What to do about go fmt 1.4 ?

[John Meinel]

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().

What I *really* don't understand is that if I'm at the top level and I do
"go fmt" it shows:

~/jc $ go fmt
...
stat ../dev/go/src/github.com/juju/juju/doc.go: no such file or directory

~/jc $ cd worker/uniter/filter
~/jc/worker/uniter/filter $ go fmt
...
stat ../../../../dev/go/src/
github.com/juju/juju/worker/uniter/filter/filter.go: no such file or
directory

I really don't understand all the interactions with PWD or why it is trying
to stat "../../../../". How does it know about dev/go/src/
github.com/juju/juju but then try to apply that to PWD?

If you have go 1.4 it should be easy to test this.

John
=:->
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