http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47296
--- Comment #9 from Jerry DeLisle <jvdelisle at gcc dot gnu.org> 2011-01-16 08:29:55 UTC --- After getting Win7-cygwin build of gcc latest trunk built, I was able to do some more testing. I could then reproduce another segfault. As Janne suggested and I certainly agree, the following simple patch clears this second segfault. It is interesting that the Windows/cygwin execution behaves differently and the opp->file somewhere is getting touched or not initialized. Index: unix.c =================================================================== --- unix.c (revision 168844) +++ unix.c (working copy) @@ -1085,7 +1085,11 @@ #endif /* HAVE_MKSTEMP */ if (fd < 0) - free (template); + { + free (template); + opp->file = NULL; + opp->file_len = 0; + } else { opp->file = template; I will commit this sometime tomorrow.