Inlay hint suggest the type of parameter for function:
To turn this into a proper feature, we should add completion which:
local_name: LocalTypeas completion for function parameter
I've actually used this as if it was a feature before. But for local variables, not function parameters.
For local variables it is a feature, for function parameters it is not deliberate.
This sumtimes gives inappropriate beliefs that rustc type inference will do the work, e.g. it is common for rust-analyzer to show a type parameter hint for closure parameters, but flycheck still reports an error requiring me to specify the type explicitly...