MAINT014-commented-out-code — commented-out code block

Property	Value
Dimension	Maintainability
Default severity	Info
CWE	CWE-1085
Languages	All

What it detects

Groups consecutive comment lines (no blank line between them) into blocks and checks whether the block looks like commented-out source code rather than human-readable prose.

A block fires when all of the following hold:

1. The block has ≥ 3 lines.
2. ≥ 50% of non-blank lines contain at least one code-like token marker: {, }, ;, =, (, ), or a common keyword (if, else, for, while, return, def, function, let, const, var, fn, pub, impl, class).
3. ≥ 1 line contains structural punctuation ({, }, ;, (, or )).
4. No line matches the annotation pattern ^\s*[A-Z]+: (e.g. TODO:, FIXME:, NOTE:) — those are already covered by DOC002-todo-fixme.

One finding is emitted per block, not per line. Confidence is low: consider this a hint to review, not an actionable defect.

Why it matters

Commented-out code is a maintenance liability: it confuses readers, may contain outdated logic, and inflates diff noise during code review. Source control already preserves history — dead code should be deleted, not hidden behind comment markers.

Examples — flagged

# def old_calculate(x, y):
#     result = x * y
#     if result > 100:
#         return result - 100
#     return result
return x * x

// let old_result = x * 2;
// if old_result > 100 {
//     return old_result - 100;
// }
x * x

// function oldCalculate(x: number, y: number) {
//   const result = x * y;
//   if (result > 100) {
//     return result - 100;
//   }
//   return result;
// }

Examples — not flagged

# This module provides utility functions.
# See the README for usage examples.
# NOTE: This is a simple implementation.

Single-line prose, annotation blocks (TODO/FIXME/NOTE), and blocks that don't reach the minimum density threshold are all suppressed.

Configuration

No configuration knobs in v1. The rule fires at Info severity and Confidence: Low; use zuit: ignore MAINT014-commented-out-code on the first line of the block to suppress individual instances.

Fix

Delete the commented-out code. If you need to preserve context, replace it with a brief prose explanation or a link to the relevant commit/PR.