x/tools/cmd/goimports: import blocks consistency

[cezarsa]

Having the following files inside $GOPATH/src:

$ tree
.
├── code.google.com
│   └── p
│       └── x
│           └── b
│               └── b.go
└── github.com
    ├── foo
    │   └── bar
    │       └── bar.go
    └── x
        └── a
            └── a.go

And the bar.go file containing:

package bar

import (
    "fmt"
)

var (
    _ = fmt.Println
    _ = a.Foo
    _ = b.Foo
)

Running goimports -d github.com/foo/bar results in:

@@ -2,6 +2,9 @@

 import (
    "fmt"
+
+   "code.google.com/p/x/b"
+   "github.com/x/a"
 )

 var (

This seems like the correct thing to do according to https://github.com/golang/go/wiki/CodeReviewComments#imports, adding a single new import block for external code.

However if we change the bar.go file to:

package bar

import (
    "fmt"

    "github.com/x/a"
)

var (
    _ = fmt.Println
    _ = a.Foo
    _ = b.Foo
)

And execute goimports -d github.com/foo/bar again, the result is quite different:

@@ -3,6 +3,8 @@
 import (
    "fmt"

+   "code.google.com/p/x/b"
+
    "github.com/x/a"
 )

Instead of adding the new import path to the existing block of external code, a new block is created. This only seems to happen if the added import path is from a domain not yet present in the existing external block. This seems weird as goimports itself adds them together if they weren't present.

So my question, is this the expected behavior for goimports or is this a bug? If it's confirmed a bug I may take a shot at creating a CL to fix it.

[bradfitz]

Have at it. Manipulating the imports is a bit of a black art. Have fun!

/cc @griesemer

[heschi]

I think this is essentially a dupe of #20818. Please comment if you disagree.