go/importer: add ForCompiler, which accepts a token.FileSet
The importer.For function logically requires a FileSet, but did not
when it was first created because export data did not then record
position information. This change adds a new function, ForCompiler,
that has an additional FileSet parameter, and deprecates the For
function.
Before this change, cmd/vet would report confusing spurious
positions for token.Pos values produced by the importer.
The bug is essentially unfixable in cmd/vet.
This CL includes a test that the FileSet is correctly populated.
The changes to cmd/vendor will be applied upstream in a follow-up.
Fixes #28995
Change-Id: I9271bcb1f28e96845c913e15f0304bac93d4d4c4
Reviewed-on: https://go-review.googlesource.com/c/152258
Run-TryBot: Alan Donovan <adonovan@google.com>
Reviewed-by: Daniel Martà <mvdan@mvdan.cc>
Reviewed-by: Robert Griesemer <gri@golang.org>