Fix multi unit session when some packages have reexported modules. #3928
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
If we are loading multiple home packages, we need to explicitly take reexports
into account when searching for target files.
If we can't find a module via the usual mean, but it is listed as a reexport of
a unit in scope, we need to look for the module from the perspective of that unit.
This is not necessary for non-home modules because GHC already handles this for
modules in the package DB.
Unfortunately we can't fix this in GHC 9.2 because it doesn't support multiple
home units and we have no way of knowing if a unit reexports modules