use_arrow_functions.rst

Rule use_arrow_functions

Anonymous functions with return as the only statement must use arrow functions.

Warning

Using this rule is risky

Risky when using isset() on outside variables that are not imported with use ().

Examples

Example #1

--- Original
+++ New
 <?php
-foo(function ($a) use ($b) {
-    return $a + $b;
-});
+foo(fn ($a) => $a + $b);

Rule sets

The rule is part of the following rule sets:

• @PHP74Migration:risky
• @PHP80Migration:risky
• @PHP82Migration:risky

References

• Fixer class: PhpCsFixer\Fixer\FunctionNotation\UseArrowFunctionsFixer
• Test class: PhpCsFixer\Tests\Fixer\FunctionNotation\UseArrowFunctionsFixerTest

The test class defines officially supported behaviour. Each test case is a part of our backward compatibility promise.