Make sure to clear previously inferred types when rechecking trait statements

Fixes #399

src/Psalm/Checker/Statements/Expression/CallChecker.php

@@ -1237,6 +1237,8 @@ class CallChecker
         $project_checker = $file_checker->project_checker;
         $source = $statements_checker->getSource();
 
+        $stmt->inferredType = null;
+
         if ($stmt->class instanceof PhpParser\Node\Name) {
             $fq_class_name = null;
 

tests/TraitTest.php

@@ -332,6 +332,26 @@ class TraitTest extends TestCase
                       use T;
                     }',
             ],
+            'differentMethodReturnTypes' => [
+                '<?php
+                    trait T {
+                        public static function getSelf() : self {
+                            return new self();
+                        }
+
+                        public static function callGetSelf() : self {
+                            return self::getSelf();
+                        }
+                    }
+
+                    class A {
+                        use T;
+                    }
+
+                    class B {
+                        use T;
+                    }',
+            ],
         ];
     }