Significant rework of scope management to unify the handling of
types in the ieee library and types/constants/components in packages.
This involved adjusting the parser rules to manage a stack of scopes
and rewriting the IEEE library support to not use global maps for
the loaded types.
In principle, some of these should be handled by overloaded operator
functions, but these are built in types with natural translations so
do the obvious things.
Implement the parser infrastructure for handling library use clauses,
and use that to handle specific packages of the ieee library. Make
the numeric types come from the numeric_* packages instead of being
built in.
There are internal types that are unbounded arrays. Allow subtype
syntax that creates bounded versions of these arrays, and elaborate
them as vectors at port boundaries. This makes some interesting types
work out.
Also start replacing vhdlint and vhdlreal with int64_t and double,
which are reasonable values for universal_integer and universal_real
from the VHDL standard. I need these cleaned up because the ints in
particular are used for the literal expressions in array index constraints.
Rather then just relying on comparing type names all throughout
elaboration, create type description data structures and use them
during elaboration to handle proper types.
Stephen Williams