x/tools/cmd/goimports: treat import paths as standard library only if they are in goroot

[kr]

The go tool sets a field to indicate whether a package is part of the standard library:

https://github.com/golang/go/blob/8d478e845c/src/cmd/go/pkg.go#L156

p.Standard = p.Goroot && p.ImportPath != "" && !strings.Contains(p.ImportPath, ".")

goimports uses a different rule:

https://github.com/golang/tools/blob/e21b7325f7/imports/fix.go#L32

if strings.Contains(importPath, ".") {

My feature request is to change the code to behave similar to the go tool:

if strings.Contains(importPath, ".") || !inGoroot(importPath) {

With an additional index of the standard library keyed by import path, I'd expect this to be reasonably fast.

If this is an acceptable idea, I'm happy to write a patch.

[ianlancetaylor]

CC @bradfitz

[sheki]

I looked at fixing this, but I would cause behavior changes

import (
"fmt"
"x/mypkg"
)

The first group would be standard libraries
The second group everything else

This would now lead to

import (
"fmt"

"x/mypkg"
)

[sheki]

Is that acceptable ?

This bites us too as we have an import called "bright" and it gets merged in with the standard library imports which is a minor nuisance.