feat(hako_check): Phase 154 MIR CFG integration & HC020 dead block detection
Implements block-level unreachable code detection using MIR CFG information.
Complements Phase 153's method-level HC019 with fine-grained analysis.
Core Infrastructure (Complete):
- CFG Extractor: Extract block reachability from MirModule
- DeadBlockAnalyzerBox: HC020 rule for unreachable blocks
- CLI Integration: --dead-blocks flag and rule execution
- Test Cases: 4 comprehensive patterns (early return, constant false, infinite loop, break)
- Smoke Test: Validation script for all test cases
Implementation Details:
- src/mir/cfg_extractor.rs: New module for CFG→JSON extraction
- tools/hako_check/rules/rule_dead_blocks.hako: HC020 analyzer box
- tools/hako_check/cli.hako: Added --dead-blocks flag and HC020 integration
- apps/tests/hako_check/test_dead_blocks_*.hako: 4 test cases
Architecture:
- Follows Phase 153 boxed modular pattern (DeadCodeAnalyzerBox)
- Optional CFG field in Analysis IR (backward compatible)
- Uses MIR's built-in reachability computation
- Gracefully skips if CFG unavailable
Known Limitation:
- CFG data bridge pending (Phase 155): analysis_consumer.hako needs MIR access
- Current: DeadBlockAnalyzerBox implemented, but CFG not yet in Analysis IR
- Estimated 2-3 hours to complete bridge in Phase 155
Test Coverage:
- Unit tests: cfg_extractor (simple CFG, unreachable blocks)
- Integration tests: 4 test cases ready (will activate with bridge)
- Smoke test: tools/hako_check_deadblocks_smoke.sh
Documentation:
- phase154_mir_cfg_inventory.md: CFG structure investigation
- phase154_implementation_summary.md: Complete implementation guide
- hako_check_design.md: HC020 rule documentation
Next Phase 155:
- Implement CFG data bridge (extract_mir_cfg builtin)
- Update analysis_consumer.hako to call bridge
- Activate HC020 end-to-end testing
🤖 Generated with Claude Code (https://claude.com/claude-code)
Co-Authored-By: Claude <noreply@anthropic.com>
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