[Bug bootstrap/51072] Build with --disable-bootstrap fails in libitm

[joseph at codesourcery dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51072

--- Comment #6 from joseph at codesourcery dot com <joseph at codesourcery dot com> 2011-11-10 17:43:30 UTC ---
On Thu, 10 Nov 2011, rguenth at gcc dot gnu.org wrote:

> Shouldn't libitm be built with the "stage1" g++ as it is a target library,
> even with --disable-bootstrap?

Yes, as I said in 
<http://gcc.gnu.org/ml/gcc-patches/2011-11/msg01382.html> building it with 
a pre-installed compiler is wrong.

More precisely: target libraries should always be built with a compiler 
from the same sources as the source tree from which the library is being 
built, configured in the same way except possibly for the host.

For a build with build == host, the compiler used should always be the 
newly built one from the same build.

For a build with build != host - a Canadian cross build - the compiler 
used should be a previously built host-x-target compiler from the same 
sources and identically configured except for the host setting.  (For 
Canadian cross builds it's better to use "make all-gcc" or "make all-host" 
etc., and copy the libraries from the host-x-target build - but if the 
libraries are being rebuilt then the host-x-target compiler is the one 
used.)

The problem here is the wrong compiler being used for a host == build 
case.