From 9c2d24c0010953a03d1830a37ff7cfb9569ee779 Mon Sep 17 00:00:00 2001
From: Pieter Vanderwerff <pieterv@meta.com>
Date: Wed, 26 Apr 2023 19:35:46 -0700
Subject: [PATCH] Ensure reparseTypeAnnotationAsIdFlow checks for type
 parameters

Summary: The `reparseTypeAnnotationAsIdFlow`

Reviewed By: avp

Differential Revision: D45331985

fbshipit-source-id: 5f44610243aacf0cfbffb937ea327a318ef08002
---
 lib/Parser/JSParserImpl-flow.cpp                    |  6 ++++--
 .../flow/predicate-asserts-type-params-error.js     | 13 +++++++++++++
 2 files changed, 17 insertions(+), 2 deletions(-)
 create mode 100644 test/Parser/flow/predicate-asserts-type-params-error.js

diff --git a/lib/Parser/JSParserImpl-flow.cpp b/lib/Parser/JSParserImpl-flow.cpp
index 4881ce164bd..cadebbd7843 100644
--- a/lib/Parser/JSParserImpl-flow.cpp
+++ b/lib/Parser/JSParserImpl-flow.cpp
@@ -3093,8 +3093,10 @@ Optional<UniqueString *> JSParserImpl::reparseTypeAnnotationAsIdFlow(
   } else if (
       auto *generic =
           dyn_cast<ESTree::GenericTypeAnnotationNode>(typeAnnotation)) {
-    if (auto *genericId = dyn_cast<ESTree::IdentifierNode>(generic->_id)) {
-      id = genericId->_name;
+    if (!generic->_typeParameters) {
+      if (auto *genericId = dyn_cast<ESTree::IdentifierNode>(generic->_id)) {
+        id = genericId->_name;
+      }
     }
   }
 
diff --git a/test/Parser/flow/predicate-asserts-type-params-error.js b/test/Parser/flow/predicate-asserts-type-params-error.js
new file mode 100644
index 00000000000..40ae5baba21
--- /dev/null
+++ b/test/Parser/flow/predicate-asserts-type-params-error.js
@@ -0,0 +1,13 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+// RUN: (! %hermesc -parse-flow -dump-ast -pretty-json %s 2>&1) | %FileCheck %s --match-full-lines
+
+function foo(x: mixed): asserts<foo> x is number {}
+// CHECK: {{.*}}:10:25: error: identifier expected
+// CHECK: function foo(x: mixed): asserts<foo> x is number {}
+// CHECK:                         ^~~~~~~~~~~~