This test exposes a lot of fundamental issues with `go list` overlays.
Now that we have the regression test framework, we can copy it over and
make any flakes completely reproducible by waiting for each change to
complete.

The issue here ended up being that initial workspace load returns
workspace packages with no associated files due to golang/go#39986.
Working around this allows invalidation to proceed as usual.

In the process of debugging this, I also noticed that packages can get
loaded as command-line-arguments even when we can get the correct
package path for them. It's pretty complicated to fix this, so
restructured the code a tiny bit and left a TODO. I'd like to come back
to this at some point, but it's not pressing since I was able to fix
this bug.

Fixes golang/go#39646.
Updates golang/go#39986.

Change-Id: Id6b08a5e92d28eddc731feb0ef3fd3b3fc69e64b
Reviewed-on: https://go-review.googlesource.com/c/tools/+/240098
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Michael Matloob <matloob@golang.org>

In the case of an invalid package name (the package name is a keyword),
`go list` doesn't report any filenames associated with the package.
As we have done previously, we can parse these out of the error message.
However, it seems like, in this case, the filename is in the error
string itself, not the error position.

Updates golang/go#39986
Updates golang/go#39763

Change-Id: Id9c68a93ac4f545e4e2152540ca85b92f1df4640
Reviewed-on: https://go-review.googlesource.com/c/tools/+/244028
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Michael Matloob <matloob@golang.org>

When CL 241577 lands, 'go list -e' will include unparseable files
(like a file without a package declaration) in GoFiles in addition to
InvalidGoFiles.

This makes go/packages more tolerant of empty test files. With
CL 241577, if a file=src.go query is given when an empty _test.go is
present, packages.Load will return two matching packages: the library
under test, and the internal test package.

This CL broadens overlay_test.go so the new behavior doesn't break the
test.

For golang/go#39986

Change-Id: I14d019129465e928a3f60a2230edd2e2d1d74687
Reviewed-on: https://go-review.googlesource.com/c/tools/+/317409
Trust: Jay Conrod <jayconrod@google.com>
Run-TryBot: Jay Conrod <jayconrod@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
gopls-CI: kokoro <noreply+kokoro@google.com>
Reviewed-by: Bryan C. Mills <bcmills@google.com>

For #45827
For #39986
Updates #45999

Change-Id: I0c919b6a2e56e7003b90425487eafe0f0eadc609
Reviewed-on: https://go-review.googlesource.com/c/go/+/317299
Trust: Bryan C. Mills <bcmills@google.com>
Run-TryBot: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Jay Conrod <jayconrod@google.com>

go/build.ImportDir returns a *build.Package with various lists of
files. If a file is invalid for some reason, for example, because it
has a different package name than other files, it's added to
InvalidGoFiles in addition to GoFiles, TestGoFiles, or other lists.

Previously, files with parse errors or build constraint errors were
not included in these lists, which causes problems for tools that use
'go list' since InvalidGoFiles is not printed. With this change, files
with any kind of error are added to one of the GoFiles lists.

Fixes #39986

Change-Id: Iee007b5092293eb4420c8a39ce731805fe32135f
Reviewed-on: https://go-review.googlesource.com/c/go/+/241577
Trust: Jay Conrod <jayconrod@google.com>
Run-TryBot: Jay Conrod <jayconrod@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>