Use Case: sveltejs/svelte - The Svelte Compiler

Repository: https://github.com/sveltejs/svelte Stack: TypeScript/JavaScript Test Date: 2025-12-08 Loctree Version: 0.6.2-dev

Overview

Testing loctree on THE Svelte compiler source - the core that powers the Svelte framework.

Repository Scale

Metric	Value
Files Scanned	405
Analysis Time	~30 seconds
Throughput	13.5 files/sec

Findings

Dead Code Detection

High Confidence: 47 candidates
False Positive Rate: 70%
True Positives: 3-4 genuinely dead internal functions

Confirmed Dead Code

ELEMENTS_WITHOUT_TEXT
log_reactions
not_equal
bind_props

False Positive Categories

TypeScript .d.ts re-exports (60% of FPs) - easing functions, SSR functions
Compiler-generated usage (30% of FPs) - functions used by compiled .svelte output
Dynamic references (10% of FPs) - runtime lookups, reflection patterns

Additional Findings

Dead Parrots: 3,942 (TypeScript definition duplicates)
Circular Dependencies: 15 (6 architectural, 9 test fixtures)

Commands Used

cd svelte-core
loct                              # Create snapshot
loct dead --confidence high       # Dead code analysis
loct cycles                       # Circular dependencies
loct twins                        # Duplicate detection

Verdict

PASSED with caveats - Excellent for internal dead code, needs --library-mode for public API.

Key Insights

Internal dead code: 100% accurate (3/3 true positives)
Public API exports: 70% FP (expected for library codebases)
Value delivered: Identified 3-4 genuinely dead functions for cleanup

Recommendations

Use --library-mode flag when analyzing framework/library source
Focus on internal modules, not public API barrel exports
Cross-reference with package.json exports field