Fix #973 - allow types to reference other new types in a given docblock

src/Psalm/Checker/CommentChecker.php

@@ -213,7 +213,7 @@ class CommentChecker
                     $type_string,
                     $aliases,
                     null,
-                    $type_aliases
+                    $type_alias_tokens + $type_aliases
                 );
             } catch (TypeParseTreeException $e) {
                 throw new DocblockParseException($type_string . ' is not a valid type');

tests/AnnotationTest.php

@@ -862,7 +862,8 @@ class AnnotationTest extends TestCase
             'typeAliasBeforeFunction' => [
                 '<?php
                     /**
-                     * @psalm-type CoolType = A|B|null
+                     * @psalm-type A_OR_B = A|B
+                     * @psalm-type CoolType = A_OR_B|null
                      * @return CoolType
                      */
                     function foo() {