We have decided that we don't like the if err := call(); err != nil
syntax, because it creates confusing scopes, but we have not cleaned up
all existing instances of that syntax. However, we have now found a
case where that syntax enables a bug: It caused readers to believe that
a later err = call() statement was assigning to an already-declared err
in the local scope, when in fact it was assigning to an
already-declared err in the parent scope of a closure. This caused our
ineffassign and staticcheck linters to be unable to analyze the
lifetime of the err variable, and so they did not complain when we
never checked the actual value of that error.
This change standardizes on the two-line error checking syntax
everywhere, so that we can more easily ensure that our linters are
correctly analyzing all error assignments.
Add `stylecheck` to our list of lints, since it got separated out from
`staticcheck`. Fix the way we configure both to be clearer and not
rely on regexes.
Additionally fix a number of easy-to-change `staticcheck` and
`stylecheck` violations, allowing us to reduce our number of ignored
checks.
Part of #5681
Aaron Gable