.code.lock();
+        let compiled = rustpython_jit::compile(&code.code, &arg_types, ret_type)
+            .map_err(|err| jit::new_jit_error(err.to_string(), vm))?;
+        let _ = zelf.jitted_code.set(compiled);
+        Ok(())
     }
 }
 

diff --git a/crates/vm/src/builtins/memory.rs b/crates/vm/src/builtins/memory.rs
@@ -1095,15 +1095,16 @@ impl Comparable for PyMemoryView {
 
 impl Hashable for PyMemoryView {
     fn hash(zelf: &Py<Self>, vm: &VirtualMachine) -> PyResult<PyHash> {
-        zelf.hash
-            .get_or_try_init(|| {
-                zelf.try_not_released(vm)?;
-                if !zelf.desc.readonly {
-                    return Err(vm.new_value_error("cannot hash writable memoryview object"));
-                }
-                Ok(zelf.contiguous_or_collect(|bytes| vm.state.hash_secret.hash_bytes(bytes)))
-            })
-            .copied()
+        if let Some(val) = zelf.hash.get() {
+            return Ok(*val);
+        }
+        zelf.try_not_released(vm)?;
+        if !zelf.desc.readonly {
+            return Err(vm.new_value_error("cannot hash writable memoryview object"));
+        }
+        let val = zelf.contiguous_or_collect(|bytes| vm.state.hash_secret.hash_bytes(bytes));
+        let _ = zelf.hash.set(val);
+        Ok(*zelf.hash.get().unwrap())
     }
 }
 

diff --git a/crates/vm/src/codecs.rs b/crates/vm/src/codecs.rs
@@ -8,6 +8,7 @@ use rustpython_common::{
     wtf8::{CodePoint, Wtf8, Wtf8Buf},
 };
 
+use crate::common::lock::OnceCell;
 use crate::{
     AsObject, Context, Py, PyObject, PyObjectRef, PyPayload, PyResult, TryFromBorrowedObject,
     TryFromObject, VirtualMachine,
@@ -18,7 +19,6 @@ use crate::{
 };
 use alloc::borrow::Cow;
 use core::ops::{self, Range};
-use once_cell::unsync::OnceCell;
 use std::collections::HashMap;
 
 pub struct CodecsRegistry {
@@ -861,22 +861,25 @@ impl<'a> ErrorsHandler<'a> {
             },
             None => Self {
                 errors: identifier!(vm, strict).as_ref(),
-                resolved: OnceCell::with_value(ResolvedError::Standard(StandardError::Strict)),
+                resolved: OnceCell::from(ResolvedError::Standard(StandardError::Strict)),
             },
         }
     }
     #[inline]
     fn resolve(&self, vm: &VirtualMachine) -> PyResult<&ResolvedError> {
-        self.resolved.get_or_try_init(|| {
-            if let Ok(standard) = self.errors.as_str().parse() {
-                Ok(ResolvedError::Standard(standard))
-            } else {
-                vm.state
-                    .codec_registry
-                    .lookup_error(self.errors.as_str(), vm)
-                    .map(ResolvedError::Handler)
-            }
-        })
+        if let Some(val) = self.resolved.get() {
+            return Ok(val);
+        }
+        let val = if let Ok(standard) = self.errors.as_str().parse() {
+            ResolvedError::Standard(standard)
+        } else {
+            vm.state
+                .codec_registry
+                .lookup_error(self.errors.as_str(), vm)
+                .map(ResolvedError::Handler)?
+        };
+        let _ = self.resolved.set(val);
+        Ok(self.resolved.get().unwrap())
     }
 }
 impl StrBuffer for PyStrRef {
@@ -998,7 +1001,7 @@ where
         encoding: s_encoding.as_str(),
         data: &s,
         pos: StrSize::default(),
-        exception: OnceCell::with_value(err.downcast().unwrap()),
+        exception: OnceCell::from(err.downcast().unwrap()),
     };
     let mut iter = s.as_wtf8().code_point_indices();
     let start = StrSize {
@@ -1038,7 +1041,7 @@ where
         data: PyDecodeData::Original(s.borrow_buf()),
         orig_bytes: s.as_object().downcast_ref(),
         pos: 0,
-        exception: OnceCell::with_value(err.downcast().unwrap()),
+        exception: OnceCell::from(err.downcast().unwrap()),
     };
     let (replace, restart) = handler.handle_decode_error(&mut ctx, range, None)?;
     Ok((replace.into(), restart))
@@ -1061,7 +1064,7 @@ where
         encoding: "",
         data: &s,
         pos: StrSize::default(),
-        exception: OnceCell::with_value(err.downcast().unwrap()),
+        exception: OnceCell::from(err.downcast().unwrap()),
     };
     let mut iter = s.as_wtf8().code_point_indices();
     let start = StrSize {

diff --git a/crates/vm/src/stdlib/os.rs b/crates/vm/src/stdlib/os.rs
@@ -657,16 +657,28 @@ pub(super) mod _os {
                     vm,
                 )
             };
-            let lstat = || self.lstat.get_or_try_init(|| do_stat(false));
+            let lstat = || match self.lstat.get() {
+                Some(val) => Ok(val),
+                None => {
+                    let val = do_stat(false)?;
+                    let _ = self.lstat.set(val);
+                    Ok(self.lstat.get().unwrap())
+                }
+            };
             let stat = if follow_symlinks.0 {
                 // if follow_symlinks == true and we aren't a symlink, cache both stat and lstat
-                self.stat.get_or_try_init(|| {
-                    if self.is_symlink(vm)? {
-                        do_stat(true)
-                    } else {
-                        lstat().cloned()
+                match self.stat.get() {
+                    Some(val) => val,
+                    None => {
+                        let val = if self.is_symlink(vm)? {
+                            do_stat(true)?
+                        } else {
+                            lstat()?.clone()
+                        };
+                        let _ = self.stat.set(val);
+                        self.stat.get().unwrap()
                     }
-                })?
+                }
             } else {
                 lstat()?
             };