Ada, treelang needs to be converted to --enable-mapped-location

[Per Bothner]

Robert Dewar wrote:

> Note that even the initial creation of source locations in the GNAT
> front end does not meet the requirement of creating locations in
> increasing order, because of scan backup.

This message discusses that issue.  Adding a small cache could
make source_location work ok with increasing order.

http://gcc.gnu.org/ml/gcc/2004-10/msg00248.html

I prefer the solution (1a) from that message.  It "generalizes"
source_location to work with "random" allocation, with a small
amount of code in libcpp, a smaller amount of code in gcc/ada,
and no need for a callback.  However, it is admittedly more code
than the callback solution.
-- 
	--Per Bothner
per@bothner.com   http://per.bothner.com/