MixedAssignment

Emitted when assigning an unannotated variable to a value for which Psalm cannot infer a type more specific than mixed.

$a = $_GET['foo'];

The above example can be fixed in a few ways – by adding an assert call:

$a = $_GET['foo'];
assert(is_string($a));

or by adding an explicit cast:

$a = (string) $_GET['foo'];

or by adding a docblock

/** @var string */
$a = $_GET['foo'];