Delete commented-out code

How to do it

Remove dead blocks when you stop using them. If you might need them later, the commit history has them. To switch a feature off, use a setting or a feature flag, not a comment.

Example

// Bad: nobody knows if this still matters
// $total = $this->applyLegacyDiscount($total);
$total = $this->applyDiscount($total);

// Good: the old line lives in the history, not in the file
$total = $this->applyDiscount($total);

# A quick check in any repository: lines that look like commented-out code
grep -rnE '^\s*(//|#)\s*[a-zA-Z_$][\w.$]*\s*(\(.*\)|=[^=]).*;?\s*$' src/ && exit 1 || exit 0

How to check

A linter rule or a script fails the build on commented-out code. Examples are eslint-plugin-no-commented-code, SonarQube's commented-out code rule and Ruff's ERA001 for Python.