In a nutshell

PHPStan is a linter for PHP, similar to ESLint for JavaScript.

Install

composer require --dev phpstan/phpstan

Analyse using config file

Ensure you have a phpstan.neon or phpstan.neon.dist file and run:

vendor/bin/phpstan

Create config file (phpstan.neon)

Minimal config file:

parameters:
	level: 9
	paths:
		- src
		- tests

Analyse with default rule (0)

vendor/bin/phpstan analyse <directories>

Analyse with specific rule

vendor/bin/phpstan analyse -l <0-9> directories

Configure rules

You can choose a level from 0 to 9 (0 is the loosest and 9 is the highest):

• 0. basic checks, unknown classes, unknown functions, unknown methods called on $this, wrong number of arguments passed to those methods and functions, always undefined variables
• 1. possibly undefined variables, unknown magic methods and properties on classes with call and get
• 2. unknown methods checked on all expressions (not just $this), validating PHPDocs
• 3. return types, types assigned to properties
• 4. basic dead code checking – always false instanceof and other type checks, dead else branches, unreachable code after return; etc.
• 5. checking types of arguments passed to methods and functions
• 6. report missing typehints
• 7. report partially wrong union types – if you call a method that only exists on some types in a union type, level 7 starts to report that; other possibly incorrect situations
• 8. report calling methods and accessing properties on nullable types
• 9. be strict about the mixed type – the only allowed operation you can do with it is to pass it to another mixed

Add more strictness

Install the phpstan/phpstan-strict-rules package: