types.cc had eight of its functions unimplemented for the "counters"
types, throwing an "unimplemented::cause::COUNTERS" when used.
A ninth function (validate) was unimplemented for counters but did not
even throw.
Many code paths did not use any of these functions so didn't care, but
some do - e.g., the silly do-nothing "SELECT CAST(c AS counter)" when
c is already a counter column, which causes this operation to fail.
When the types.cc code encounters a counter value, it is (if I understand
it correctly) already a single uint64_t ("long_type") value, so we fall
back to the long_type implementation of all the functions. To avoid mistakes,
I simply copied the reversed_type implementation for all these functions -
whereas the reversed_type implementation falls back to using the underlying
type, the counter_type implementation always falls back to long_type.
After this patch, "SELECT CAST(c AS counter)" for a counter column works.
We'll introduce a test that verifies this (and other things) in a later
patch in this series.
The following patches will also need more of these functions to be
implemented correctly (e.g., blobascounter() fails to validate the size
of the input blob if the validate function isn't implemented for the
counter type).
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
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