[Bug bootstrap/50237] [4.7 regression] bootstrap comparison failure for libcpp/lex.o

[hjl.tools at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50237

--- Comment #25 from H.J. Lu <hjl.tools at gmail dot com> 2011-11-23 16:42:43 UTC ---
(In reply to comment #24)
> > --- Comment #23 from H.J. Lu <hjl.tools at gmail dot com> 2011-11-22 18:03:09 UTC ---
> > (In reply to comment #22)
> >> But this is the common case: you cannot expect or require the bootstrap
> >> compiler to use the same linker as you configure with.  This is a
> >> bootstrap failure which is going to get us much noise if not fixed.
> >> 
> >
> > Have you tried the patch in comment 18?
> 
> Not yet, but I'm pretty sure it's wrong: In stage 1, the bootstrap
> compiler needn't be gcc, thus may not understand -B, so the result would
> be wrong even if you configure with gld 2.22.  I don't understand why
> you go through so many contortions, full of unwarranted assumptions,
> when a simple check for gld >= 2.22 (or 2.21.9x if absolutely necessary)
> would do.  If other linkers gain the same support, the test can be
> augmented accordingly.  I know this is ugly and real feature checks are
> the preferred way, but they are notoriously hard to get right portably,
> so many of them already go this route.
> 

Checking linker version is inaccurate since this feature requires
support in assembler, linker as well as libc. We can disable it by'
default when 2 linkers are used.