fix(runtime): expose core intrinsic Symbol.toStringTag descriptors

[proggeramlug]

Fixes #10633.

Map, Set, WeakMap, WeakSet, Promise, ArrayBuffer, and DataView now define the standard own Symbol.toStringTag data property on their prototypes with the expected descriptor flags. Native instances also resolve the inherited property through their actual prototype.

Validation:

• cargo build --profile perry-dev -p perry -p perry-runtime-static -p perry-stdlib-static
• cargo fmt --all -- --check
• scripts/check_file_size.sh
• ./run_parity_tests.sh --filter test_gap_10633_core_tostringtag (prebuilt compiler/runtime; 1/1 pass)
• ./run_parity_tests.sh --filter test_gap_10555_symbol_tostringtag_web_builtins (prebuilt compiler/runtime; 1/1 pass)

Summary by CodeRabbit

• Bug Fixes

  • Improved Symbol.toStringTag behavior for Map, Set, WeakMap, WeakSet, Promise, ArrayBuffer, and DataView instances.
  • Built-in prototypes now expose the appropriate standard string tags through inheritance.
  • Corrected property descriptor behavior, including preventing changes to the built-in Map tag.

• Tests

  • Added coverage for tag values, string representations, descriptor flags, and protected built-in tag properties.

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ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Advanced

Run ID: 0aaca822-aada-4f3e-8408-8c92a0ac3c3d

📥 Commits

Reviewing files that changed from the base of the PR and between c7cbc3c and ce0d900.

📒 Files selected for processing (4)

• changelog.d/10998-core-tostringtag.md
• crates/perry-runtime/src/object/global_this/proto_methods.rs
• crates/perry-runtime/src/symbol/get.rs
• test-files/test_gap_10633_core_tostringtag.ts

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📝 Walkthrough

Walkthrough

The runtime now assigns Symbol.toStringTag properties to core built-in prototypes. Symbol reads can resolve these tags through actual prototypes for pointer-backed instances. Tests cover values, descriptors, and Map.prototype assignment behavior.

Changes

Core Symbol.toStringTag support

Layer / File(s)	Summary
Intrinsic prototype tags crates/perry-runtime/src/object/global_this/proto_methods.rs	Map, Set, WeakMap, WeakSet, ArrayBuffer, DataView, and Promise prototypes receive intrinsic Symbol.toStringTag values.
Reflective tag resolution crates/perry-runtime/src/symbol/get.rs	The symbol resolver reflects the actual prototype for Symbol.toStringTag reads and returns the prototype tag for pointer-backed instances.
Descriptor and instance validation test-files/test_gap_10633_core_tostringtag.ts, changelog.d/10998-core-tostringtag.md	Tests check tag values, descriptor flags, instance resolution, and failed Map.prototype assignment. The changelog records the supported built-ins.

Priority: ➖ Normal

Estimated code review effort: 3 (Moderate) | ~20 minutes

Change: Bug fix · Severity of issue fixed: Medium

Sequence Diagram(s)

sequenceDiagram
  participant Instance
  participant SymbolResolver
  participant BuiltinPrototype
  Instance->>SymbolResolver: Read Symbol.toStringTag
  SymbolResolver->>BuiltinPrototype: Resolve actual prototype
  BuiltinPrototype-->>SymbolResolver: Return intrinsic tag
  SymbolResolver-->>Instance: Return tag value

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Merge Risk: ⚪ Minimal · up to ce0d9

The runtime adds standard Symbol.toStringTag behavior for core built-ins, with no identified merge-blocking impact. Mergeable with normal checks.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and concisely describes the primary runtime change: exposing core intrinsic Symbol.toStringTag descriptors.
Description check	✅ Passed	The description explains the change, references issue #10633, and lists concrete validation commands. It does not reproduce the template headings or checklist, but it contains the main required inform…
Linked Issues check	✅ Passed	The change satisfies the coding requirements in issue #10633. populate_builtin_prototype_methods installs Symbol.toStringTag on the collection, Promise, ArrayBuffer, and DataView prototypes. The i…
Out of Scope Changes check	✅ Passed	The changes remain within the scope of issue #10633. Set, WeakMap, and WeakSet use the same core intrinsic Symbol.toStringTag implementation and extend the requested prototype conformance consistent…
Docstring Coverage	✅ Passed	Docstring coverage is 83.33% which is sufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 6 functions across 3 files. (1 skipped: 1 u…

✨ Finishing Touches 💡 1

🧪 Generate unit tests (beta)

• Create a new PR

🛠️ Fix failing CI checks 💡

• Commit to this branch
• Create a new PR

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[proggeramlug]

Landed on main in merge train 258 (#11078, v0.5.1641), main e27f0a068a.

Carried at head ce0d900c0d. CI on the train head was fully green — 22 jobs, zero failures, the first train since the public-baseline artifact was regenerated, so no known-red line to read past.

This train was bisect-verified: after an earlier 35-PR assembly hit five gap regressions, the lowering-touching PRs were split into probes, and this set (#11070) came back with all six gap shards clean while the other half reproduced all five.

Trains rebase-merge, so commits get new SHAs and GitHub cannot mark this merged. Closed as landed.