fix(deforest): exclude super-using class member bodies from call-site rewrite (#5780 cluster A)

[proggeramlug]

Root cause

Commit 5d47364 (#5772) extended the DEFOREST pass to cover class member bodies (constructors, methods, getters, setters, static methods) as valid call-site rewrite targets — fixing the arity-mismatch SIGSEGV where a producer called from a class method had its signature rewritten but the call site was never updated (#5136-class).

A member body that also uses super (super.x, super[e], super(…)) had its [[HomeObject]] setup corrupted by the synthetic-local introduction done by the call-site rewriter, causing:

TypeError: Cannot convert undefined or null to object

at runtime for ~24 test262 cases (cluster A of #5780).

Fix

detect.rs — body_has_super(stmts) walks a member body for any super expression variant (SuperPropertyGet, SuperCall, SuperMethodCall, SuperMethodCallSpread, SuperCallSpread, ObjectSuper*). In the third detection pass (unsafe-call-site scan) any class member body for which body_has_super returns true has all its producer calls flagged as unsafe, removing those producers from the candidate set before the rewrite phase. A producer whose only callers are super-using bodies is therefore excluded entirely; one with callers in both super-using and super-free bodies is also excluded (conservative but correct).

mod.rs — belt-and-suspenders guard: phase-3 skips rewrite_call_sites_in_stmts for any class member body where body_has_super is true, ensuring [[HomeObject]] is never disturbed even if the detect exclusion were somehow bypassed.

Before / after

Scenario	Before	After
class C extends B { m() { super.x; } } near a deforestable helper()	super.x throws TypeError	works correctly
class C { m() { const v = helper(); return v.length; } } (no super)	deforested, correct	deforested, correct (no regression)

Tests

Two new unit tests in crates/perry-transform/src/deforest/tests.rs:

• rejects_deforest_when_class_method_uses_super — producer called from a super-using method is excluded from deforestation; signature unchanged after run().
• still_deforests_when_method_has_no_super — control: same producer called from a super-free method is still deforested (fix(deforest): rewrite producer call sites in class member bodies #5772 guard).

All 11 deforest unit tests pass; cargo fmt --all -- --check and bash scripts/check_file_size.sh clean.

Closes #5780 (cluster A — super.prop / super[expr] / super() in class methods adjacent to deforestable helpers).

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Generated by Claude Code

Summary by CodeRabbit

• Bug Fixes
  • Improved deforestation safety for class members that use super, preventing producer calls in those bodies from being rewritten.
  • Producer candidates are now excluded when they appear in methods, getters, setters, constructors, or static methods that reference super.
  • Class member bodies without super continue to be optimized as before.

[coderabbitai]

📝 Walkthrough

Walkthrough

Adds body_has_super and flag_producer_calls_in_super_body helpers to detect super references in class member bodies. Wires these into detect_producers (third pass) and the run rewriting loop so that producer candidates and call-site rewrites are suppressed when the enclosing class member body uses super. Two regression tests cover both the rejected and accepted cases.

Deforestation super-body guard

Layer / File(s)	Summary
super detection and producer flagging helpers crates/perry-transform/src/deforest/detect.rs	body_has_super recursively walks stmts/exprs to detect super variants; flag_producer_calls_in_super_body traverses the same body and marks any producer appearing as a callee as unsafe.
detect_producers third-pass guard crates/perry-transform/src/deforest/detect.rs	Third pass now calls body_has_super for each class member (constructor, method, getter, setter, static method); routes to flag_producer_calls_in_super_body instead of scan_unsafe_call_sites when super is present.
Call-site rewriting guards in run crates/perry-transform/src/deforest/mod.rs	Constructor and method/getter/setter/static-method rewriting in run is now wrapped in !body_has_super(...) guards; detect re-exports are reformatted (no functional change).
Regression tests crates/perry-transform/src/deforest/tests.rs	rejects_deforest_when_class_method_uses_super asserts empty detection and no param mutation; still_deforests_when_method_has_no_super asserts detection and synthetic accumulator param added.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~25 minutes

Possibly related PRs

• PerryTS/perry#5772: Directly introduced producer call-site rewriting inside class member bodies (the feature this PR guards against when super is present), overlapping in detect.rs and mod.rs.

Poem

🐰 Hop hop, I sniff the super trail,
Where class bodies dare to call their base.
I plant a guard without fail —
No deforest in this sacred space!
The accumulator waits outside,
While super.foo flows with pride. 🌿

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly summarizes the main change: excluding super-using class member bodies from deforest call-site rewriting.
Description check	✅ Passed	The description covers the root cause, fix, before/after behavior, related issue, and tests, even though it uses custom headings.
Linked Issues check	✅ Passed	The PR implements the cluster A super-related regression fix in #5780 and preserves deforestation for super-free class members.
Out of Scope Changes check	✅ Passed	The changes stay focused on deforest detection, rewrite guards, and regression tests with no evident unrelated scope creep.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/deforest-super-prop-5780

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[coderabbitai]

🧹 Nitpick comments (2)

crates/perry-transform/src/deforest/tests.rs (2)

494-579: 🎯 Functional Correctness | 🔵 Trivial | ⚡ Quick win

Assert the rewritten call-site arity here too.

This control only checks that helper gained the synthetic param. It would still pass if run() rewrote the producer signature but left the class-method call as helper(), which is the original arity-mismatch regression. Mirror the args.len() == 1 assertion from deforests_producer_called_from_class_method or reuse that helper.

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@crates/perry-transform/src/deforest/tests.rs` around lines 494 - 579, The new
control test in still_deforests_when_method_has_no_super only verifies that
helper gains the synthetic accumulator parameter, but it does not confirm the
call site was rewritten. Update this test to also assert the rewritten
Expr::Call inside the class method now has one argument, mirroring
deforests_producer_called_from_class_method, so run() cannot regress by changing
the producer signature while leaving helper() at the old arity.

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400-492: 📐 Maintainability & Code Quality | 🔵 Trivial | ⚡ Quick win

Broaden this regression beyond super.foo on an instance method.

The implementation changes also guard constructors, accessors, static methods, and other super forms, but this test only covers Expr::SuperPropertyGet in one method body. A bug in those newly touched branches would still merge untested.

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@crates/perry-transform/src/deforest/tests.rs` around lines 400 - 492, Broaden
the regression in rejects_deforest_when_class_method_uses_super to cover all
super-using class contexts, not just Expr::SuperPropertyGet in a single instance
method. Add cases for constructors, getters/setters, and static methods (and any
other super forms handled by the new logic), then assert detect_producers still
excludes the producer and run() leaves the helper signature unchanged for each
case. Use the existing make_simple_producer, detect_producers, and run setup to
keep the test focused while exercising the newly touched branches.

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Nitpick comments:
In `@crates/perry-transform/src/deforest/tests.rs`:
- Around line 494-579: The new control test in
still_deforests_when_method_has_no_super only verifies that helper gains the
synthetic accumulator parameter, but it does not confirm the call site was
rewritten. Update this test to also assert the rewritten Expr::Call inside the
class method now has one argument, mirroring
deforests_producer_called_from_class_method, so run() cannot regress by changing
the producer signature while leaving helper() at the old arity.
- Around line 400-492: Broaden the regression in
rejects_deforest_when_class_method_uses_super to cover all super-using class
contexts, not just Expr::SuperPropertyGet in a single instance method. Add cases
for constructors, getters/setters, and static methods (and any other super forms
handled by the new logic), then assert detect_producers still excludes the
producer and run() leaves the helper signature unchanged for each case. Use the
existing make_simple_producer, detect_producers, and run setup to keep the test
focused while exercising the newly touched branches.

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ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: 70218386-cdc5-4a2b-b59d-7d281b940ac2

📥 Commits

Reviewing files that changed from the base of the PR and between 4603b8b and 0733197.

📒 Files selected for processing (3)

• crates/perry-transform/src/deforest/detect.rs
• crates/perry-transform/src/deforest/mod.rs
• crates/perry-transform/src/deforest/tests.rs