How does lazy load works in packer.nvim, why "module not found"?

[winkee01]

When I put a plugin in lazy load mode, nvim complains that module not found, because packer.nvim downloaded it into .../pack/packer/opt/ directory but didn't set the plugin's path into runtimepath, why?

use({
  'L3MON4D3/LuaSnip', 
  requires = {'rafamadriz/friendly-snippets'}, 
  after = 'cmp_luasnip'
})

How can I fix it? (or how to tell nvim to set the runtimepath?)

[milanglacier]

oneshot solution, call vim.cmd [[packadd LuaSnip]] at your config file of nvim cmp.
If you don't spend useless time on figuring out the loading dependency, this is the easist way

[winkee01]

@milanglacier I do want to know how the opt/ dir works because I keep encountering such problems

[milanglacier]

You can take a look at compiled.lua generated by packer. In short, it just defines that when certain condition is satisfied, the vim.cmd [[packadd xxx]] will be called and then your config will be called.
Packadd command will add the the 1st level sub folder in opt folder ( vim will search for the folder name) into its runtime path. That’s it, nothing special.

[winkee01]

Great explanations, thanks a lot!