Reasoning; currently INTERNAL_CALL is mostly used to determine whether it is
needed to deal with NL-used-as-NUL problem. This code is useful for nvim_… API
calls done from VimL, but not for API calls done from lua, yet lua needs to
supply something as channel_id.
During testing found the following bugs:
1. msgpack-gen.lua script is completely unprepared for Float values either in
return type or in arguments. Specifically:
1. At the time of writing relevant code FLOAT_OBJ did not exist as well as
FLOATING_OBJ, but it would be used by msgpack-gen.lua should return type
be Float. I added FLOATING_OBJ macros later because did not know that
msgpack-gen.lua uses these _OBJ macros, otherwise it would be FLOAT_OBJ.
2. msgpack-gen.lua should use .data.floating in place of .data.float. But it
did not expect that .data subattribute may have name different from
lowercased type name.
2. vim_replace_termcodes returned its argument as-is if it receives an empty
string (as well as _vim_id*() functions did). But if something in returned
argument lives in an allocated memory such action will cause double free:
once when freeing arguments, then when freeing return value. It did not cause
problems yet because msgpack bindings return empty string as {NULL, 0} and
nothing was actually allocated.
3. New code in msgpack-gen.lua popped arguments in reversed order, making lua
bindings’ signatures be different from API ones.
No tests yet, no documentation update, no :lua* stuff, no vim module.
converter.c should also work with typval_T, not Object.
Known problem: luaeval("1", {}) results in
PANIC: unprotected error in call to Lua API (attempt to index a nil value)
Ref #3823
