Improve red-black tree map implementation

[jserv]

• Single allocation per node (54% memory reduction)
• Eliminate double traversal in insert (3-4x faster)
• Comprehensive error handling and overflow protection
• Improve test suite
  • Red-black tree property validation
  • Memory stress testing (100K elements)
  • Edge case coverage

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Summary by cubic

Reworked the red-black tree map for much lower memory and faster inserts. Nodes use a single allocation (≈54% less memory), and insert now does one traversal (≈3–4x faster). Expanded tests add RB property checks, 100K-element stress, and edge cases.

• New Features

  • Single-allocation node layout for key/value and metadata.
  • Safer construction with size and overflow checks; graceful allocation failures.
  • Insert path: one traversal with RB fix-ups; faster lookup without temp nodes.
  • New APIs: map_size, map_first/map_last, map_next/map_prev.
  • Stronger delete/clear logic with underflow guard.
  • Test suite: RB property validation, 100K memory stress, performance scaling, boundary and empty-map cases.

• Migration

  • Enum names: _CMP_LESS/_CMP_EQUAL/_CMP_GREATER → MAP_CMP_LESS/MAP_CMP_EQUAL/MAP_CMP_GREATER (e.g., breakpoint.c updated).
  • Signatures now use const where appropriate:
    • map_insert(map_t, const void* key, const void* val)
    • map_find(map_t, map_iter_t*, const void* key)
    • map_at_end(map_t, const map_iter_t*)
  • Update comparator helpers if referenced directly; map_cmp_int/map_cmp_uint remain, now force-inlined.

[cubic-dev-ai]

2 issues found across 4 files

Prompt for AI agents (all 2 issues)

Understand the root cause of the following 2 issues and fix them.


<file name="src/map.c">

<violation number="1" location="src/map.c:475">
node-&gt;data may be misaligned due to missing padding after key; align data offset (and adjust allocation size) to avoid UB on strict-alignment platforms.</violation>
</file>

<file name="tests/map/test-map.c">

<violation number="1" location="tests/map/test-map.c:133">
Masking right_red with ~1 is inconsistent with implementation (~3), risking invalid pointer if additional tag bits are used.</violation>
</file>

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