scopelint

README

scopelint

scopelint checks for unpinned variables in go programs.

What's this?

Sample problem code from: https://github.com/kyoh86/scopelint/blob/master/example/readme.go

6  values := []string{"a", "b", "c"}
7  var funcs []func()
8  for _, val := range values {
9  	funcs = append(funcs, func() {
10 		fmt.Println(val)
11 	})
12 }
13 for _, f := range funcs {
14 	f()
15 }
16 /*output:
17 c
18 c
19 c
20 */
21 var copies []*string
22 for _, val := range values {
23 	copies = append(copies, &val)
24 }
25 /*(in copies)
26 &"c"
27 &"c"
28 &"c"
29 */

In Go, the val variable in the above loops is actually a single variable. So in many case (like the above), using it makes for us annoying bugs.

You can find them with scopelint, and fix it.

$ scopelint ./example/readme.go
example/readme.go:10:16: Using the variable on range scope "val" in function literal
example/readme.go:23:28: Using a reference for the variable on range scope "val"
Found 2 lint problems; failing.

(Fixed sample):

values := []string{"a", "b", "c"}
var funcs []func()
for _, val := range values {
  val := val // pin!
	funcs = append(funcs, func() {
		fmt.Println(val)
	})
}
for _, f := range funcs {
	f()
}
var copies []*string
for _, val := range values {
  val := val // pin!
	copies = append(copies, &val)
}

Install

go get -u github.com/kyoh86/scopelint

Use

Give the package paths of interest as arguments:

scopelint github.com/kyoh86/scopelint/example

To check all packages recursively in the current directory:

scopelint ./...

And also, scopelint supports the following options:

• The --set-exit-status flag makes it to set exit status to 1 if any problem variables are found (if you DO NOT it, set --no-set-exit-status)
• The --vendor flag enables checking in the vendor directories (if you DO NOT it, set --no-vendor flag)
• The --test flag enables checking in the *_test.go files" (if you DO NOT it, set --no-test flag)

Nolint

To ignore issues from use an option comment like //scopelint:ignore. For example, if it's used inline (not from the beginning of the line), it ignores issues only for the line.

var copies []*string
for _, val := range values {
	copies = append(copies, &val) //scopelint:ignore
}

To ignore issues for the block of code put it on the beginning of a line before the block:

var copies []*string
//scopelint:ignore
for _, val := range values {
	copies = append(copies, &val)
}

Also, you can exclude all issues in a file by:

//scopelint:ignore
package pkg

You may add a comment explaining or justifying why //scopelint:ignore is being used on the same line as the flag itself:

//scopelint:ignore // any comment

Use with gometalinter

scopelint can be used with gometalinter in --linter flag.

gometalinter --disable-all --linter 'scope:scopelint {path}:^(?P<path>.*?\.go):(?P<line>\d+):(?P<col>\d+):\s*(?P<message>.*)$'

Exit Codes

scopelint returns 1 if any problems were found in the checked files. It returns 2 if there were any other failures.

Known Issues

• False positive for for table tests #4
  • I won't fix it because scopelint supports ignore them all. => nolint

TODO

• Write tests
• License (Some codes copied from golint)

Documentation

Overview

scopelint checks for unpinned variables in go programs.