We now specialize std::less<const std::type_info*> to use
std::type_info::before(), and on Windows and Mac that Just Works. It even
works on Linux when using gcc 4.4+: more recent implementations of gcc's
std::type_info::before() apparently do name()-string comparisons internally.
It doesn't work so well on Linux with gcc 4.1, though, and that's the compiler
we still use on our Linux build-farm machines. But rather than give up,
perform explicit name()-string comparison in that case.
Instead of forbidding std::map<const std::type_info*, ...> outright (which
includes LLRegistry<const std::type_info*, ...> and LLRegistrySingleton<const
std::type_info*, ...>), try to make it work by specializing std::less<const
std::type_info*> to use std::type_info::before().
Make LLRegistryDefaultComparator<T> use std::less<T> so it can capitalize on
that specialization.
The changeset above touched every consumer of the two LLRegistrySingletons
originally defined with std::type_info* as keys. Those two
LLRegistrySingletons were changed to use const char* as keys, then all
consumers were changed to pass std::type_info::name() instead of the plain
std::type_info* pointer -- to deal with the observed fact that on Linux, a
given type might produce different std::type_info* pointers in different load
modules. Since then, Richard turned up the fascinating fact that at least some
implementations of gcc's std::type_info::before() method already accommodate
this peculiarity. It seems worth backing out the (dismayingly pervasive)
change to see if properly using std::type_info::before() as the map comparator
will work just as well, with conceptually simpler source code.
This backout is transitional: we don't expect things to build/run properly
until we've cherry-picked certain other pertinent changes.
Oz Linden