"doesn't have a size known at compile-time" should underline the type, not the whole size_of function

[scottmcm]

Low-importance nitpick: If I do

std::mem::size_of::<[String]>()

I get an error like

2 | std::mem::size_of::<[String]>()
  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ doesn't have a size known at compile-time

Arguably I should get a smaller underline like this:

2 | std::mem::size_of::<[String]>()
  |                     ^^^^^^^^ doesn't have a size known at compile-time

because it's the generic argument that doesn't have the size, not the function.