Reproducer

Author: VincentLanglet

.github/workflows/e2e-tests.yml

@@ -282,6 +282,9 @@ jobs:
               cd e2e/ignore-error-extension
               composer install
               ../../bin/phpstan
+          - script: |
+              cd e2e/bug-10483
+              ../../bin/phpstan
 
     steps:
       - name: "Checkout"

e2e/bug-10483/bug-10483.php

@@ -0,0 +1,7 @@
+<?php
+
+define("FILTER_VALIDATE_FLOAT",false);
+
+$mixed = doFoo();
+if (filter_var($mixed, FILTER_VALIDATE_BOOLEAN)) {
+}

e2e/bug-10483/phpstan.dist.neon

@@ -0,0 +1,4 @@
+parameters:
+    level: 9
+    paths:
+        - bug-10483.php