chore!: remove ensure_installed='maintained'

Removes all support (and tests) for the parser category "maintained", as
this is no longer a useful category.

BREAKING CHANGE: replace `ensure_installed='maintained'` by an explicit
list of parsers, or use `'all'` (not recommended).

autoload/nvim_treesitter.vim

@@ -7,11 +7,11 @@ function! nvim_treesitter#foldexpr() abort
 endfunction
 
 function! nvim_treesitter#installable_parsers(arglead, cmdline, cursorpos) abort
-  return join(luaeval("require'nvim-treesitter.parsers'.available_parsers()") + ['all', 'maintained'], "\n")
+  return join(luaeval("require'nvim-treesitter.parsers'.available_parsers()") + ['all'], "\n")
 endfunction
 
 function! nvim_treesitter#installed_parsers(arglead, cmdline, cursorpos) abort
-  return join(luaeval("require'nvim-treesitter.info'.installed_parsers()") + ['all', 'maintained'], "\n")
+  return join(luaeval("require'nvim-treesitter.info'.installed_parsers()") + ['all'], "\n")
 endfunction
 
 function! nvim_treesitter#available_modules(arglead, cmdline, cursorpos) abort

lua/nvim-treesitter/install.lua

@@ -402,9 +402,6 @@ local function install(options)
     if ... == "all" then
       languages = parsers.available_parsers()
       ask = false
-    elseif ... == "maintained" then
-      languages = parsers.maintained_parsers()
-      ask = false
     else
       languages = vim.tbl_flatten { ... }
       ask = ask_reinstall
@@ -467,15 +464,9 @@ function M.uninstall(...)
     path_sep = "\\"
   end
 
-  if vim.tbl_contains({ "all", "maintained" }, ...) then
+  if vim.tbl_contains({ "all" }, ...) then
     reset_progress_counter()
     local installed = info.installed_parsers()
-    if ... == "maintained" then
-      local maintained = parsers.maintained_parsers()
-      installed = vim.tbl_filter(function(l)
-        return vim.tbl_contains(maintained, l)
-      end, installed)
-    end
     for _, langitem in pairs(installed) do
       M.uninstall(langitem)
     end

lua/nvim-treesitter/parsers.lua

@@ -1085,19 +1085,6 @@ function M.available_parsers()
   end
 end
 
-function M.maintained_parsers()
-  require("nvim-treesitter.utils").notify(
-    "ensure_installed='maintained' will be removed April 30, 2022. Specify parsers explicitly or use 'all'.",
-    vim.log.levels.WARN
-  )
-  local has_tree_sitter_cli = vim.fn.executable "tree-sitter" == 1 and vim.fn.executable "node" == 1
-  return vim.tbl_filter(function(lang)
-    return M.list[lang].maintainers
-      and not M.list[lang].experimental
-      and (has_tree_sitter_cli or not M.list[lang].install_info.requires_generate_from_grammar)
-  end, M.available_parsers())
-end
-
 function M.get_parser_configs()
   return M.list
 end

tests/unit/parsers_spec.lua

@@ -1,46 +0,0 @@
-local stub = require "luassert.stub"
-local parsers = require "nvim-treesitter.parsers"
-
-describe("maintained_parsers", function()
-  before_each(function()
-    stub(vim.fn, "executable")
-  end)
-
-  after_each(function()
-    vim.fn.executable:clear()
-  end)
-
-  it("does not return experimental parsers", function()
-    local old_list = parsers.list
-    parsers.list = {
-      c = {
-        install_info = {
-          url = "https://github.com/tree-sitter/tree-sitter-c",
-          files = { "src/parser.c" },
-        },
-        maintainers = { "@vigoux" },
-      },
-      d = {
-        install_info = {
-          url = "https://github.com/CyberShadow/tree-sitter-d",
-          files = { "src/parser.c", "src/scanner.cc" },
-          requires_generate_from_grammar = true,
-        },
-        maintainers = { "@nawordar" },
-        experimental = true,
-      },
-      haskell = {
-        install_info = {
-          url = "https://github.com/tree-sitter/tree-sitter-haskell",
-          files = { "src/parser.c", "src/scanner.cc" },
-        },
-      },
-    }
-
-    local expected = { "c" }
-
-    assert.same(parsers.maintained_parsers(), expected)
-
-    parsers.list = old_list
-  end)
-end)