[Bug fortran/51779] gcc 4.6.2 build fails on Mac OS X Lion w/Xcode 4.2, with gfortran erorr

["zippy at anl dot gov" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51779

--- Comment #11 from Tim Williams <zippy at anl dot gov> 2012-01-10 19:45:44 UTC ---
(In reply to comment #10)
> (In reply to comment #9)
> > Thanks, Tobias. I did try out the gfortran 4.6.2 from here, and it does compile
> > runnable code. Unfortunately, it still does not work with any version of gdb I
> > have tried on Mac OS X. My end goal in building the whole of gcc 4.6.2 was to
> > try building a Fortran code and debug it with the latest gdb version (7.3.1).
> > No luck with this prebuilt gfortran binary either.
> 
>    You will need to compile binaries with -Wl,-no_pie if you want to debug in
> FSF gdb
> under Lion (which defaults to -pie in the linker).  Apple's gdb automatically
> disables
> aslr under Lion (which can be turned back on by setting the  disable-aslr flag
> to 0 within
> Apple's gdb). This option doesn't exist in FSF gdb yet as far as I know.
> 
> ps There is some discussion of this at
> http://reverse.put.as/2011/08/11/how-gdb-disables-aslr-in-mac-os-x-lion/.

The -Wl,-no_pie linker flag is definitely secret sauce I was missing. This made
gdb 7.3.1 work with my test fortran program---was able to set breakpoints and
look at some variables. Thanks, Jack.