If a symbol name can only be imported from one place for a type, and
as long as it was not glob-imported anywhere in the current crate, we
can trim its printed path and print only the name.
This has wide implications on error messages with types, for example,
shortening `std::vec::Vec` to just `Vec`, as long as there is no other
`Vec` importable anywhere.
This adds a new '-Z trim-diagnostic-paths=false' option to control this
feature.
On the good path, with no diagnosis printed, we should try to avoid
issuing this query, so we need to prevent trimmed_def_paths query on
several cases.
This change also relies on a previous commit that differentiates
between `Debug` and `Display` on various rustc types, where the latter
is trimmed and presented to the user and the former is not.
When evaluating the derived obligations from super traits, maintain a
reference to the original obligation in order to give more actionable
context in the output.
add test to for the fix
add descriptive text for the fix
simplified code logics
update descriptive comments
update to cope with the tidyness requirement
merged commit suggestions
Co-Authored-By: varkor <github@varkor.com>
truncated redundant comments
update to cope with tidy-check
