Handle conditional return type in ArrayMap

src/Type/Php/ArrayMapFunctionReturnTypeExtension.php

@@ -8,6 +8,7 @@
 use PHPStan\Type\Accessory\AccessoryArrayListType;
 use PHPStan\Type\Accessory\NonEmptyArrayType;
 use PHPStan\Type\ArrayType;
+use PHPStan\Type\ConditionalTypeForParameter;
 use PHPStan\Type\Constant\ConstantArrayTypeBuilder;
 use PHPStan\Type\Constant\ConstantIntegerType;
 use PHPStan\Type\DynamicFunctionReturnTypeExtension;
@@ -16,6 +17,7 @@
 use PHPStan\Type\NeverType;
 use PHPStan\Type\Type;
 use PHPStan\Type\TypeCombinator;
+use PHPStan\Type\TypeTraverser;
 use PHPStan\Type\TypeUtils;
 use function array_slice;
 use function count;
@@ -73,7 +75,7 @@ public function getTypeFromFunctionCall(FunctionReflection $functionReflection,
 						foreach ($constantArray->getKeyTypes() as $i => $keyType) {
 							$returnedArrayBuilder->setOffsetValueType(
 								$keyType,
-								$valueType,
+								$this->mapValueType($constantArray->getOffsetValueType($keyType), $valueType),
 								$constantArray->isOptionalKey($i),
 							);
 						}
@@ -88,24 +90,24 @@ public function getTypeFromFunctionCall(FunctionReflection $functionReflection,
 				} else {
 					$mappedArrayType = TypeCombinator::intersect(new ArrayType(
 						$arrayType->getIterableKeyType(),
-						$valueType,
+						$this->mapValueType($arrayType->getIterableValueType(), $valueType),
 					), ...TypeUtils::getAccessoryTypes($arrayType));
 				}
 			} elseif ($arrayType->isArray()->yes()) {
 				$mappedArrayType = TypeCombinator::intersect(new ArrayType(
 					$arrayType->getIterableKeyType(),
-					$valueType,
+					$this->mapValueType($arrayType->getIterableValueType(), $valueType),
 				), ...TypeUtils::getAccessoryTypes($arrayType));
 			} else {
 				$mappedArrayType = new ArrayType(
 					new MixedType(),
-					$valueType,
+					$this->mapValueType($arrayType->getIterableValueType(), $valueType),
 				);
 			}
 		} else {
 			$mappedArrayType = TypeCombinator::intersect(new ArrayType(
 				new IntegerType(),
-				$valueType,
+				$this->mapValueType($arrayType->getIterableValueType(), $valueType),
 			), ...TypeUtils::getAccessoryTypes($arrayType));
 		}
 
@@ -116,4 +118,15 @@ public function getTypeFromFunctionCall(FunctionReflection $functionReflection,
 		return $mappedArrayType;
 	}
 
+	private function mapValueType(Type $initialValue, Type $returnType): Type
+	{
+		return TypeTraverser::map($returnType, static function (Type $type, callable $traverse) use ($initialValue): Type {
+			if ($type instanceof ConditionalTypeForParameter) {
+				$type = $type->toConditional($initialValue);
+			}
+
+			return $traverse($type);
+		});
+	}
+
 }

tests/PHPStan/Rules/Methods/ReturnTypeRuleTest.php

@@ -1044,6 +1044,11 @@ public function testBug3759(): void
 		$this->analyse([__DIR__ . '/data/bug-3759.php'], []);
 	}
 
+	public function testBug10715(): void
+	{
+		$this->analyse([__DIR__ . '/data/bug-10715.php'], []);
+	}
+
 	public function testBug11337(): void
 	{
 		$this->analyse([__DIR__ . '/data/bug-11337.php'], []);

tests/PHPStan/Rules/Methods/data/bug-10715.php

@@ -0,0 +1,30 @@
+<?php declare(strict_types = 1);
+
+namespace Bug10715;
+
+class Test
+{
+	/**
+	 * @param string|array<string> $word
+	 *
+	 * @return ($word is array<string> ? array<string> : string)
+	 */
+	public static function wgtrim(string|array $word): string|array
+	{
+		if (\is_array($word)) {
+			return array_map(static::wgtrim(...), $word);
+		}
+
+		return 'word';
+	}
+
+	/**
+	 * @param array{foo: array<string>, bar: string} $array
+	 *
+	 * @return array{foo: array<string>, bar: string}
+	 */
+	public static function example(array $array): array
+	{
+		return array_map(static::wgtrim(...), $array);
+	}
+}