fix(runtime): materialize ordinary parent prototypes

[proggeramlug]

Release-blocker follow-up to #8766.

The full gap shard exposed a second lazy-prototype case on current main: an ordinary runtime-valued function superclass (class Child extends WithDefault) threw Class extends value does not have valid prototype property unless some unrelated code had read WithDefault.prototype first.

#8766 correctly added lazy materialization for bound native constructor exports, but implemented it as a raw dynamic-slot probe plus an ordinary_function_prototype_value_for_read fallback. This follow-up routes the class-definition Get(superclass, "prototype") through the existing canonical js_function_prototype_value_for_read helper instead. That one path preserves explicit/deleted/generator prototype semantics while lazily materializing both ordinary-function and bound-native-constructor prototypes.

The existing failing regression is test_gap_class_extends_runtime_value_super; no snapshot or expectation is weakened.

Validation on the rebased result:

• cargo fmt --all -- --check

• git diff --check

• cargo test -p perry-runtime class_parent_prototype_tests: 2 passed, 0 failed

• release-profile compiler/runtime rebuilt from this branch

• exact Node/Perry output parity for test_gap_class_extends_runtime_value_super:

  s.x: 7
  s.y: 9
  c.flag: default-from-parent
  w.ownField: subclass-init
  

No version bump and no tag.

Summary by CodeRabbit

• Bug Fixes
  • Fixed inheritance for subclasses of runtime-valued functions.
  • Subclasses now correctly observe and link the same prototype object returned by reading the parent function’s prototype, including when it has not been accessed previously.
  • Improved consistency for plain functions, bound constructors, and functions with explicit, deleted, or generator prototypes.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: 77c7cf97-4551-4c5e-891d-4a50c30a88dc

📥 Commits

Reviewing files that changed from the base of the PR and between 1b0c300 and a49a724.

📒 Files selected for processing (2)

• changelog.d/8768-runtime-parent-function-prototype.md
• crates/perry-runtime/src/object/class_registry/state.rs

Included review availability: Your plan provides up to 8 included reviews per hour; 0 remain after this review.

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📝 Walkthrough

Walkthrough

The class registry now resolves runtime-valued function parent prototypes through the observable prototype-read path. This materializes unread lazy prototypes and preserves explicit, deleted, and generator prototype behavior. A changelog entry documents the fix.

Changes

Runtime parent prototype resolution

Layer / File(s)	Summary
Standardize parent prototype reads crates/perry-runtime/src/object/class_registry/state.rs, changelog.d/8768-runtime-parent-function-prototype.md	Dynamic parent prototype resolution uses js_function_prototype_value_for_read. The changelog documents lazy prototype materialization and prototype linking for subclasses.

Estimated code review effort: 2 (Simple) | ~10 minutes

Merge Risk: ⚪ Minimal · up to a49a7

This localized runtime change materializes ordinary parent prototypes through the canonical prototype-read path and includes targeted regression and parity validation; no actionable merge-blocking risk remains beyond normal checks and review.

Suggested reviewers: thehypnoo

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and concisely describes the runtime fix for materializing ordinary parent prototypes.
Description check	✅ Passed	The description explains the issue, implementation, related issue, validation steps, expected output, and release constraints.
Docstring Coverage	✅ Passed	Docstring check was indeterminate for this PR — some files could not be analyzed in time. Not blocking.
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 docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch codex/class-parent-prototype-read

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[proggeramlug]

Landed on main via #8778 (squash 1f5c3bb80), with the rest of this batch.

Validated on the merged result: all 30 lint checkers, runtime 2674/0 at RUST_TEST_THREADS=1, codegen 1230/0, all codegen integration suites clean, and perry-ext-mysql2 --lib 10/0.