I noticed that Ubuntu, as well as Debian and original packages come
without some variants of threaded debugging binaries.
A recent change added of printing a stack trace with -xc option requires
using both -ticky and profiling compile options,
which in turn forces program to be compiled in a -debug RTS way.
Since stack trace looks like indispensable debugging tool, and
convenient parallelization is strength of Haskell,
I wonder is there any remaining reason to leave beginners with a cryptic
error message
when they try to debug a parallel or threaded application, and want to
take advantage of stack trace?
The resulting ghc-prof package would be increased by less than 1%.
Here is a patch for Ubuntu/Debian GHC 7.4.2 package, as well as upstream
thanks for the suggestion. Note that the 7.4 package in unstable will
not be changed, as we are in a freeze. There it already seems already to
be enabled, or at least I do see
/usr/lib/ghc/libHSrts_thr_debug.a
/usr/lib/ghc/libHSrts_thr_p.a
But then, I already see this file in in the 7.4.2 package. What is the
precise effect of your patch on the contents of /usr/lib/ghc/libHSrts*?
Are you sure that it is not actually present?