promu build does not work on Windows

[carlpett]

I'm trying to use promu for wmi_exporter and ran into some issues on Windows. I have some fixes coming in a pull request, but here is a list of the things I've noticed so far:

• The user part of the build info is mangled in ldflags, this is what it looks like on my machine -X github.com /m@MY-HOST
• The go-shell package does not report panics in any way, but instead simply swallows any errors. Unsure if this is a bug in the package or the use of it (defer shell.ErrExit())
• The default shell is /bin/sh, which does not exist on Windows, and causes a panic (which as mentioned is swallowed, and promu exits with status code 0)

Is Windows compatibility a goal of promu? I have a patch which fixes the first item, but from some experimentation with go-shell, it seems a bit hard to make it work on Windows. Will try some more, but if it is a non-goal for this project, I'll just have to use something else.

[carlpett]

Go-shell does some management of argument quoting internally it seems, after which Go (on Windows only) applies some rules of its own (https://github.com/golang/go/blob/master/src/syscall/exec_windows.go#L17). The effect is that the ldflags parameter has its quotes escaped, which turns the call into go build [...] -ldflags "\"-s" -X[...]. Might be possible to work around, somehow

[sdurrheimer]

To be honest, I never really thought about Windows when I was doing promu, so I'm not surprised we got some issues here.

I would totally merge Windows compatibility PRs, if we are able to make it work.

I will also take a look on my side to see if I can improve those things.

[carlpett]

@sdurrheimer Cool! I think the main culprit is go-shell, really. I'll give fixing it a try (probably just providing another code path if running on Windows).