I just upgraded to typescript-eslint 3.0 in a TypeScript project which uses @typescript-eslint/experimental-utils and got a slightly surprising compile error. The usage of ES private field syntax introduced in #2023 requires downstream TypeScript consumers to target ES2015 / ES6 or newer (TS docs).

../../node_modules/@typescript-eslint/experimental-utils/dist/eslint-utils/RuleTester.d.ts:7:5 - error TS18028: Private identifiers are only available when targeting ECMAScript 2015 and higher.
7     #private;
      ~~~~~~~~

This isn't a big problem for me, since I can update my "target" compiler option, but I just wanted to note this slight breaking change.

Versions