gopls/internal/lsp/source: show both the original declaration and the value of constants in hover

This change improves the hover information for constants by showing
both the original declaration and the value. The value is displayed
as an inline comment. If the original declaration and the value are
the same, there will be no inline comment.

Examples:

```go
const duration time.Duration = 15*time.Minute + 10*time.Second // 15m10s

const octal untyped int = 0o777 // 511

const expr untyped int = 2 << (0b111&0b101 - 2) // 16

const boolean untyped bool = (55 - 3) == (26 * 2) // true

const dec untyped int = 500
```

Other changes:

- Calls to `objectString` that format methods or variables have been
  replaced with `types.ObjectString`.
- The logic of inferred signature formatting has been extracted from
  `objectString` to a new function `inferredSignatureString`.
- Remove unused function `extractFieldList`.
- Port `gopls/internal/lsp/testdata/godef/a/g.go` to the new marker
  tests.
- Fix `-min_go` constraint for marker tests by replacing hardcoded
  `1.18` with an actual flag value.

Fixes golang/go#47453

Change-Id: Ib9012dae8554a3b646c3059d2f8967e425974fbf
GitHub-Last-Rev: 8cc75a79d5651b3f5e1e3a0a7bfc4e3795d77763
GitHub-Pull-Request: golang/tools#432
Reviewed-on: https://go-review.googlesource.com/c/tools/+/480695
Run-TryBot: Robert Findley <rfindley@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
gopls-CI: kokoro <noreply+kokoro@google.com>
Reviewed-by: Robert Findley <rfindley@google.com>
8 files changed
tree: 214756dab423e5f29f551ef0c62f99e6de001226
  1. benchmark/
  2. blog/
  3. cmd/
  4. container/
  5. copyright/
  6. cover/
  7. go/
  8. godoc/
  9. gopls/
  10. imports/
  11. internal/
  12. playground/
  13. present/
  14. refactor/
  15. txtar/
  16. .gitattributes
  17. .gitignore
  18. .prettierrc
  19. codereview.cfg
  20. CONTRIBUTING.md
  21. go.mod
  22. go.sum
  23. LICENSE
  24. PATENTS
  25. README.md
README.md

Go Tools

PkgGoDev

This repository provides the golang.org/x/tools module, comprising various tools and packages mostly for static analysis of Go programs, some of which are listed below. Use the “Go reference” link above for more information about any package.

It also contains the golang.org/x/tools/gopls module, whose root package is a language-server protocol (LSP) server for Go. An LSP server analyses the source code of a project and responds to requests from a wide range of editors such as VSCode and Vim, allowing them to support IDE-like functionality.

Selected commands:

  • cmd/goimports formats a Go program like go fmt and additionally inserts import statements for any packages required by the file after it is edited.
  • cmd/callgraph prints the call graph of a Go program.
  • cmd/digraph is a utility for manipulating directed graphs in textual notation.
  • cmd/stringer generates declarations (including a String method) for “enum” types.
  • cmd/toolstash is a utility to simplify working with multiple versions of the Go toolchain.

These commands may be fetched with a command such as

go install golang.org/x/tools/cmd/goimports@latest

Selected packages:

  • go/ssa provides a static single-assignment form (SSA) intermediate representation (IR) for Go programs, similar to a typical compiler, for use by analysis tools.

  • go/packages provides a simple interface for loading, parsing, and type checking a complete Go program from source code.

  • go/analysis provides a framework for modular static analysis of Go programs.

  • go/callgraph provides call graphs of Go programs using a variety of algorithms with different trade-offs.

  • go/ast/inspector provides an optimized means of traversing a Go parse tree for use in analysis tools.

  • go/cfg provides a simple control-flow graph (CFG) for a Go function.

  • go/expect reads Go source files used as test inputs and interprets special comments within them as queries or assertions for testing.

  • go/gcexportdata and go/gccgoexportdata read and write the binary files containing type information used by the standard and gccgo compilers.

  • go/types/objectpath provides a stable naming scheme for named entities (“objects”) in the go/types API.

Numerous other packages provide more esoteric functionality.

Contributing

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

JavaScript and 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.