Add Fixed Slot Infrastructure

[mgyoo86]

Summary

• Add FIXED_SLOT_FIELDS constant tuple as single source of truth for fixed slot field names
• Add foreach_fixed_slot @generated function for type-stable, zero-allocation iteration
• Add ComplexF32 as new fixed slot type
• Refactor hardcoded iteration tuples in utils.jl to use foreach_fixed_slot

What's Changed

New: FIXED_SLOT_FIELDS

const FIXED_SLOT_FIELDS = (:float64, :float32, :int64, :int32, :complexf64, :complexf32, :bool)

Single source of truth for fixed slot field names. Used by foreach_fixed_slot and tests.

New: foreach_fixed_slot

foreach_fixed_slot(pool) do tp
    # Compile-time unrolled, type-stable iteration
end

Zero-allocation iteration via @generated function that reads from FIXED_SLOT_FIELDS.

Refactored (utils.jl only)

• pool_stats, Base.show, _check_pointer_overlap: hardcoded tuple → foreach_fixed_slot

Not Changed

Adding a new fixed slot still requires updating 4 places:

1. FIXED_SLOT_FIELDS
2. AdaptiveArrayPool struct
3. AdaptiveArrayPool() constructor
4. get_typed_pool! dispatch

Benefits

• Type stability: runtime getfield(pool, field::Symbol) → compile-time unrolling
• Zero allocation: no allocation after warmup
• Improved utils.jl maintainability: iteration logic syncs with FIXED_SLOT_FIELDS

Test Coverage

• test_fixed_slots.jl: auto-verifies FIXED_SLOT_FIELDS and struct synchronization

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 96.46%. Comparing base (bfd4c31) to head (9ef76f4).
⚠️ Report is 5 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master       #7      +/-   ##
==========================================
+ Coverage   94.60%   96.46%   +1.85%     
==========================================
  Files           7        7              
  Lines         575      565      -10     
==========================================
+ Hits          544      545       +1     
+ Misses         31       20      -11     

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[Copilot]

Pull request overview

This PR adds infrastructure to improve maintainability and performance when working with fixed slot types in the AdaptiveArrayPool. The main contribution is the introduction of FIXED_SLOT_FIELDS as a single source of truth and foreach_fixed_slot for type-stable, zero-allocation iteration. Additionally, ComplexF32 is added as a new fixed slot type.

Key Changes:

• New FIXED_SLOT_FIELDS constant tuple centralizes the list of fixed slot field names
• New foreach_fixed_slot @generated function enables compile-time unrolled iteration over fixed slots
• ComplexF32 added as the 7th fixed slot type alongside existing Float64, Float32, Int64, Int32, ComplexF64, and Bool

Reviewed changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
src/types.jl	Added FIXED_SLOT_FIELDS constant, foreach_fixed_slot @generated function, ComplexF32 fixed slot type definition and dispatch
src/state.jl	Refactored checkpoint!, rewind!, and empty! to use foreach_fixed_slot instead of hardcoded iteration
src/utils.jl	Refactored _check_pointer_overlap, pool_stats, and Base.show to use foreach_fixed_slot for consistent fixed slot iteration
src/acquire.jl	Removed internal _acquire_impl! and _unsafe_acquire_impl! fallback methods for ::Nothing (no longer needed as macros handle pool=nothing separately)
test/test_fixed_slots.jl	New comprehensive test file verifying FIXED_SLOT_FIELDS synchronization, foreach_fixed_slot behavior, type stability, and zero allocation
test/test_basic.jl	Added test coverage for ComplexF32 fixed slot type
test/test_state.jl	Updated checkpoint!/rewind! tests to include ComplexF32
test/test_utils.jl	Updated _validate_pool_return tests to include ComplexF32
test/test_aliases.jl	Added runtime coverage tests for similar-style _impl! methods called via macro transformation
test/runtests.jl	Included new test_fixed_slots.jl in test suite

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