`stack setup` and `stack build` using different versions of GHC

[bendmorris]

bmorris (master)$ stack build
No GHC found, expected version 7.10.3 (x86_64) (based on resolver setting in /Users/bmorris/Dev/mydir/stack.yaml). Try running stack setup

bmorris (master)$ stack setup
Already downloaded.
Installed GHC.
Would add the following to PATH: /Users/bmorris/.stack/programs/x86_64-osx/ghc-7.10.2/bin

bmorris (master)$ stack build
No GHC found, expected version 7.10.3 (x86_64) (based on resolver setting in /Users/bmorris/Dev/mydir/stack.yaml). Try running stack setup

[mgsloan]

Strange! What's the contents of /Users/bmorris/Dev/mydir/stack.yaml?

[harendra-kumar]

It seems setup and build are not agreeing on the compiler version. Setup is installing 7.10.2 and build is asking 7.10.3. What does your stack.yaml look like? What does stack path say?

[mgsloan]

Would also be good to know stack --version

[bendmorris]

$ cat stack.yaml
resolver: lts-4.1
$ stack --version
Version 0.1.2.0, Git revision 65246552936b7da4b64b38372feac903d96a8911

Running stack path seems to have the same issue as stack build:

$ stack path
No GHC found, expected version 7.10.3 (x86_64) (based on resolver setting in /Users/bmorris/Dev/mydir/stack.yaml). Try running stack setup

[harendra-kumar]

You seem to be running a pretty old version of stack. Can you try upgrading or installing the latest version?

[mgsloan]

Yeah, that's 7 months old, which is an aeon ago in terms of stack's development. Did it come from some distro's set of packages?

[bendmorris]

It's also the version I get from cabal install stack.

[mgsloan]

@bendmorris There are two possible explanations for that. One is that your hackage index is very old (run cabal update). The other possible reason is that you have old packages installed. In this case, cabal install will pick a version of stack that is compatible with the installed packages, even if it's quite old. This is one of the reasons stack exists. cabal-install's behavior is determined by the state of the package DB, often with unintended results.

[borsboom]

Try forcing cabal-install to install the latest version using cabal install stack-1.0.2. If you get dependency errors with that, building in a cabal sandbox may help. And there's always the nuclear option: rm -rf ~/.cabal ~/.ghc and start from scratch :)

[devonhollowood]

I've been having the same issue, with the same version of stack (0.1.2.0). It's the version that is included in Ubuntu's main repository, in the haskell-stack package. Is that package no longer considered a good way to install stack?

[harendra-kumar]

Stack has undergone rapid development and has changed a lot since. The standard distro repositories might have older versions. You can try uninstalling the one from ubuntu repository and try this one: http://docs.haskellstack.org/en/stable/install_and_upgrade.html#ubuntu.

[devonhollowood]

That worked, thanks. Another workaround that I found was passing the --install-ghc flag to each stack command, although that seemed like overkill. So I'm glad using the fpcomplete repository worked!