Known pitfalls in building Glasgow Haskell

WARNINGS about pitfalls and known "problems":

1. One difficulty that comes up from time to time is running out of space in `/tmp'. (It is impossible for the configuration stuff to compensate for the vagaries of different sysadmin approaches re temp space.) The quickest way around it is `setenv TMPDIR /usr/tmp' or even `setenv TMPDIR .' (or the equivalent incantation with the shell of your choice). The best way around it is to say

   export TMPDIR=<dir>
   

   in your `build.mk' file. Then GHC and the other `fptools' programs will use the appropriate directory in all cases.
2. In compiling some support-code bits, e.g., in `ghc/runtime/gmp' and even in `ghc/lib', you may get a few C-compiler warnings. We think these are OK.
3. When compiling via C, you'll sometimes get "warning: assignment from incompatible pointer type" out of GCC. Harmless.
4. Similarly, `ar'chiving warning messages like the following are not a problem:

   ar: filename GlaIOMonad__1_2s.o truncated to GlaIOMonad_
   ar: filename GlaIOMonad__2_2s.o truncated to GlaIOMonad_
   ...
   

5. Also harmless are some specialisation messages that you may see when compiling GHC; e.g.:

   SPECIALISATION MESSAGES (Desirable):
   *** INSTANCES
   {-# SPECIALIZE instance Eq [Class] #-}
   {-# SPECIALIZE instance Eq (Class, [Class]) #-}
   {-# SPECIALIZE instance Outputable [ClassOp] #-}
   {-# SPECIALIZE instance Outputable [Id] #-}
   

6. In compiling the compiler proper (in `compiler/'), you may get an "Out of heap space" error message. These can vary with the vagaries of different systems, it seems. The solution is simple: (1) add a suitable `-H' flag to the `<module>_HC_OPTS' `make' variable in the appropriate `Makefile'; (2) try again: `gmake'. (Section See section Pattern rules and options.) Alternatively, just cut to the chase scene:

   % cd ghc/compiler
   % make EXTRA_HC_OPTS=-H32m  # or some nice big number
   

7. Not too long into the build process, you may get a huge complaint of the form:

   Giant error 'do'ing getopts.pl:  at ./lit2pgm.BOOT line 27.
   

   This indicates that your `perl' was mis-installed; the binary is unable to find the files for its "built-in" library. Speak to your perl installer, then re-try.
8. If you try to compile some Haskell, and you get errors from GCC about lots of things from `/usr/include/math.h', then your GCC was mis-installed. `fixincludes' wasn't run when it should've been. As `fixincludes' is now automagically run as part of GCC installation, this bug also suggests that you have an old GCC.
9. You may need to re-`ranlib' your libraries (on Sun4s).

   % cd $(libdir)/ghc-x.xx/sparc-sun-sunos4
   % foreach i ( `find . -name '*.a' -print` ) # or other-shell equiv...
   ?    ranlib $i
   ?    # or, on some machines: ar s $i
   ? end
   

   We'd be interested to know if this is still necessary.
10. If you end up making documents that involve (La)TeX and/or `tib' (Simon's favourite), the odds are that something about your/our setup will reach out and bite you. Yes, please complain; meanwhile, you can do `make -n whatever.dvi' to see the intended commands, then try to muddle through, doing them by hand.
11. GHC's sources go through `cpp' before being compiled, and `cpp' varies a bit from one Unix to another. One particular gotcha is macro calls like this:

      SLIT("Hello, world")
    

    Some `cpp's treat the comma inside the string as separating two macro arguments, so you get

      :731: macro `SLIT' used with too many (2) args
    

    Alas, `cpp' doesn't tell you the offending file! Workaround: don't put wierd things in string args to `cpp' macros.