array_shift() should invalidate remembered count() call

Author: ondrejmirtes

src/Analyser/NodeScopeResolver.php

@@ -1478,6 +1478,7 @@ function (MutatingScope $scope) use ($expr, $nodeCallback, $context): Expression
 			) {
 				$arrayArg = $expr->args[0]->value;
 				$constantArrays = TypeUtils::getConstantArrays($scope->getType($arrayArg));
+				$scope = $scope->invalidateExpression($arrayArg);
 				if (count($constantArrays) > 0) {
 					$resultArrayTypes = [];
 
@@ -1489,14 +1490,14 @@ function (MutatingScope $scope) use ($expr, $nodeCallback, $context): Expression
 						}
 					}
 
-					$scope = $scope->invalidateExpression($arrayArg)->specifyExpressionType(
+					$scope = $scope->specifyExpressionType(
 						$arrayArg,
 						TypeCombinator::union(...$resultArrayTypes)
 					);
 				} else {
 					$arrays = TypeUtils::getAnyArrays($scope->getType($arrayArg));
 					if (count($arrays) > 0) {
-						$scope = $scope->invalidateExpression($arrayArg)->specifyExpressionType($arrayArg, TypeCombinator::union(...$arrays));
+						$scope = $scope->specifyExpressionType($arrayArg, TypeCombinator::union(...$arrays));
 					}
 				}
 			}

tests/PHPStan/Analyser/NodeScopeResolverTest.php

@@ -10240,6 +10240,11 @@ public function dataBug3991(): array
 		return $this->gatherAssertTypes(__DIR__ . '/data/bug-3991.php');
 	}
 
+	public function dataBug3993(): array
+	{
+		return $this->gatherAssertTypes(__DIR__ . '/data/bug-3993.php');
+	}
+
 	/**
 	 * @dataProvider dataBug2574
 	 * @dataProvider dataBug2577
@@ -10330,6 +10335,7 @@ public function dataBug3991(): array
 	 * @dataProvider dataArraySliceNonEmpty
 	 * @dataProvider dataBug3990
 	 * @dataProvider dataBug3991
+	 * @dataProvider dataBug3993
 	 * @param string $assertType
 	 * @param string $file
 	 * @param mixed ...$args

tests/PHPStan/Analyser/data/bug-3993.php

@@ -0,0 +1,24 @@
+<?php
+
+namespace Bug3993;
+
+use function PHPStan\Analyser\assertType;
+
+class Foo
+{
+
+	public function doFoo($arguments)
+	{
+		if (!isset($arguments) || count($arguments) === 0) {
+			return;
+		}
+
+		assertType('mixed~null', $arguments);
+
+		array_shift($arguments);
+
+		assertType('mixed~null', $arguments);
+		assertType('int<0, max>', count($arguments));
+	}
+
+}