Check deprecated things in Go

How deprecate functions?

Go official suggest to using Deprecated: comment in the doc that wants to deprecate functions, struct fields.
Godoc: documenting Go code

It is using in standard libraries. Ref: standard library.

For example, SEEK_SET const of os/file.go , using comment as follows.

// Deprecated: Use io.SeekStart, io.SeekCurrent, and io.SeekEnd.
const (
    SEEK_SET int = 0 // seek relative to the origin of the file
    SEEK_CUR int = 1 // seek relative to the current offset
    SEEK_END int = 2 // seek relative to the end
) 

So we should follow this rule in our libraries.

But if you follow this rule, deprecated functions show in Go doc now(Related discussion).
Also, golint does not check about deprecated comments(Related discussion).
As such, go official tools does not have particular behavior for deprecated comments.

Using staticcheck for check

staticcheck in go-tools can check deprecated things.

staticcheck reports as follows if using deprecated things.

package main

import (
    "net/http/httputil"
)

func main() {
    httputil.NewClientConn(nil, nil)
}

$ staticcheck main.go
deprecated.go:8:2: httputil.NewClientConn is deprecated: Use the Client or Transport in package net/http instead.  (SA1019)

staticcheck shows comments as it is behinds Deprecated:. Using this in CI is good.

Conclusion

• Using Deprecated:comment for deprecated things.
• Check to deprecated things with staticcheck.