internal/lsp/source: improve completion of printf operands

We now rank printf operand candidates according to the corresponding
formatting verb. We follow what fmt allows for the most part, but I
omitted some things because they are uncommon and would result in many
false positives, or didn't seem worth it to support:

- We don't prefer fmt.Stringer or error types for "%x" or "%X".
- We don't prefer pointers for any verbs except "%p".
- We don't prefer recursive application of verbs (e.g. we won't prefer
  []string for "%s").

I decided against sharing code with the printf analyzer. It was
tangled somewhat with go/analysis, and I needed only a very small
subset of the format parsing.

I tweaked candidate type evaluation to accommodate the printf hints.
We now skip expected type of "interface{}" when matching candidate
types because it matches everything and would always supersede the
coarser object kind checks.

Fixes golang/go#40485.

Change-Id: I6440702e33d5ec85d701f8be65453044b5dab746
Reviewed-on: https://go-review.googlesource.com/c/tools/+/246699
Run-TryBot: Muir Manders <muir@mnd.rs>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Findley <rfindley@google.com>
6 files changed
tree: be87b9f4a3777a849360109f04ec1e8c52992982
  1. .gitattributes
  2. .gitignore
  3. .prettierrc
  4. AUTHORS
  5. CONTRIBUTING.md
  6. CONTRIBUTORS
  7. LICENSE
  8. PATENTS
  9. README.md
  10. benchmark/
  11. blog/
  12. cmd/
  13. codereview.cfg
  14. container/
  15. cover/
  16. go.mod
  17. go.sum
  18. go/
  19. godoc/
  20. gopls/
  21. imports/
  22. internal/
  23. playground/
  24. present/
  25. refactor/
  26. txtar/
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.

JS/CSS Formatting

This repository uses prettier to format JS and CSS files.

The version of prettier used is 1.18.2.

It is encouraged that all JS and CSS code be run through this before submitting a change. However, it is not a strict requirement enforced by CI.

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.