RustPython · ShaharNaveh · Jun 5, 2026 · Jun 5, 2026 · Jun 5, 2026 · Jun 5, 2026
diff --git a/Cargo.toml b/Cargo.toml
@@ -49,7 +49,7 @@
 flamescope = { version = "0.1.2", optional = true }

 rustls = { workspace = true, optional = true }
 rustls-graviola = { workspace = true, optional = true }

 [target.'cfg(windows)'.dependencies]
 libc = { workspace = true }
@@ -368,6 +368,10 @@
 debug_assert_with_mut_call = "warn"
 derive_partial_eq_without_eq = "warn"
 imprecise_flops = "warn"
+iter_on_empty_collections = "warn"
+iter_on_single_items = "warn"
+literal_string_with_formatting_args = "warn"
+needless_collect = "warn"
 or_fun_call = "warn"
 redundant_clone = "warn"
 search_is_some = "warn"
@@ -379,21 +383,33 @@
 useless_let_if_seq = "warn"
 
 # pedantic lints to enforce gradually
+checked_conversions = "warn"
 cloned_instead_of_copied = "warn"
 collapsible_else_if = "warn"
 comparison_chain = "warn"
+duration_suboptimal_units = "warn"
 explicit_into_iter_loop = "warn"
 explicit_iter_loop = "warn"
 filter_map_next = "warn"
 flat_map_option = "warn"
 format_collect = "warn"
 from_iter_instead_of_collect = "warn"
 inconsistent_struct_constructor = "warn"
+index_refutable_slice = "warn"
 inefficient_to_string = "warn"
+iter_filter_is_ok = "warn"
+iter_filter_is_some = "warn"
 manual_is_variant_and = "warn"
 map_unwrap_or = "warn"
+match_bool = "warn"
 must_use_candidate = "warn"
+mut_mut = "warn"
+needless_bitwise_bool = "warn"
+needless_for_each = "warn"
+option_as_ref_cloned = "warn"
+ptr_offset_by_literal = "warn"
 redundant_else = "warn"
+return_self_not_must_use = "warn"
 uninlined_format_args = "warn"
 unnecessary_wraps = "warn"
 unnested_or_patterns = "warn"
diff --git a/crates/capi/src/traceback.rs b/crates/capi/src/traceback.rs
@@ -14,9 +14,7 @@ pub unsafe extern "C" fn PyTraceBack_Print(tb: *mut PyObject, file: *mut PyObjec
         let tb_module = vm.import("traceback", 0)?;
         let print_tb = tb_module.get_attr("print_tb", vm)?;
 
-        let kwargs: KwArgs = [("file".to_string(), file.to_owned())]
-            .into_iter()
-            .collect();
+        let kwargs: KwArgs = core::iter::once(("file".to_string(), file.to_owned())).collect();
         print_tb.call(FuncArgs::new(vec![tb.to_owned()], kwargs), vm)?;
 
         Ok(())

diff --git a/crates/common/src/boxvec.rs b/crates/common/src/boxvec.rs
@@ -127,7 +127,7 @@ impl<T> BoxVec<T> {
                 let p: *mut _ = self.get_unchecked_ptr(index);
                 // Shift everything over to make space. (Duplicating the
                 // `index`th element into two consecutive places.)
-                ptr::copy(p, p.offset(1), len - index);
+                ptr::copy(p, p.add(1), len - index);
                 // Write it in, overwriting the first copy of the `index`th
                 // element.
                 ptr::write(p, element);

diff --git a/crates/common/src/cformat.rs b/crates/common/src/cformat.rs
@@ -160,16 +160,22 @@ pub trait FormatBuf:
     Extend<Self::Char> + Default + FromIterator<Self::Char> + From<String>
 {
     type Char: FormatChar;
+
     fn chars(&self) -> impl Iterator<Item = Self::Char>;
+
     fn len(&self) -> usize;
+
     fn is_empty(&self) -> bool {
         self.len() == 0
     }
+
+    #[must_use]
     fn concat(self, other: Self) -> Self;
 }
 
 pub trait FormatChar: Copy + Into<CodePoint> + From<u8> {
     fn to_char_lossy(self) -> char;
+
     fn eq_char(self, c: char) -> bool;
 }
 

diff --git a/crates/derive-impl/src/pyclass.rs b/crates/derive-impl/src/pyclass.rs
@@ -1671,11 +1671,14 @@ impl ItemMeta for SlotItemMeta {
         I: core::iter::Iterator<Item = NestedMeta>,
     {
         let meta_map = if let Some(nested_meta) = nested.next() {
-            match nested_meta {
-                NestedMeta::Meta(meta) => {
-                    Some([("name".to_owned(), (0, meta))].iter().cloned().collect())
-                }
-                _ => None,
+            if let NestedMeta::Meta(meta) = nested_meta {
+                Some(
+                    core::iter::once(&("name".to_owned(), (0, meta)))
+                        .cloned()
+                        .collect(),
+                )
+            } else {
+                None
             }
         } else {
             Some(HashMap::default())

diff --git a/crates/sre_engine/src/string.rs b/crates/sre_engine/src/string.rs
@@ -75,7 +75,7 @@ impl StrDrive for &[u8] {
 
     #[inline]
     fn back_peek(cursor: &StringCursor) -> u32 {
-        unsafe { *cursor.ptr.offset(-1) as u32 }
+        unsafe { *cursor.ptr.sub(1) as u32 }
     }
 
     #[inline]
@@ -227,7 +227,7 @@ impl StrDrive for &Wtf8 {
 const unsafe fn next_code_point(ptr: &mut *const u8) -> u32 {
     // Decode UTF-8
     let x = unsafe { **ptr };
-    *ptr = unsafe { ptr.offset(1) };
+    *ptr = unsafe { ptr.add(1) };
 
     if x < 128 {
         return x as u32;
@@ -240,15 +240,15 @@ const unsafe fn next_code_point(ptr: &mut *const u8) -> u32 {
     // SAFETY: `bytes` produces an UTF-8-like string,
     // so the iterator must produce a value here.
     let y = unsafe { **ptr };
-    *ptr = unsafe { ptr.offset(1) };
+    *ptr = unsafe { ptr.add(1) };
     let mut ch = utf8_acc_cont_byte(init, y);
     if x >= 0xE0 {
         // [[x y z] w] case
         // 5th bit in 0xE0 .. 0xEF is always clear, so `init` is still valid
         // SAFETY: `bytes` produces an UTF-8-like string,
         // so the iterator must produce a value here.
         let z = unsafe { **ptr };
-        *ptr = unsafe { ptr.offset(1) };
+        *ptr = unsafe { ptr.add(1) };
         let y_z = utf8_acc_cont_byte((y & CONT_MASK) as u32, z);
         ch = (init << 12) | y_z;
         if x >= 0xF0 {
@@ -257,7 +257,7 @@ const unsafe fn next_code_point(ptr: &mut *const u8) -> u32 {
             // SAFETY: `bytes` produces an UTF-8-like string,
             // so the iterator must produce a value here.
             let w = unsafe { **ptr };
-            *ptr = unsafe { ptr.offset(1) };
+            *ptr = unsafe { ptr.add(1) };
             ch = ((init & 7) << 18) | utf8_acc_cont_byte(y_z, w);
         }
     }
@@ -274,7 +274,7 @@ const unsafe fn next_code_point(ptr: &mut *const u8) -> u32 {
 #[inline]
 const unsafe fn next_code_point_reverse(ptr: &mut *const u8) -> u32 {
     // Decode UTF-8
-    *ptr = unsafe { ptr.offset(-1) };
+    *ptr = unsafe { ptr.sub(1) };
     let w = match unsafe { **ptr } {
         next_byte if next_byte < 128 => return next_byte as u32,
         back_byte => back_byte,
@@ -285,19 +285,19 @@ const unsafe fn next_code_point_reverse(ptr: &mut *const u8) -> u32 {
     let mut ch;
     // SAFETY: `bytes` produces an UTF-8-like string,
     // so the iterator must produce a value here.
-    *ptr = unsafe { ptr.offset(-1) };
+    *ptr = unsafe { ptr.sub(1) };
     let z = unsafe { **ptr };
     ch = utf8_first_byte(z, 2);
     if utf8_is_cont_byte(z) {
         // SAFETY: `bytes` produces an UTF-8-like string,
         // so the iterator must produce a value here.
-        *ptr = unsafe { ptr.offset(-1) };
+        *ptr = unsafe { ptr.sub(1) };
         let y = unsafe { **ptr };
         ch = utf8_first_byte(y, 3);
         if utf8_is_cont_byte(y) {
             // SAFETY: `bytes` produces an UTF-8-like string,
             // so the iterator must produce a value here.
-            *ptr = unsafe { ptr.offset(-1) };
+            *ptr = unsafe { ptr.sub(1) };
             let x = unsafe { **ptr };
             ch = utf8_first_byte(x, 4);
             ch = utf8_acc_cont_byte(ch, y);

diff --git a/crates/stdlib/src/_asyncio.rs b/crates/stdlib/src/_asyncio.rs
@@ -564,7 +564,7 @@ pub(crate) mod _asyncio {
                 let args = if let Some(ctx) = context {
                     FuncArgs::new(
                         vec![callback, future_arg],
-                        KwArgs::new([("context".to_owned(), ctx)].into_iter().collect()),
+                        KwArgs::new(core::iter::once(("context".to_owned(), ctx)).collect()),
                     )
                 } else {
                     FuncArgs::new(vec![callback, future_arg], KwArgs::default())
@@ -1494,7 +1494,7 @@ pub(crate) mod _asyncio {
                 let args = if let Some(ctx) = context {
                     FuncArgs::new(
                         vec![callback, task_arg],
-                        KwArgs::new([("context".to_owned(), ctx)].into_iter().collect()),
+                        KwArgs::new(core::iter::once(("context".to_owned(), ctx)).collect()),
                     )
                 } else {
                     FuncArgs::new(vec![callback, task_arg], KwArgs::default())
@@ -1522,7 +1522,7 @@ pub(crate) mod _asyncio {
                 let cancel_args = if let Some(ref m) = msg_value {
                     FuncArgs::new(
                         vec![],
-                        KwArgs::new([("msg".to_owned(), m.clone())].into_iter().collect()),
+                        KwArgs::new(core::iter::once(("msg".to_owned(), m.clone())).collect()),
                     )
                 } else {
                     FuncArgs::new(vec![], KwArgs::default())
@@ -2202,7 +2202,7 @@ pub(crate) mod _asyncio {
                 let cancel_args = if let Some(ref m) = cancel_msg {
                     FuncArgs::new(
                         vec![],
-                        KwArgs::new([("msg".to_owned(), m.clone())].into_iter().collect()),
+                        KwArgs::new(core::iter::once(("msg".to_owned(), m.clone())).collect()),
                     )
                 } else {
                     FuncArgs::new(vec![], KwArgs::default())

diff --git a/crates/vm/src/builtins/dict.rs b/crates/vm/src/builtins/dict.rs
@@ -342,10 +342,10 @@ impl PyDict {
         default: OptionalArg<PyObjectRef>,
         vm: &VirtualMachine,
     ) -> PyResult {
-        match self.entries.get(vm, &*key)? {
-            Some(value) => Ok(value),
-            None => Ok(default.unwrap_or_none(vm)),
-        }
+        Ok(self
+            .entries
+            .get(vm, &*key)?
+            .unwrap_or_else(|| default.unwrap_or_none(vm)))
     }
 
     #[pymethod]
@@ -360,6 +360,7 @@ impl PyDict {
     }
 
     #[pymethod]
+    #[must_use]
     pub fn copy(&self) -> Self {
         Self {
             entries: self.entries.clone(),

diff --git a/crates/vm/src/builtins/getset.rs b/crates/vm/src/builtins/getset.rs
@@ -70,6 +70,7 @@ impl GetDescriptor for PyGetSet {
 }
 
 impl PyGetSet {
+    #[must_use]
     pub fn new(name: String, class: &'static Py<PyType>) -> Self {
         Self {
             name,
@@ -79,6 +80,7 @@ impl PyGetSet {
         }
     }
 
+    #[must_use]
     pub fn with_get<G, X>(mut self, getter: G) -> Self
     where
         G: IntoPyGetterFunc<X>,
@@ -87,6 +89,7 @@ impl PyGetSet {
         self
     }
 
+    #[must_use]
     pub fn with_set<S, X>(mut self, setter: S) -> Self
     where
         S: IntoPySetterFunc<X>,

diff --git a/crates/vm/src/builtins/memory.rs b/crates/vm/src/builtins/memory.rs
@@ -117,7 +117,8 @@ impl PyMemoryView {
         Ok(zelf)
     }
 
-    /// this should be the only way to create a memoryview from another memoryview
+    /// this should be the only way to create a memoryview from another memoryview.
+    #[must_use]
     pub fn new_view(&self) -> Self {
         let zelf = Self {
             buffer: self.buffer.clone(),

diff --git a/crates/vm/src/builtins/str.rs b/crates/vm/src/builtins/str.rs
@@ -1886,22 +1886,20 @@ impl ToPyObject for Wtf8Buf {
 impl ToPyObject for char {
     fn to_pyobject(self, vm: &VirtualMachine) -> PyObjectRef {
         let cp = self as u32;
-        if cp <= u8::MAX as u32 {
-            vm.ctx.latin1_char(cp as u8).into()
-        } else {
-            vm.ctx.new_str(self).into()
-        }
+        u8::try_from(cp).map_or_else(
+            |_| vm.ctx.new_str(self).into(),
+            |v| vm.ctx.latin1_char(v).into(),
+        )
     }
 }
 
 impl ToPyObject for CodePoint {
     fn to_pyobject(self, vm: &VirtualMachine) -> PyObjectRef {
         let cp = self.to_u32();
-        if cp <= u8::MAX as u32 {
-            vm.ctx.latin1_char(cp as u8).into()
-        } else {
-            vm.ctx.new_str(self).into()
-        }
+        u8::try_from(cp).map_or_else(
+            |_| vm.ctx.new_str(self).into(),
+            |v| vm.ctx.latin1_char(v).into(),
+        )
     }
 }
 

diff --git a/crates/vm/src/bytes_inner.rs b/crates/vm/src/bytes_inner.rs
@@ -407,7 +407,9 @@ impl PyBytesInner {
         let mut new: Vec<u8> = Vec::with_capacity(self.elements.len());
         if let Some((first, second)) = self.elements.split_first() {
             new.push(first.to_ascii_uppercase());
-            second.iter().for_each(|x| new.push(x.to_ascii_lowercase()));
+            for x in second {
+                new.push(x.to_ascii_lowercase());
+            }
         }
         new
     }

diff --git a/crates/vm/src/frame.rs b/crates/vm/src/frame.rs
@@ -8933,7 +8933,7 @@ impl ExecutingFrame<'_> {
         } else if iter.downcast_ref_if_exact::<PyTupleIterator>(vm).is_some() {
             Some(Instruction::ForIterTuple)
         } else if iter.downcast_ref_if_exact::<PyGenerator>(vm).is_some()
-            && jump_delta <= i16::MAX as u32
+            && i16::try_from(jump_delta).is_ok()
             && self.for_iter_has_end_for_shape(instr_idx, jump_delta)
             && !self.specialization_eval_frame_active(vm)
         {

diff --git a/crates/vm/src/stdlib/sys.rs b/crates/vm/src/stdlib/sys.rs
@@ -1129,7 +1129,7 @@ pub mod sys {
             let tb_module = vm.import("traceback", 0)?;
             let print_tb = tb_module.get_attr("print_tb", vm)?;
             let stderr_obj = super::get_stderr(vm)?;
-            let kwargs: KwArgs = [("file".to_string(), stderr_obj)].into_iter().collect();
+            let kwargs: KwArgs = core::iter::once(("file".to_string(), stderr_obj)).collect();
             let _ = print_tb.call(
                 FuncArgs::new(vec![unraisable.exc_traceback.clone()], kwargs),
                 vm,

diff --git a/crates/vm/src/types/slot_defs.rs b/crates/vm/src/types/slot_defs.rs
@@ -1503,16 +1503,13 @@ mod tests {
     #[test]
     fn find_by_name() {
         // __len__ appears in both sequence and mapping
-        let len_defs: Vec<_> = find_slot_defs_by_name("__len__").collect();
-        assert_eq!(len_defs.len(), 2);
+        assert_eq!(find_slot_defs_by_name("__len__").count(), 2);
 
         // __init__ appears once
-        let init_defs: Vec<_> = find_slot_defs_by_name("__init__").collect();
-        assert_eq!(init_defs.len(), 1);
+        assert_eq!(find_slot_defs_by_name("__init__").count(), 1);
 
         // __add__ appears in number (left/right) and sequence
-        let add_defs: Vec<_> = find_slot_defs_by_name("__add__").collect();
-        assert_eq!(add_defs.len(), 2); // NbAdd(Left) and SqConcat
+        assert_eq!(find_slot_defs_by_name("__add__").count(), 2); // NbAdd(Left) and SqConcat
     }
 
     #[test]

diff --git a/crates/vm/src/vm/interpreter.rs b/crates/vm/src/vm/interpreter.rs
@@ -229,6 +229,7 @@ impl InterpreterBuilder {
     ///     })
     ///     .build();
     /// ```
+    #[must_use]
     pub fn init_hook<F>(mut self, init: F) -> Self
     where
         F: FnOnce(&mut VirtualMachine) + 'static,
@@ -250,6 +251,7 @@ impl InterpreterBuilder {
     ///     // In practice: .add_frozen_modules(rustpython_pylib::FROZEN_STDLIB)
     ///     .build();
     /// ```
+    #[must_use]
     pub fn add_frozen_modules<I>(mut self, frozen: I) -> Self
     where
         I: IntoIterator<Item = (&'static str, FrozenModule)>,