derive `Copy` where possible by ShaharNaveh · Pull Request #6844 · RustPython/RustPython

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📝 Walkthrough

Walkthrough

Adds many Clone/Copy derives across crates, a workspace lint, small API fields (buffer release/retain), a TryLockThreadError and SingleThreadId change, and makes ExceptionTableEntry::new a const fn. No behavioral control-flow changes beyond by-value usage where derives permit it.

Changes

Cohort / File(s)	Summary
Lint Configuration `\`Cargo.toml``	Added workspace lint: `workspace.lints.rust.missing_copy_implementations = "warn"`.
Codegen `\`crates/codegen/src/compile.rs``,` `crates/codegen/src/error.rs``,` `crates/codegen/src/ir.rs``,` `crates/codegen/src/symboltable.rs``	Added `Clone, Copy` derives to `CompileOpts`, `DoneWithFuture`, `PatternUnreachableReason`, `InstructionInfo`, `ExceptHandlerInfo`, `SymbolUsage`; replaced some `.clone()` with by-value uses in `ir.rs`.
Common — formats/encodings/hash/int/str/cformat `\`crates/common/src/format.rs``,` `crates/common/src/encodings.rs``,` `crates/common/src/hash.rs``,` `crates/common/src/int.rs``,` `crates/common/src/str.rs``,` `crates/common/src/cformat.rs``	Added `Clone, Copy` derives to many small/public types and error structs (Format*, encoding errors, `HashSecret`, `BytesToIntError`, `UnicodeEscapeCodepoint`, `CFormatErrorType`, `CFormatError`).
Common — locking / single-thread id `\`crates/common/src/lock/thread_mutex.rs``,` `crates/common/src/lock/cell_lock.rs``	Added `TryLockThreadError` (Clone/Copy), introduced `SingleThreadId` (Clone/Copy) with `unsafe impl GetThreadId` using `NonZero::new_unchecked(1)`, and adjusted try_lock-related debug paths.
Compiler-core `\`crates/compiler-core/src/bytecode.rs``,` `crates/compiler-core/src/marshal.rs``,` `crates/compiler-core/src/mode.rs``	`ExceptionTableEntry` now derives `Copy` and its `new` is `pub const fn`; added `Clone, Copy` to `MarshalError` and `ModeParseError`.
SRE engine `\`crates/sre_engine/src/constants.rs``	Added `Clone, Copy` derives to `SreOpcode`, `SreAtCode`, `SreCatCode`, and `SreInfo`.
VM — builtins & core types `\`crates/vm/src/builtins/.rs``,` `crates/vm/src/dict_inner.rs``,` `crates/vm/src/sliceable.rs``,` `crates/vm/src/function/``,` `crates/vm/src/function/number.rs``	Widespread addition of `Clone, Copy` to many VM/public types (singletons, ellipsis, base object, namespace → unit-like, module types, method defs, ArgInto* types, DictSize, SequenceIndex, SaturatedSliceIter, etc.); added `MemberGetter` and `MemberSetter` enums.
VM — protocol & buffers `\`crates/vm/src/protocol/buffer.rs``,` `crates/vm/src/protocol/mapping.rs``,` `crates/vm/src/protocol/sequence.rs``	`BufferMethods` now `Clone, Copy` and gained `release: fn(&PyBuffer)` and `retain: fn(&PyBuffer)` fields; `PyMappingMethods` and `PySequenceMethods` gain `Clone, Copy`.
VM — stdlib / misc / examples `\`crates/vm/src/stdlib/*.rs``,` `crates/vm/src/anystr.rs``,` `crates/vm/src/builtins/zip.rs``,` `crates/wasm/src/vm_class.rs``,` `examples/dis.rs``	Added `Clone, Copy` derives to various stdlib/public types (`DumpError`, `TargetIsDirectory`, `Generic` → unit-like, `NoDefault`, Split/Expand args, `PyZipNewArgs`, etc.); `VMStore` gained `Clone, Copy`; `examples/dis.rs` stops cloning opts in loop (uses copy).
Windows fileutils `\`crates/common/src/fileutils.rs``	Added `Clone, Copy` to several Windows-specific stat structs and enums to allow by-value copies.

Sequence Diagram(s)

(Skipped — changes are primarily trait derives, small API additions, and minor signature tweaks that do not introduce a new multi-component sequential flow.)

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Possibly related PRs

Apply some clippy lints #6045 — touches crates/compiler-core/src/bytecode.rs with const fn and Copy derives changes (direct overlap with ExceptionTableEntry edits).
Remove wrong Deref #6620 — modifies ArgInto* types in crates/vm/src/function/number.rs (related to the derives added here).
a few unreachable->unimplemented, clippy #6405 — also changes PyBaseObject in crates/vm/src/builtins/object.rs (overlaps with derive adjustments).

Suggested reviewers

youknowone
arihant2math

Poem

🐰
I nudged the structs, light as air,
Gave them Copy feet to skip and share.
No heavy clones, just tiny hops,
A lint gave notice — mind the props.
Now fields can flutter — hop, hop, hop!

🚥 Pre-merge checks | ✅ 2 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 31.03% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The PR title 'derive `Copy` where possible' accurately and clearly describes the main objective of the changeset—adding Copy trait derivations to multiple types across the codebase.

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✨ Finishing touches

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