Point at the span for the definition of ADTs internal to the current
crate.
Look at the leading char of the ident to determine whether we're
expecting a likely fn or any of a fn, a tuple struct or a tuple variant.
Turn fn `add_typo_suggestion` into a `Resolver` method.
Increase spacing for suggestions in diagnostics
Make the spacing between the code snippet and verbose structured
suggestions consistent with note and help messages.
r? @Centril
also updated some error messages
removed the code manually checking for `receiver_ty: Deref<Target=self_ty>`, in favour of using autoderef but only doing one iteration. This will cause error messages to be more consistent. Before, a "mismatched method receiver" error would be emitted when `receiver_ty` was valid except for a lifetime parameter, but only when `feature(arbitrary_self_types)` was enabled, and without the feature flag the error would be "uncoercible receiver". Now it emits "mismatched method receiver" in both cases.
It looks like we tend to use angle-brackets around the placeholder in
the few other places we use `Applicability::HasPlaceholders`, but that
would be confusing here, so ...
