fix(gates): restore addr-class lint, broken on main by #7579

[proggeramlug]

lint has been red on main — and therefore on every open PR — since #7579 merged. My fault: I audited that PR against raw_handle_debt, check_file_size and cargo fmt, but not addr_class_inventory.py, which CLAUDE.md lists as a gate. Found by an agent working an unrelated issue in the same file.

crates/perry-runtime/src/iter_result.rs:139: [gcheader-cast]
  let gc_header = (keys as *mut u8).sub(crate::gc::GC_HEADER_SIZE) as *mut crate::gc::GcHeader;

The fix, and why not an allowlist entry

The obvious repair is a 127th entry in scripts/addr_class_allowlist.txt. I didn't take it. Every one of the 126 grandfathered entries carries the same sentence — "migrate to addr_class::try_read_gc_header in a follow-up" — so adding another is borrowing against a debt nobody is paying down.

The reason none of them has migrated is structural, not neglect: try_read_gc_header returns &'static GcHeader, a shared reference. That is deliberate — it is the safe probe for an address that might be a handle, so it must not be able to write. These call sites all want to set a flag. No amount of follow-up work makes a shared reference serve a *mut write; they needed a second, narrower entry point that never existed.

So this adds it: gc::mark_shape_shared, in gc/ where the cast is permitted, with the precondition stated — the pointer must come from allocation this thread just performed, never from a NaN-box payload, which is the same discipline the arena walkers are already allowlisted under. iter_result.rs calls it and the cast is gone. The allowlist does not grow, and the other sites now have a real migration target.

Also

Drops one stale ratchet entry the tool itself reported as over-counted (field_get_set.rs lone-valid-obj-ptr: baseline says 1, found 0). Same family as #7582 — a suppression that outlived its subject.

Validation

• addr_class_inventory.py passes (885 files, 267 allowlisted, 542 sites held by the ratchet).
• cargo test -p perry-runtime --lib: 1818 passed, 0 failed, including shared_iter_result_keys_are_marked_copy_on_write, which is the test that guards this exact flag write.
• raw_handle_debt 998 (baseline 998), check_file_size.sh clean, cargo fmt --check clean.

CI has a deep backlog and may not report; this is local validation.

Summary by CodeRabbit

• Bug Fixes

  • Improved runtime handling of shared iterator-result data to support safer memory management and reduce the risk of related issues.

• Documentation

  • Added release documentation for the shared-data memory-management update.

• Chores

  • Updated the application version from 0.5.1328 to 0.5.1329.

[coderabbitai]

Caution

Review failed

The pull request is closed.

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: e69639ec-fb5e-4fa4-a0d5-ca8f00435552

📥 Commits

Reviewing files that changed from the base of the PR and between 9688bbe and ebf1d0c.

⛔ Files ignored due to path filters (1)

• Cargo.lock is excluded by !**/*.lock

📒 Files selected for processing (6)

• CLAUDE.md
• Cargo.toml
• changelog.d/7585-addr-class-mark-shape-shared.md
• crates/perry-runtime/src/gc/mod.rs
• crates/perry-runtime/src/iter_result.rs
• scripts/addr_class_ratchet_baseline.txt

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📝 Walkthrough

Walkthrough

The runtime adds gc::mark_shape_shared for shared-object header marking and updates iterator-result handling to use it. The address-class baseline and changelog are updated. The workspace and documented versions advance to 0.5.1329.

Changes

Shared-shape GC metadata

Layer / File(s)	Summary
GC header marking helper crates/perry-runtime/src/gc/mod.rs, crates/perry-runtime/src/iter_result.rs, scripts/addr_class_ratchet_baseline.txt, changelog.d/7585-addr-class-mark-shape-shared.md	Adds mark_shape_shared, uses it for shared iterator-result keys, removes the stale address-class allowance, and documents the change.
Release metadata update Cargo.toml, CLAUDE.md	Updates the workspace and documented versions from 0.5.1328 to 0.5.1329.

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

Possibly related PRs

• PerryTS/perry#6810: Introduced the shared-shape GC marking logic that this PR extracts into gc::mark_shape_shared.
• PerryTS/perry#6636: Modified related runtime GC pointer handling and address-class ratchet validation.
• PerryTS/perry#7525: Modified GC metadata handling for shared key arrays.

Suggested reviewers: jdalton, thehypnoo

✨ 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/addr-class-iter-result

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