PHPStan: Building a Strict PHP Codebase

Adopt stricter PHPStan checks incrementally, using precise PHPDoc collection types and CI checks instead of ignoring warnings.

What It Does

Start with a reachable analysis level. A non-empty-list annotation expresses a stronger input contract.

Requirements and Compatibility

Use a supported PHP runtime and install any third-party tool or extension explicitly shown in the examples. Commands should be run from the project root unless stated otherwise.

Syntax, Inputs and Results

The examples separate configuration, the smallest working operation and a realistic follow-up task. Adapt file paths and dependency versions to your own project.

Example 1: Basic Use

Start with a reachable analysis level.

composer require --dev phpstan/phpstan
vendor/bin/phpstan analyse src --level=6
vendor/bin/phpstan analyse --level=max

Example 2: Another Case

A non-empty-list annotation expresses a stronger input contract.

<?php
/** @param non-empty-list<int> $prices */
function maxPrice(array $prices): int { return max($prices); }
echo maxPrice([10,20,15]);

Practical Example

Move toward strict rules and track pre-existing findings explicitly.

vendor/bin/phpstan analyse --level=max
vendor/bin/phpstan analyse --generate-baseline
vendor/bin/phpstan analyse --level=max

For production, apply the compatibility and edge-case limits described below.

Important Behavior and Edge Cases

A baseline should document known debt, not become a permanent substitute for correcting type errors.

Comparison with Related Functions and Tools

Subject	Key difference
Static analysis vs runtime tests	PHPStan checks source types without executing business behavior; tests confirm actual outcomes.

Common Beginner Mistakes

Mistake	Correct approach
Ignoring unknown or mixed types	Add valid PHPDoc element types or proper native declarations, then re-run the analyzer.
Skipping the prerequisite of this specific workflow	Install or configure the named tool and confirm the example can actually run.
Ignoring edge conditions	A baseline should document known debt, not become a permanent substitute for correcting type errors.

Key Takeaways

Adopt stricter PHPStan checks incrementally, using precise PHPDoc collection types and CI checks instead of ignoring warnings.
A baseline should document known debt, not become a permanent substitute for correcting type errors.
Keep application configuration, source code and validation tests under version control.

Use these examples as a starting point, then validate the result with the actual PHP build, dependencies and inputs used by your application.