[Bug bootstrap/54419] [4.8 Regression] Compiling libstdc++-v3/src/c++11/random.cc fails on platforms not knowing rdrand

[glisse at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54419

--- Comment #29 from Marc Glisse <glisse at gcc dot gnu.org> 2012-09-04 18:24:05 UTC ---
(In reply to comment #26)

> The Apple clang 4.0 compiler defaults to its integrated
> assembler
> such that the simple test case...
> 
> 
> int
> main ()
> {
>   asm("rdrand %eax");
>   return 0;
> }
> 
> is compiled without errors into the assembly....

[...]

> This leaves config.log with ac_cv_x86_rdrand=yes which fails later in the
> bootstrap when the newly built FSF gcc compiler is used and the legacy system
> assembler is used.

Er, why should this test ever be run with the system compiler? libstdc++ should
only ever be built by a newly built g++.