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Re: Plugin API Comments (was Re: GCC Plug-in Framework ready to port)
On Fri, 2009-02-06 at 12:32 +0000, Joseph S. Myers wrote:
> On Fri, 6 Feb 2009, Sean Callanan wrote:
>
> > - Modify the GCC link process to use libltdl and libtool -export-dynamic
>
> Although this may make theoretical sense in terms of the work for a
> cross-platform implementation already being done, I doubt it's a good idea
> in practice if you want plugin-enabled GCC to be widely buildable and the
> binaries not to be very closely tied to the exact system on which they
> were built. (For example, for a while it was impossible to build current
> versions of guile on systems with current versions of libtool installed
> because of incompatible changes to libltdl,
IOH, the test part of the guile build was not adequate/sufficient.
The plugin implementation will have a good test coverage.
> and I don't have much
> confidence in future compatibility of libltdl, or of it working reliably
> with GCC unless GCC always builds its own GCC-specific copy and links
> against it using -Wl,-rpath,(something involving $ORIGIN). I also don't
> see support for $ORIGIN in libtool, but toolchain relocatability means
> that absolute RPATH settings must not be used when linking GCC.)
Each plugin must do minimum checking for libraries compatibilities on
the libltdl library they want to used.
> I'd suggest we simply put the host-dependent code in GCC, appropriately
> conditional, add code for more hosts as and when people wish to support
> them with plugins, and make sure that plugin-disabled builds continue to
> work for all hosts. There will undoubtedly be GCC-specific build system
> changes needed for such things as building almost everything into a DLL
> for Windows systems so that plugins on Windows can access symbols from
> GCC (I understand from the previous discussions that this will be
> necessary) and I doubt libtool would make such changes any easier.
Just want to add that it is supposed to be the libtool's responsibility
to resolve quirks, platforms, distribution problems.
Well, i means i want the linking mechanism for plugin.