new library handling in binutils causes trouble with --enable-shared

[Bernd Jendrissek]

On 7/25/07, Mike Frysinger <vapier@gentoo.org> wrote:
> the new build system in binutils sets up custom LD_LIBRARY_PATHs which can
> cause conflicts between the build and host.  if you take
> binutils-2.17.50.0.17 and build/install it with --enable-shared, your host
> binutils will all be linked against libbfd-2.17.50.0.17.20070615.so:
>
> $ readelf -d `which as` | grep NEEDED.*2.17
>  0x0000000000000001 (NEEDED)             Shared library:
> [libopcodes-2.17.50.0.17.20070615.so]
>  0x0000000000000001 (NEEDED)             Shared library:
> [libbfd-2.17.50.0.17.20070615.so]
>  0x0000000000000001 (NEEDED)             Shared library: [libc.so.6]
>
> but if you turn and and try to build it again, the LD_LIBRARY_PATH will be set
> to your local build directories:
> LD_LIBRARY_PATH=.../build/bfd/.libs:.../build/opcodes/.libs:....

That looks like libtool magic where build/binutils/objdump is really a
shell script that sets up LD_LIBRARY_PATH and then runs
build/binutils/.libs/objdump (the uninstalled binary).

Your use of passive voice ("will be set") confuses me... where is
LD_LIBRARY_PATH getting set other than in the libtool wrapper scripts?

> and this makes your installed `as` very angry, especially when cross-compiling
> as the local libraries are not targetting the same thing as your host
> libraries.

How does your installed 'as' even see the LD_LIBRARY_PATH pointing
into your build directory?

Also, doesn't a cross-as use RPATH so that it dynamically links to
exactly the target-specific libraries?

> about the only use i can think of for these LD_LIBRARY_PATHs is when you go to
> run `make check`, so perhaps the setting of this variable should be
> restricted to that case ?
> -mike

I find it convenient while I'm (re)doing my OMF port to be able to run
objdump from the build directory without having to install it.  YMMV.