Remove BEFORE_WITH,BINARY_SUBSCR#6822

youknowone

Summary by CodeRabbit

Refactor
- Aligned bytecode compiler with CPython 3.14 standards by removing custom opcodes and restructuring how context manager and subscript operations are compiled.
- Updated instruction handling for with/async-with statements and item subscripting to follow Python standard conventions.
- Enhanced special method resolution in bytecode generation.

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coderabbitai

📝 Walkthrough

Walkthrough

This PR aligns RustPython's bytecode with CPython 3.14 by removing custom opcodes (BeforeWith, BeforeAsyncWith, BinarySubscr, BuildConstKeyMap), introducing a SpecialMethod enum for explicit context-manager method resolution, and unifying subscripting into BinaryOperator::Subscr across compilation and runtime execution.

Changes

Cohort / File(s)	Summary
Spell-check Dictionary `.cspell.dict/cpython.txt`	Added six CPython-related tokens (INCREF, inplace, Lshift, repr, Rshift, subscr) to the spell-check dictionary; no functional code changes.
Bytecode Type Definitions `crates/compiler-core/src/bytecode/oparg.rs`	Introduced new public `SpecialMethod` enum with four variants (Enter, Exit, AEnter, AExit) and Display impl; extended `BinaryOperator` with `Subscr = 26` variant.
Instruction Enum & Exports `crates/compiler-core/src/bytecode/instruction.rs`, `crates/compiler-core/src/bytecode.rs`	Removed RustPython-specific opcodes (BeforeAsyncWith, BeforeWith, BinarySubscr, BuildConstKeyMap); changed `LoadSpecial` signature from `arg: Arg<u32>` to `method: Arg<SpecialMethod>`; added `SpecialMethod` to public re-exports.
Codegen & Compilation `crates/codegen/src/compile.rs`	Replaced `BinarySubscr` with `BinaryOp { op: BinaryOperator::Subscr }` for subscripting contexts; replaced `BeforeWith`/`BeforeAsyncWith` with explicit `LoadSpecial` + stack manipulation (PushNull, Call) for context-manager method loading.
Runtime Execution `crates/vm/src/frame.rs`	Removed instruction handlers for `BeforeAsyncWith` and `BeforeWith`; added `LoadSpecial { method }` handler to resolve and push bound context-manager methods; added `BinaryOperator::Subscr` dispatch to `execute_bin_op`.

Estimated code review effort

🎯 4 (Complex) | ⏱️ ~40 minutes

The changes span multiple compilation pipeline layers with significant structural modifications: removal of public opcodes, introduction of new enum types, updates to codegen emission patterns, and corresponding runtime execution changes. Verification requires checking consistency across codegen, bytecode representation, and VM execution paths.

Possibly related PRs

RustPython#6741: Directly conflicts with this PR by making overlapping changes to the bytecode Instruction enum and opcode discriminants.
RustPython#6317: Related through bytecode-level binary operator handling; this PR adds Subscr while the other unifies and extends BinaryOperator variants.
RustPython#6638: Modifies the same bytecode/instruction surface and VM handling for with-statements, implementing the BeforeWith/BeforeAsyncWith variants that this PR removes.

Suggested reviewers

ShaharNaveh

Poem

🐰 Hopping through bytecode with glee,
We've trimmed the opcodes, now 3.14-free!
LoadSpecial hops, subscripts align,
CPython's path becomes yours and mine! 🎯

🚥 Pre-merge checks | ✅ 2 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 50.00% 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 title accurately identifies the primary changes: removal of BEFORE_WITH and BINARY_SUBSCR opcodes, which are the main public API removals across the codebase.

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✨ Finishing touches

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github-actions

📦 Library Dependencies

The following Lib/ modules were modified. Here are their dependencies:

Click to expand dependency information

[+] lib: cpython/Lib/_opcode_metadata.py
[-] test: cpython/Lib/test/test__opcode_metadata
soft_deps:
- [ ] _opcode_metadata

Legend:

[+] path exists, [-] path missing
[x] up-to-date, [ ] outdated
native: Rust/C extension modules

coderabbitai

Actionable comments posted: 1

🤖 Fix all issues with AI agents

In `@crates/vm/src/frame.rs`:
- Around line 1234-1267: Update the user-facing TypeError message in the
Instruction::LoadSpecial handling so it uses "missing" instead of "missed":
locate the vm.new_type_error call inside the LoadSpecial match arm (in frame
handling where get_special_method returns None) and change the message string to
"'{}' object does not support the context manager protocol (missing {} method)"
to correct the grammar.

Remove BEFORE_WITH,BINARY_SUBSCR

f3abd71

ShaharNaveh reviewed Jan 20, 2026

View reviewed changes

youknowone marked this pull request as ready for review January 20, 2026 17:09

coderabbitai Bot reviewed Jan 20, 2026

View reviewed changes

youknowone deleted the remove-before-with branch January 20, 2026 17:58

coderabbitai Bot mentioned this pull request Mar 16, 2026

Upgrade test_code and fix code bugs #7440

Merged

coderabbitai Bot mentioned this pull request Mar 25, 2026

Bytecode parity #7504

Merged

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Remove BEFORE_WITH,BINARY_SUBSCR#6822