Starting overload selection in signature help doesn't account for discriminating arguments

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TypeScript Version: 3.8.0-dev.20200201

Search Terms

• overload

Incorrect types sugestion with overload
https://gitlab.com/kamidere-laboratory/duat/tree/testy
overload is declarated in src/database/Controller.ts method create

• VSCode Version: 1.41.1
• OS Version: Windows_NT x64 10.0.18362

Steps to Reproduce:

1. Write Database.create(DatabaseType.Graphite, {}) // now we get Influx overload xD
2. Change DatabaseType.Graphite to DatabaseType.Sqlite // now we get Sqlite overload :D
3. Change back to DatabaseType.Graphite // now we still get Sqlite overload :(
   https://youtu.be/a7FHxIItceA

Does this issue occur when all extensions are disabled?: Yes

interface a {
  a: string;
  b: string;
  c: {
    a:number;
    b:string;
  }
}

interface b {
  a: string;
  b: string;
  c: {
    a: number;
    b: string;
    c: string[];
  }
}

interface c {
  a: string;
  b: string;
}

enum d {
  "A" = 'a',
  "B" = 'b',
  "C" = 'c',
}

class testClass {
  constructor(arg1: d, arg2: a | b | c) {
    console.log(arg1, arg2)
  }
  static doSomething(arg1: d.A, arg2: a): testClass;
  static doSomething(arg1: d.B, arg2: b): testClass;
  static doSomething(arg1: d.C, arg2: c): testClass;
  static doSomething(arg1: d, arg2: a | b | c): testClass {
    return new this(arg1, arg2);
  }
}

testClass.doSomething(d.C, {});

Start by reproducing the overload example in the issue and inspect TypeScript's signature-help handling for overload selection. Verify the behavior when the discriminating first argument changes between enum values; done means signature help selects the overload matching that argument rather than retaining the previously selected overload.