Align CallFunctionEx to 3.14 by youknowone · Pull Request #6786 · RustPython/RustPython

youknowone

📝 Walkthrough

Walkthrough

The PR simplifies keyword argument handling in function calls by removing a per-call has_kwargs flag from the CallFunctionEx bytecode instruction. Instead, the system now relies on stack state: when kwargs are absent, a Null value is pushed onto the stack, enabling uniform CallFunctionEx invocation logic across compiler and VM execution layers.

Changes

Cohort / File(s)	Summary
CallFunctionEx Instruction Simplification `crates/compiler-core/src/bytecode/instruction.rs`	Changed `CallFunctionEx` enum variant from struct-like with `has_kwargs: Arg<bool>` field to unit-like variant `CallFunctionEx = 54`. Updated stack-effect computation to use fixed value instead of variable logic. Simplified display/formatting code.
Compiler Codegen Updates `crates/codegen/src/compile.rs`	Replaced conditional has_kwargs presence checks with direct branching: compiles kwargs via `compile_keywords(...)` when present, or pushes `Null` when absent. Removed has_kwargs parameter passing to `CallFunctionEx` emission calls.
VM Frame Execution Updates `crates/vm/src/frame.rs`	Updated `CallFunctionEx` instruction dispatch to remove has_kwargs deconstruction. Changed `collect_ex_args` signature from flag-driven to stack-driven via `pop_value_opt`. Added `iterate_mapping_keys` helper to preserve key order when extracting kwargs from mapping objects.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~25 minutes

Possibly related PRs

Sort Instruction enum & related match arms #6322: Both PRs modify the Instruction::CallFunctionEx shape and its handling throughout the codebase, with this PR removing the per-call has_kwargs field entirely.
Replace CallMethod/LoadMethod opcodes with plain Call #6674: Both PRs modify CallFunctionEx opcode and call-handling paths; the referenced PR introduced centralized CallFunctionEx with has_kwargs, while this PR removes the flag and converts to stack-driven kwargs via PushNull.
Pseudo ops #6678: Both PRs touch the CallFunctionEx and kwargs codepath, modifying how keyword arguments are represented and handled across compiler and VM layers.

Suggested reviewers

ShaharNaveh

Poem

🐰 No more flags upon the stack, just Nulls to light the way,
Where kwargs once were whispered true, now silence wins the day,
The CallFunctionEx hops along, so simple and so clean,
From flag-driven dreams to stack-based streams—the best refactor seen! ✨

🚥 Pre-merge checks | ✅ 2 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 71.43% 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 'Align CallFunctionEx to 3.14' directly corresponds to the main refactoring described in all three modified files: removing the per-call has_kwargs flag from CallFunctionEx and aligning its behavior.

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✨ Finishing touches

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