Add inlinable &CORE::functions
This commit allows this to work:
BEGIN { *entangle = \&CORE::tie };
entangle $foo, $package;
And the entangle call gets inlined as a tie op, the resulting op tree
being indistinguishable.
These subs are not yet callable via &foo syntax or through a refer-
ence. That will come later, except for some functions, like sort(),
which will probably never support it.
Almost all overridable functions are supported. These few are not:
- infix operators
- not and getprotobynumber (can’t get the precedence right yet;
prototype problem)
- dump
Subsequent commits (hopefully!) will deal with those.
How this works:
gv_fetchpvn_flags is extended with hooks to create subs inside the
CORE package. Those subs are XSUBs (whose C function dies with an
error, for now at least) with a call checker that blows away the
entersub op and replaces it with whatever op the sub represents.
This is slightly inefficient right now, as gv_fetchpvn_flags calls
keyword(), only to have core_prototype call it again. That will
be fixed in a future refactoring.