internal/lsp: suggest completions that satisfy interfaces

When checking if a completion candidate matches the expected type at
the cursor position, we now use types.AssignableTo instead of
types.Identical. This properly handles cases like using a concrete
type to satisfy an interface type.

Calling AssignableTo triggered some crashes related to the fake
"resolved" types we create. Their underlying type was nil, which is
not allowed. We now set their underlying type to the invalid type.

I've also rearranged things so expected type information lives in a
dedicated typeInference struct. For now there is no new information added,
but in subsequent commits there will be more metadata about the
expected type.

Change-Id: I14e537c548960c30e444cf512a4413d75bb3ee45
GitHub-Last-Rev: 7e64ebe32938562648938d7a480195d954b018f2
GitHub-Pull-Request: golang/tools#116
Run-TryBot: Rebecca Stambler <>
TryBot-Result: Gobot Gobot <>
Reviewed-by: Rebecca Stambler <>
5 files changed
tree: b3eabd947fc557926dd2802f2bddbdd4c20d7911
  1. .gitattributes
  2. .gitignore
  9. benchmark/
  10. blog/
  11. cmd/
  12. codereview.cfg
  13. container/
  14. cover/
  15. go.mod
  16. go.sum
  17. go/
  18. godoc/
  19. gopls/
  20. imports/
  21. internal/
  22. playground/
  23. present/
  24. refactor/

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.


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

Report Issues / Send Patches

This repository uses Gerrit for code changes. To learn how to submit changes to this repository, see

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