stack exec pacman fails

[ndmitchell]

C:\Neil\hlint>stack exec pacman
Executable named pacman not found on path: ["C:\\Neil\\hlint\\.stack-work\\install\\7ca85f7b\\bin","C:\\Users\\ndmit_000\\AppData\\Roaming\\stack\\snapshots\\7a8350a1\\bin","C:\\ProgramData\\Oracle\\Java\\javapath","C:\\Python27\\","C:\\Python27\\Scripts","C:\\WINDOWS\\system32","C:\\WINDOWS","C:\\WINDOWS\\System32\\Wbem","C:\\WINDOWS\\System32\\WindowsPowerShell\\v1.0\\","C:\\Program Files (x86)\\Git\\cmd","C:\\Program Files (x86)\\GNU\\GnuPG\\pub","C:\\Program Files\\SlikSvn\\bin","C:\\Program Files (x86)\\CMake\\bin","C:\\Program Files (x86)\\QuickTime\\QTSystem\\","C:\\Leksah\\bin\\","C:\\Users\\ndmit_000\\.dnx\\bin","C:\\Program Files\\Microsoft DNX\\Dnvm\\","C:\\Program Files (x86)\\Windows Kits\\8.1\\Windows Performance Toolkit\\","C:\\Program Files (x86)\\MiKTeX 2.9\\miktex\\bin\\","C:\\Program Files\\nodejs\\","C:\\ghc\\minghc-7.10.2-i386\\switch","C:\\ghc\\minghc-7.10.2-i386\\git-2.4.0.1\\cmd","C:\\ghc\\minghc-7.10.2-i386\\git-2.4.0.1\\usr\\bin","C:\\ghc\\minghc-7.10.2-i386\\ghc-7.10.2\\mingw\\bin","C:\\ghc\\minghc-7.10.2-i386\\ghc-7.10.2\\bin","C:\\ghc\\minghc-7.10.2-i386\\bin","C:\\Users\\ndmit_000\\AppData\\Roaming\\cabal\\bin","C:\\Program Files (x86)\\MinGHC-7.10.1\\switch","C:\\Users\\ndmit_000\\Desktop\\Radio","C:\\Program Files (x86)\\MinGHC-7.6.3\\switch","C:\\bin","C:\\Program Files (x86)\\MinGHC-7.8.3\\switch","C:\\Program Files (x86)\\MinGHC-7.8.3\\msys-1.0.1\\bin","C:\\Program Files (x86)\\MinGHC-7.8.3\\ghc-7.8.3\\mingw\\bin","C:\\Program Files (x86)\\MinGHC-7.8.3\\ghc-7.8.3\\bin","C:\\Program Files (x86)\\MinGHC-7.8.3\\bin","C:\\Users\\ndmit_000\\AppData\\Local\\atom\\bin","C:\\Program Files (x86)\\NSIS","C:\\Program Files (x86)\\Java\\jdk1.8.0_45\\bin","C:\\Users\\ndmit_000\\AppData\\Roaming\\local\\bin","C:\\Users\\ndmit_000\\AppData\\Roaming\\npm"]

Where should I be expecting pacman to live? I can't find it under C:\Users\ndmit_000\AppData\Roaming\stack, which is where I expected it? This is using stack HEAD.

[ndmitchell]

For info, I do have C:\Users\ndmit_000\AppData\Local\Programs\stack\i386-windows\msys2-20150512\usr\bin\pacman.exe, but seems Stack doesn't put it on my path. I think stack has some "default context" stuff, e.g. which ghc/bitness is selected by default?

I think this might have all started going wrong when I ran:

stack setup --compiler ghcjs-0.1.0.20150924_ghc-7.10.2

[ndmitchell]

For info, stack setup for ghcjs failed because it couldn't find cmp.exe on the PATH, which is located next to pacman.

[mgsloan]

Is it when compiling ghcjs or when booting it?

If when compiling it, then yes, that'd make sense, because msys gets installed after the compiler, and isn't available when building ghcjs.

Otherwise, though, the logic for msys is identical to when it is used with ghc.

[ndmitchell]

It fails to find cmp when compiling. Note that msys is already installed, and even a normal stack exec has "lost" if from the path, without going anywhere near ghcjs. So it seems my failed attempt to install ghcjs has broken stack.

[mgsloan]

Ok, yeah, sounds like the fix is simple - install msys before installing the compiler - and have it on the path during that process. Hopefully this won't affect the success of normal ghc setup.

[mgsloan]

Oh wait, looking at this issue more carefully, obviously you aren't using ghcjs with hlint. A botched ghcjs setup really shouldn't affect anything. Weird!

[byorgey]

My student ran into this same issue. @mgsloan suggested doing stack setup --no-system-ghc, which actually forced it to download GHC and a bunch of other stuff---previously it had been using a system GHC. We actually saw it downloading pacman as we watched the messages scroll by. But when it was done, stack exec pacman still gave the same error.

What finally fixed it was uninstalling the system GHC and deleting everything we could find that looked like either a cache used by stack or something GHC-related (e.g. .stack-work, the global stack directory, several directories that had minghc in their name), then rerunning stack setup --no-system-ghc (just for good measure, though the --no-system-ghc was probably unnecessary at this point). It went through all the same work of downloading GHC and a bunch of other stuff that we had seen it do before, but when it was done, this time stack exec pacman worked!

[mgsloan]

@byorgey The issue with your first stack exec pacman was likely that you didn't pass --no-system-ghc to it. So, it was still using the system GHC. Deleting the system GHC resolved this.

That isn't your fault, I think it is a funky default that the system ghc is preferred even if you've done stack setup --no-system-ghc. I've opened an issue to fix this: #1901

You can also put system-ghc: false in your stack.yaml or config.yaml

[byorgey]

I thought we also tried stack exec --no-system-ghc -- pacman, but I can't be sure, and there's no way to test it now!

[mgsloan]

Closing this as an old support issue.