Re: Linux vs. libio

[Per Bothner <per at bothner dot com>]

Mark Mitchell <mark@codesourcery.com> writes:

> As was suggested, for example, the vtable pointer issue can probably
> be solved by having *two* vtable pointers in the new objects -- the
> one the C++ ABI requires, and the one the libio routines expect.  I
> think that's the *only* way to solve that particular problem, and I
> expect there will be other problems as well.

Well, for C code, it is not even clear you need to maintain
compatibility in terms of vtables.  As far as I know, of the
public C header files (such as stdio.h or libio.h) only call
named function;  calling a "method" (a slot in a jump table
or vtable) is only done internally.

So whether "vtable compatibility" is an issue or not depends
on which extended glibc-specific features are a documented
part of the API and how programs access these features.
There is also a slight danger of programs that use undocumented
backdoor features and functions;  that is what testing (such as
re-building all of say Debian) is for.
-- 
	--Per Bothner
per@bothner.com   http://www.bothner.com/~per/