Cannot infer generic argument type from passed callback

TypeScript Version: 3.4.0-dev.201xxxxx

Search Terms:

infer, parameter, argument, callback, function

Code

function inferArguments<T>(callback: ((t: T) => void)) {
  return callback;
}

function noop(){}

const explicit = inferArguments(({a = noop}: {a: Function}) => {});
explicit({a: noop}); // OK!
explicit({a: false}); // Expected error - Got one!

const implicit = inferArguments(({a = noop}) => {});
implicit({a: noop}); // OK!
implicit({a: false}); // Expected error - No Error!

Expected behavior:
Both function calls with ({a: false}) should cause a type error

Actual behavior:
Only the function call with the explicit typing causes a type error

Playground Link

Related Issues: #30975 Looks similar but seems different since there should be a clear way for inference to work in this case

Note that Parameters is correctly able to extract the correct types for such a construct as seen in this bit of code:

function noop() { }
function callback({ a = noop }) { }
let args: Parameters<typeof callback>;
args[0].a as Function

This appears to be an error with inline callback functions used in this fashion

Reproduisez les cas explicites et implicites dans le TypeScript Playground lié, puis comparez leurs types de paramètres de callback inférés et le comportement de Parameters. L’issue ne mentionne aucun fichier du dépôt ni aucun test ; le travail est terminé lorsque les deux appels utilisant {a: false} produisent des erreurs de type, tandis que les cas noop valides restent acceptés.