IntelliSense signature help forgets inferred parameter names in completed call

[fatcerberus]

Per #31845 (comment), posting this as a new ticket for posterity.

TypeScript Version: 3.6.0-dev.20190621

Search Terms: n/a

Code

function frob<T, A extends any[]>(f: (...args: A) => T, ...args: A)
{
    return f(...args);
}

function blub(foo: string, bar: number) {}

// press Ctrl+Shift+Space inside the parentheses here:
frob(blub, "banana slamma", 812);

Parameter names are correctly displayed while initially typing out the frob() function call:

However, once all the arguments are filled out, it reverts to generic names such as args_0, args_1, etc. ☹️

Expected behavior:
Parameter names originating from an inferred parameter tuple should be preserved in IntelliSense.

Actual behavior:
Parameter names are preserved while typing out the function call, but once the call is completed it reverts to using generic parameter names and remains that way for all subsequent invocations of signature help for that call (unless an argument is deleted).

Playground Link:
⏯ Click here

Related Issues:
#31845