On Mon, May 10, 2010 at 05:20:22PM +0100, Dave Korn wrote: > On 10/05/2010 17:16, Dave Korn wrote: > > On 10/05/2010 16:19, Jack Howarth wrote: > > > >> Compiler executable checksum: c54eb6db87684e4d5a5bb9ad02c2b2c4 > >> 20081222_1.c:16: error: 'EXT_x' aliased to undefined symbol 'INT_x' > > > The error comes from finish_aliases_1 in varasm.c, where it is suppressed > > in > > the case of a weakref. I don't know why. > > Well, I can infer that it would be because it's legitimate not to define a > weak symbol. I guess the problem might be that find_decl_and_mark_needed when > called on EXT_x gets confused by the combination of an asm decl as well as an > alias maybe? > > cheers, > DaveK
Dave, When I pointed out to the darwin linker maintainer that their gcc 4.0.1 compiler produced an error message... > gcc-4.0 -O0 -c -o c_lto_20081222_1.o 20081222_1.c > 20081222_1.c:16: error: 'EXT_x' aliased to undefined symbol 'INT_x' > 20081222_1.c:16: warning: alias definitions not supported in Mach-O; > ignored but that for the newer Apple gcc 4.2.1 compiler (and FSF gcc) we don't get the 'warning: alias definitions not supported in Mach-O' warning, his reply was... -------------------------------------------------------------------------- My understanding is the mach-o file format does not have a way to encode aliases. The weak alias case works sometimes, because the compiler just ignores the alias part and just makes a weak def of the function with the aliased name. --------------------------------------------------------------------------- I also found http://gcc.gnu.org/ml/gcc/2005-12/msg00009.html where Geoffrey Keating indicates that Mach-O doesn't support aliases in the object file at all. Jack ps I am still trying to find the patch that removed the warning "alias definitions not upported in Mach-O" from Apple's gcc since that might have some useful comments on the current situation.
