cmd is creating a duplicated, invalid command

[gbrlsnchs]

By following the markdown-preview.nvim example, I end up with an invalid :MarkdownPreview command which is available as soon as I start the editor. Then when the plugin kicks in (I only enable it for markdown filetypes) I end up with two :MarkdownPreview commands.

[wbthomason]

What makes the initial command invalid? The way cmd lazy-loading works is by creating a "fake" command with the same name at startup. Running this command deletes the fake definition and then loads the plugin.

Does the fake command cause an error, or not load the plugin? I'm also not sure what you mean by "two :MarkdownPreview commands" - usually, redefining a command name will remove old definitions for that command (or throw an error).

[wbthomason]

(there is an alternative way to implement cmd lazy-loading by using the CmdUndefined event. I've considered moving to that style, but haven't had problems with the current implementation, and so haven't done so)

[gbrlsnchs]

Just to make a little bit clearer, I have set markdown-preview.nvim to only load when I fire :MarkdownPreview. So I understand it's there as soon as I open the editor because lazy loading.

However, I have also set it up to only be loaded by Packer for certain filetypes (for example, markdown). markdown-preview.nvim itself needs to know for which filetypes it should set its commands, so it really felt double weird to have that command there without having a Markdown file open, but I understand this should be a debate for another issue.

The real issue here is that, when I open a Markdown file, I end up with two :MarkdownPreview commands. They seem to both work exactly the same, but it would be better if there was only one option. If I remove the cmd option from its configuration, only one command is loaded.

Here's a picture of my editor showing both commands:

[wbthomason]

Fascinating, I didn't think that was possible. Could you please post your config for this plugin? I think I know what's going on - lazy-loaders represent a union of conditions, so if you open a Markdown file the plugin gets loaded but the original lazy-load command is still there - but I'd like to verify.

The fix will be making the lazy-load handler delete all loader shims on any shim activating, which shouldn't be too bad. EDIT: Wait, this should actually already be happening. Once you post your config, I'll trace through and see why it isn't.

[gbrlsnchs]

Sorry for taking some time to reply back with my config for the plugin!

I tend to split specs in different files, so there is this file specs/markdown_preview.lua:

local M = {'iamcco/markdown-preview.nvim'}

M.run = 'cd app && yarn install'

M.cmd = 'MarkdownPreview'

M.ft = {'markdown', 'plantuml'}

M.config = function()
    vim.cmd([[
function! g:Open_browser(url)
    silent exec 'silent !firefox -new-window ' . a:url
endfunction
    ]])

    vim.g.mkdp_filetypes = {'markdown', 'plantuml'}
    vim.g.mkdp_browserfunc = 'g:Open_browser'
end

M.cond = function()
    return vim.fn.executable('yarn') == 1
end

return M

And in plugins.lua:

return require('packer').startup(function()
    -- ...
    use(require('specs.markdown_preview'))
    -- ...
end)

[ranjithshegde]

I am going to watch this space! I have the exact same problem with the same plugin(markdown-preview), and a few other (vim-processing)

[ranjithshegde]

i can confirm that this issue is valid on many other plugins apart from markdown-preview

[wbthomason]

I'm still not sure why this happens, but #449 should incidentally also close this issue.

[nanotee]

markdown-preview.nvim creates buffer-local commands: https://github.com/iamcco/markdown-preview.nvim/blob/e5bfe9b89dc9c2fbd24ed0f0596c85fd0568b143/plugin/mkdp.vim#L103-L105

The issue is reproducible without packer in both Vim and Neovim by creating a global and a local command with the same name:

:command! Test echo 'globaltest'
:command! -buffer Test echo 'localtest'

I think this is an upstream bug