Merge remote-tracking branch 'upstream/master' into usermarksusermarks

8 files changed, 653 insertions, 219 deletions

diff --git a/src/nvim/lua/converter.c b/src/nvim/lua/converter.c
index 49d49f76b9..6160b84485 100644
--- a/src/nvim/lua/converter.c
+++ b/src/nvim/lua/converter.c
@@ -4,27 +4,31 @@
 #include <assert.h>
 #include <lauxlib.h>
 #include <lua.h>
-#include <lualib.h>
 #include <stdbool.h>
+#include <stddef.h>
 #include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
 
 #include "nvim/api/private/defs.h"
 #include "nvim/api/private/helpers.h"
-#include "nvim/assert.h"
-#include "nvim/func_attr.h"
 #include "nvim/memory.h"
 // FIXME: vim.h is not actually needed, but otherwise it states MAXPATHL is
 //        redefined
+#include "klib/kvec.h"
 #include "nvim/ascii.h"
 #include "nvim/eval/decode.h"
 #include "nvim/eval/typval.h"
+#include "nvim/eval/typval_defs.h"
+#include "nvim/eval/typval_encode.h"
 #include "nvim/eval/userfunc.h"
-#include "nvim/globals.h"
-#include "nvim/lib/kvec.h"
+#include "nvim/garray.h"
+#include "nvim/gettext.h"
 #include "nvim/lua/converter.h"
 #include "nvim/lua/executor.h"
 #include "nvim/macros.h"
 #include "nvim/message.h"
+#include "nvim/types.h"
 #include "nvim/vim.h"
 
 /// Determine, which keys lua table contains
@@ -385,15 +389,12 @@ nlua_pop_typval_table_processing_end:
       break;
     }
     case LUA_TFUNCTION: {
-      LuaCFunctionState *state = xmalloc(sizeof(LuaCFunctionState));
-      state->lua_callable.func_ref = nlua_ref_global(lstate, -1);
+      LuaRef func = nlua_ref_global(lstate, -1);
 
-      char_u *name = register_cfunc(&nlua_CFunction_func_call,
-                                    &nlua_CFunction_func_free,
-                                    state);
+      char *name = register_luafunc(func);
 
       cur.tv->v_type = VAR_FUNC;
-      cur.tv->vval.v_string = (char *)vim_strsave(name);
+      cur.tv->vval.v_string = xstrdup(name);
       break;
     }
     case LUA_TUSERDATA: {
@@ -476,8 +477,8 @@ static bool typval_conv_special = false;
 #define TYPVAL_ENCODE_CONV_FUNC_START(tv, fun) \
   do { \
     ufunc_T *fp = find_func(fun); \
-    if (fp != NULL && fp->uf_cb == nlua_CFunction_func_call) { \
-      nlua_pushref(lstate, ((LuaCFunctionState *)fp->uf_cb_state)->lua_callable.func_ref); \
+    if (fp != NULL && fp->uf_flags & FC_LUAREF) { \
+      nlua_pushref(lstate, fp->uf_luaref); \
     } else { \
       TYPVAL_ENCODE_CONV_NIL(tv); \
     } \
@@ -568,6 +569,7 @@ static bool typval_conv_special = false;
 #define TYPVAL_ENCODE_FIRST_ARG_TYPE lua_State *const
 #define TYPVAL_ENCODE_FIRST_ARG_NAME lstate
 #include "nvim/eval/typval_encode.c.h"
+
 #undef TYPVAL_ENCODE_SCOPE
 #undef TYPVAL_ENCODE_NAME
 #undef TYPVAL_ENCODE_FIRST_ARG_TYPE
@@ -909,9 +911,8 @@ Float nlua_pop_Float(lua_State *lstate, Error *err)
   lua_pop(lstate, 1);
   if (table_props.type != kObjectTypeFloat) {
     return 0;
-  } else {
-    return (Float)table_props.val;
   }
+  return (Float)table_props.val;
 }
 
 /// Convert lua table to array without determining whether it is array
diff --git a/src/nvim/lua/converter.h b/src/nvim/lua/converter.h
index f6a85900ba..ddc0acfbfa 100644
--- a/src/nvim/lua/converter.h
+++ b/src/nvim/lua/converter.h
@@ -9,14 +9,6 @@
 #include "nvim/eval/typval.h"
 #include "nvim/func_attr.h"
 
-typedef struct {
-  LuaRef func_ref;
-} LuaCallable;
-
-typedef struct {
-  LuaCallable lua_callable;
-} LuaCFunctionState;
-
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "lua/converter.h.generated.h"
 #endif
diff --git a/src/nvim/lua/executor.c b/src/nvim/lua/executor.c
index d1d1480696..5ffd90fddd 100644
--- a/src/nvim/lua/executor.c
+++ b/src/nvim/lua/executor.c
@@ -1,17 +1,22 @@
 // This is an open source non-commercial project. Dear PVS-Studio, please check
 // it. PVS-Studio Static Code Analyzer for C, C++ and C#: http://www.viva64.com
 
+#include <assert.h>
+#include <inttypes.h>
 #include <lauxlib.h>
 #include <lua.h>
 #include <lualib.h>
+#include <stddef.h>
+#include <string.h>
 #include <tree_sitter/api.h>
+#include <uv.h>
 
+#include "klib/kvec.h"
 #include "luv/luv.h"
+#include "nvim/api/extmark.h"
 #include "nvim/api/private/defs.h"
 #include "nvim/api/private/helpers.h"
-#include "nvim/api/vim.h"
 #include "nvim/ascii.h"
-#include "nvim/assert.h"
 #include "nvim/buffer_defs.h"
 #include "nvim/change.h"
 #include "nvim/cursor.h"
@@ -19,27 +24,39 @@
 #include "nvim/eval.h"
 #include "nvim/eval/funcs.h"
 #include "nvim/eval/typval.h"
+#include "nvim/eval/typval_defs.h"
 #include "nvim/eval/userfunc.h"
+#include "nvim/event/defs.h"
 #include "nvim/event/loop.h"
+#include "nvim/event/multiqueue.h"
 #include "nvim/event/time.h"
 #include "nvim/ex_cmds.h"
+#include "nvim/ex_cmds_defs.h"
 #include "nvim/ex_getln.h"
-#include "nvim/extmark.h"
-#include "nvim/func_attr.h"
 #include "nvim/garray.h"
 #include "nvim/getchar.h"
+#include "nvim/gettext.h"
+#include "nvim/globals.h"
+#include "nvim/keycodes.h"
 #include "nvim/lua/converter.h"
 #include "nvim/lua/executor.h"
 #include "nvim/lua/stdlib.h"
 #include "nvim/lua/treesitter.h"
 #include "nvim/macros.h"
-#include "nvim/map.h"
+#include "nvim/main.h"
 #include "nvim/memline.h"
+#include "nvim/memory.h"
 #include "nvim/message.h"
 #include "nvim/msgpack_rpc/channel.h"
+#include "nvim/option_defs.h"
+#include "nvim/os/fileio.h"
 #include "nvim/os/os.h"
+#include "nvim/path.h"
+#include "nvim/pos.h"
 #include "nvim/profile.h"
 #include "nvim/runtime.h"
+#include "nvim/strings.h"
+#include "nvim/ui.h"
 #include "nvim/undo.h"
 #include "nvim/usercmd.h"
 #include "nvim/version.h"
@@ -188,8 +205,8 @@ static int nlua_luv_cfpcall(lua_State *lstate, int nargs, int nresult, int flags
   if (status) {
     if (status == LUA_ERRMEM && !(flags & LUVF_CALLBACK_NOEXIT)) {
       // consider out of memory errors unrecoverable, just like xmalloc()
-      mch_errmsg(e_outofmem);
-      mch_errmsg("\n");
+      os_errmsg(e_outofmem);
+      os_errmsg("\n");
       preserve_exit();
     }
     const char *error = lua_tostring(lstate, -1);
@@ -241,10 +258,10 @@ static int nlua_luv_thread_common_cfpcall(lua_State *lstate, int nargs, int nres
     if (status == LUA_ERRMEM && !(flags & LUVF_CALLBACK_NOEXIT)) {
       // Terminate this thread, as the main thread may be able to continue
       // execution.
-      mch_errmsg(e_outofmem);
-      mch_errmsg("\n");
+      os_errmsg(e_outofmem);
+      os_errmsg("\n");
       lua_close(lstate);
-#ifdef WIN32
+#ifdef MSWIN
       ExitThread(0);
 #else
       pthread_exit(0);
@@ -306,6 +323,36 @@ static int nlua_thr_api_nvim__get_runtime(lua_State *lstate)
   return 1;
 }
 
+/// Copies args starting at `lua_arg0` to Lua `_G.arg`, and sets `_G.arg[0]` to the scriptname.
+///
+/// Example (arg[0] => "foo.lua", arg[1] => "--arg1", …):
+///     nvim -l foo.lua --arg1 --arg2
+///
+/// @note Lua CLI sets args before "-e" as _negative_ `_G.arg` indices, but we currently don't.
+///
+/// @see https://www.lua.org/pil/1.4.html
+/// @see https://github.com/premake/premake-core/blob/1c1304637f4f5e50ba8c57aae8d1d80ec3b7aaf2/src/host/premake.c#L563-L594
+///
+/// @returns number of args
+static int nlua_init_argv(lua_State *const L, char **argv, int argc, int lua_arg0)
+{
+  int i = 0;
+  lua_newtable(L);  // _G.arg
+
+  if (lua_arg0 > 0) {
+    lua_pushstring(L, argv[lua_arg0 - 1]);
+    lua_rawseti(L, -2, 0);  // _G.arg[0] = "foo.lua"
+
+    for (; lua_arg0 >= 0 && i + lua_arg0 < argc; i++) {
+      lua_pushstring(L, argv[i + lua_arg0]);
+      lua_rawseti(L, -2, i + 1);  // _G.arg[i+1] = "--foo"
+    }
+  }
+
+  lua_setglobal(L, "arg");
+  return i;
+}
+
 static void nlua_schedule_event(void **argv)
 {
   LuaRef cb = (LuaRef)(ptrdiff_t)argv[0];
@@ -396,7 +443,7 @@ static int nlua_wait(lua_State *lstate)
 
   bool fast_only = false;
   if (lua_top >= 4) {
-    fast_only =  lua_toboolean(lstate, 4);
+    fast_only = lua_toboolean(lstate, 4);
   }
 
   MultiQueue *loop_events = fast_only || in_fast_callback > 0
@@ -581,14 +628,79 @@ static bool nlua_init_packages(lua_State *lstate)
   lua_getglobal(lstate, "require");
   lua_pushstring(lstate, "vim._init_packages");
   if (nlua_pcall(lstate, 1, 0)) {
-    mch_errmsg(lua_tostring(lstate, -1));
-    mch_errmsg("\n");
+    os_errmsg((char *)lua_tostring(lstate, -1));
+    os_errmsg("\n");
     return false;
   }
 
   return true;
 }
 
+/// "vim.ui_attach(ns_id, {ext_foo=true}, cb)" function
+static int nlua_ui_attach(lua_State *lstate)
+  FUNC_ATTR_NONNULL_ALL
+{
+  uint32_t ns_id = (uint32_t)luaL_checkinteger(lstate, 1);
+
+  if (!ns_initialized(ns_id)) {
+    return luaL_error(lstate, "invalid ns_id");
+  }
+  if (!lua_istable(lstate, 2)) {
+    return luaL_error(lstate, "ext_widgets must be a table");
+  }
+  if (!lua_isfunction(lstate, 3)) {
+    return luaL_error(lstate, "callback must be a Lua function");
+  }
+
+  bool ext_widgets[kUIGlobalCount] = { false };
+  bool tbl_has_true_val = false;
+
+  lua_pushvalue(lstate, 2);
+  lua_pushnil(lstate);
+  while (lua_next(lstate, -2)) {
+    // [dict, key, val]
+    size_t len;
+    const char *s = lua_tolstring(lstate, -2, &len);
+    bool val = lua_toboolean(lstate, -1);
+
+    for (size_t i = 0; i < kUIGlobalCount; i++) {
+      if (strequal(s, ui_ext_names[i])) {
+        if (val) {
+          tbl_has_true_val = true;
+        }
+        ext_widgets[i] = val;
+        goto ok;
+      }
+    }
+
+    return luaL_error(lstate, "Unexpected key: %s", s);
+ok:
+    lua_pop(lstate, 1);
+  }
+
+  if (!tbl_has_true_val) {
+    return luaL_error(lstate, "ext_widgets table must contain at least one 'true' value");
+  }
+
+  LuaRef ui_event_cb = nlua_ref_global(lstate, 3);
+  ui_add_cb(ns_id, ui_event_cb, ext_widgets);
+  return 0;
+}
+
+/// "vim.ui_detach(ns_id)" function
+static int nlua_ui_detach(lua_State *lstate)
+  FUNC_ATTR_NONNULL_ALL
+{
+  uint32_t ns_id = (uint32_t)luaL_checkinteger(lstate, 1);
+
+  if (!ns_initialized(ns_id)) {
+    return luaL_error(lstate, "invalid ns_id");
+  }
+
+  ui_remove_cb(ns_id);
+  return 0;
+}
+
 /// Initialize lua interpreter state
 ///
 /// Called by lua interpreter itself to initialize state.
@@ -604,7 +716,7 @@ static bool nlua_state_init(lua_State *const lstate) FUNC_ATTR_NONNULL_ALL
   lua_setfield(lstate, -2, "debug");
   lua_pop(lstate, 1);
 
-#ifdef WIN32
+#ifdef MSWIN
   // os.getenv
   lua_getglobal(lstate, "os");
   lua_pushcfunction(lstate, &nlua_getenv);
@@ -649,6 +761,14 @@ static bool nlua_state_init(lua_State *const lstate) FUNC_ATTR_NONNULL_ALL
   lua_pushcfunction(lstate, &nlua_wait);
   lua_setfield(lstate, -2, "wait");
 
+  // ui_attach
+  lua_pushcfunction(lstate, &nlua_ui_attach);
+  lua_setfield(lstate, -2, "ui_attach");
+
+  // ui_detach
+  lua_pushcfunction(lstate, &nlua_ui_detach);
+  lua_setfield(lstate, -2, "ui_detach");
+
   nlua_common_vim_init(lstate, false);
 
   // patch require() (only for --startuptime)
@@ -675,10 +795,8 @@ static bool nlua_state_init(lua_State *const lstate) FUNC_ATTR_NONNULL_ALL
   return true;
 }
 
-/// Initialize global lua interpreter
-///
-/// Crashes Nvim if initialization fails.
-void nlua_init(void)
+/// Initializes global Lua interpreter, or exits Nvim on failure.
+void nlua_init(char **argv, int argc, int lua_arg0)
 {
 #ifdef NLUA_TRACK_REFS
   const char *env = os_getenv("NVIM_LUA_NOTRACK");
@@ -689,20 +807,19 @@ void nlua_init(void)
 
   lua_State *lstate = luaL_newstate();
   if (lstate == NULL) {
-    mch_errmsg(_("E970: Failed to initialize lua interpreter\n"));
+    os_errmsg(_("E970: Failed to initialize lua interpreter\n"));
     os_exit(1);
   }
   luaL_openlibs(lstate);
   if (!nlua_state_init(lstate)) {
-    mch_errmsg(_("E970: Failed to initialize builtin lua modules\n"));
+    os_errmsg(_("E970: Failed to initialize builtin lua modules\n"));
     os_exit(1);
   }
 
   luv_set_thread_cb(nlua_thread_acquire_vm, nlua_common_free_all_mem);
-
   global_lstate = lstate;
-
   main_thread = uv_thread_self();
+  nlua_init_argv(lstate, argv, argc, lua_arg0);
 }
 
 static lua_State *nlua_thread_acquire_vm(void)
@@ -935,8 +1052,8 @@ static int nlua_require(lua_State *const lstate)
   time_push(&rel_time, &start_time);
   int status = lua_pcall(lstate, 1, 1, 0);
   if (status == 0) {
-    vim_snprintf((char *)IObuff, IOSIZE, "require('%s')", name);
-    time_msg((char *)IObuff, &start_time);
+    vim_snprintf(IObuff, IOSIZE, "require('%s')", name);
+    time_msg(IObuff, &start_time);
   }
   time_pop(rel_time);
 
@@ -967,12 +1084,12 @@ static int nlua_debug(lua_State *lstate)
     if (input.v_type != VAR_STRING
         || input.vval.v_string == NULL
         || *input.vval.v_string == NUL
-        || STRCMP(input.vval.v_string, "cont") == 0) {
+        || strcmp(input.vval.v_string, "cont") == 0) {
       tv_clear(&input);
       return 0;
     }
     if (luaL_loadbuffer(lstate, (const char *)input.vval.v_string,
-                        STRLEN(input.vval.v_string), "=(debug command)")) {
+                        strlen(input.vval.v_string), "=(debug command)")) {
       nlua_error(lstate, _("E5115: Error while loading debug string: %.*s"));
     } else if (nlua_pcall(lstate, 0, 0)) {
       nlua_error(lstate, _("E5116: Error while calling debug string: %.*s"));
@@ -990,7 +1107,7 @@ int nlua_in_fast_event(lua_State *lstate)
 
 static bool viml_func_is_fast(const char *name)
 {
-  const EvalFuncDef *const fdef = find_internal_func((const char *)name);
+  const EvalFuncDef *const fdef = find_internal_func(name);
   if (fdef) {
     return fdef->fast;
   }
@@ -1027,15 +1144,15 @@ int nlua_call(lua_State *lstate)
     // TODO(bfredl): this should be simplified in error handling refactor
     force_abort = false;
     suppress_errthrow = false;
-    current_exception = NULL;
+    did_throw = false;
     did_emsg = false;
 
     try_start();
     typval_T rettv;
     funcexe_T funcexe = FUNCEXE_INIT;
-    funcexe.firstline = curwin->w_cursor.lnum;
-    funcexe.lastline = curwin->w_cursor.lnum;
-    funcexe.evaluate = true;
+    funcexe.fe_firstline = curwin->w_cursor.lnum;
+    funcexe.fe_lastline = curwin->w_cursor.lnum;
+    funcexe.fe_evaluate = true;
     // call_func() retval is deceptive, ignore it.  Instead we set `msg_list`
     // (TRY_WRAP) to capture abort-causing non-exception errors.
     (void)call_func((char *)name, (int)name_len, &rettv, nargs, vim_args, &funcexe);
@@ -1093,13 +1210,14 @@ static int nlua_rpc(lua_State *lstate, bool request)
     Object result = rpc_send_call(chan_id, name, args, &res_mem, &err);
     if (!ERROR_SET(&err)) {
       nlua_push_Object(lstate, result, false);
-      arena_mem_free(res_mem, NULL);
+      arena_mem_free(res_mem);
     }
   } else {
     if (!rpc_send_event(chan_id, name, args)) {
       api_set_error(&err, kErrorTypeValidation,
                     "Invalid channel: %" PRIu64, chan_id);
     }
+    api_free_array(args);  // TODO(bfredl): no
   }
 
 check_err:
@@ -1124,7 +1242,7 @@ static int nlua_empty_dict_tostring(lua_State *lstate)
   return 1;
 }
 
-#ifdef WIN32
+#ifdef MSWIN
 /// os.getenv: override os.getenv to maintain coherency. #9681
 ///
 /// uv_os_setenv uses SetEnvironmentVariableW which does not update _environ.
@@ -1224,7 +1342,7 @@ void nlua_typval_eval(const String str, typval_T *const arg, typval_T *const ret
   const size_t lcmd_len = sizeof(EVALHEADER) - 1 + str.size + 1;
   char *lcmd;
   if (lcmd_len < IOSIZE) {
-    lcmd = (char *)IObuff;
+    lcmd = IObuff;
   } else {
     lcmd = xmalloc(lcmd_len);
   }
@@ -1234,7 +1352,7 @@ void nlua_typval_eval(const String str, typval_T *const arg, typval_T *const ret
 #undef EVALHEADER
   nlua_typval_exec(lcmd, lcmd_len, "luaeval()", arg, 1, true, ret_tv);
 
-  if (lcmd != (char *)IObuff) {
+  if (lcmd != IObuff) {
     xfree(lcmd);
   }
 }
@@ -1248,7 +1366,7 @@ void nlua_typval_call(const char *str, size_t len, typval_T *const args, int arg
   const size_t lcmd_len = sizeof(CALLHEADER) - 1 + len + sizeof(CALLSUFFIX) - 1;
   char *lcmd;
   if (lcmd_len < IOSIZE) {
-    lcmd = (char *)IObuff;
+    lcmd = IObuff;
   } else {
     lcmd = xmalloc(lcmd_len);
   }
@@ -1261,7 +1379,7 @@ void nlua_typval_call(const char *str, size_t len, typval_T *const args, int arg
 
   nlua_typval_exec(lcmd, lcmd_len, "v:lua", args, argcount, false, ret_tv);
 
-  if (lcmd != (char *)IObuff) {
+  if (lcmd != IObuff) {
     xfree(lcmd);
   }
 }
@@ -1322,11 +1440,11 @@ int nlua_source_using_linegetter(LineGetter fgetline, void *cookie, char *name)
   estack_push(ETYPE_SCRIPT, name, 0);
 
   garray_T ga;
-  char_u *line = NULL;
+  char *line = NULL;
 
-  ga_init(&ga, (int)sizeof(char_u *), 10);
-  while ((line = (char_u *)fgetline(0, cookie, 0, false)) != NULL) {
-    GA_APPEND(char_u *, &ga, line);
+  ga_init(&ga, (int)sizeof(char *), 10);
+  while ((line = fgetline(0, cookie, 0, false)) != NULL) {
+    GA_APPEND(char *, &ga, line);
   }
   char *code = ga_concat_strings_sep(&ga, "\n");
   size_t len = strlen(code);
@@ -1348,23 +1466,22 @@ int nlua_source_using_linegetter(LineGetter fgetline, void *cookie, char *name)
 /// @param[in]  argcount Count of typval arguments
 /// @param[in]  argvars Typval Arguments
 /// @param[out] rettv The return value from the called function.
-int typval_exec_lua_callable(lua_State *lstate, LuaCallable lua_cb, int argcount, typval_T *argvars,
-                             typval_T *rettv)
+int typval_exec_lua_callable(LuaRef lua_cb, int argcount, typval_T *argvars, typval_T *rettv)
 {
-  LuaRef cb = lua_cb.func_ref;
+  lua_State *lstate = global_lstate;
 
-  nlua_pushref(lstate, cb);
+  nlua_pushref(lstate, lua_cb);
 
   PUSH_ALL_TYPVALS(lstate, argvars, argcount, false);
 
   if (nlua_pcall(lstate, argcount, 1)) {
     nlua_print(lstate);
-    return ERROR_OTHER;
+    return FCERR_OTHER;
   }
 
   nlua_pop_typval(lstate, rettv);
 
-  return ERROR_NONE;
+  return FCERR_NONE;
 }
 
 /// Execute Lua string
@@ -1422,9 +1539,10 @@ bool nlua_ref_is_function(LuaRef ref)
 /// @param name    if non-NULL, sent to callback as first arg
 ///                if NULL, only args are used
 /// @param retval  if true, convert return value to Object
-///                if false, discard return value
+///                if false, only check if return value is truthy
 /// @param err     Error details, if any (if NULL, errors are echoed)
-/// @return        Return value of function, if retval was set. Otherwise NIL.
+/// @return        Return value of function, if retval was set. Otherwise
+/// BOOLEAN_OBJ(true) or NIL.
 Object nlua_call_ref(LuaRef ref, const char *name, Array args, bool retval, Error *err)
 {
   lua_State *const lstate = global_lstate;
@@ -1438,7 +1556,7 @@ Object nlua_call_ref(LuaRef ref, const char *name, Array args, bool retval, Erro
     nlua_push_Object(lstate, args.items[i], false);
   }
 
-  if (nlua_pcall(lstate, nargs, retval ? 1 : 0)) {
+  if (nlua_pcall(lstate, nargs, 1)) {
     // if err is passed, the caller will deal with the error.
     if (err) {
       size_t len;
@@ -1458,7 +1576,10 @@ Object nlua_call_ref(LuaRef ref, const char *name, Array args, bool retval, Erro
     }
     return nlua_pop_Object(lstate, false, err);
   } else {
-    return NIL;
+    bool value = lua_toboolean(lstate, -1);
+    lua_pop(lstate, 1);
+
+    return value ? BOOLEAN_OBJ(true) : NIL;
   }
 }
 
@@ -1524,7 +1645,7 @@ void ex_luado(exarg_T *const eap)
                            + (sizeof(DOEND) - 1));
   char *lcmd;
   if (lcmd_len < IOSIZE) {
-    lcmd = (char *)IObuff;
+    lcmd = IObuff;
   } else {
     lcmd = xmalloc(lcmd_len + 1);
   }
@@ -1561,7 +1682,7 @@ void ex_luado(exarg_T *const eap)
       break;
     }
     if (lua_isstring(lstate, -1)) {
-      size_t old_line_len = STRLEN(old_line);
+      size_t old_line_len = strlen(old_line);
 
       size_t new_line_len;
       const char *const new_line = lua_tolstring(lstate, -1, &new_line_len);
@@ -1578,7 +1699,7 @@ void ex_luado(exarg_T *const eap)
   }
   lua_pop(lstate, 1);
   check_cursor();
-  update_screen(NOT_VALID);
+  redraw_curbuf_later(UPD_NOT_VALID);
 }
 
 /// Run lua file
@@ -1592,21 +1713,51 @@ void ex_luafile(exarg_T *const eap)
   nlua_exec_file((const char *)eap->arg);
 }
 
-/// execute lua code from a file.
+/// Executes Lua code from a file or "-" (stdin).
 ///
-/// Note: we call the lua global loadfile as opposed to calling luaL_loadfile
-/// in case loadfile has been overridden in the users environment.
+/// Calls the Lua `loadfile` global as opposed to `luaL_loadfile` in case `loadfile` was overridden
+/// in the user environment.
 ///
-/// @param  path  path of the file
+/// @param path Path to the file, may be "-" (stdin) during startup.
 ///
-/// @return  true if everything ok, false if there was an error (echoed)
+/// @return true on success, false on error (echoed) or user canceled (CTRL-c) while reading "-"
+/// (stdin).
 bool nlua_exec_file(const char *path)
   FUNC_ATTR_NONNULL_ALL
 {
   lua_State *const lstate = global_lstate;
+  if (!strequal(path, "-")) {
+    lua_getglobal(lstate, "loadfile");
+    lua_pushstring(lstate, path);
+  } else {
+    FileDescriptor *stdin_dup = file_open_stdin();
+
+    StringBuilder sb = KV_INITIAL_VALUE;
+    kv_resize(sb, 64);
+    ptrdiff_t read_size = -1;
+    // Read all input from stdin, unless interrupted (ctrl-c).
+    while (true) {
+      if (got_int) {  // User canceled.
+        return false;
+      }
+      read_size = file_read(stdin_dup, IObuff, 64);
+      if (read_size < 0) {  // Error.
+        return false;
+      }
+      if (read_size > 0) {
+        kv_concat_len(sb, IObuff, (size_t)read_size);
+      }
+      if (read_size < 64) {  // EOF.
+        break;
+      }
+    }
+    kv_push(sb, NUL);
+    file_free(stdin_dup, false);
 
-  lua_getglobal(lstate, "loadfile");
-  lua_pushstring(lstate, path);
+    lua_getglobal(lstate, "loadstring");
+    lua_pushstring(lstate, sb.items);
+    kv_destroy(sb);
+  }
 
   if (nlua_pcall(lstate, 1, 2)) {
     nlua_error(lstate, _("E5111: Error calling lua: %.*s"));
@@ -1662,6 +1813,9 @@ static void nlua_add_treesitter(lua_State *const lstate) FUNC_ATTR_NONNULL_ALL
   lua_pushcfunction(lstate, tslua_has_language);
   lua_setfield(lstate, -2, "_ts_has_language");
 
+  lua_pushcfunction(lstate, tslua_remove_lang);
+  lua_setfield(lstate, -2, "_ts_remove_language");
+
   lua_pushcfunction(lstate, tslua_inspect_lang);
   lua_setfield(lstate, -2, "_ts_inspect_language");
 
@@ -1675,7 +1829,7 @@ static void nlua_add_treesitter(lua_State *const lstate) FUNC_ATTR_NONNULL_ALL
   lua_setfield(lstate, -2, "_ts_get_minimum_language_version");
 }
 
-int nlua_expand_pat(expand_T *xp, char_u *pat, int *num_results, char ***results)
+int nlua_expand_pat(expand_T *xp, char *pat, int *num_results, char ***results)
 {
   lua_State *const lstate = global_lstate;
   int ret = OK;
@@ -1688,7 +1842,7 @@ int nlua_expand_pat(expand_T *xp, char_u *pat, int *num_results, char ***results
   luaL_checktype(lstate, -1, LUA_TFUNCTION);
 
   // [ vim, vim._expand_pat, buf ]
-  lua_pushlstring(lstate, (const char *)pat, STRLEN(pat));
+  lua_pushlstring(lstate, (const char *)pat, strlen(pat));
 
   if (nlua_pcall(lstate, 1, 2) != 0) {
     nlua_error(lstate,
@@ -1723,7 +1877,7 @@ int nlua_expand_pat(expand_T *xp, char_u *pat, int *num_results, char ***results
       goto cleanup_array;
     }
 
-    GA_APPEND(char_u *, &result_array, (char_u *)string_to_cstr(v.data.string));
+    GA_APPEND(char *, &result_array, string_to_cstr(v.data.string));
   }
 
   xp->xp_pattern += prefix_len;
@@ -1749,27 +1903,7 @@ static int nlua_is_thread(lua_State *lstate)
   return 1;
 }
 
-// Required functions for lua c functions as VimL callbacks
-
-int nlua_CFunction_func_call(int argcount, typval_T *argvars, typval_T *rettv, void *state)
-{
-  lua_State *const lstate = global_lstate;
-  LuaCFunctionState *funcstate = (LuaCFunctionState *)state;
-
-  return typval_exec_lua_callable(lstate, funcstate->lua_callable,
-                                  argcount, argvars, rettv);
-}
-
-void nlua_CFunction_func_free(void *state)
-{
-  lua_State *const lstate = global_lstate;
-  LuaCFunctionState *funcstate = (LuaCFunctionState *)state;
-
-  nlua_unref_global(lstate, funcstate->lua_callable.func_ref);
-  xfree(funcstate);
-}
-
-bool nlua_is_table_from_lua(typval_T *const arg)
+bool nlua_is_table_from_lua(const typval_T *const arg)
 {
   if (arg->v_type == VAR_DICT) {
     return arg->vval.v_dict->lua_table_ref != LUA_NOREF;
@@ -1780,7 +1914,7 @@ bool nlua_is_table_from_lua(typval_T *const arg)
   }
 }
 
-char_u *nlua_register_table_as_callable(typval_T *const arg)
+char *nlua_register_table_as_callable(const typval_T *const arg)
 {
   LuaRef table_ref = LUA_NOREF;
   if (arg->v_type == VAR_DICT) {
@@ -1814,11 +1948,9 @@ char_u *nlua_register_table_as_callable(typval_T *const arg)
   }
   lua_pop(lstate, 2);  // [table]
 
-  LuaCFunctionState *state = xmalloc(sizeof(LuaCFunctionState));
-  state->lua_callable.func_ref = nlua_ref_global(lstate, -1);
+  LuaRef func = nlua_ref_global(lstate, -1);
 
-  char_u *name = register_cfunc(&nlua_CFunction_func_call,
-                                &nlua_CFunction_func_free, state);
+  char *name = register_luafunc(func);
 
   lua_pop(lstate, 1);  // []
   assert(top == lua_gettop(lstate));
@@ -1828,8 +1960,8 @@ char_u *nlua_register_table_as_callable(typval_T *const arg)
 
 void nlua_execute_on_key(int c)
 {
-  char_u buf[NUMBUFLEN];
-  size_t buf_len = special_to_buf(c, mod_mask, false, buf);
+  char buf[NUMBUFLEN];
+  size_t buf_len = special_to_buf(c, mod_mask, false, (char_u *)buf);
 
   lua_State *const lstate = global_lstate;
 
@@ -1845,7 +1977,7 @@ void nlua_execute_on_key(int c)
   luaL_checktype(lstate, -1, LUA_TFUNCTION);
 
   // [ vim, vim._on_key, buf ]
-  lua_pushlstring(lstate, (const char *)buf, buf_len);
+  lua_pushlstring(lstate, buf, buf_len);
 
   int save_got_int = got_int;
   got_int = false;  // avoid interrupts when the key typed is Ctrl-C
@@ -1924,6 +2056,9 @@ int nlua_do_ucmd(ucmd_T *cmd, exarg_T *eap, bool preview)
   nlua_pushref(lstate, preview ? cmd->uc_preview_luaref : cmd->uc_luaref);
 
   lua_newtable(lstate);
+  lua_pushstring(lstate, cmd->uc_name);
+  lua_setfield(lstate, -2, "name");
+
   lua_pushboolean(lstate, eap->forceit == 1);
   lua_setfield(lstate, -2, "bang");
 
@@ -1940,7 +2075,7 @@ int nlua_do_ucmd(ucmd_T *cmd, exarg_T *eap, bool preview)
 
   // Split args by unescaped whitespace |<f-args>| (nargs dependent)
   if (cmd->uc_argt & EX_NOSPC) {
-    if ((cmd->uc_argt & EX_NEEDARG) || STRLEN(eap->arg)) {
+    if ((cmd->uc_argt & EX_NEEDARG) || strlen(eap->arg)) {
       // For commands where nargs is 1 or "?" and argument is passed, fargs = { args }
       lua_rawseti(lstate, -2, 1);
     } else {
@@ -1950,7 +2085,7 @@ int nlua_do_ucmd(ucmd_T *cmd, exarg_T *eap, bool preview)
   } else if (eap->args == NULL) {
     // For commands with more than one possible argument, split if argument list isn't available.
     lua_pop(lstate, 1);  // Pop the reference of opts.args
-    size_t length = STRLEN(eap->arg);
+    size_t length = strlen(eap->arg);
     size_t end = 0;
     size_t len = 0;
     int i = 1;
@@ -1975,7 +2110,8 @@ int nlua_do_ucmd(ucmd_T *cmd, exarg_T *eap, bool preview)
   }
   lua_setfield(lstate, -2, "fargs");
 
-  lua_pushstring(lstate, (const char *)&eap->regname);
+  char reg[2] = { (char)eap->regname, NUL };
+  lua_pushstring(lstate, reg);
   lua_setfield(lstate, -2, "reg");
 
   lua_pushinteger(lstate, eap->addr_count);
@@ -1998,7 +2134,7 @@ int nlua_do_ucmd(ucmd_T *cmd, exarg_T *eap, bool preview)
 
   lua_newtable(lstate);  // smods table
 
-  lua_pushinteger(lstate, cmdmod.cmod_tab);
+  lua_pushinteger(lstate, cmdmod.cmod_tab - 1);
   lua_setfield(lstate, -2, "tab");
 
   lua_pushinteger(lstate, cmdmod.cmod_verbose - 1);
@@ -2019,6 +2155,8 @@ int nlua_do_ucmd(ucmd_T *cmd, exarg_T *eap, bool preview)
 
   lua_pushboolean(lstate, cmdmod.cmod_split & WSP_VERT);
   lua_setfield(lstate, -2, "vertical");
+  lua_pushboolean(lstate, cmdmod.cmod_split & WSP_HOR);
+  lua_setfield(lstate, -2, "horizontal");
   lua_pushboolean(lstate, cmdmod.cmod_flags & CMOD_SILENT);
   lua_setfield(lstate, -2, "silent");
   lua_pushboolean(lstate, cmdmod.cmod_flags & CMOD_ERRSILENT);
@@ -2113,3 +2251,80 @@ plain:
   kv_printf(str, "<Lua %d>", ref);
   return str.items;
 }
+
+char *nlua_read_secure(const char *path)
+{
+  lua_State *const lstate = global_lstate;
+  const int top = lua_gettop(lstate);
+
+  lua_getglobal(lstate, "vim");
+  lua_getfield(lstate, -1, "secure");
+  lua_getfield(lstate, -1, "read");
+  lua_pushstring(lstate, path);
+  if (nlua_pcall(lstate, 1, 1)) {
+    nlua_error(lstate, _("Error executing vim.secure.read: %.*s"));
+    lua_settop(lstate, top);
+    return NULL;
+  }
+
+  size_t len = 0;
+  const char *contents = lua_tolstring(lstate, -1, &len);
+  char *buf = NULL;
+  if (contents != NULL) {
+    // Add one to include trailing null byte
+    buf = xcalloc(len + 1, sizeof(char));
+    memcpy(buf, contents, len + 1);
+  }
+
+  lua_settop(lstate, top);
+  return buf;
+}
+
+bool nlua_trust(const char *action, const char *path)
+{
+  lua_State *const lstate = global_lstate;
+  const int top = lua_gettop(lstate);
+
+  lua_getglobal(lstate, "vim");
+  lua_getfield(lstate, -1, "secure");
+  lua_getfield(lstate, -1, "trust");
+
+  lua_newtable(lstate);
+  lua_pushstring(lstate, "action");
+  lua_pushstring(lstate, action);
+  lua_settable(lstate, -3);
+  if (path == NULL) {
+    lua_pushstring(lstate, "bufnr");
+    lua_pushnumber(lstate, 0);
+    lua_settable(lstate, -3);
+  } else {
+    lua_pushstring(lstate, "path");
+    lua_pushstring(lstate, path);
+    lua_settable(lstate, -3);
+  }
+
+  if (nlua_pcall(lstate, 1, 2)) {
+    nlua_error(lstate, _("Error executing vim.secure.trust: %.*s"));
+    lua_settop(lstate, top);
+    return false;
+  }
+
+  bool success = lua_toboolean(lstate, -2);
+  const char *msg = lua_tostring(lstate, -1);
+  if (msg != NULL) {
+    if (success) {
+      if (strcmp(action, "allow") == 0) {
+        smsg("Allowed \"%s\" in trust database.", msg);
+      } else if (strcmp(action, "deny") == 0) {
+        smsg("Denied \"%s\" in trust database.", msg);
+      } else if (strcmp(action, "remove") == 0) {
+        smsg("Removed \"%s\" from trust database.", msg);
+      }
+    } else {
+      semsg(e_trustfile, msg);
+    }
+  }
+
+  lua_settop(lstate, top);
+  return success;
+}
diff --git a/src/nvim/lua/executor.h b/src/nvim/lua/executor.h
index 78346fd81f..c6747833e5 100644
--- a/src/nvim/lua/executor.h
+++ b/src/nvim/lua/executor.h
@@ -3,13 +3,17 @@
 
 #include <lauxlib.h>
 #include <lua.h>
+#include <stdbool.h>
 
 #include "nvim/api/private/defs.h"
+#include "nvim/api/private/helpers.h"
 #include "nvim/assert.h"
 #include "nvim/eval/typval.h"
 #include "nvim/ex_cmds_defs.h"
 #include "nvim/func_attr.h"
 #include "nvim/lua/converter.h"
+#include "nvim/macros.h"
+#include "nvim/types.h"
 #include "nvim/usercmd.h"
 
 // Generated by msgpack-gen.lua
diff --git a/src/nvim/lua/spell.c b/src/nvim/lua/spell.c
index 31a2b2d19f..d510d25e90 100644
--- a/src/nvim/lua/spell.c
+++ b/src/nvim/lua/spell.c
@@ -1,15 +1,25 @@
 // This is an open source non-commercial project. Dear PVS-Studio, please check
 // it. PVS-Studio Static Code Analyzer for C, C++ and C#: http://www.viva64.com
 
+#include <assert.h>
 #include <lauxlib.h>
+#include <limits.h>
 #include <lua.h>
-
+#include <stdbool.h>
+#include <stddef.h>
+
+#include "nvim/ascii.h"
+#include "nvim/buffer_defs.h"
+#include "nvim/gettext.h"
+#include "nvim/globals.h"
+#include "nvim/highlight_defs.h"
 #include "nvim/lua/spell.h"
+#include "nvim/message.h"
 #include "nvim/spell.h"
-#include "nvim/vim.h"
+#include "nvim/types.h"
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
-# include "lua/spell.c.generated.h"
+# include "lua/spell.c.generated.h"  // IWYU pragma: export
 #endif
 
 int nlua_spell_check(lua_State *lstate)
@@ -51,7 +61,7 @@ int nlua_spell_check(lua_State *lstate)
 
   while (*str != NUL) {
     attr = HLF_COUNT;
-    len = spell_check(curwin, (char_u *)str, &attr, &capcol, false);
+    len = spell_check(curwin, (char *)str, &attr, &capcol, false);
     assert(len <= INT_MAX);
 
     if (attr != HLF_COUNT) {
diff --git a/src/nvim/lua/stdlib.c b/src/nvim/lua/stdlib.c
index 5a82ae30b5..6ebca6d97e 100644
--- a/src/nvim/lua/stdlib.c
+++ b/src/nvim/lua/stdlib.c
@@ -1,62 +1,51 @@
 // This is an open source non-commercial project. Dear PVS-Studio, please check
 // it. PVS-Studio Static Code Analyzer for C, C++ and C#: http://www.viva64.com
 
+#include <assert.h>
 #include <lauxlib.h>
 #include <lua.h>
-#include <lualib.h>
-
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <string.h>
+#include <sys/types.h>
+
+#include "auto/config.h"
 #include "cjson/lua_cjson.h"
-#include "luv/luv.h"
 #include "mpack/lmpack.h"
 #include "nvim/api/private/defs.h"
 #include "nvim/api/private/helpers.h"
-#include "nvim/api/vim.h"
 #include "nvim/ascii.h"
-#include "nvim/assert.h"
 #include "nvim/buffer_defs.h"
-#include "nvim/change.h"
-#include "nvim/cursor.h"
 #include "nvim/eval.h"
-#include "nvim/eval/userfunc.h"
-#include "nvim/event/loop.h"
-#include "nvim/event/time.h"
+#include "nvim/eval/typval.h"
+#include "nvim/eval/typval_defs.h"
 #include "nvim/ex_eval.h"
-#include "nvim/ex_getln.h"
-#include "nvim/extmark.h"
-#include "nvim/func_attr.h"
-#include "nvim/garray.h"
-#include "nvim/getchar.h"
 #include "nvim/globals.h"
 #include "nvim/lua/converter.h"
-#include "nvim/lua/executor.h"
 #include "nvim/lua/spell.h"
 #include "nvim/lua/stdlib.h"
-#include "nvim/lua/treesitter.h"
 #include "nvim/lua/xdiff.h"
-#include "nvim/macros.h"
 #include "nvim/map.h"
+#include "nvim/mbyte.h"
 #include "nvim/memline.h"
-#include "nvim/message.h"
-#include "nvim/msgpack_rpc/channel.h"
-#include "nvim/os/os.h"
+#include "nvim/memory.h"
+#include "nvim/pos.h"
 #include "nvim/regexp.h"
-#include "nvim/regexp_defs.h"
-#include "nvim/screen.h"
 #include "nvim/types.h"
-#include "nvim/undo.h"
-#include "nvim/version.h"
 #include "nvim/vim.h"
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "lua/stdlib.c.generated.h"
 #endif
 
-static int regex_match(lua_State *lstate, regprog_T **prog, char_u *str)
+static int regex_match(lua_State *lstate, regprog_T **prog, char *str)
 {
   regmatch_T rm;
   rm.regprog = *prog;
   rm.rm_ic = false;
-  bool match = vim_regexec(&rm, (char *)str, 0);
+  bool match = vim_regexec(&rm, str, 0);
   *prog = rm.regprog;
 
   if (match) {
@@ -71,7 +60,7 @@ static int regex_match_str(lua_State *lstate)
 {
   regprog_T **prog = regex_check(lstate);
   const char *str = luaL_checkstring(lstate, 2);
-  int nret = regex_match(lstate, prog, (char_u *)str);
+  int nret = regex_match(lstate, prog, (char *)str);
 
   if (!*prog) {
     return luaL_error(lstate, "regex: internal error");
@@ -111,14 +100,14 @@ static int regex_match_line(lua_State *lstate)
     return luaL_error(lstate, "invalid row");
   }
 
-  char_u *line = ml_get_buf(buf, rownr + 1, false);
-  size_t len = STRLEN(line);
+  char *line = ml_get_buf(buf, rownr + 1, false);
+  size_t len = strlen(line);
 
   if (start < 0 || (size_t)start > len) {
     return luaL_error(lstate, "invalid start");
   }
 
-  char_u save = NUL;
+  char save = NUL;
   if (end >= 0) {
     if ((size_t)end > len || end < start) {
       return luaL_error(lstate, "invalid end");
@@ -187,7 +176,7 @@ int nlua_str_utfindex(lua_State *const lstate) FUNC_ATTR_NONNULL_ALL
   }
 
   size_t codepoints = 0, codeunits = 0;
-  mb_utflen((const char_u *)s1, (size_t)idx, &codepoints, &codeunits);
+  mb_utflen(s1, (size_t)idx, &codepoints, &codeunits);
 
   lua_pushinteger(lstate, (long)codepoints);
   lua_pushinteger(lstate, (long)codeunits);
@@ -209,7 +198,7 @@ static int nlua_str_utf_pos(lua_State *const lstate) FUNC_ATTR_NONNULL_ALL
   size_t idx = 1;
   size_t clen;
   for (size_t i = 0; i < s1_len && s1[i] != NUL; i += clen) {
-    clen = (size_t)utf_ptr2len_len((const char_u *)(s1) + i, (int)(s1_len - i));
+    clen = (size_t)utf_ptr2len_len(s1 + i, (int)(s1_len - i));
     lua_pushinteger(lstate, (long)i + 1);
     lua_rawseti(lstate, -2, (int)idx);
     idx++;
@@ -277,8 +266,7 @@ int nlua_str_byteindex(lua_State *const lstate) FUNC_ATTR_NONNULL_ALL
     use_utf16 = lua_toboolean(lstate, 3);
   }
 
-  ssize_t byteidx = mb_utf_index_to_bytes((const char_u *)s1, s1_len,
-                                          (size_t)idx, use_utf16);
+  ssize_t byteidx = mb_utf_index_to_bytes(s1, s1_len, (size_t)idx, use_utf16);
   if (byteidx == -1) {
     return luaL_error(lstate, "index out of range");
   }
@@ -304,8 +292,10 @@ int nlua_regex(lua_State *lstate)
     nlua_push_errstr(lstate, "couldn't parse regex: %s", err.msg);
     api_clear_error(&err);
     return lua_error(lstate);
+  } else if (prog == NULL) {
+    nlua_push_errstr(lstate, "couldn't parse regex");
+    return lua_error(lstate);
   }
-  assert(prog);
 
   regprog_T **p = lua_newuserdata(lstate, sizeof(regprog_T *));
   *p = prog;
@@ -369,15 +359,21 @@ int nlua_setvar(lua_State *lstate)
     return 0;
   }
 
+  bool watched = tv_dict_is_watched(dict);
+
   if (del) {
     // Delete the key
     if (di == NULL) {
       // Doesn't exist, nothing to do
       return 0;
-    } else {
-      // Delete the entry
-      tv_dict_item_remove(dict, di);
     }
+    // Notify watchers
+    if (watched) {
+      tv_dict_watcher_notify(dict, key.data, NULL, &di->di_tv);
+    }
+
+    // Delete the entry
+    tv_dict_item_remove(dict, di);
   } else {
     // Update the key
     typval_T tv;
@@ -388,17 +384,29 @@ int nlua_setvar(lua_State *lstate)
       return luaL_error(lstate, "Couldn't convert lua value");
     }
 
+    typval_T oldtv = TV_INITIAL_VALUE;
+
     if (di == NULL) {
       // Need to create an entry
       di = tv_dict_item_alloc_len(key.data, key.size);
       tv_dict_add(dict, di);
     } else {
+      if (watched) {
+        tv_copy(&di->di_tv, &oldtv);
+      }
       // Clear the old value
       tv_clear(&di->di_tv);
     }
 
     // Update the value
     tv_copy(&tv, &di->di_tv);
+
+    // Notify watchers
+    if (watched) {
+      tv_dict_watcher_notify(dict, key.data, &tv, &oldtv);
+      tv_clear(&oldtv);
+    }
+
     // Clear the temporary variable
     tv_clear(&tv);
   }
@@ -474,6 +482,48 @@ static int nlua_stricmp(lua_State *const lstate) FUNC_ATTR_NONNULL_ALL
   return 1;
 }
 
+/// Convert string from one encoding to another
+static int nlua_iconv(lua_State *lstate)
+{
+  int narg = lua_gettop(lstate);
+
+  if (narg < 3) {
+    return luaL_error(lstate, "Expected at least 3 arguments");
+  }
+
+  for (int i = 1; i <= 3; i++) {
+    if (lua_type(lstate, i) != LUA_TSTRING) {
+      return luaL_argerror(lstate, i, "expected string");
+    }
+  }
+
+  size_t str_len = 0;
+  const char *str = lua_tolstring(lstate, 1, &str_len);
+
+  char *from = enc_canonize(enc_skip((char *)lua_tolstring(lstate, 2, NULL)));
+  char *to   = enc_canonize(enc_skip((char *)lua_tolstring(lstate, 3, NULL)));
+
+  vimconv_T vimconv;
+  vimconv.vc_type = CONV_NONE;
+  convert_setup_ext(&vimconv, from, false, to, false);
+
+  char *ret = string_convert(&vimconv, (char *)str, &str_len);
+
+  convert_setup(&vimconv, NULL, NULL);
+
+  xfree(from);
+  xfree(to);
+
+  if (ret == NULL) {
+    lua_pushnil(lstate);
+  } else {
+    lua_pushlstring(lstate, ret, str_len);
+    xfree(ret);
+  }
+
+  return 1;
+}
+
 void nlua_state_add_stdlib(lua_State *const lstate, bool is_thread)
 {
   if (!is_thread) {
@@ -519,6 +569,11 @@ void nlua_state_add_stdlib(lua_State *const lstate, bool is_thread)
     // vim.spell
     luaopen_spell(lstate);
     lua_setfield(lstate, -2, "spell");
+
+    // vim.iconv
+    // depends on p_ambw, p_emoji
+    lua_pushcfunction(lstate, &nlua_iconv);
+    lua_setfield(lstate, -2, "iconv");
   }
 
   // vim.mpack
diff --git a/src/nvim/lua/treesitter.c b/src/nvim/lua/treesitter.c
index f0d847e352..56f4daed1a 100644
--- a/src/nvim/lua/treesitter.c
+++ b/src/nvim/lua/treesitter.c
@@ -6,20 +6,28 @@
 // trees and nodes, and could be broken out as a reusable lua package
 
 #include <assert.h>
-#include <inttypes.h>
 #include <lauxlib.h>
+#include <limits.h>
 #include <lua.h>
-#include <lualib.h>
 #include <stdbool.h>
 #include <stdint.h>
+#include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <uv.h>
 
+#include "klib/kvec.h"
 #include "nvim/api/private/helpers.h"
-#include "nvim/buffer.h"
-#include "nvim/lib/kvec.h"
+#include "nvim/buffer_defs.h"
+#include "nvim/globals.h"
 #include "nvim/lua/treesitter.h"
+#include "nvim/macros.h"
+#include "nvim/map.h"
 #include "nvim/memline.h"
+#include "nvim/memory.h"
+#include "nvim/pos.h"
+#include "nvim/strings.h"
+#include "nvim/types.h"
 #include "tree_sitter/api.h"
 
 #define TS_META_PARSER "treesitter_parser"
@@ -85,6 +93,10 @@ static struct luaL_Reg node_meta[] = {
   { "prev_sibling", node_prev_sibling },
   { "next_named_sibling", node_next_named_sibling },
   { "prev_named_sibling", node_prev_named_sibling },
+  { "named_children", node_named_children },
+  { "root", node_root },
+  { "byte_length", node_byte_length },
+
   { NULL, NULL }
 };
 
@@ -145,40 +157,50 @@ int tslua_has_language(lua_State *L)
   return 1;
 }
 
+// Creates the language into the internal language map.
+//
+// Returns true if the language is correctly loaded in the language map
 int tslua_add_language(lua_State *L)
 {
   const char *path = luaL_checkstring(L, 1);
   const char *lang_name = luaL_checkstring(L, 2);
+  const char *symbol_name = lang_name;
+
+  if (lua_gettop(L) >= 3 && !lua_isnil(L, 3)) {
+    symbol_name = luaL_checkstring(L, 3);
+  }
 
   if (pmap_has(cstr_t)(&langs, lang_name)) {
-    return 0;
+    lua_pushboolean(L, true);
+    return 1;
   }
 
 #define BUFSIZE 128
   char symbol_buf[BUFSIZE];
-  snprintf(symbol_buf, BUFSIZE, "tree_sitter_%s", lang_name);
+  snprintf(symbol_buf, BUFSIZE, "tree_sitter_%s", symbol_name);
 #undef BUFSIZE
 
   uv_lib_t lib;
   if (uv_dlopen(path, &lib)) {
-    snprintf((char *)IObuff, IOSIZE, "Failed to load parser: uv_dlopen: %s",
-             uv_dlerror(&lib));
+    snprintf(IObuff, IOSIZE, "Failed to load parser for language '%s': uv_dlopen: %s",
+             lang_name, uv_dlerror(&lib));
     uv_dlclose(&lib);
-    lua_pushstring(L, (char *)IObuff);
+    lua_pushstring(L, IObuff);
     return lua_error(L);
   }
 
   TSLanguage *(*lang_parser)(void);
   if (uv_dlsym(&lib, symbol_buf, (void **)&lang_parser)) {
-    snprintf((char *)IObuff, IOSIZE, "Failed to load parser: uv_dlsym: %s",
+    snprintf(IObuff, IOSIZE, "Failed to load parser: uv_dlsym: %s",
              uv_dlerror(&lib));
     uv_dlclose(&lib);
-    lua_pushstring(L, (char *)IObuff);
+    lua_pushstring(L, IObuff);
     return lua_error(L);
   }
 
   TSLanguage *lang = lang_parser();
   if (lang == NULL) {
+    uv_dlclose(&lib);
     return luaL_error(L, "Failed to load parser %s: internal error", path);
   }
 
@@ -198,6 +220,19 @@ int tslua_add_language(lua_State *L)
   return 1;
 }
 
+int tslua_remove_lang(lua_State *L)
+{
+  const char *lang_name = luaL_checkstring(L, 1);
+  bool present = pmap_has(cstr_t)(&langs, lang_name);
+  if (present) {
+    char *key = (char *)pmap_key(cstr_t)(&langs, lang_name);
+    pmap_del(cstr_t)(&langs, lang_name);
+    xfree(key);
+  }
+  lua_pushboolean(L, present);
+  return 1;
+}
+
 int tslua_inspect_lang(lua_State *L)
 {
   const char *lang_name = luaL_checkstring(L, 1);
@@ -302,8 +337,8 @@ static const char *input_cb(void *payload, uint32_t byte_index, TSPoint position
     *bytes_read = 0;
     return "";
   }
-  char *line = (char *)ml_get_buf(bp, (linenr_T)position.row + 1, false);
-  size_t len = STRLEN(line);
+  char *line = ml_get_buf(bp, (linenr_T)position.row + 1, false);
+  size_t len = strlen(line);
   if (position.column > len) {
     *bytes_read = 0;
     return "";
@@ -593,7 +628,7 @@ void push_tree(lua_State *L, TSTree *tree, bool do_copy)
   lua_setfenv(L, -2);  // [udata]
 }
 
-static TSTree **tree_check(lua_State *L, uint16_t index)
+static TSTree **tree_check(lua_State *L, int index)
 {
   TSTree **ud = luaL_checkudata(L, index, TS_META_TREE);
   return ud;
@@ -804,7 +839,7 @@ static int node_field(lua_State *L)
     do {
       const char *current_field = ts_tree_cursor_current_field_name(&cursor);
 
-      if (current_field != NULL && !STRCMP(field_name, current_field)) {
+      if (current_field != NULL && !strcmp(field_name, current_field)) {
         push_node(L, ts_tree_cursor_current_node(&cursor), 1);  // [table, node]
         lua_rawseti(L, -2, (int)++curr_index);
       }
@@ -1036,6 +1071,57 @@ static int node_prev_named_sibling(lua_State *L)
   return 1;
 }
 
+static int node_named_children(lua_State *L)
+{
+  TSNode source;
+  if (!node_check(L, 1, &source)) {
+    return 0;
+  }
+  TSTreeCursor cursor = ts_tree_cursor_new(source);
+
+  lua_newtable(L);
+  int curr_index = 0;
+
+  if (ts_tree_cursor_goto_first_child(&cursor)) {
+    do {
+      TSNode node = ts_tree_cursor_current_node(&cursor);
+      if (ts_node_is_named(node)) {
+        push_node(L, node, 1);
+        lua_rawseti(L, -2, ++curr_index);
+      }
+    } while (ts_tree_cursor_goto_next_sibling(&cursor));
+  }
+
+  ts_tree_cursor_delete(&cursor);
+  return 1;
+}
+
+static int node_root(lua_State *L)
+{
+  TSNode node;
+  if (!node_check(L, 1, &node)) {
+    return 0;
+  }
+
+  TSNode root = ts_tree_root_node(node.tree);
+  push_node(L, root, 1);
+  return 1;
+}
+
+static int node_byte_length(lua_State *L)
+{
+  TSNode node;
+  if (!node_check(L, 1, &node)) {
+    return 0;
+  }
+
+  uint32_t start_byte = ts_node_start_byte(node);
+  uint32_t end_byte = ts_node_end_byte(node);
+
+  lua_pushnumber(L, end_byte - start_byte);
+  return 1;
+}
+
 /// assumes the match table being on top of the stack
 static void set_match(lua_State *L, TSQueryMatch *match, int nodeidx)
 {
@@ -1195,8 +1281,8 @@ int tslua_parse_query(lua_State *L)
   TSQuery *query = ts_query_new(lang, src, (uint32_t)len, &error_offset, &error_type);
 
   if (!query) {
-    return luaL_error(L, "query: %s at position %d",
-                      query_err_string(error_type), (int)error_offset);
+    return luaL_error(L, "query: %s at position %d for language %s",
+                      query_err_string(error_type), (int)error_offset, lang_name);
   }
 
   TSQuery **ud = lua_newuserdata(L, sizeof(TSQuery *));  // [udata]
@@ -1288,7 +1374,7 @@ static int query_inspect(lua_State *L)
       lua_rawseti(L, -2, nextitem++);  // [retval, patterns, pat, pred]
     }
     // last predicate should have ended with TypeDone
-    lua_pop(L, 1);  // [retval, patters, pat]
+    lua_pop(L, 1);  // [retval, patterns, pat]
     lua_rawseti(L, -2, (int)i + 1);  // [retval, patterns]
   }
   lua_setfield(L, -2, "patterns");  // [retval]
diff --git a/src/nvim/lua/xdiff.c b/src/nvim/lua/xdiff.c
index b2b5dfedee..857b159af5 100644
--- a/src/nvim/lua/xdiff.c
+++ b/src/nvim/lua/xdiff.c
@@ -1,21 +1,26 @@
 // This is an open source non-commercial project. Dear PVS-Studio, please check
 // it. PVS-Studio Static Code Analyzer for C, C++ and C#: http://www.viva64.com
 
-#include <errno.h>
 #include <lauxlib.h>
 #include <lua.h>
-#include <lualib.h>
-#include <stdio.h>
-#include <stdlib.h>
+#include <stdbool.h>
 #include <string.h>
 
+#include "luaconf.h"
+#include "nvim/api/private/defs.h"
 #include "nvim/api/private/helpers.h"
+#include "nvim/linematch.h"
 #include "nvim/lua/converter.h"
 #include "nvim/lua/executor.h"
 #include "nvim/lua/xdiff.h"
+#include "nvim/macros.h"
+#include "nvim/memory.h"
 #include "nvim/vim.h"
 #include "xdiff/xdiff.h"
 
+#define COMPARED_BUFFER0 (1 << 0)
+#define COMPARED_BUFFER1 (1 << 1)
+
 typedef enum {
   kNluaXdiffModeUnified = 0,
   kNluaXdiffModeOnHunkCB,
@@ -25,12 +30,81 @@ typedef enum {
 typedef struct {
   lua_State *lstate;
   Error *err;
+  mmfile_t *ma;
+  mmfile_t *mb;
+  bool linematch;
+  bool iwhite;
 } hunkpriv_t;
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "lua/xdiff.c.generated.h"
 #endif
 
+static void lua_pushhunk(lua_State *lstate, long start_a, long count_a, long start_b, long count_b)
+{
+  // Mimic extra offsets done by xdiff, see:
+  // src/xdiff/xemit.c:284
+  // src/xdiff/xutils.c:(356,368)
+  if (count_a > 0) {
+    start_a += 1;
+  }
+  if (count_b > 0) {
+    start_b += 1;
+  }
+  lua_createtable(lstate, 0, 0);
+  lua_pushinteger(lstate, start_a);
+  lua_rawseti(lstate, -2, 1);
+  lua_pushinteger(lstate, count_a);
+  lua_rawseti(lstate, -2, 2);
+  lua_pushinteger(lstate, start_b);
+  lua_rawseti(lstate, -2, 3);
+  lua_pushinteger(lstate, count_b);
+  lua_rawseti(lstate, -2, 4);
+  lua_rawseti(lstate, -2, (signed)lua_objlen(lstate, -2) + 1);
+}
+
+static void get_linematch_results(lua_State *lstate, mmfile_t *ma, mmfile_t *mb, long start_a,
+                                  long count_a, long start_b, long count_b, bool iwhite)
+{
+  // get the pointer to char of the start of the diff to pass it to linematch algorithm
+  const char *diff_begin[2] = { ma->ptr, mb->ptr };
+  int diff_length[2] = { (int)count_a, (int)count_b };
+
+  fastforward_buf_to_lnum(&diff_begin[0], start_a + 1);
+  fastforward_buf_to_lnum(&diff_begin[1], start_b + 1);
+
+  int *decisions = NULL;
+  size_t decisions_length = linematch_nbuffers(diff_begin, diff_length, 2, &decisions, iwhite);
+
+  long lnuma = start_a, lnumb = start_b;
+
+  long hunkstarta = lnuma;
+  long hunkstartb = lnumb;
+  long hunkcounta = 0;
+  long hunkcountb = 0;
+  for (size_t i = 0; i < decisions_length; i++) {
+    if (i && (decisions[i - 1] != decisions[i])) {
+      lua_pushhunk(lstate, hunkstarta, hunkcounta, hunkstartb, hunkcountb);
+
+      hunkstarta = lnuma;
+      hunkstartb = lnumb;
+      hunkcounta = 0;
+      hunkcountb = 0;
+      // create a new hunk
+    }
+    if (decisions[i] & COMPARED_BUFFER0) {
+      lnuma++;
+      hunkcounta++;
+    }
+    if (decisions[i] & COMPARED_BUFFER1) {
+      lnumb++;
+      hunkcountb++;
+    }
+  }
+  lua_pushhunk(lstate, hunkstarta, hunkcounta, hunkstartb, hunkcountb);
+  xfree(decisions);
+}
+
 static int write_string(void *priv, mmbuffer_t *mb, int nbuf)
 {
   luaL_Buffer *buf = (luaL_Buffer *)priv;
@@ -52,30 +126,15 @@ static int write_string(void *priv, mmbuffer_t *mb, int nbuf)
 // hunk_func callback used when opts.hunk_lines = true
 static int hunk_locations_cb(long start_a, long count_a, long start_b, long count_b, void *cb_data)
 {
-  // Mimic extra offsets done by xdiff, see:
-  // src/xdiff/xemit.c:284
-  // src/xdiff/xutils.c:(356,368)
-  if (count_a > 0) {
-    start_a += 1;
-  }
-  if (count_b > 0) {
-    start_b += 1;
+  hunkpriv_t *priv = (hunkpriv_t *)cb_data;
+  lua_State *lstate = priv->lstate;
+  if (priv->linematch) {
+    get_linematch_results(lstate, priv->ma, priv->mb, start_a, count_a, start_b, count_b,
+                          priv->iwhite);
+  } else {
+    lua_pushhunk(lstate, start_a, count_a, start_b, count_b);
   }
 
-  lua_State *lstate = (lua_State *)cb_data;
-  lua_createtable(lstate, 0, 0);
-
-  lua_pushinteger(lstate, start_a);
-  lua_rawseti(lstate, -2, 1);
-  lua_pushinteger(lstate, count_a);
-  lua_rawseti(lstate, -2, 2);
-  lua_pushinteger(lstate, start_b);
-  lua_rawseti(lstate, -2, 3);
-  lua_pushinteger(lstate, count_b);
-  lua_rawseti(lstate, -2, 4);
-
-  lua_rawseti(lstate, -2, (signed)lua_objlen(lstate, -2) + 1);
-
   return 0;
 }
 
@@ -149,7 +208,7 @@ static bool check_xdiff_opt(ObjectType actType, ObjectType expType, const char *
 }
 
 static NluaXdiffMode process_xdl_diff_opts(lua_State *lstate, xdemitconf_t *cfg, xpparam_t *params,
-                                           Error *err)
+                                           bool *linematch, Error *err)
 {
   const DictionaryOf(LuaRef) opts = nlua_pop_Dictionary(lstate, true, err);
 
@@ -205,6 +264,11 @@ static NluaXdiffMode process_xdl_diff_opts(lua_State *lstate, xdemitconf_t *cfg,
         goto exit_1;
       }
       cfg->interhunkctxlen = v->data.integer;
+    } else if (strequal("linematch", k.data)) {
+      *linematch = api_object_to_bool(*v, "linematch", false, err);
+      if (ERROR_SET(err)) {
+        goto exit_1;
+      }
     } else {
       struct {
         const char *name;
@@ -244,10 +308,8 @@ static NluaXdiffMode process_xdl_diff_opts(lua_State *lstate, xdemitconf_t *cfg,
 
   if (had_on_hunk) {
     mode = kNluaXdiffModeOnHunkCB;
-    cfg->hunk_func = call_on_hunk_cb;
   } else if (had_result_type_indices) {
     mode = kNluaXdiffModeLocations;
-    cfg->hunk_func = hunk_locations_cb;
   }
 
 exit_1:
@@ -268,6 +330,7 @@ int nlua_xdl_diff(lua_State *lstate)
   xdemitconf_t cfg;
   xpparam_t params;
   xdemitcb_t ecb;
+  bool linematch = false;
 
   CLEAR_FIELD(cfg);
   CLEAR_FIELD(params);
@@ -280,7 +343,7 @@ int nlua_xdl_diff(lua_State *lstate)
       return luaL_argerror(lstate, 3, "expected table");
     }
 
-    mode = process_xdl_diff_opts(lstate, &cfg, &params, &err);
+    mode = process_xdl_diff_opts(lstate, &cfg, &params, &linematch, &err);
 
     if (ERROR_SET(&err)) {
       goto exit_0;
@@ -288,7 +351,7 @@ int nlua_xdl_diff(lua_State *lstate)
   }
 
   luaL_Buffer buf;
-  hunkpriv_t *priv = NULL;
+  hunkpriv_t priv;
   switch (mode) {
   case kNluaXdiffModeUnified:
     luaL_buffinit(lstate, &buf);
@@ -296,14 +359,24 @@ int nlua_xdl_diff(lua_State *lstate)
     ecb.out_line = write_string;
     break;
   case kNluaXdiffModeOnHunkCB:
-    priv = xmalloc(sizeof(*priv));
-    priv->lstate = lstate;
-    priv->err = &err;
-    ecb.priv = priv;
+    cfg.hunk_func = call_on_hunk_cb;
+    priv = (hunkpriv_t) {
+      .lstate = lstate,
+      .err    = &err,
+    };
+    ecb.priv = &priv;
     break;
   case kNluaXdiffModeLocations:
+    cfg.hunk_func = hunk_locations_cb;
+    priv = (hunkpriv_t) {
+      .lstate    = lstate,
+      .ma        = &ma,
+      .mb        = &mb,
+      .linematch = linematch,
+      .iwhite    = (params.flags & XDF_IGNORE_WHITESPACE) > 0
+    };
+    ecb.priv = &priv;
     lua_createtable(lstate, 0, 0);
-    ecb.priv = lstate;
     break;
   }
 
@@ -314,8 +387,6 @@ int nlua_xdl_diff(lua_State *lstate)
     }
   }
 
-  XFREE_CLEAR(priv);
-
 exit_0:
   if (ERROR_SET(&err)) {
     luaL_where(lstate, 1);