Occasional segfault in GHCi w/ 7.4.1-rc1 and 64bit OS X

[Evan Laforge]

> of the time.  It seems random when it segfaults and when it runs.  I
> don't know if it's worth anything, but the gdb backtrace looks
> similar:
>
> (gdb) bt
> #0  0x00000001f6c930da in evacuate1 ()
> #1  0x00000001f6c98868 in scavenge_block1 ()
> Previous frame inner to this frame (gdb could not unwind past this frame)

Oh, and I should say this is from a core dump, though there are a few
suspicious errors starting up.  And oddly I get more info from a bogus
binary than the actual ghc binary:

% gdb /Library/Frameworks/GHC.framework/Versions/7.4.0.20111219-x86_64/usr/lib/ghc-7.4.0.20111219/ghc
/cores/core.67101
GNU gdb 6.3.50-20050815 (Apple version gdb-1510) (Wed Sep 22 02:45:02 UTC 2010)
Copyright 2004 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and you are
welcome to change it and/or distribute copies of it under certain conditions.
Type "show copying" to see the conditions.
There is absolutely no warranty for GDB.  Type "show warranty" for details.
This GDB was configured as "x86_64-apple-darwin"...unable to read
unknown load command 0x24
unable to read unknown load command 0x26
Reading symbols for shared libraries .... done
unable to read unknown load command 0x24
unable to read unknown load command 0x26

warning: Could not find object file
"/Users/ian/zz64/ghc-7.4.0.20111219/rts/dist/build/libHSrts_thr.a(ffi64.o)"
- no debug information available for "../src/x86/ffi64.c".


warning: Could not find object file
"/Users/ian/zz64/ghc-7.4.0.20111219/rts/dist/build/libHSrts_thr.a(prep_cif.o)"
- no debug information available for "../src/prep_cif.c".


warning: Could not find object file
"/Users/ian/zz64/ghc-7.4.0.20111219/rts/dist/build/libHSrts_thr.a(types.o)"
- no debug information available for "../src/types.c".


Reading symbols for shared libraries . done
unable to read unknown load command 0x24
unable to read unknown load command 0x26
Reading symbols for shared libraries .... done
#0  0x00000001f6c930da in ?? ()
(gdb) bt
#0  0x00000001f6c930da in ?? ()
(gdb)


Versus a bogus binary:

% gdb foo /cores/core.67101
GNU gdb 6.3.50-20050815 (Apple version gdb-1510) (Wed Sep 22 02:45:02 UTC 2010)
Copyright 2004 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and you are
welcome to change it and/or distribute copies of it under certain conditions.
Type "show copying" to see the conditions.
There is absolutely no warranty for GDB.  Type "show warranty" for details.
This GDB was configured as "x86_64-apple-darwin"...foo: No such file
or directory

Reading symbols for shared libraries . done
unable to read unknown load command 0x24
unable to read unknown load command 0x26
Reading symbols for shared libraries
warning: Could not find object file
"/Users/ian/zz64/ghc-7.4.0.20111219/rts/dist/build/libHSrts_thr.a(ffi64.o)"
- no debug information available for "../src/x86/ffi64.c".


warning: Could not find object file
"/Users/ian/zz64/ghc-7.4.0.20111219/rts/dist/build/libHSrts_thr.a(prep_cif.o)"
- no debug information available for "../src/prep_cif.c".


warning: Could not find object file
"/Users/ian/zz64/ghc-7.4.0.20111219/rts/dist/build/libHSrts_thr.a(types.o)"
- no debug information available for "../src/types.c".

..... done
#0  0x00000001f6c930da in evacuate1 ()
(gdb) bt
#0  0x00000001f6c930da in evacuate1 ()
#1  0x00000001f6c98868 in scavenge_block1 ()
Previous frame inner to this frame (gdb could not unwind past this frame)
(gdb)