Proposal: allow to extend C++ template argument deduction via plugins

[Dan Klishch]

Hi,

As far as I understand the currently available plugin extension points, it is
not possible to modify template argument deduction algorithm (except the
theoretical possibility to completely override parsing step). However, such
opportunity might be beneficial for projects like libpqxx, for example, when
database schema and query text are available at compile-time, return types of
the query might be inferred by the plugin.

I propose to add something like PLUGIN_FUNCTION_CALL plugin_event which will
allow to modify function calls conditionally. Will a patch adding such
functionality be welcomed?

Thanks,
Dan Klishch