nvim_call_atomic not available via Lua on nvim 0.4.3 or 0.4.4

[chipsenkbeil]

• nvim --version:

NVIM v0.4.3
Build type: Release
LuaJIT 2.0.5
Compilation: /usr/bin/cc -march=x86-64 -mtune=generic -O2 -pipe -fno-plt -O2 -DNDEBUG -DMIN_LOG_LEVEL=3 -Wall -Wextra -pedantic -Wno-unused-parameter -Wstrict-prototypes -std=gnu99 -Wshadow -Wconversion -Wmissing-prototypes -Wimplicit-fallthrough -Wvla -fstack-protector-strong -fdiagnostics-color=always -DINCLUDE_GENERATED_DECLARATIONS -D_GNU_SOURCE -DNVIM_MSGPACK_HAS_FLOAT32 -DNVIM_UNIBI_HAS_VAR_FROM -I/build/neovim/src/build/config -I/build/neovim/src/neovim-0.4.3/src -I/usr/include -I/build/neovim/src/build/src/nvim/auto -I/build/neovim/src/build/include
Compiled by builduser

Features: +acl +iconv +tui
See ":help feature-compile"

   system vimrc file: "$VIM/sysinit.vim"
  fall-back for $VIM: "/usr/share/nvim"

Run :checkhealth for more info

NVIM v0.4.4
Build type: Release
LuaJIT 2.0.5
Compilation: /usr/bin/cc -D_FORTIFY_SOURCE=2 -march=x86-64 -mtune=generic -O2 -pipe -fno-plt -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=1 -O2 -DNDEBUG -DMIN_LOG_LEVEL=3 -Wall -Wextra -pedantic -Wno-unused-parameter -Wstrict-prototypes -std=gnu99 -Wshadow -Wconversion -Wmissing-prototypes -Wimplicit-fallthrough -Wvla -fstack-protector-strong -fno-common -fdiagnostics-color=always -DINCLUDE_GENERATED_DECLARATIONS -D_GNU_SOURCE -DNVIM_MSGPACK_HAS_FLOAT32 -DNVIM_UNIBI_HAS_VAR_FROM -I/build/neovim/src/build/config -I/build/neovim/src/neovim-0.4.4/src -I/usr/include -I/build/neovim/src/build/src/nvim/auto -I/build/neovim/src/build/includeCompiled by builduser
Features: +acl +iconv +tui
See ":help feature-compile"

   system vimrc file: "$VIM/sysinit.vim"
  fall-back for $VIM: "/usr/share/nvim"

Run :checkhealth for more info

• vim -u DEFAULTS (version: ) behaves differently?
• Operating system/version: ArchLinux w/ kernel 5.7.12-arch1-1
• Terminal name/version: Blink Shell v13.5.7.224
• $TERM: screen-256color

Steps to reproduce using nvim -u NORC

nvim -u NORC +'lua vim.api.nvim_call_atomic({{"nvim_get_var", {"fish"}}, {"nvim_del_var", {"fish"}}})'

Actual behaviour

Function is missing from API despite being listed in api.txt.

E5105: Error while calling lua chunk: [string "<VimL compiled string>"]:1: attempt to call field 'nvim_call_atomic' (a nil value)

Was also mentioned here.

Expected behaviour

Function is accessible. In the above case, we'd return a two-element array with errors not being nil.

[erw7]

The FUNC_API_REMOTE_ONLY attribute is set to nvim_call_atomic() as shown below. Therefore, it will not be exported to vim.api.

neovim/src/nvim/func_attr.h

Lines 212 to 213 in 90f3a8b

	/// API function not exposed in VimL/eval.
	# define FUNC_API_REMOTE_ONLY

neovim/src/nvim/api/vim.c

Lines 1887 to 1888 in 90f3a8b

	Array nvim_call_atomic(uint64_t channel_id, Array calls, Error *err)
	FUNC_API_SINCE(1) FUNC_API_REMOTE_ONLY

The built in lua execution should always be atomic, so there is no need for nvim_call_atomic(). The api.txt does not indicate whether it is "REMOTE ONLY" or not, so you will need to look at the source code. I think the api.txt needs to be improved.

[chipsenkbeil]

I didn't know where to look, so this is good to know. Agree that having some mention of what is remote only, etc. in the doc would also be helpful. :)

[lewis6991]

nvim_call_atomic is now documented with:

                Attributes: ~
                    |RPC| only