Re: [Bug pch/14400] Cannot compile qt-x11-free-3.3.0

[Ian Lance Taylor <ian@wasabisystems.com>]

Geoff Keating <geoffk@apple.com> writes:

> On Apr 3, 2004, at 7:38 PM, Ian Lance Taylor wrote:
> 
> > Any thoughts on how difficult it would be to, when a PCH can not be
> > loaded at the correct address, skip the PCH and try for the original
> > header files?  We'd want to issue a warning, but the result will still
> > be better then a compiler crash, particularly since the crash will be
> > awkward to work around without manually removing the PCH.  Of course,
> > the result will not necessarily be equivalent--the original headers
> > might not be present, or might have been modified since the PCH was
> > created.

...

> Again, my experience is that on all unix-like platforms, you *can*
> always get a suitable chunk of address space in some fashion, if you
> try hard enough.

Even if that turns out to be true, it doesn't really help us with a
gcc release when in actual fact that work has only been done on two
platforms, namely Darwin and GNU/Linux.  Nobody is working to fix this
on mainline, much less for 3.4.

You didn't like the idea of disabling PCH on other platforms, so we
have to consider the case in which there is no platform specific
implementation, and the default implementation of PCH, using mmap,
fails.  Right now, in that case, the compiler simply fails, either
with a segmentation violation or a call to sorry, and it is rather
difficult to work around the crash without simply discarding the PCH.

Ian