From 5d6812914831a386997b453b4db1e3283e26005d Mon Sep 17 00:00:00 2001
From: Ben Lichtman <uniqueiniquity@users.noreply.github.com>
Date: Tue, 9 Jun 2020 12:58:08 -0700
Subject: [PATCH] fix(typescript-estree): handle TS4.0 breaking change in
 TupleType (#2197)

---
 .prettierignore                           | 1 +
 packages/typescript-estree/src/convert.ts | 9 ++++++++-
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/.prettierignore b/.prettierignore
index 2578aad23b7..5155a78aa50 100644
--- a/.prettierignore
+++ b/.prettierignore
@@ -5,6 +5,7 @@
 **/shared-fixtures
 **/.vscode
 **/.nyc_output
+**/.vs
 packages/eslint-plugin-tslint/tests/test-tslint-rules-directory/alwaysFailRule.js
 .github
 packages/eslint-plugin/src/configs/*.json
diff --git a/packages/typescript-estree/src/convert.ts b/packages/typescript-estree/src/convert.ts
index 44279a76d97..2a6db370570 100644
--- a/packages/typescript-estree/src/convert.ts
+++ b/packages/typescript-estree/src/convert.ts
@@ -2617,9 +2617,16 @@ export class Converter {
         });
       }
       case SyntaxKind.TupleType: {
+        // In TS 4.0, the `elementTypes` property was changed to `elements`.
+        // To support both at compile time, we cast to access the newer version
+        // if the former does not exist.
+        const elementTypes = node.elementTypes
+          ? node.elementTypes.map(el => this.convertType(el))
+          : (node as any).elements.map((el: ts.Node) => this.convertType(el));
+
         return this.createNode<TSESTree.TSTupleType>(node, {
           type: AST_NODE_TYPES.TSTupleType,
-          elementTypes: node.elementTypes.map(el => this.convertType(el)),
+          elementTypes,
         });
       }
       case SyntaxKind.UnionType: {