Confirmed.  The testsuite misses something like dg-require asan.

asan.exp starts with
if ![check_effective_target_faddress_sanitizer] {
  return
}
but that just checks whether -fsanitize=address works, not whether libasan has been built.  That further check is in asan_init, guess we could return 0/1 from asan_init on whether it found libasan and if it hasn't, don't call gcc-dg-runtest.

Created attachment 28875 [details]
gcc48-pr55587.patch

Does this patch work for you?  Worked for me in a quick testing (both with libsanitizer around and without).

(In reply to comment #3)
> Created attachment 28875 [details]
> gcc48-pr55587.patch
> 
> Does this patch work for you?  Worked for me in a quick testing (both with
> libsanitizer around and without).

Yes, it works for me.  Thanks

Author: jakub
Date: Tue Dec  4 13:21:11 2012
New Revision: 194134

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=194134
Log:
	PR testsuite/55587
	* lib/asan-dg.exp (asan_init): Return 1 if libasan has been found,
	0 if not.
	* g++.dg/asan/asan.exp: Don't run gcc-dg-runtest if [asan_init]
	returned 0.
	* gcc.dg/asan/asan.exp: Likewise.

Modified:
    trunk/gcc/testsuite/ChangeLog
    trunk/gcc/testsuite/g++.dg/asan/asan.exp
    trunk/gcc/testsuite/gcc.dg/asan/asan.exp
    trunk/gcc/testsuite/lib/asan-dg.exp

Fixed.

This patch is broken for testing the already installed GCC.