Quo Vadis tr1? Was: [libstdc++, PATCH] PR libstdc++/83140 - assoc_legendre returns negated value when m is odd.

[Ed Smith-Rowland]

All,

> We could consider dropping the TR1 support, and just provide these
> functions for ISO/IEC 29124:2010 in C++11 (or later) and for C++17.
> But that decision should be taken separately, and should only happen
> on trunk anyway so we need to use _Tp(+1) here.

I am in favour of splitting new versions of the special functions out of 
tr1 and into std/bits.
I personally am itching to use at least C++11 for implementation.
We have been defaulting to C++11 for, IIRC, two releases (Hence my 
-Tp{+1} slip LOL).
I have a lot of work towards this that I wanted to get into 9 anyway.

This would end the last useful thing in tr1 that's not better 
implemented elsewhere. There are certainly people using tr1. Can we 
deprecate the whole namespace?  That might be too noisy.  I think we 
should be done with maths bugs in Bugzilla pretty soon.  We should do 
whatever we decide relatively early in 9.

Ed

Also, I think 83566 should go into tr1 first because it's not a 
signature change.