fix(deforest): rewrite producer call sites in class member bodies

[proggeramlug]

Problem

Deforestation promotes an array-producer function

function f() { const out = []; /* ...out.push(x)... */ return out; }

to take the accumulator as a synthetic trailing __deforest_out parameter, then rewrites every call site to allocate the array and pass it in.

detect_producers scans free functions, module-init, and class member bodies (methods + constructors) when deciding whether a producer is safe to rewrite — a plain let v = f() inside a method counts as a supported call site, so the producer is admitted. But phase 3 only rewrote call sites in module-init and free functions.

So a producer whose call site lives in a class method had its signature rewritten (gaining the out-param) while the method's call kept its original arity. Codegen then passes undefined for the missing argument, and the body runs out.push(...) / return out on a non-array:

function build() { const out = []; out.push(1); return out; }   // becomes build(__deforest_out)
class C { m() { const v = build(); return v.length; } }         // call site NOT rewritten → build(undefined)
new C().m();   // SIGSEGV (push on undefined)

When the (now undefined) result is later spread / for…of'd, it surfaces instead as TypeError: is not iterable.

This is the same arity-mismatch class as the in-closure bail-out (#5136). There the fix was to drop the producer; method/ctor/accessor bodies are ordinary statement lists, so we can rewrite them rather than bail.

Fix

Make detection, fresh-id seeding, and the phase-3 rewrite cover the identical complete set of code bodies — module-init, free functions, constructors, methods, getters, setters, and static methods:

• deforest/mod.rs (phase 3): rewrite producer call sites in every class member body, not just module-init + free functions.
• deforest/detect.rs: extend the three safety scans (funcref misuse, unsafe call sites, in-closure usage) to getters/setters/static methods so admission and rewrite stay symmetric (previously they covered only methods + constructors).
• deforest/walk.rs (max_local_id): include getter/setter/static-method locals so the synthetic-id seed can't collide with a local already living in those bodies.

Test

Adds deforests_producer_called_from_class_method: a producer called via let v = helper() inside a class method is deforested and its call site is rewritten to pass the accumulator (the surviving call's arity matches the rewritten producer). Full perry-transform suite green (40 passed).

Summary by CodeRabbit

• Bug Fixes

  • Improved deforestation so call sites inside class methods, getters, setters, and static methods are rewritten correctly.
  • Fixed producer detection to consider these class member bodies when deciding whether a producer can be transformed.
  • Prevented identifier conflicts by including class accessors and static members in local ID tracking.

• Tests

  • Added regression coverage for producer calls inside class methods.

[coderabbitai]

📝 Walkthrough

Walkthrough

Producer deforestation is extended to cover class getters, setters, and static_methods. Three validation passes in detect_producers, the max_local_id walk, and the phase-3 call-site rewriting step in run all gain iteration over these additional class member bodies. A regression test verifies detection and call-site arity rewriting for a producer called from a class method.

Changes

Deforest class member coverage

Layer / File(s)	Summary
Producer validation and LocalId scanning crates/perry-transform/src/deforest/detect.rs, crates/perry-transform/src/deforest/walk.rs	Three validation passes (FuncRef misuse, unsupported call-site shape, used-in-closure) each gain traversal of class getter/setter/static method bodies. max_local_id similarly extended to scan params and bodies of those members.
Call-site rewriting in class members crates/perry-transform/src/deforest/mod.rs	run phase-3 now iterates constructor, methods, getters, setters, and static methods per class and calls rewrite_call_sites_in_stmts on each body.
Regression test crates/perry-transform/src/deforest/tests.rs	deforests_producer_called_from_class_method builds a producer and a class method calling it, asserts detection, checks the producer gains the accumulator param, and verifies the call site is rewritten to arity 1.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Possibly related PRs

• PerryTS/perry#5179: Added the "used inside closures" disqualification pass in detect.rs that this PR now extends to class getters/setters/static methods.

Poem

🐇 Hop through the getter, leap past the setter,
Static methods too — now coverage is better!
The deforester scans each nook of the class,
Rewrites call sites so no stale arity shall pass.
No local id left behind, no body unseen —
The warren is tidy, the transform is clean! ✨

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately summarizes the main change: rewriting producer call sites in class member bodies.
Description check	✅ Passed	The description is mostly complete: it explains the problem, fix, and test, with only minor template sections omitted.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[coderabbitai]

🧹 Nitpick comments (2)

crates/perry-transform/src/deforest/mod.rs (1)

177-230: 📐 Maintainability & Code Quality | 🔵 Trivial | 🏗️ Heavy lift

Centralize class-member traversal before it drifts again.

This member list now lives in detect.rs, walk.rs, and run(), which is the exact contract that got out of sync here. A shared helper over class-member Function bodies would make future member-kind additions much harder to miss.

🤖 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/mod.rs` around lines 177 - 230, The
class-member traversal logic is duplicated across multiple places and is already
drifting out of sync; centralize it into a shared helper that walks all
class-member Function bodies. Refactor the member-body rewriting in the deforest
pipeline (the logic around module.classes, class.constructor, class.methods,
class.getters, class.setters, and class.static_methods) to call that helper so
future member-kind additions only need one update.

crates/perry-transform/src/deforest/tests.rs (1)

282-398: 📐 Maintainability & Code Quality | 🔵 Trivial | ⚡ Quick win

Add an accessor/static-member regression case.

This only exercises class.methods, so the new getter/setter/static-method loops in detect_producers, max_local_id, and phase 3 can still regress without any test failing. Parameterizing the fixture by member kind would cover the new surface with little extra code.

🤖 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 282 - 398, Add a
regression test that covers class accessor/static member bodies, not just
class.methods, because the new getter/setter/static-method handling in
detect_producers, max_local_id, and phase 3 can still miss call-site rewrites.
Reuse the existing deforestation fixture pattern in deforest/tests.rs by
parameterizing the member kind and asserting the producer still gains the
synthetic accumulator param and every FuncRef(1) call inside the member body is
rewritten to arity 1. Keep the same style as
deforests_producer_called_from_class_method so the new test exercises the same
run() pipeline across getter, setter, and static method cases.

🤖 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/mod.rs`:
- Around line 177-230: The class-member traversal logic is duplicated across
multiple places and is already drifting out of sync; centralize it into a shared
helper that walks all class-member Function bodies. Refactor the member-body
rewriting in the deforest pipeline (the logic around module.classes,
class.constructor, class.methods, class.getters, class.setters, and
class.static_methods) to call that helper so future member-kind additions only
need one update.

In `@crates/perry-transform/src/deforest/tests.rs`:
- Around line 282-398: Add a regression test that covers class accessor/static
member bodies, not just class.methods, because the new
getter/setter/static-method handling in detect_producers, max_local_id, and
phase 3 can still miss call-site rewrites. Reuse the existing deforestation
fixture pattern in deforest/tests.rs by parameterizing the member kind and
asserting the producer still gains the synthetic accumulator param and every
FuncRef(1) call inside the member body is rewritten to arity 1. Keep the same
style as deforests_producer_called_from_class_method so the new test exercises
the same run() pipeline across getter, setter, and static method cases.

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ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: 9bb37e94-34dd-4068-9992-8e044f4b2b36

📥 Commits

Reviewing files that changed from the base of the PR and between 1f4a2c5 and 029f1ab.

📒 Files selected for processing (4)

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