Case sensitive when completion source is in a non-latin language

[RobberFox]

FAQ

• I have checked the FAQ and it didn't resolve my problem.

Announcement

• I have checked Breaking change announcement.

Minimal reproducible full config

local lazypath = vim.fn.stdpath("data") .. "/lazy/lazy.nvim"
if not (vim.uv or vim.loop).fs_stat(lazypath) then
	local lazyrepo = "https://github.com/folke/lazy.nvim.git"
	local out = vim.fn.system({ "git", "clone", "--filter=blob:none", "--branch=stable", lazyrepo, lazypath })
	if vim.v.shell_error ~= 0 then
		vim.api.nvim_echo({
			{ "Failed to clone lazy.nvim:\n", "ErrorMsg" },
			{ out, "WarningMsg" },
			{ "\nPress any key to exit..." },
		}, true, {})
		vim.fn.getchar()
		os.exit(1)
	end
end

vim.opt.rtp:prepend(lazypath)

require("lazy").setup({
	spec = {
		{
			'hrsh7th/nvim-cmp',
			event = 'InsertEnter',
			dependencies = {
				'saadparwaiz1/cmp_luasnip',
				'hrsh7th/cmp-nvim-lsp',
				'hrsh7th/cmp-path',
			},

			config = function()
				local cmp = require("cmp")
				local luasnip = require("luasnip")

				cmp.setup {
					snippet = {
						expand = function(args)
							luasnip.lsp_expand(args.body)
						end,
					},
					completion = { completeopt = "menu,menuone,noinsert" },

					-- See `:help ins-completion`
					mapping = {
						["<C-n>"] = cmp.mapping.select_next_item(),
						["<C-p>"] = cmp.mapping.select_prev_item(),
						["<C-y>"] = cmp.mapping.confirm { select = true },
					},
					sources = {
						{ name = "luasnip" },
					},
				}
			end,
		},

		{
			"L3MON4D3/LuaSnip",
			version = "v2.*",
			build = "make install_jsregexp",

			config = function()
				local ls = require("luasnip")
				local s = ls.snippet
				local t = ls.text_node

				ls.add_snippets("all", {
					s({ trig="МУЛ" }, t">[!multi-column]"),
				})
			end
		},
	},
})

You can replace "МУЛ" with some other non-latin language

Description

When I have a completion source in a foreign language (let it be a luasnip snippet, or a markdown note filename, etc.)

-- Luasnip for this example:
s({ trig="МУЛ" }, t">[!multi-column]"),

Then the smartcase doesn't work, so I have to explicitly type uppercase МУЛ instead of мул.

Steps to reproduce

Start inserting мул, there is no completion pop-up. But with МУЛ there is.

Expected behavior

Smartcase behaviour, so that мул matches МУЛ.

Actual behavior

I have to explicitly type uppercase characters.

Additional context

No response