Rollup merge of #53562 - varkor:bastion-of-the-turbofish, r=nagisa

Rollup merge of #53562 - varkor:bastion-of-the-turbofish, r=nagisa

Lament the invincibility of the Turbofish

Here a test case is added to ensure that any others attempting to drive the Turbofish to extinction have second thoughts. Previously the [entire test suite would succeed](https://github.com/rust-lang/rust/pull/53511) if generic arguments were accepted without disambiguation, making for [confusing and heartbreaking circumstances](https://github.com/rust-lang/rfcs/pull/2527).