[xmonad] Segfault on startup

[Rafael Almeida]

On Thu, 6 Mar 2008 06:52:00 -0500, "Brent Yorgey" <byorgey at gmail.com> wrote:
>
>
> On Thu, Mar 6, 2008 at 1:41 AM, Don Stewart <dons at galois.com> wrote:
>      roma:
>      > * Rafael Almeida <almeidaraf at gmail.com> [2008-03-06 02:57:16-0300]
>      > > On Thu, Mar 6, 2008 at 2:36 AM, Don Stewart <dons at galois.com>
>      wrote:
>      > > > almeidaraf:
>      > > >
>      > > > > Hello,
>      > > >  >
>      > > >  > I've been using xmonad from darcs. Today I pulled the latest
>      version
>      > > >  > and, after compiling xmonad, I found it segfaults during the
>      startup.
>      > > >  > I'm running a debian 4.0 (etch) and I've installed X11 1.4.1
>      on my
>      > > >  > local user.
>      > > >
>      > > >  Almost certainly this is because you have a partially
>      recompiled xmonad.
>      > > >  Please do a full make clean, then try again.
>      > > >
>      > > >     runhaskell Setup.lhs clean
>      > > >
>      > > >  then rebuild.
>      > > >
>      > > >     http://haskell.org/haskellwiki/Xmonad/
>      Frequently_asked_questions#Help.21_xmonad_just_segfaulted
>      > > >
>      > > >  Same for any config repo you use.
>      > > >
>      > >
>      > > That doesn't seem the issue because I would always delete xmonad-
>      new
>      > > directory and recreate it using
>      > >
>      > > $ darcs get xmonad --to-patch=patchname xmonad-new
>      > >
>      > > in order to find out which patch broke it. Just in case I just
>      did:
>      > >
>      > > $ darcs get http://code.haskell.org/xmonad --to-patch="Core.hs:
>      add an
>      > > Applicative" xmonad-new
>      > >
>      > > and compiled it. Sure enough, xmonad segfaulted on startup.
>      >
>      > As far as I see from your config, you also use xmonad contrib
>      library.
>      > Have you recompiled it as well?
>
>      Ah yes, that needs to be fully cleaned and recompiled.
>
>      And then confirm that without any config file it either is ok, or
>      crashes.
>
> Just to make sure everything is completely clear: every time you rebuild
> xmonad, you must do a full clean and rebuild of xmonad-contrib.  Otherwise it
> doesn't realize that a library it depends on has changed, and continues
> referencing the old library, which may or may not cause a crash. =(
>
> I'm pretty sure there's no way that simply adding an instance could cause a
> crash, except for the recompilation problem explained above, or a bug in ghc.
>
> -Brent
>

Oh yes. That was indeed the problem here. My bad :(. I was kinda thrown
away because I thought you'd never get a Segmentation Fault from a code
written in Haskell. But I supose that the error came from the C code on
X11, right? Shouldn't it return a nicer error instead of segfaulting? Or
is this behaviour expectable?