internal/lsp: refactor find-references and rename

The main goal is to push the package variant logic from internal/lsp
into internal/lsp/source so all users of internal/lsp/source benefit.

"references" and "rename" now have top-level source.References() and
source.Rename() entry points (as opposed to hanging off
source.Identifier()). I expanded objectsAtProtocolPos() to know about
implicit objects (type switch and import spec), and to
handle *ast.ImportSpec generically. This gets rid of special case
handling of *types.PkgName in various places.

The biggest practical benefit, though, is that "references" no longer
needs to compute the objectpath for every types.Object comparison it
does, instead using direct types.Object equality. This speeds up
"references" and "rename" a lot.

Two other notable improvements that fell out of not using
source.Identifier()'s logic:

- Finding references on an embedded field now shows references to the
  field, not the type being embedded.
- Finding references on an imported object now works
  correctly (previously it searched the importing package's dependents
  rather than the imported package's dependents).

Finally, I refactored findIdentifier() to use pathEnclosingObjNode()
instead of astutil.PathEnclosingInterval. Now we only need a single
call to get the path because pathEnclosingObjNode() has the
"try pos || try pos-1" logic built in.

Change-Id: I667be9bed6ad83912404b90257c5c1485b3a7025
Reviewed-on: https://go-review.googlesource.com/c/tools/+/211999
Run-TryBot: Muir Manders <muir@mnd.rs>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Rebecca Stambler <rstambler@golang.org>
10 files changed
tree: 563d038d91eb58ac1b5c212fe35afc9f5140bfbd
  1. benchmark/
  2. blog/
  3. cmd/
  4. container/
  5. cover/
  6. go/
  7. godoc/
  8. gopls/
  9. imports/
  10. internal/
  11. playground/
  12. present/
  13. refactor/
  14. txtar/
  15. .gitattributes
  16. .gitignore
  17. AUTHORS
  18. codereview.cfg
  19. CONTRIBUTING.md
  20. CONTRIBUTORS
  21. go.mod
  22. go.sum
  23. LICENSE
  24. PATENTS
  25. README.md
README.md

Go Tools

This subrepository holds the source for various packages and tools that support the Go programming language.

Some of the tools, godoc and vet for example, are included in binary Go distributions.

Others, including the Go guru and the test coverage tool, can be fetched with go get.

Packages include a type-checker for Go and an implementation of the Static Single Assignment form (SSA) representation for Go programs.

Download/Install

The easiest way to install is to run go get -u golang.org/x/tools/.... You can also manually git clone the repository to $GOPATH/src/golang.org/x/tools.

Report Issues / Send Patches

This repository uses Gerrit for code changes. To learn how to submit changes to this repository, see https://golang.org/doc/contribute.html.

The main issue tracker for the tools repository is located at https://github.com/golang/go/issues. Prefix your issue with “x/tools/(your subdir):” in the subject line, so it is easy to find.