overloads in meta files

[lewis6991]

--- @meta

--- @param what 'cache'|'config'|'config_dirs'|'data'|'data_dirs'|'log'|'run'|'state'
--- @return string|string[]
function stdpath(what) end

--- @param what 'cache'|'config'|'data'|'log'|'run'|'state'
--- @return string
function stdpath(what) end

--- @param what 'config_dirs'|'data_dirs'
--- @return string[]
function stdpath(what) end

--- @type string
local a = stdpath('cache') -- error (wrong)

--- @type string[]
local b = stdpath('config_dirs') -- error (wrong)

local c = stdpath('config_dirs') .. 'c' -- no error (wrong)

[CppCXY]

Currently, there is no overloading for global functions. This requires a new round of consideration.

[lewis6991]

Just in case in makes a difference, the problem is actually on vim.fn.stdpath(), though that is still a global.

[CppCXY]

I think because

There are three overloads here, and the first overload is also reasonable. So how should I decide which overload is appropriate?

[lewis6991]

If it makes more sense, we can drop the first signature. I did try without it and there were still some problems.

And additionally, if we do know the value, and if it is outside of the allowable values, we'd like a diagnostic.

local a ---@type string
stdpath(a) -- > error, not valid value
stdpath('foo') -- > error, not valid value
stdpath('config_dirs') -- > string[]
stdpath('cache') -- > string

Ok, so it would make the most sense to remove the first overload and just have:

--- @param what 'cache'|'config'|'data'|'log'|'run'|'state'
--- @return string
function stdpath(what) end

--- @param what 'config_dirs'|'data_dirs'
--- @return string[]
function stdpath(what) end

[CppCXY]

for last:

local ccc = vim.fn.stdpath("config_dirs") .. 'c'

Currently, there is no type checking for operators.