GHC 6.2.1 and FedoraCore2: ar-related build problem, looked like readline problem

[Henrik Nilsson]

Interestingly, I first thought this problem was related to the long
"readline story", since the build process complained about
"readline" when it failed. But that turned out not to be the case!

The subject of the mail reflects this, hopefully making this mail
easier to find should someone face similar problems.

Background:

I'm trying to build GHC 6.2.1 on a Fedora Core 2 (FC2) Linux box.
The reason is that ghci from the available binary releases (the RH9 rpm
and the generic Linux version for glibc 2.3) segfaults.
However, the compiler itself seems to run fine, so I decided to try to
build and install a system from sources, using the GHC compiler from
the generic binary release.

Problem:

After a long time with a lot of activity, the build process halts
with the following error:

     /home/henrik/ghc-6.2.1/libraries/readline/libHSreadline.a:
     could not read symbols: Archive has no index; run ranlib to add one
     collect2: ld returned 1 exit status
     <<ghc: 3845976 bytes, 2 GCs, 129524/129524 avg/max bytes residency
     (1 samples), 5M in use, 0.00 INIT (0.00 elapsed), 0.01 MUT (3.80 
elapsed),
      0.00 GC (0.00 elapsed) :ghc>>

It turns out that "libHSreadline.a" actually isn't an archive at all:
the building of it has failed, but somehow this has gone unnoticed.

What happened was this:

     seshat-31% make libHSreadline.a
     rm -f libHSreadline.a libHSreadline.a.tmp
     echo System/Console/Readline_stub.o > libHSreadline.a.list
     echo HsReadline_cbits.o System/Console/Readline_hsc.o >> \
         libHSreadline.a.list
     echo  >> libHSreadline.a.list
     /usr/bin/find System/Console/Readline_split \
                   System/Console/SimpleLineEditor_split \
                   -name '*.o' -print >> libHSreadline.a.list
     /usr/bin/ar q    libHSreadline.a -input libHSreadline.a.list
     /usr/bin/ar: creating libHSreadline.a
     /usr/bin/ar: '-input': No such file
     rm -f libHSreadline.a.list
     : libHSreadline.a

The resulting in an archive essentially containing a list of filenames,
rather than binary object code.

The reason for this, in turn, as can be seen, is that the GNU version of
"ar", at least the ones shipped with FC2 (and Mandrake 9.2,
which I also checked), does not support the "-input" option.

Temporary Solution:

I then checked in the "mk" directory, and in "config.mk" I found the
line

     ArSupportsInput         = -input

Changing this to

     ArSupportsInput         =

allows "libHSreadline.a" to be built correctly, using a different
way of passing the desired file name arguments to "ar".

I do not know why the configuration scripts concluded that the version
of "ar" on my system supports "-input".

So, in summary, there were two problems:

   * The configuration tools somehow thinks the system's "ar"
     supports "-input".
   * The build system fails to detect when "ar" failed in the first
     place.

/Henrik

-- 
Henrik Nilsson
School of Computer Science and Information Technology
The University of Nottingham
nhn at cs.nott.ac.uk

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