plenary.async.uv: Attempt to yield across C-call boundary

[chuwy]

I'm starting to write a very minimalistic plugin with async example from README. Basically there's only init.lua file with:

local a = require("plenary.async")

read = function(path)
  local err, fd = a.uv.fs_open(path, "r", 438)
  assert(not err, err)
end

return { read_token = read }

But it fails with the following error, whenever I try to call the function:

E5108: Error executing lua ...te/pack/packer/start/myplugin.nvim/lua/myplugin/init.lua:4: attempt to yield across C-call boundary

Although in fact I see the same error even when call it directly:

:lua require("plenary.async").uv.fs_open("/etc/fstab", "r", 438)

:version output:

:version
NVIM v0.6.0-dev
Build type: Release
LuaJIT 2.1.0-beta3
Compiled by antonparkhomenko

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

   system vimrc file: "$VIM/sysinit.vim"
  fall-back for $VIM: "/nix/store/nzy87w4j77l1jiyrmxlifn9nv6i1jyc1-neovim-unwrapped-master/share/nvim"

[chuwy]

Same error with:

> nvim --clean \
  --cmd set\ rtp+=/Users/antonparkhomenko/.local/share/nvim/site/pack/packer/start/plenary.nvim \
  --cmd ":lua require('plenary.async').uv.fs_open('/Users/antonparkhomenko/.zshrc', 'r', 438)"

And even if I run it with 0.4.4 I get:

E5105: Error while calling lua chunk: [string "<VimL compiled string>"]:1: attempt to yield across C-call boundary

[w0ng]

I can reproduce this

NVIM v0.5.1
Build type: Release
LuaJIT 2.1.0-beta3
Compilation: clang -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=1 -DNVIM_TS_HAS_SET_MATCH_LIMIT -O2 -DNDEBUG -Wall -Wextra -pedantic -Wno-unused-parameter -Wstrict-prototypes -std=gnu99 -Wshadow -Wconversion -Wmissing-prototypes -Wimplicit-fallthrough -Wvla -fstack-protector-strong -fno-common -fdiagnostics-color=auto -DINCLUDE_GENERATED_DECLARATIONS -D_GNU_SOURCE -DNVIM_MSGPACK_HAS_FLOAT32 -DNVIM_UNIBI_HAS_VAR_FROM -DMIN_LOG_LEVEL=3 -I/tmp/neovim-20210927-1441-demfsz/neovim-0.5.1/build/config -I/tmp/neovim-20210927-1441-demfsz/neovim-0.5.1/src -I/usr/local/include -I/Library/Developer/CommandLineTools/SDKs/MacOSX11.sdk/usr/include -I/usr/local/opt/gettext/include -I/tmp/neovim-20210927-1441-demfsz/neovim-0.5.1/build/src/nvim/auto -I/tmp/neovim-20210927-1441-demfsz/neovim-0.5.1/build/include
Compiled by brew@BigSur

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

   system vimrc file: "$VIM/sysinit.vim"
  fall-back for $VIM: "/usr/local/Cellar/neovim/0.5.1/share/nvim"

Run :checkhealth for more info

[rcarriga]

Async functions must be called from an async context or with async.run. Calling an async function directly means the current function must be async as well. This is very similar to JS or Python where it is more explicit because it's built-in

local a = require("plenary.async")

-- `read` is an async function
read = function(path)
  local err, fd = a.uv.fs_open(path, "r", 438)
  assert(not err, err)
end

a.run(function() read("mypath") end)