Stack setup fails with busybox tar

[kfigiela]

stack setup relies on compression autodetection feature of tar. However, some versions of tar (i.e. that one shipped with busybox or Alpine Linux) don't autodetect compressed archives, so that Stack fails.

Steps to reproduce
Use GHC + Alpine Linux docker image (https://github.com/mitchty/alpine-ghc)

$ docker run --rm -it mitchty/alpine-ghc 
# apk update && apk add xz make # stack asks to install them
# stack setup --resolver ghc-7.10.2`

Expected behavior: Stack installs GHC
Actual behavior: Stack fails to extract GHC source archive, as existing tar implementation doesn't autodetect compression. Installing GNU tar (apk add tar) solves is a workaround.

# stack setup --resolver ghc-7.10.2
Run from outside a project, using implicit global project config
Using resolver: ghc-7.10.2 specified on command line
Preparing to install GHC to an isolated location.
This will not interfere with any system-level installation.
Already downloaded.
Running /bin/tar xf /root/.stack/programs/x86_64-linux/ghc-7.10.2.tar.xz in directory /tmp/stack-setup29074/ exited with ExitFailure 1


tar: invalid tar magic

Unpacking GHC into /tmp/stack-setup29074/ ...

[mgsloan]

Pinging @borsboom , thoughts on what should be done about this? A few options:

• On failure, retry tar with a guessed format specific arg. So, it'd see .tar.xz in the URL and guess to use the -J flag.
• Detect these tar versions and install a newer one.
• Detect these tar versions and fail with an error about it.

[mgsloan]

@kfigiela This should now be addressed by 0ae5411 , let me know if not