typeof 'function' using with Exclude<T, Function>

<!-- 🚨 STOP 🚨 𝗦𝗧𝗢𝗣 🚨 𝑺𝑻𝑶𝑷 🚨 Half of all issues filed here are duplicates, answered in the FAQ, or not appropriate for the bug tracker. Even if you think you've found a *bug*, please read the FAQ first, especially the Common "Bugs" That Aren't Bugs section! Please help us by doing the following steps before logging an issue: * Search: https://github.com/Microsoft/TypeScript/search?type=Issues * Read the FAQ: https://github.com/Microsoft/TypeScript/wiki/FAQ Please fill in the *entire* template below. --> <!-- Please try to reproduce the issue with `typescript@next`. It may have already been fixed. --> **TypeScript Version:** 3.2.2 <!-- Search terms you tried before logging this (so others can find this issue more easily) --> **Search Terms:** Generic typeof **Code** ```ts function f2<T>(v: Exclude<T, Function> | (() => T)): T { if (typeof v === 'function') { v = v() // error! } return v } ``` **Expected behavior:** No error, type v is just (() => T). **Actual behavior:** Line 3 report an error: Type '(() => T) | (Exclude<T, Function> & Function)' has no compatible call signatures. **Playground Link:** https://www.typescriptlang.org/play/index.html#src=function%20f2%3CT%3E(v%3A%20Exclude%3CT%2C%20Function%3E%20%7C%20(()%20%3D%3E%20T))%3A%20T%20%7B%0D%0A%20%20%20%20if%20(typeof%20v%20%3D%3D%3D%20'function')%20%7B%0D%0A%20%20%20%20%20%20%20%20v%20%3D%20v()%0D%0A%20%20%20%20%7D%0D%0A%20%20%20%20return%20v%0D%0A%7D