edf9e5eb63
Prefer explict closure sig types over expected ones fixes #100800 Previously we only checked that given closure arguments are equal to expected closure arguments, but now we choose the given closure arguments for the signature that is used when type checking the closure body, and keep the other signature for the type of the closure as seen outside of it.
For high-level intro to how type checking works in rustc, see the type checking chapter of the rustc dev guide.