Cover non-empty-array in array_merge

Author: staabm

src/Type/Php/ArrayMergeFunctionDynamicReturnTypeExtension.php

@@ -6,6 +6,7 @@
 use PHPStan\Analyser\Scope;
 use PHPStan\Reflection\FunctionReflection;
 use PHPStan\Reflection\ParametersAcceptorSelector;
+use PHPStan\Type\Accessory\NonEmptyArrayType;
 use PHPStan\Type\ArrayType;
 use PHPStan\Type\GeneralizePrecision;
 use PHPStan\Type\Type;
@@ -29,6 +30,7 @@ public function getTypeFromFunctionCall(FunctionReflection $functionReflection,
 
 		$keyTypes = [];
 		$valueTypes = [];
+		$nonEmpty = false;
 		foreach ($functionCall->args as $arg) {
 			$argType = $scope->getType($arg->value);
 			if ($arg->unpack) {
@@ -42,12 +44,24 @@ public function getTypeFromFunctionCall(FunctionReflection $functionReflection,
 
 			$keyTypes[] = TypeUtils::generalizeType($argType->getIterableKeyType(), GeneralizePrecision::moreSpecific());
 			$valueTypes[] = $argType->getIterableValueType();
+
+			if (!$argType->isIterableAtLeastOnce()->yes()) {
+				continue;
+			}
+
+			$nonEmpty = true;
 		}
 
-		return new ArrayType(
+		$arrayType = new ArrayType(
 			TypeCombinator::union(...$keyTypes),
 			TypeCombinator::union(...$valueTypes)
 		);
+
+		if ($nonEmpty) {
+			$arrayType = TypeCombinator::intersect($arrayType, new NonEmptyArrayType());
+		}
+
+		return $arrayType;
 	}
 
 }

tests/PHPStan/Analyser/LegacyNodeScopeResolverTest.php

@@ -5129,31 +5129,31 @@ public function dataArrayFunctions(): array
 				'array_values($generalStringKeys)',
 			],
 			[
-				'array<int|non-empty-string, stdClass>',
+				'array<int|non-empty-string, stdClass>&nonEmpty',
 				'array_merge($stringOrIntegerKeys)',
 			],
 			[
 				'array<int|string, DateTimeImmutable|int>',
 				'array_merge($generalStringKeys, $generalDateTimeValues)',
 			],
 			[
-				'array<int|string, int|stdClass>',
+				'array<int|string, int|stdClass>&nonEmpty',
 				'array_merge($generalStringKeys, $stringOrIntegerKeys)',
 			],
 			[
-				'array<int|string, int|stdClass>',
+				'array<int|string, int|stdClass>&nonEmpty',
 				'array_merge($stringOrIntegerKeys, $generalStringKeys)',
 			],
 			[
-				'array<int|non-empty-string, \'foo\'|stdClass>',
+				'array<int|non-empty-string, \'foo\'|stdClass>&nonEmpty',
 				'array_merge($stringKeys, $stringOrIntegerKeys)',
 			],
 			[
-				'array<int|non-empty-string, \'foo\'|stdClass>',
+				'array<int|non-empty-string, \'foo\'|stdClass>&nonEmpty',
 				'array_merge($stringOrIntegerKeys, $stringKeys)',
 			],
 			[
-				'array<int|non-empty-string, 2|4|\'a\'|\'b\'|\'green\'|\'red\'|\'trapezoid\'>',
+				'array<int|non-empty-string, 2|4|\'a\'|\'b\'|\'green\'|\'red\'|\'trapezoid\'>&nonEmpty',
 				'array_merge(array("color" => "red", 2, 4), array("a", "b", "color" => "green", "shape" => "trapezoid", 4))',
 			],
 			[

tests/PHPStan/Analyser/data/non-empty-array.php

@@ -42,5 +42,10 @@ public function arrayFunctions($array, $list): void
 	{
 		assertType('array&nonEmpty', array_combine($array, $array));
 		assertType('array&nonEmpty', array_combine($list, $list));
+
+		assertType('array&nonEmpty', array_merge($array));
+		assertType('array&nonEmpty', array_merge([], $array));
+		assertType('array&nonEmpty', array_merge($array, []));
+		assertType('array&nonEmpty', array_merge($array, $array));
 	}
 }