marcelorodrigo/phpstan-fixer

PHPStan Error Fixer

Fix PHPStan static analysis errors through proper type annotations, PHPDocs, and code improvements. This skill teaches agents how to resolve errors without suppressing them, respecting the project's configured strictness level.

Core Principles

1. Never suppress errors as first resort — Fix the root cause with proper types and annotations
2. Respect user configuration — Never modify phpstan.neon settings (level, paths, parameters)
3. No silent ignoring — Never add ignoreErrors to config without explicit user approval
4. Context-aware fixes — Understand the project type (Laravel, Symfony, vanilla PHP) before proposing solutions
5. Ask before ignoring — If a legitimate ignore is needed, explain why and get user approval first
6. Don't fix third-party code — Never modify files in vendor/. Use stub files instead to override wrong types

Workflow

Step 1: Understand the Project Context

Before fixing errors, identify the project type:

# Check for Laravel
grep laravel/framework composer.json

# Check for Symfony
grep symfony/symfony composer.json

# Check for PHPStan extensions
grep phpstan composer.json

# Read PHPStan config
cat phpstan.neon

# Check project guidelines
cat AGENTS.md

Key information to extract:

• PHPStan level (0-10, or max)
• Installed PHPStan extensions (larastan, phpstan-strict-rules, etc.)
• Framework-specific helpers (Laravel IDE Helper, Symfony plugin)
• Project-specific type conventions

Step 2: Analyze the Error

PHPStan errors have this structure:

------ ----------------------------------------------
Line   /path/to/File.php
------ ----------------------------------------------
42     Parameter $user of method foo() has invalid
       type App\User.
       💡 Identifier: parameter.type
------ ----------------------------------------------

Extract:

1. Error identifier (e.g., parameter.type, missingType.return)
2. Error location (file, line number)
3. Context (what's the code trying to do?)

Step 3: Apply the Right Fix

Use the error identifier to determine the fix strategy:

Step 4: Verify the Fix

After applying fixes, run PHPStan again to confirm:

vendor/bin/phpstan analyse

Important:

• If new errors appear, the fix may have been incorrect. Re-analyze the error and try a different approach.
• If the same error persists, the fix wasn't applied correctly. Double-check the code.
• If errors are resolved, mark the fix as successful and move to the next error.

---

Common Error Fixes

Type-Related Errors

missingType.parameter — Missing parameter type

Error:

Parameter $name has no type specified.

Fix — Add native type:

// Before
function greet($name) {
    return "Hello, $name";
}

// After
function greet(string $name): string {
    return "Hello, $name";
}

Fix — Use PHPDoc for complex types:

// Before
function processUsers($users) { ... }

// After
/**
 * @param array<int, User> $users
 */
function processUsers(array $users): void { ... }

---

missingType.return — Missing return type

Error:

Method foo() has no return type specified.

Fix — Add native return type:

// Before
public function getUser() {
    return $this->user;
}

// After
public function getUser(): User {
    return $this->user;
}

Fix — Use PHPDoc for union/intersection types:

// Before
public function findUser($id) { ... }

// After
/**
 * @return User|null
 */
public function findUser(int $id): ?User { ... }

---

argument.type — Wrong argument type

Error:

Parameter #1 $id of method find() expects int, string given.

Fix — Cast the argument:

// Before
$user = $repository->find($request->input('id'));

// After
$user = $repository->find((int) $request->input('id'));

Fix — Narrow the type earlier:

// Better approach
$id = $request->integer('id'); // Laravel helper
$user = $repository->find($id);

---

return.type — Wrong return type

Error:

Method foo() should return User but returns User|null.

Fix — Adjust return type:

// Before
public function getUser(): User {
    return $this->user ?? null;
}

// After
public function getUser(): ?User {
    return $this->user ?? null;
}

Fix — Ensure non-null with assertion:

public function getUser(): User {
    assert($this->user !== null);
    return $this->user;
}

---

Property Errors

property.notFound — Undefined property access

Error:

Access to an undefined property User::$name.

Fix — Add property declaration:

class User {
    private string $name;
    
    public function __construct(string $name) {
        $this->name = $name;
    }
}

Fix — Document magic property:

/**
 * @property string $name
 */
class User {
    public function __get($key) { ... }
}

Fix (Laravel) — Use IDE Helper:

# Generate PHPDocs for Eloquent models
php artisan ide-helper:models

---

property.onlyWritten — Property written but never read

Error:

Property User::$name is never read, only written.

Fix — Remove unused property or add getter:

// If truly unused, remove it
// If needed, add usage:
public function getName(): string {
    return $this->name;
}

---

Method Errors

method.notFound — Undefined method call

Error:

Call to an undefined method App\User::getFullName().

Fix — Add method:

class User {
    public function getFullName(): string {
        return $this->first_name . ' ' . $this->last_name;
    }
}

Fix — Document magic method:

/**
 * @method string getFullName()
 */
class User {
    public function __call($method, $args) { ... }
}

Fix (Laravel) — Add to @mixin for query builders:

/**
 * @mixin \Illuminate\Database\Eloquent\Builder
 */
class User extends Model { ... }

---

Array/Offset Errors

offsetAccess.notFound — Undefined array offset

Error:

Offset 'email' does not exist on array.

Fix — Use array shape PHPDoc:

/**
 * @param array{email: string, name: string} $data
 */
function createUser(array $data): void {
    echo $data['email']; // PHPStan knows this exists
}

Fix — Add existence check:

if (isset($data['email'])) {
    echo $data['email'];
}

Fix — Use null coalescing:

$email = $data['email'] ?? '[email protected]';

---

Generics Errors

missingType.generics — Missing generic type

Error:

Class Collection has @template T but does not specify it.

Fix — Specify generic type in PHPDoc:

// Before
/** @var Collection $users */
$users = User::all();

// After
/** @var Collection<int, User> $users */
$users = User::all();

Fix (Laravel) — Use IDE Helper stubs for collections.

---

Dead Code Errors

deadCode.unreachable — Unreachable code

Error:

Unreachable statement - code above always terminates.

Fix — Remove dead code:

// Before
function foo() {
    return true;
    echo "This never runs"; // Error
}

// After
function foo() {
    return true;
}

---

identical.alwaysTrue / identical.alwaysFalse — Condition is always true/false

Error:

Strict comparison using === between int and string will always evaluate to false.

Fix — Remove useless condition or fix type:

// Before
if ($id === '123') { ... } // $id is int

// After
if ($id === 123) { ... }

---

Framework-Specific Fixes

Laravel

Install Larastan for Laravel-aware analysis:

composer require --dev larastan/larastan

Check phpstan.neon includes Larastan (ask user to add if missing):

includes:
    - vendor/larastan/larastan/extension.neon

Common Laravel fixes:

// Eloquent relationships - use @property PHPDoc
/**
 * @property-read \Illuminate\Database\Eloquent\Collection<int, Post> $posts
 */
class User extends Model {
    public function posts() {
        return $this->hasMany(Post::class);
    }
}

// Collections - specify generic types
/** @var \Illuminate\Support\Collection<int, User> $users */
$users = User::all();

// Request input - use typed helpers
$id = $request->integer('id'); // Not $request->input('id')
$email = $request->string('email')->toString();

Symfony

Install Symfony PHPStan extension:

composer require --dev phpstan/phpstan-symfony

Check phpstan.neon includes Symfony extension (ask user to add if missing):

includes:
    - vendor/phpstan/phpstan-symfony/extension.neon
parameters:
    symfony:
        containerXmlPath: var/cache/dev/App_KernelDevDebugContainer.xml

Common Symfony fixes:

// Service container - use proper type hints
public function __construct(
    private UserRepository $userRepository, // Not mixed
) {}

// Forms - type the data
/** @var array{email: string, password: string} $data */
$data = $form->getData();

---

When Ignoring is Acceptable (Last Resort)

Sometimes a legitimate ignore is needed. Always ask the user first using the Question tool:

Step 1: Explain the situation

I found a PHPStan error that cannot be easily fixed:

Error: [describe error]
Location: [file:line]
Reason: [explain why it can't be fixed]

Step 2: Use Question tool to get user choice

Use the Question tool with these options:
- Header: "PHPStan Error Resolution"
- Question: "How would you like to handle this error?"
- Options:
  1. "Use @phpstan-ignore with comment" - description: "Add inline ignore with explanation (recommended for third-party type issues)"
  2. "Add to baseline" - description: "Generate baseline file (recommended for legacy code migration)"
  3. "Refactor code" - description: "Modify code to satisfy PHPStan (most robust but may require significant changes)"
  4. "Skip for now" - description: "Leave unfixed and continue with other errors"

Example Question tool usage:

{
  "questions": [{
    "header": "PHPStan Error Resolution",
    "question": "File src/Service.php:42 has argument type mismatch with third-party API. How should I handle this?",
    "options": [
      {
        "label": "Use @phpstan-ignore (Recommended)",
        "description": "Add inline ignore with explanation"
      },
      {
        "label": "Add to baseline",
        "description": "Include in baseline file for tracking"
      },
      {
        "label": "Refactor code",
        "description": "Modify to satisfy PHPStan"
      },
      {
        "label": "Skip for now",
        "description": "Continue with other errors"
      }
    ]
  }]
}

Valid reasons for ignoring:

• Third-party library with wrong types (and no stub file available)
• Reflection-based code that's correct but PHPStan can't understand
• Complex business logic that's type-safe at runtime but not provably so statically
• Temporary during large refactoring (use baseline)

How to ignore (if approved):

// Inline ignore with explanation
/** @phpstan-ignore argument.type (API returns string|int, we handle both) */
$result = $api->getValue();

// Baseline for legacy code
vendor/bin/phpstan analyse --generate-baseline

Never do this without approval:

# Don't add this to phpstan.neon without user consent
parameters:
    ignoreErrors:
        - '#.*#' # NEVER

---

Debugging Types

Use \PHPStan\dumpType() to see what PHPStan thinks:

$user = User::find($id);
\PHPStan\dumpType($user); // Reports: App\User|null

// Remove before committing!

---

Troubleshooting

PHPStan doesn't recognize a valid type

Check:

1. Is the class autoloadable? (composer dump-autoload)
2. Does PHPStan scan the file? (Check paths in phpstan.neon)
3. Is there a typo in the namespace?

Type inference doesn't work

Check:

1. Are you using inline @var too much? (Fix at source instead)
2. Is the function/method return type specified?
3. Are you using dynamic features PHPStan can't analyze?

Laravel magic methods not recognized

Install and run:

composer require --dev barryvdh/laravel-ide-helper
php artisan ide-helper:generate
php artisan ide-helper:models --write
php artisan ide-helper:meta

---

Error Identifier Reference

Full list: https://phpstan.org/error-identifiers

Most common categories:

• argument.* — Function/method argument issues
• return.* — Return type mismatches
• missingType.* — Missing type declarations
• property.* — Property access/declaration issues
• method.* — Method call issues
• offsetAccess.* — Array/ArrayAccess issues
• class.* — Class inheritance/usage issues
• deadCode.* — Unreachable code
• identical.* / equal.* — Comparison issues

---

Resources

• PHPStan User Guide
• PHPDoc Types
• Error Identifiers
• Troubleshooting Types
• Larastan (Laravel)
• PHPStan Symfony Extension