• I have tried restarting my IDE and the issue persists.
• I have updated to the latest version of the packages.
• I have read the FAQ and my problem is not listed.

Repro

type TestTest1 = ReadonlyArray<string> & Readonly<{ foo: string; }>;
type TestTest2 = Readonly<ReadonlyArray<string>> & Readonly<{ foo: string; }>;

isTypeReadonly(checker, type, {})

Expected Result

isTypeReadonly should return true

Actual Result

isTypeReadonly returns false

Additional Info

The error seems to be that TypeScript treats Readonly<ReadonlyArray<string>> the same as ReadonlyArray<string> and thus the methods are still mutable. We need a special case to handle intersections with readonly arrays.

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