IntelliSense for generic Promise function shows truncated return type

*TS Template added by @mjbvz* **TypeScript Version**: 4.0.0-dev.20200702 **Search Terms** - hover / quick info - truncation --- <!-- ⚠️⚠️ Do Not Delete This! bug_report_template ⚠️⚠️ --> <!-- Please read our Rules of Conduct: https://opensource.microsoft.com/codeofconduct/ --> <!-- Please search existing issues to avoid creating duplicates. --> <!-- Also please test using the latest insiders build to make sure your issue has not already been fixed: https://code.visualstudio.com/insiders/ --> <!-- Use Help > Report Issue to prefill these. --> - VSCode Version: 1.46.1 (user setup) - OS Version: Windows_NT x64 10.0.18363 Steps to Reproduce: **App.ts:** ```typescript import { Repro} from "./Repro"; function test() { Repro.repro<number>("test"); } ``` **Repro.ts:** ```typescript export namespace Repro { export interface Arg { argName: string, argValue: any } // export async function repro<T>(AbcdefghijklmnopqrstuvwxyzAbcdefghijklmnopqrstuvwxyzAbcdefghijklmnopqrstuvwxyzAbcdefghijklmnopqrstuvwxyzAbcdefghijkl: string, ...methodArgs: Arg[]): Promise<T> // Working export async function repro<T>(AbcdefghijklmnopqrstuvwxyzAbcdefghijklmnopqrstuvwxyzAbcdefghijklmnopqrstuvwxyzAbcdefghijklmnopqrstuvwxyzAbcdefghijklX: string, ...methodArgs: Arg[]): Promise<T> // Broken { return (new Promise<T>(null)); } } ``` **Problem:** In App.ts, hover over the `.repro` function. The IntelliSense shows `repro` as having a return type of `Promise<...>`. This is incorrect: it should be `Promise<number>`. Now, in Repro.ts edit the `repro` function by remove the trailing `X` in the first parameter name. Return to App.ts and note that the IntelliSense for `repro` is now correct (the function return type is shown as `Promise<number>`). While at first glance this may appear to be an edge case due to the long identifier name, it is not. I ran into this problem with "normal length" parameters, but the example above was the simplest repro I could find. Here's the signature o…