Re: [PATCH] build: allow turning off --no-undefined and -z,defs

[Florian Weimer <fweimer@redhat.com>]

* Evgeny Vereshchagin:

> ASan, UBSan and MSan provided by clang aren't compatible with --no-undefined and -z,defs:
> https://clang.llvm.org/docs/AddressSanitizer.html#usage
> https://github.com/google/sanitizers/issues/380
> so to build elfutils with clang with the sanitizers it should be possible
> to turn them off.
>
> Without this patch something like
>
> sed -i 's/^\(ZDEFS_LDFLAGS=\).*/\1/' configure.ac
> find -name Makefile.am | xargs sed -i 's/,--no-undefined//'
>
> should be used to make elfutils compile.
>
> The patch was tested in https://github.com/evverx/elfutils/pull/24 by
> compiling elfutils with both gcc and clang with and without ASan/UBsan
> and running `make check && make distcheck`. --no-undefined and -z,defs
> are still passed by default as expected.

Why isn't this a bug in the compiler driver?  Nowadays, GCC passes
-lasan if -fsanitize=address is used.  I think that's quite reasonable.

Thanks,
Florian