Cast PHPDoc array key type with array key casting rules

src/PhpDoc/TypeNodeResolver.php

@@ -456,7 +456,7 @@ private function resolveGenericTypeNode(GenericTypeNode $typeNode, NameScope $na
 					new IntegerType(),
 					new StringType(),
 				]));
-				$arrayType = new ArrayType($keyType, $genericTypes[1]);
+				$arrayType = new ArrayType(!$keyType instanceof NeverType ? ArrayType::castToArrayKeyType($keyType) : $keyType, $genericTypes[1]);
 			} else {
 				return new ErrorType();
 			}

tests/PHPStan/Rules/Properties/TypesAssignedToPropertiesRuleTest.php

@@ -382,4 +382,9 @@ public function testBug3339(): void
 		$this->analyse([__DIR__ . '/data/bug-3339.php'], []);
 	}
 
+	public function testBug6117(): void
+	{
+		$this->analyse([__DIR__ . '/data/bug-6117.php'], []);
+	}
+
 }

tests/PHPStan/Rules/Properties/data/bug-6117.php

@@ -0,0 +1,32 @@
+<?php declare(strict_types = 1);
+
+namespace Bug6117;
+
+final class Mapping
+{
+}
+
+final class Stuff
+{
+	/**
+	 * @var string
+	 */
+	const CATEGORY_TYPE_ONE = '44';
+
+	/**
+	 * @var string
+	 */
+	const CATEGORY_TYPE_TWO = '45';
+
+	/**
+	 * @var array<self::CATEGORY_*, Mapping>
+	 */
+	private $mappings = [];
+
+	public function testMe(): void
+	{
+		$this->mappings[self::CATEGORY_TYPE_TWO] = new Mapping();
+
+		$this->mappings[(string)self::CATEGORY_TYPE_TWO] = new Mapping();
+	}
+}