Feat: add PG_FUNCTION_V1_RAW

[angaz]

PG_FUNCTION_V1_RAW is for registering a standard Postgres V1 funcion, without any type conversions.

This will come in handy for functions where we don't have a pgzx abstraction for the types yet.

[angaz]

I might have found a better way adding FunctionCallInfo, and other types to directMappings. But this might still be useful for types not yet provided.

[urso]

Thank you for contributing.

I'm just not sure I understand why we need the PR. The pgzx.fmgr.args module wraps the type conversion and has a special case for FunctionCallInfo. See: https://github.com/xataio/pgzx/blob/main/src/pgzx/fmgr/args.zig#L48

That is it should be possible to write this already:

const pgzx = @import("pgzx");
const pg = pgzx.c;

comptime {
  PG_FUNCTION_V1("my_func", my_func);
}

fn my_func(fcinfo pg.FunctionCallInfo) c.Datum {
  ...
}

Unfortunately we don't have a test case (sample extension) doing this as of today. But if that pattern does not work I would consider this a bug.

Assuming that this functions, do we still need PG_FUNCTION_V1_RAW ?

[angaz]

Yeah, this was my first approach, and I understand the code a lot more now. So I don't think this won't be needed.