Color differences between `found` and `expected` in errors

[mdinger]

Apply coloring to highlight the differences between found and expected errors and which is desired. This pic is old and slightly out of date but shows what I'm interested in:

[ahmedcharles]

I looked into this. It would seem that there isn't an easy way to do this and it would probably require extending the diagnostics framework to make this work without making it seem hacky.

[steveklabnik]

Triage: no change.

[estebank]

#41205 addresses this with bolding, not coloring. It does so at the type level, not at the path segment level.

[mdinger]

That looks better than what is currently available. You might want to mark this as a possible future extension. Not having used the other, this might not even be necessary depending on how well the other works out in practice.

[estebank]

@mdinger it's been a while since the highlighting code has been in the wild. Do you still miss this the coloring feature despite this?

[mdinger]

I don't have a strong opinion. I'd mark it as WFM. If someone else wants it, they can reopen.