r220455 - Revert r218541 - Don't link in sanitizer runtimes if -nostdlib/-nodefaultlibs is provided.

[Joerg Sonnenberger]

On Thu, Oct 23, 2014 at 01:35:37PM -0700, Alexey Samsonov wrote:
> On Thu, Oct 23, 2014 at 12:04 PM, Joerg Sonnenberger <
> joerg at britannica.bec.de> wrote:
> 
> > On Thu, Oct 23, 2014 at 12:46:10AM -0000, Alexey Samsonov wrote:
> > > "-nodefaultlibs" is told to link only the libraries explicitly provided
> > > by the user, and providing "-fsanitize=address" is a clear indication of
> > > intention to link with ASan runtime.
> >
> > Is it? I would expect such use for free-standing for example and I can
> > think of use cases for ASAN that do not involve the normal userland
> > libraries. As such, I believe this needs more thought...
> >
> 
> Please elaborate what example / use case you have in mind.

Consider that you want to debug a boot loader in userland. You provide a
small glue library that emulates the normal hardware access via direct
system calls. You don't use libc at all. You still have to provide your
own ASAN implementation of course, but now keeping -fsanitize=address on
the command line breaks things badly.

Joerg