TypeScript Version: 3.5.2 (it works with 3.4.4). Also tested on 3.6.0-dev.20190622

Search Terms:

Code (not real-life, just a repro)

const actions = ['resizeTo', 'resizeBy'] as const;
for (const action of actions) {
	window[action] = (x, y) => {
		window[action](x, y);
	}
}

Expected behavior:

x and y are of type number (like in 3.4)

Actual behavior:

x and y are of type any

Playground Link: (enable noImplicitAny, but it seems to be on 3.4)

https://www.typescriptlang.org/play/#src=%0D%0Aconst%20actions%20%3D%20%5B'resizeTo'%2C%20'resizeBy'%5D%20as%20const%3B%0D%0Afor%20(const%20action%20of%20actions)%20%7B%0D%0A%09window%5Baction%5D%20%3D%20(x%2C%20y)%20%3D%3E%20%7B%0D%0A%09%09window%5Baction%5D(x%2C%20y)%3B%0D%0A%09%7D%0D%0A%7D

Related Issues:

#32037