Code actions that apply convenience fixes were filtered by the start
line so it wasn't possible to narrow the scope to a specific range.

This change allows clients to send a specific range (or cursor position)
to filter all fixes where the range doesn't intersect with the provided
range. It also widens the diagnostic returned by fillstruct analysis.

The idea is to provide a way to narrow the scope without breaking
clients that do want to ask for code actions using the entire line.

Updates golang/go#40438

Change-Id: Ifd984a092a4a3bf0b3a2a5426d3e65023ba4eebc
Reviewed-on: https://go-review.googlesource.com/c/tools/+/244519
Run-TryBot: Pontus Leitzler <leitzler@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Rebecca Stambler <rstambler@golang.org>

This change adds "go test" as a code action and also introduce the
concept of explicit code actions, i.e. code actions that aren't returned
to the client unless it explicitly ask for it.

The purpose is to be able to have a mechanism that allows users to
execute a specific command in one shot, and future CL:s will add more of
the existing code lenses as explicit code actions. Code lenses can't be
used directly since they lack the range/kind combo to make them unique.

Updates golang/go#40438

Change-Id: I245df4e26c9e02e529662181e2c1bc44f999e101
Reviewed-on: https://go-review.googlesource.com/c/tools/+/259377
Trust: Rebecca Stambler <rstambler@golang.org>
Trust: Peter Weinberger <pjw@google.com>
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
gopls-CI: kokoro <noreply+kokoro@google.com>
Reviewed-by: Rebecca Stambler <rstambler@golang.org>

This CL lays the groundwork for future refactoring, by defining a formal
(Go) interface for the set of commands provided by gopls in the
workspace/executeCommand RPC. It then creates some boilerplate bindings
via code generation.

The intent is to, first of all, clean up our current usage of commands.
Currently the 'specification' of a command is really split across
internal/lsp/command.go, internal/lsp/source/command.go, and
internal/lsp/source/code_lens.go. Changing a command signature might
require altering all three of those files, and it's easy to get wrong.

But also, we'd like to eventually be able to tell plugin authors that
they can call our commands in an ad-hoc manner (meaning with arguments
that they assign, rather than extract from a code lens). In order to do
that, we need to be able to generate documentation for the command
signature, and should also stop using positional arguments.  This CL
aims to solve that as well, by providing a commandmeta package that can
be used for document generation.

For golang/go#40438

Change-Id: I0d29de044e107d6e7b267f340879a5282f0b4944
Reviewed-on: https://go-review.googlesource.com/c/tools/+/289489
Trust: Robert Findley <rfindley@google.com>
Run-TryBot: Robert Findley <rfindley@google.com>
gopls-CI: kokoro <noreply+kokoro@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Rebecca Stambler <rstambler@golang.org>
Reviewed-by: Heschi Kreinick <heschi@google.com>

Fully switch to the new generated command API, and remove the old
dynamic command configuration.

This involved several steps:
 + Switch the command dispatch in internal/lsp/command.go to go through
   the command package. This means that all commands must now use the new
   signature.
 + Update commandHandler to use the new command signatures.
 + Fix some errors discovered in the command interface now that we're
   actually using it.
 + Regenerate bindings.
 + Update all code lens and suggested fixes to new the new command
   constructors.
 + Generate values in the command package to hold command names and the
   full set of commands, so that they may be referenced by name.
 + Update any references to command names to use the command package.
 + Delete command metadata from the source package. Rename command.go to
   fix.go.
 + Update lsp tests to execute commands directly rather than use an
   internal API. This involved a bit of hackery to collect the edits.
 + Update document generation to use command metadata. Documenting the
   arguments is left to a later CL.
 + Various small fixes related to the above.

This change is intended to be invisible to users. We have changed the
command signatures, but have not (previously) committed to backwards
compatibility for commands. Notably, the gopls.test and gopls.gc_details
signatures are preserved, as these are the two cases where we are aware
of LSP clients calling them directly, not from a code lens or
diagnostic.

For golang/go#40438

Change-Id: Ie1b92c95d6ce7e2fc25fc029d1f85b942f40e851
Reviewed-on: https://go-review.googlesource.com/c/tools/+/290111
Trust: Robert Findley <rfindley@google.com>
Run-TryBot: Robert Findley <rfindley@google.com>
gopls-CI: kokoro <noreply+kokoro@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Heschi Kreinick <heschi@google.com>

Update our docgen to include documentation for commands. This is done in
an ad-hoc manner. We'll probably need to iterate on this as we go.

For golang/go#40438

Change-Id: I0a6922aa2f5e7dc4c8a43e0f843ddb54971cbe44
Reviewed-on: https://go-review.googlesource.com/c/tools/+/290190
Trust: Robert Findley <rfindley@google.com>
Run-TryBot: Robert Findley <rfindley@google.com>
gopls-CI: kokoro <noreply+kokoro@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Heschi Kreinick <heschi@google.com>