Linux linker errors with binutils >= 2.27

[ketmar via Digitalmars-d]

Marco Leise wrote:

> Since binutils 2.27 I can not compile dmd with the `gold`
> linker any more. On my Gentoo Linux amd64 host, when linking
> the 32-bit version of druntime the following error is
> repeatedly output for all kinds of symbols:
>
>   libdruntime.so.a(libdruntime.so.o):
>   relocation R_386_GOTOFF against preemptible symbol <some
>   mangled name> cannot be used when making a shared object
>
> Now starting with binutils 2.28 - in addition to the above -
> dynamically linked Dlang executables error out in druntime
> with an error message of this type:
>
>   Fatal Error while loading '/usr/lib64/libphobos2.so.0.74':
>   The module '<some module>' is already defined in '<executable>'.
>
> Does anyone have solutions to one or both of these issues at
> hand? For Gentoo packages I made shared linking the default
> and unless my configuration is a unique snowflake this is
> right now affecting all DMD users there.
> From reading `checkModuleCollisions()`
> [https://github.com/dlang/druntime/blob/master/src/rt/sections_elf_shared.d#L891]
> it would seem that changes in copy-relocations have something
> to do with the second issue it.

1. patch your compiler to use old ELF_COMDAT hack in elfobj.c:
	#define ELF_COMDAT      TARGET_LINUX
	+#undef ELF_COMDAT
	+#define ELF_COMDAT  0

2. downgrade to old binutils, new binutils are not working with dmd .so's.

step "2" is essential. alas.