From d2737044fafa735ddd9165870df95e0637a6a855 Mon Sep 17 00:00:00 2001
From: Jake Bailey <5341706+jakebailey@users.noreply.github.com>
Date: Mon, 28 Mar 2022 15:23:25 -0700
Subject: [PATCH 1/2] Add failing test case

---
 .../completionsOverridingMethodCrash1.ts      | 28 +++++++++++++++++++
 1 file changed, 28 insertions(+)
 create mode 100644 tests/cases/fourslash/completionsOverridingMethodCrash1.ts

diff --git a/tests/cases/fourslash/completionsOverridingMethodCrash1.ts b/tests/cases/fourslash/completionsOverridingMethodCrash1.ts
new file mode 100644
index 0000000000000..49233409b485a
--- /dev/null
+++ b/tests/cases/fourslash/completionsOverridingMethodCrash1.ts
@@ -0,0 +1,28 @@
+/// <reference path="fourslash.ts" />
+
+// @newline: LF
+// @Filename: a.ts
+////declare class Component<T> {
+////    setState(stateHandler: ((oldState: T, newState: T) => void)): void;
+////}
+////
+////class SubComponent extends Component<{}> {
+////    /*$*/
+////}
+
+verify.completions({
+    marker: "$",
+    isNewIdentifierLocation: true,
+    preferences: {
+        includeCompletionsWithInsertText: true,
+        includeCompletionsWithSnippetText: false,
+        includeCompletionsWithClassMemberSnippets: true,
+    },
+    includes: [
+        {
+            name: "setState",
+            sortText: completion.SortText.ClassMemberSnippets,
+            insertText: "setState(stateHandler: (oldState: {}, newState: {}) => void): void {\n}",
+        }
+    ]
+});

From 944315e1753132bed70021145a3a3e2c0248fa5f Mon Sep 17 00:00:00 2001
From: Jake Bailey <5341706+jakebailey@users.noreply.github.com>
Date: Wed, 30 Mar 2022 13:39:24 -0700
Subject: [PATCH 2/2] Ensure that we copy empty NodeArrays during transform

---
 src/compiler/checker.ts | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 1cd7e00d0dd6c..ec9a5fe31499d 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -5239,7 +5239,18 @@ namespace ts {
                         if (!nodeIsSynthesized(node) && getParseTreeNode(node) === node) {
                             return node;
                         }
-                        return setTextRange(factory.cloneNode(visitEachChild(node, deepCloneOrReuseNode, nullTransformationContext)), node);
+                        return setTextRange(factory.cloneNode(visitEachChild(node, deepCloneOrReuseNode, nullTransformationContext, deepCloneOrReuseNodes)), node);
+                    }
+
+                    function deepCloneOrReuseNodes<T extends Node>(nodes: NodeArray<T>, visitor: Visitor | undefined, test?: (node: Node) => boolean, start?: number, count?: number): NodeArray<T>;
+                    function deepCloneOrReuseNodes<T extends Node>(nodes: NodeArray<T> | undefined, visitor: Visitor | undefined, test?: (node: Node) => boolean, start?: number, count?: number): NodeArray<T> | undefined;
+                    function deepCloneOrReuseNodes<T extends Node>(nodes: NodeArray<T> | undefined, visitor: Visitor | undefined, test?: (node: Node) => boolean, start?: number, count?: number): NodeArray<T> | undefined {
+                        if (nodes && nodes.length === 0) {
+                            // Ensure we explicitly make a copy of an empty array; visitNodes will not do this unless the array has elements,
+                            // which can lead to us reusing the same empty NodeArray more than once within the same AST during type noding.
+                            return setTextRange(factory.createNodeArray<T>(/*nodes*/ undefined, nodes.hasTrailingComma), nodes);
+                        }
+                        return visitNodes(nodes, visitor, test, start, count);
                     }
                 }