setTimeout defined in lib.dom.d.ts is not type safe

TypeScript Version: 3.5.2

Search Terms:
settimeout type safe
Code

// A *self-contained* demonstration of the problem follows...
// Test this by running `tsc` on the command-line, rather than through another build tool such as Gulp, Webpack, etc.
const f = (foo: number) => console.log(foo + 1);
setTimeout(f, 0, 'a');

Expected behavior:
It shall not pass thanks to the type error.
Actual behavior:
It passes.
Playground Link:
https://www.typescriptlang.org/play/#code/MYewdgzgLgBAZjAvDAFHEIBcMwFcC2ARgKYBOAlEgHwyiQgA2xAdAyAOZoYwDUMAjOQDcAKAjEoAFQCW+YiFxQ0AGhgAGVQHIAhoULBgAE0PFNWwpuFA
Related Issues:
emm, maybe not.

lib.dom.d.ts の setTimeout 宣言を調査し、まず tsc またはリンク先の TypeScript Playground で例を再現してください。コールバックが number を受け取る場合に追加の string 引数が拒否され、宣言テストまたは同等のコンパイラチェックがパスすれば完了です。