What to do about go fmt 1.4 ?

[roger peppe]

On 11 March 2015 at 06:52, John Meinel <john at arbash-meinel.com> wrote:
>
>
> On Tue, Mar 10, 2015 at 6:13 PM, roger peppe <roger.peppe at canonical.com>
> wrote:
>>
>> On 10 March 2015 at 12:52, John Meinel <john at arbash-meinel.com> wrote:
>> > So there are 2 changes that I encountered with upgrading go to 1.4.2:
>> >
>> > 1) They changed how they sort import paths. Currently all our imports
>> > are:
>> >
>> >  "github.com/juju/juju/bar"
>> >  coretesting "github.com/juju/juju/testing"
>> > (sorted by the import string)
>> >
>> > It wants to sort them as:
>> >
>> >  coretesting "github.com/juju/juju/testing"
>> >  "github.com/juju/juju/bar"
>> >
>> > (sorted by the local name)
>>
>> Are you sure about this? I believe that play.golang.org
>> is running go 1.4 and this code is canonically formatted there,
>> despite unordered local names: http://play.golang.org/p/5R8dyHJG5e
>>
>
> Yeah, I was wrong here. It had moved a line I hadn't changed, and I was
> confused, but it was user error, not the tool.
>
>
>>
>> > 2) It no longer works if you have a symlink in your PWD
>> > Because of the need for exact paths, I have a link from $HOME/jc =>
>> > $HOME/dev/go/src/github.com/juju/juju
>> > However, if I do "go fmt" it now complains that:
>> > stat ../../../dev/go/src/github.com/juju/juju/worker/uniter/deployer.go:
>> > no
>> > such file or directory
>> >
>> > (it seems to be using pwd -P and then using relative paths to that)
>> >
>> > Anyone know why it would need to do that?
>> >
>> > I can work around it with "cd jc; cd `pwd -P`" or some other form so I
>> > don't
>> > have to type the long form each time.
>>
>> Can you show a step-by-step way to reproduce this please?
>> If you cd into jc, surely you are now in
>> $HOME/dev/go/src/github.com/juju/juju,
>> and I don't see how that's a problem. (but I've not seen the pwd -P flag
>> before and don't understand how that works either - how can the pwd
>> command know what symlinks were used to get to the current working
>> directory?)
>>
>>   cheers,
>>     rog.
>
>
> So if I do:
>
> $ cd $HOME
> $ mkdir $HOME/dev/foo
> $ ln -s $HOME/dev/foo bar
> $ cd bar
> $ echo $PWD
> /home/jameinel/bar
> $ pwd
> /home/jameinel/bar
> $ pwd -P
> /home/jameinel/dev/foo
>
> So Bash sets $PWD based on what you actually issued to "cd".
> If I write this go code:
>
> package main
>
> import (
>  "os"
>  "fmt"
>  "path/filepath"
> )
>
> func main() {
>   dir, _ := os.Getwd()
>   fmt.Printf("dir: %s\n", dir)
>   pwd := os.Getenv("PWD")
>   fmt.Printf("PWD: %s\n", pwd)
>   expand, _ := filepath.EvalSymlinks(pwd)
>   fmt.Printf("expanded: %s\n", expand)
> }
>
>
> I get:
>
> dir: /home/jameinel/dev/foo
> PWD: /home/jameinel/bar
> expanded: /home/jameinel/dev/foo
>
> So it would seem that "go fmt" is using os.Getenv("PWD") or some variant
> instead of using os.Getwd().

OK, having looked at the pwd source and os.Getwd, I understand
more of the issue now. os.Getwd uses os.Getenv("PWD") to find
an alternative reachable current directory path. I had no
idea about this hack - it's useful to know about. That said, os.Getwd
has been like this since go1.0, so that at least hasn't changed recently.

I can't reproduce your issue.

$ ls -l ~/jc
lrwxrwxrwx 1 rog rog 41 Mar 11 12:44 /home/rog/jc ->
/home/rog/src/go/src/github.com/juju/juju
$ cd ~/jc/worker/uniter
$ pwd
/home/rog/jc/worker/uniter
$ GOROOT=~/go1.4 PATH=~/go1.4/bin:$PATH
$ go version
go version go1.4.1 linux/amd64
$ rm -r $GOPATH/pkg
$ go install
$ env | grep PWD
OLDPWD=/home/rog/jc/worker/uniter/relation
PWD=/home/rog/jc/worker/uniter
$

Do you see an error in the above example?
It would be nice to have a complete script that demonstrates the
problem you're having.

  cheers,
    rog.