Plan: Moo All Tests Passing

Goal: ./jcpan --jobs 8 -t Moo → 71/71 test programs pass, 841/841 subtests pass

Branch: feature/destroy-weaken

Current state: 71/71 pass, 841/841 subtests pass — GOAL ACHIEVED

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All Failures Resolved

All 841/841 Moo subtests now pass across all 71 test files.

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Completed Fixes

Category C: Optree Reaping — FIXED (2025-04-09)

2 test files, 2 subtests fixed (test 19 in each accessor-weaken file).

Root cause: When *mk_ref = sub {} replaces a subroutine, Perl 5 frees the old sub's op-tree including compile-time constants. Weak references to those constants become undef. On the JVM, there's no op-tree to reap — constants are cached RuntimeScalarReadOnly objects.

Fix: Track cached string constants referenced via backslash inside each subroutine ("pad constants"). When the CODE slot of a glob is overwritten, clear weak references to the old sub's pad constants. This is done by:

1. Recording which cached constants are referenced via \ during compilation (EmitOperator.handleCreateReference -> JavaClassInfo.padConstants)
2. Transferring pad constants from compile context to RuntimeCode at runtime (via EmitSubroutine for anon subs, SubroutineParser for named subs)
3. Calling clearPadConstantWeakRefs() on the old RuntimeCode when a glob's CODE slot is overwritten (RuntimeGlob.set CODE case)

Commit: 84c483a24

Category A: quote_sub Inlining — FIXED (2025-04-09)

6 test files, ~49 subtests — all now passing.

Root cause: When weaken() was called on an unblessed birth-tracked object (like deferred coderefs from Sub::Quote/Sub::Defer) with refCount > 0, the mortal mechanism could bring refCount to 0 and trigger clearWeakRefsTo() prematurely.

Fix: In weaken(), when an unblessed object has remaining strong refs after decrement (refCount > 0 && blessId == 0), transition immediately to WEAKLY_TRACKED (refCount=-2). Also removed MortalList.flush() from RuntimeCode.apply() methods to prevent flushing pending decrements before callees capture return values.

Commit: cad2f2566

Category B: Weak Ref Scope-Exit — MOSTLY FIXED (2025-04-09)

2 test files, 4 of 6 subtests fixed (tests 10, 11 in each file).

Root cause: Anonymous hashes created via {} were birth-tracked in createReference() (which is also called for named hashes \%h). This meant named hashes got refCount=0 even though their JVM local variable isn't counted. When weaken() brought refCount to 0, we couldn't distinguish "anonymous hash with truly no strong refs" from "named hash with untracked lexical slot", so we always went to WEAKLY_TRACKED.

Fix: Moved birth tracking from RuntimeHash.createReference() to createReferenceWithTrackedElements() (only called for anonymous {}). Named hashes keep refCount=-1. In weaken(), when refCount reaches 0, destroy immediately — only anonymous objects can reach this state, and their refCount is complete.

Key insight: set() already routes reference copies to setLarge() when MortalList.active, so refCount IS accurate for all stored references to anonymous objects.

Commit: 800f70faa

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Architecture Notes

RefCount States

Value	Meaning
-1	Untracked (default). Named objects, CODE refs, objects created before MortalList.active
-2 (WEAKLY_TRACKED)	Named/global object with weak refs. Strong refs can't be counted accurately.
0	Birth-tracked anonymous object (via createReferenceWithTrackedElements). No strong refs yet.
> 0	Tracked with N strong references (via setLarge increments)
MIN_VALUE	Destroyed

Birth Tracking

Only anonymous objects (created via createReferenceWithTrackedElements) get birth-tracked:

• {a => 1} → RuntimeHash.createReferenceWithTrackedElements() → refCount=0
• \%h → RuntimeHash.createReference() → refCount stays -1

This distinction is critical: anonymous objects are ONLY reachable through references (all tracked by setLarge), so refCount is complete. Named objects have their JVM local variable as an untracked strong reference.

WEAKLY_TRACKED Transition

When weaken() decrements refCount from N to M > 0 for unblessed objects, transition to WEAKLY_TRACKED. This is necessary because:

1. Closure captures hold references not tracked in refCount
2. new RuntimeScalar(RuntimeScalar) copies aren't tracked
3. Without this, mortal flush can bring refCount to 0 while the object is still alive

Files Changed

File	Changes
WeakRefRegistry.java	Simplified weaken(): destroy at refCount=0 for both blessed/unblessed; WEAKLY_TRACKED for refCount>0 unblessed
RuntimeHash.java	Moved birth tracking from createReference() to createReferenceWithTrackedElements()
RuntimeCode.java	Removed MortalList.flush() from 3 apply() methods
MortalList.java	No changes in this round

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Progress Tracking

Current Status: 841/841 subtests passing (100%) — COMPLETE

Completed

• Category A fix: quote_sub inlining (2025-04-09) — commit cad2f2566
• Category B fix: anonymous hash weak ref clearing (2025-04-09) — commit 800f70faa
• Category C fix: optree reaping emulation (2025-04-09) — commit 84c483a24

Remaining

None — all 71/71 test files and 841/841 subtests pass.