support non-empty-array type in [] != $arr conditions

Author: staabm

src/Analyser/TypeSpecifier.php

@@ -25,6 +25,7 @@
 use PHPStan\Type\Accessory\HasPropertyType;
 use PHPStan\Type\Accessory\NonEmptyArrayType;
 use PHPStan\Type\BooleanType;
+use PHPStan\Type\Constant\ConstantArrayType;
 use PHPStan\Type\Constant\ConstantBooleanType;
 use PHPStan\Type\Constant\ConstantIntegerType;
 use PHPStan\Type\Constant\ConstantStringType;
@@ -374,6 +375,22 @@ public function specifyTypesInCondition(
 				);
 			}
 
+			if (
+				$context->falsey()
+				&& $rightType->isArray()->yes()
+				&& $leftType instanceof ConstantArrayType && $leftType->isEmpty()
+			) {
+				return $this->create($expr->right, new NonEmptyArrayType(), $context->negate(), false, $scope);
+			}
+
+			if (
+				$context->falsey()
+				&& $leftType->isArray()->yes()
+				&& $rightType instanceof ConstantArrayType && $rightType->isEmpty()
+			) {
+				return $this->create($expr->left, new NonEmptyArrayType(), $context->negate(), false, $scope);
+			}
+
 			if (
 				$expr->left instanceof FuncCall
 				&& $expr->left->name instanceof Name

tests/PHPStan/Analyser/data/sizeof.php

@@ -44,4 +44,20 @@ function doFoo4(array $arr): string
 		}
 		return "";
 	}
+
+	function doFoo5(array $arr): void
+	{
+		if ([] != $arr) {
+			assertType('array&nonEmpty', $arr);
+		}
+		assertType('array', $arr);
+	}
+
+	function doFoo6(array $arr): void
+	{
+		if ($arr != []) {
+			assertType('array&nonEmpty', $arr);
+		}
+		assertType('array', $arr);
+	}
 }