fix type

Author: staabm

src/Analyser/MutatingScope.php

@@ -1738,7 +1738,11 @@ static function (Node $node, Scope $scope) use ($arrowScope, &$arrowFunctionImpu
 					if ($node instanceof Expr\PreInc) {
 						if ($varValue === '') {
 							$varValue = '1';
-						} elseif (is_string($varValue) && function_exists('str_increment')) {
+						} elseif (
+							is_string($varValue)
+							&& !is_numeric($varValue)
+							&& function_exists('str_increment')
+						) {
 							$varValue = str_increment($varValue);
 						} elseif (!is_bool($varValue)) {
 							++$varValue;

tests/PHPStan/Analyser/nsrt/pre-inc.php

@@ -13,7 +13,7 @@ function doFoo() {
 function doFoo2() {
 	$s = '123';
 	++$s;
-	assertType("'124'", $s);
+	assertType("124", $s);
 }
 
 function doFooBar() {