Inconsistent Indentation

Also Known As

TL;DR

Explanation

PSR-1/PSR-12 mandates 4 spaces per indent level, no tabs. Inconsistent indentation typically enters codebases when developers with different editor settings commit without formatting, or when code is pasted from an external source. .editorconfig and PHP-CS-Fixer enforce consistent indentation automatically. Mixed tabs and spaces are the worst offender — the visual appearance depends entirely on the editor's tab-width setting.

Common Misconception

Why It Matters

Common Mistakes

• Pasting code from Stack Overflow or documentation that uses 2-space or tab indentation.
• Editor auto-indent set to tabs in a spaces project.
• Using 2 spaces for nested closures 'to save horizontal space'.
• Not having .editorconfig in the repository to enforce consistent settings across all editors.

Code Examples

<?php
function calculate(int $x): int
{
	$result = 0;        // Tab
    if ($x > 0) {     // 4 spaces
      $result = $x;   // 2 spaces — 3 different styles in 4 lines
    }
    return $result;
}

// .editorconfig in project root:
[*.php]
indent_style = space
indent_size = 4

// .php-cs-fixer.dist.php:
'indentation_type' => true,  // Enforces 4-space indentation

<?php
function calculate(int $x): int
{
    $result = 0;
    if ($x > 0) {
        $result = $x;
    }
    return $result;
}

References

• ↗ https://www.php-fig.org/psr/psr-12/#24-lines

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