Fix #10552

src/Psalm/Internal/Analyzer/Statements/Expression/Call/MethodCallAnalyzer.php

@@ -28,11 +28,13 @@
 use Psalm\Issue\UndefinedMethod;
 use Psalm\IssueBuffer;
 use Psalm\Type;
+use Psalm\Type\Atomic\TConditional;
 use Psalm\Type\Atomic\TNamedObject;
 use Psalm\Type\Atomic\TObject;
 use Psalm\Type\Atomic\TTemplateParam;
 use Psalm\Type\Union;
 
+use function array_merge;
 use function array_reduce;
 use function count;
 use function is_string;
@@ -175,6 +177,17 @@ public static function analyze(
 
         $lhs_types = $class_type->getAtomicTypes();
 
+        foreach ($lhs_types as $k => $lhs_type_part) {
+            if ($lhs_type_part instanceof TConditional) {
+                $lhs_types = array_merge(
+                    $lhs_types,
+                    $lhs_type_part->if_type->getAtomicTypes(),
+                    $lhs_type_part->else_type->getAtomicTypes(),
+                );
+                unset($lhs_types[$k]);
+            }
+        }
+
         $result = new AtomicMethodCallAnalysisResult();
 
         $possible_new_class_types = [];
@@ -398,7 +411,7 @@ public static function analyze(
             $types = $class_type->getAtomicTypes();
 
             foreach ($types as $key => &$type) {
-                if (!$type instanceof TNamedObject && !$type instanceof TObject) {
+                if (!$type instanceof TNamedObject && !$type instanceof TObject && !$type instanceof TConditional) {
                     unset($types[$key]);
                 } else {
                     $type = $type->setFromDocblock(false);

tests/MethodCallTest.php

@@ -1230,6 +1230,27 @@ public function bar(&$object): void {}
                     $x = new Foo();
                     $x->bar($x);',
             ],
+            'conditional' => [
+                'code' => '<?php
+
+                    class Old {
+                        public function x(): void {}
+                    }
+                    class Child1 extends Old {}
+                    class Child2 extends Old {}
+
+                    /**
+                     * @template IsClient of bool
+                     */
+                    class A {
+                        /**
+                         * @psalm-param (IsClient is true ? Child1 : Child2) $var
+                         */
+                        public function test(Old $var): void {
+                            $var->x();
+                        }
+                    }',
+            ],
         ];
     }