fix(eslint-plugin): isTypeReadonly error with <TS3.7 (#3731)

typescript-eslint · Aug 30, 2021 · 5696407 · 5696407
1 parent 921cbca
commit 5696407
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diff --git a/.all-contributorsrc b/.all-contributorsrc
@@ -400,6 +400,13 @@
       "avatar_url": "https://avatars.githubusercontent.com/u/16860535?v=4",
       "profile": "https://github.com/soobing",
       "contributions": []
+    },
+    {
+      "login": "RebeccaStevens",
+      "name": "Rebecca Stevens",
+      "avatar_url": "https://avatars.githubusercontent.com/u/7224206?v=4",
+      "profile": "https://github.com/RebeccaStevens",
+      "contributions": []
     }
   ],
   "contributorsPerLine": 5

diff --git a/packages/eslint-plugin/src/util/isTypeReadonly.ts b/packages/eslint-plugin/src/util/isTypeReadonly.ts
@@ -23,7 +23,12 @@ function isTypeReadonlyArrayOrTuple(
   seenTypes: Set<ts.Type>,
 ): Readonlyness {
   function checkTypeArguments(arrayType: ts.TypeReference): Readonlyness {
-    const typeArguments = checker.getTypeArguments(arrayType);
+    const typeArguments =
+      // getTypeArguments was only added in TS3.7
+      checker.getTypeArguments
+        ? checker.getTypeArguments(arrayType)
+        : arrayType.typeArguments ?? [];
+
     // this shouldn't happen in reality as:
     // - tuples require at least 1 type argument
     // - ReadonlyArray requires at least 1 type argument