Fwd: Using Cabal to install terminfo-0.4.0.0 breaks GHC on Debian x86_64

Hi, thanks for your reply. Yes, I know for a fact I was installing to the global registry. All of my Haskell projects depend on a few important packages, and I always install these globally. For stuff I just want to play around with, I just install into the user registry. Actually terminfo-0.4.0.0 is not something any of my projects depend on, but I had installed it globally anyway and then this problem occurred. Also, the behavior Cabal installing Crypto-4.2.5.1 was odd. As I explained in my first e-mail, some of the shared modules were being built with file extensions of ".hi" instead of ".dyn_hi", but the "copy" phase of the Cabal installation was searching for files with ".dyn_hi" extensions and was failing. And not all modules were being built incorrectly, some modules had the correct ".dyn_hi", others had just ".hi". This may be a problem with the Crypto.cabal file, however. But anyway, the transition to using shared libraries by default has (in my experience) caused just these two hiccups. I'm glad I was able to expose this problem. -- Ramin Honary On Mon, Apr 14, 2014 at 10:07 PM, Austin Seipp wrote:

Hi Ramin,

Can I ask if you're installing packages into the global user database? If so, that's definitely the way for this to happen - otherwise, Cabal should never overwrite *anything* in the 'global' package directory (in your case, under /usr/local/lib/ghc-7.8.2...) This is the only way I can see this happening. In particular, installing 'terminfo' into my local package database ('cabal install terminfo') works fine...

Carefully review your cabal configuration if you don't mind. You can also always force the installation using '--user' when running cabal.

However, thank you very much for bringing this to my attention. What you have discovered is a real brainfart I don't think we had considered! The problem is that now that GHC is dynamically linked, we *cannot* get away with lying about whether those packages are installed - because they must install shared objects for GHC itself to work. That means overwriting them by accident (because we don't think they're installed) is a real possibility.

Relatedly, the NixOS Haskell users are suffering from the same problem with 7.8.2 - http://lists.science.uu.nl/pipermail/nix-dev/2014-April/012992.html - same problem, slightly different symptoms.

See https://ghc.haskell.org/trac/ghc/ticket/8919 for the ticket.

So this is definitely a real problem. I think scheduling the change for 7.8.3 is correct.

My intuition tells me the fix might actually be quite simple - don't lie about xhtml and terminfo being installed, and just be honest. Is there any particular downside to doing this? I don't think so, *other* than the fact it does mean terminfo has to come along when it's not part of the Haskell Platform!

...

I am using Debian, not Mac. It is possible the problem may be with the binary release for Debian x86_64, or it could just be my Cabal config file.

When I install the binary distribution onto Debian, I simply run "make install" in the ghc-7.8.2 directory. I don't know how this install

On Mon, Apr 14, 2014 at 7:08 AM, Ramin Honary wrote: process

...

the creates the GHC package registry, but after a fresh install, the output of the "ghc-pkg list" command shows that "terminfo-0.4.0.0" is NOT installed even though there the /usr/local/lib/ghc-7.8.2/terminfo-0.4.0.0 directory clearly exists and is populated with the correct library files. But since it is not registered Cabal tries to re-build it and overwrites the existing "terminfo-0.4.0.0" package.

After a fresh install on Mac or Fedora, I wonder if "terminfo-0.4.0.0" shows up in the GHC package registry? It could be the package registry for the Debian binary distribution missed that detail.

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-- Regards,

Austin Seipp, Haskell Consultant Well-Typed LLP, http://www.well-typed.com/