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

8 files changed, 881 insertions, 1016 deletions

diff --git a/src/nvim/lua/converter.c b/src/nvim/lua/converter.c
index 8a702ddd60..4d6e6090b8 100644
--- a/src/nvim/lua/converter.c
+++ b/src/nvim/lua/converter.c
@@ -49,7 +49,6 @@ typedef struct {
 #define LUA_PUSH_STATIC_STRING(lstate, s) \
   lua_pushlstring(lstate, s, sizeof(s) - 1)
 
-
 static LuaTableProps nlua_traverse_table(lua_State *const lstate)
   FUNC_ATTR_NONNULL_ALL FUNC_ATTR_WARN_UNUSED_RESULT
 {
@@ -156,7 +155,7 @@ static LuaTableProps nlua_traverse_table(lua_State *const lstate)
             && ret.string_keys_num == 0)) {
       ret.type = kObjectTypeArray;
       if (tsize == 0 && lua_getmetatable(lstate, -1)) {
-        nlua_pushref(lstate, nlua_empty_dict_ref);
+        nlua_pushref(lstate, nlua_global_refs->empty_dict_ref);
         if (lua_rawequal(lstate, -2, -1)) {
           ret.type = kObjectTypeDictionary;
         }
@@ -286,9 +285,7 @@ bool nlua_pop_typval(lua_State *lstate, typval_T *ret_tv)
       break;
     case LUA_TBOOLEAN:
       cur.tv->v_type = VAR_BOOL;
-      cur.tv->vval.v_bool = (lua_toboolean(lstate, -1)
-                               ? kBoolVarTrue
-                               : kBoolVarFalse);
+      cur.tv->vval.v_bool = (lua_toboolean(lstate, -1) ? kBoolVarTrue : kBoolVarFalse);
       break;
     case LUA_TSTRING: {
       size_t len;
@@ -316,7 +313,7 @@ bool nlua_pop_typval(lua_State *lstate, typval_T *ret_tv)
       LuaRef table_ref = LUA_NOREF;
       if (lua_getmetatable(lstate, -1)) {
         lua_pop(lstate, 1);
-        table_ref = nlua_ref(lstate, -1);
+        table_ref = nlua_ref_global(lstate, -1);
       }
 
       const LuaTableProps table_props = nlua_traverse_table(lstate);
@@ -389,19 +386,19 @@ nlua_pop_typval_table_processing_end:
     }
     case LUA_TFUNCTION: {
       LuaCFunctionState *state = xmalloc(sizeof(LuaCFunctionState));
-      state->lua_callable.func_ref = nlua_ref(lstate, -1);
+      state->lua_callable.func_ref = nlua_ref_global(lstate, -1);
 
       char_u *name = register_cfunc(&nlua_CFunction_func_call,
                                     &nlua_CFunction_func_free,
                                     state);
 
       cur.tv->v_type = VAR_FUNC;
-      cur.tv->vval.v_string = vim_strsave(name);
+      cur.tv->vval.v_string = (char *)vim_strsave(name);
       break;
     }
     case LUA_TUSERDATA: {
       // TODO(bfredl): check mt.__call and convert to function?
-      nlua_pushref(lstate, nlua_nil_ref);
+      nlua_pushref(lstate, nlua_global_refs->nil_ref);
       bool is_nil = lua_rawequal(lstate, -2, -1);
       lua_pop(lstate, 1);
       if (is_nil) {
@@ -445,7 +442,7 @@ static bool typval_conv_special = false;
     if (typval_conv_special) { \
       lua_pushnil(lstate); \
     } else { \
-      nlua_pushref(lstate, nlua_nil_ref); \
+      nlua_pushref(lstate, nlua_global_refs->nil_ref); \
     } \
   } while (0)
 
@@ -478,7 +475,12 @@ static bool typval_conv_special = false;
 
 #define TYPVAL_ENCODE_CONV_FUNC_START(tv, fun) \
   do { \
-    TYPVAL_ENCODE_CONV_NIL(tv); \
+    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); \
+    } else { \
+      TYPVAL_ENCODE_CONV_NIL(tv); \
+    } \
     goto typval_encode_stop_converting_one_item; \
   } while (0)
 
@@ -495,7 +497,7 @@ static bool typval_conv_special = false;
       nlua_create_typed_table(lstate, 0, 0, kObjectTypeDictionary); \
     } else { \
       lua_createtable(lstate, 0, 0); \
-      nlua_pushref(lstate, nlua_empty_dict_ref); \
+      nlua_pushref(lstate, nlua_global_refs->empty_dict_ref); \
       lua_setmetatable(lstate, -2); \
     } \
   } while (0)
@@ -551,8 +553,8 @@ static bool typval_conv_special = false;
       const MPConvStackVal mpval = kv_A(*mpstack, backref - 1); \
       if (mpval.type == conv_type) { \
         if (conv_type == kMPConvDict \
-              ? (void *)mpval.data.d.dict == (void *)(val) \
-              : (void *)mpval.data.l.list == (void *)(val)) { \
+            ? (void *)mpval.data.d.dict == (void *)(val) \
+            : (void *)mpval.data.l.list == (void *)(val)) { \
           lua_pushvalue(lstate, \
                         -((int)((kv_size(*mpstack) - backref + 1) * 2))); \
           break; \
@@ -671,7 +673,6 @@ static inline void nlua_create_typed_table(lua_State *lstate, const size_t narr,
   lua_rawset(lstate, -3);
 }
 
-
 /// Convert given String to lua string
 ///
 /// Leaves converted string on top of the stack.
@@ -726,7 +727,7 @@ void nlua_push_Dictionary(lua_State *lstate, const Dictionary dict, bool special
   } else {
     lua_createtable(lstate, 0, (int)dict.size);
     if (dict.size == 0 && !special) {
-      nlua_pushref(lstate, nlua_empty_dict_ref);
+      nlua_pushref(lstate, nlua_global_refs->empty_dict_ref);
       lua_setmetatable(lstate, -2);
     }
   }
@@ -774,7 +775,7 @@ void nlua_push_Object(lua_State *lstate, const Object obj, bool special)
     if (special) {
       lua_pushnil(lstate);
     } else {
-      nlua_pushref(lstate, nlua_nil_ref);
+      nlua_pushref(lstate, nlua_global_refs->nil_ref);
     }
     break;
   case kObjectTypeLuaRef: {
@@ -805,7 +806,6 @@ void nlua_push_Object(lua_State *lstate, const Object obj, bool special)
   }
 }
 
-
 /// Convert lua value to string
 ///
 /// Always pops one value from the stack.
@@ -1125,10 +1125,7 @@ Object nlua_pop_Object(lua_State *const lstate, bool ref, Error *const err)
     case LUA_TSTRING: {
       size_t len;
       const char *s = lua_tolstring(lstate, -1, &len);
-      *cur.obj = STRING_OBJ(((String) {
-          .data = xmemdupz(s, len),
-          .size = len,
-        }));
+      *cur.obj = STRING_OBJ(((String) { .data = xmemdupz(s, len), .size = len }));
       break;
     }
     case LUA_TNUMBER: {
@@ -1146,11 +1143,7 @@ Object nlua_pop_Object(lua_State *const lstate, bool ref, Error *const err)
 
       switch (table_props.type) {
       case kObjectTypeArray:
-        *cur.obj = ARRAY_OBJ(((Array) {
-            .items = NULL,
-            .size = 0,
-            .capacity = 0,
-          }));
+        *cur.obj = ARRAY_OBJ(((Array) { .items = NULL, .size = 0, .capacity = 0 }));
         if (table_props.maxidx != 0) {
           cur.obj->data.array.items =
             xcalloc(table_props.maxidx,
@@ -1161,11 +1154,7 @@ Object nlua_pop_Object(lua_State *const lstate, bool ref, Error *const err)
         }
         break;
       case kObjectTypeDictionary:
-        *cur.obj = DICTIONARY_OBJ(((Dictionary) {
-            .items = NULL,
-            .size = 0,
-            .capacity = 0,
-          }));
+        *cur.obj = DICTIONARY_OBJ(((Dictionary) { .items = NULL, .size = 0, .capacity = 0 }));
         if (table_props.string_keys_num != 0) {
           cur.obj->data.dictionary.items =
             xcalloc(table_props.string_keys_num,
@@ -1191,14 +1180,14 @@ Object nlua_pop_Object(lua_State *const lstate, bool ref, Error *const err)
 
     case LUA_TFUNCTION:
       if (ref) {
-        *cur.obj = LUAREF_OBJ(nlua_ref(lstate, -1));
+        *cur.obj = LUAREF_OBJ(nlua_ref_global(lstate, -1));
       } else {
         goto type_error;
       }
       break;
 
     case LUA_TUSERDATA: {
-      nlua_pushref(lstate, nlua_nil_ref);
+      nlua_pushref(lstate, nlua_global_refs->nil_ref);
       bool is_nil = lua_rawequal(lstate, -2, -1);
       lua_pop(lstate, 1);
       if (is_nil) {
@@ -1232,7 +1221,7 @@ type_error:
 
 LuaRef nlua_pop_LuaRef(lua_State *const lstate, Error *err)
 {
-  LuaRef rv = nlua_ref(lstate, -1);
+  LuaRef rv = nlua_ref_global(lstate, -1);
   lua_pop(lstate, 1);
   return rv;
 }
@@ -1244,7 +1233,7 @@ LuaRef nlua_pop_LuaRef(lua_State *const lstate, Error *err)
     type ret; \
     if (lua_type(lstate, -1) != LUA_TNUMBER) { \
       api_set_error(err, kErrorTypeValidation, "Expected Lua number"); \
-      ret = (type)-1; \
+      ret = (type) - 1; \
     } else { \
       ret = (type)lua_tonumber(lstate, -1); \
     } \
@@ -1305,7 +1294,6 @@ void nlua_init_types(lua_State *const lstate)
   lua_rawset(lstate, -3);
 }
 
-
 void nlua_pop_keydict(lua_State *L, void *retval, field_hash hashy, Error *err)
 {
   if (!lua_istable(L, -1)) {
diff --git a/src/nvim/lua/executor.c b/src/nvim/lua/executor.c
index cfdbe7b344..ad03ebd1ed 100644
--- a/src/nvim/lua/executor.c
+++ b/src/nvim/lua/executor.c
@@ -4,6 +4,7 @@
 #include <lauxlib.h>
 #include <lua.h>
 #include <lualib.h>
+#include <tree_sitter/api.h>
 
 #include "luv/luv.h"
 #include "nvim/api/private/defs.h"
@@ -14,6 +15,7 @@
 #include "nvim/buffer_defs.h"
 #include "nvim/change.h"
 #include "nvim/cursor.h"
+#include "nvim/eval/typval.h"
 #include "nvim/eval/userfunc.h"
 #include "nvim/event/loop.h"
 #include "nvim/event/time.h"
@@ -34,21 +36,33 @@
 #include "nvim/message.h"
 #include "nvim/msgpack_rpc/channel.h"
 #include "nvim/os/os.h"
+#include "nvim/profile.h"
 #include "nvim/screen.h"
 #include "nvim/undo.h"
 #include "nvim/version.h"
 #include "nvim/vim.h"
+#include "nvim/window.h"
 
 static int in_fast_callback = 0;
 
 // Initialized in nlua_init().
 static lua_State *global_lstate = NULL;
 
+static LuaRef require_ref = LUA_REFNIL;
+
+static uv_thread_t main_thread;
+
 typedef struct {
   Error err;
   String lua_err_str;
 } LuaError;
 
+typedef struct {
+  char *name;
+  const uint8_t *data;
+  size_t size;
+} ModuleDef;
+
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "lua/executor.c.generated.h"
 # include "lua/vim_module.generated.h"
@@ -64,11 +78,16 @@ typedef struct {
   }
 
 #if __has_feature(address_sanitizer)
-static PMap(handle_T) nlua_ref_markers = MAP_INIT;
 static bool nlua_track_refs = false;
 # define NLUA_TRACK_REFS
 #endif
 
+typedef enum luv_err_type {
+  kCallback,
+  kThread,
+  kThreadCallback,
+} luv_err_t;
+
 /// Convert lua error into a Vim error message
 ///
 /// @param  lstate  Lua interpreter state.
@@ -77,7 +96,22 @@ static void nlua_error(lua_State *const lstate, const char *const msg)
   FUNC_ATTR_NONNULL_ALL
 {
   size_t len;
-  const char *const str = lua_tolstring(lstate, -1, &len);
+  const char *str = NULL;
+
+  if (luaL_getmetafield(lstate, -1, "__tostring")) {
+    if (lua_isfunction(lstate, -1) && luaL_callmeta(lstate, -2, "__tostring")) {
+      // call __tostring, convert the result and pop result.
+      str = lua_tolstring(lstate, -1, &len);
+      lua_pop(lstate, 1);
+    }
+    // pop __tostring.
+    lua_pop(lstate, 1);
+  }
+
+  if (!str) {
+    // defer to lua default conversion, this will render tables as [NULL].
+    str = lua_tolstring(lstate, -1, &len);
+  }
 
   msg_ext_set_kind("lua_error");
   semsg_multiline(msg, (int)len, str);
@@ -105,7 +139,6 @@ static int nlua_pcall(lua_State *lstate, int nargs, int nresults)
   return status;
 }
 
-
 /// Gets the version of the current Nvim build.
 ///
 /// @param  lstate  Lua interpreter state.
@@ -117,12 +150,24 @@ static int nlua_nvim_version(lua_State *const lstate) FUNC_ATTR_NONNULL_ALL
   return 1;
 }
 
-
 static void nlua_luv_error_event(void **argv)
 {
   char *error = (char *)argv[0];
+  luv_err_t type = (luv_err_t)(intptr_t)argv[1];
   msg_ext_set_kind("lua_error");
-  semsg_multiline("Error executing luv callback:\n%s", error);
+  switch (type) {
+  case kCallback:
+    semsg_multiline("Error executing luv callback:\n%s", error);
+    break;
+  case kThread:
+    semsg_multiline("Error in luv thread:\n%s", error);
+    break;
+  case kThreadCallback:
+    semsg_multiline("Error in luv callback, thread:\n%s", error);
+    break;
+  default:
+    break;
+  }
   xfree(error);
 }
 
@@ -147,7 +192,7 @@ static int nlua_luv_cfpcall(lua_State *lstate, int nargs, int nresult, int flags
     const char *error = lua_tostring(lstate, -1);
 
     multiqueue_put(main_loop.events, nlua_luv_error_event,
-                   1, xstrdup(error));
+                   2, xstrdup(error), (intptr_t)kCallback);
     lua_pop(lstate, 1);  // error message
     retval = -status;
   } else {  // LUA_OK
@@ -161,12 +206,109 @@ static int nlua_luv_cfpcall(lua_State *lstate, int nargs, int nresult, int flags
   return retval;
 }
 
+static int nlua_luv_thread_cb_cfpcall(lua_State *lstate, int nargs, int nresult, int flags)
+{
+  return nlua_luv_thread_common_cfpcall(lstate, nargs, nresult, flags, true);
+}
+
+static int nlua_luv_thread_cfpcall(lua_State *lstate, int nargs, int nresult, int flags)
+  FUNC_ATTR_NONNULL_ALL
+{
+  return nlua_luv_thread_common_cfpcall(lstate, nargs, nresult, flags, false);
+}
+
+static int nlua_luv_thread_cfcpcall(lua_State *lstate, lua_CFunction func, void *ud, int flags)
+  FUNC_ATTR_NONNULL_ARG(1, 2)
+{
+  lua_pushcfunction(lstate, func);
+  lua_pushlightuserdata(lstate, ud);
+  int retval = nlua_luv_thread_cfpcall(lstate, 1, 0, flags);
+  return retval;
+}
+
+static int nlua_luv_thread_common_cfpcall(lua_State *lstate, int nargs, int nresult, int flags,
+                                          bool is_callback)
+  FUNC_ATTR_NONNULL_ALL
+{
+  int retval;
+
+  int top = lua_gettop(lstate);
+  int status = lua_pcall(lstate, nargs, nresult, 0);
+  if (status) {
+    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");
+      lua_close(lstate);
+#ifdef WIN32
+      ExitThread(0);
+#else
+      pthread_exit(0);
+#endif
+    }
+    const char *error = lua_tostring(lstate, -1);
+
+    loop_schedule_deferred(&main_loop,
+                           event_create(nlua_luv_error_event, 2,
+                                        xstrdup(error),
+                                        is_callback
+                                        ? (intptr_t)kThreadCallback
+                                        : (intptr_t)kThread));
+    lua_pop(lstate, 1);  // error message
+    retval = -status;
+  } else {  // LUA_OK
+    if (nresult == LUA_MULTRET) {
+      nresult = lua_gettop(lstate) - top + nargs + 1;
+    }
+    retval = nresult;
+  }
+
+  return retval;
+}
+
+static int nlua_thr_api_nvim__get_runtime(lua_State *lstate)
+{
+  if (lua_gettop(lstate) != 3) {
+    return luaL_error(lstate, "Expected 3 arguments");
+  }
+
+  luaL_checktype(lstate, -1, LUA_TTABLE);
+  lua_getfield(lstate, -1, "is_lua");
+  if (!lua_isboolean(lstate, -1)) {
+    return luaL_error(lstate, "is_lua is not a boolean");
+  }
+  bool is_lua = lua_toboolean(lstate, -1);
+  lua_pop(lstate, 2);
+
+  luaL_checktype(lstate, -1, LUA_TBOOLEAN);
+  bool all = lua_toboolean(lstate, -1);
+  lua_pop(lstate, 1);
+
+  Error err = ERROR_INIT;
+  const Array pat = nlua_pop_Array(lstate, &err);
+  if (ERROR_SET(&err)) {
+    luaL_where(lstate, 1);
+    lua_pushstring(lstate, err.msg);
+    api_clear_error(&err);
+    lua_concat(lstate, 2);
+    return lua_error(lstate);
+  }
+
+  ArrayOf(String) ret = runtime_get_named_thread(is_lua, pat, all);
+  nlua_push_Array(lstate, ret, true);
+  api_free_array(ret);
+  api_free_array(pat);
+
+  return 1;
+}
+
 static void nlua_schedule_event(void **argv)
 {
   LuaRef cb = (LuaRef)(ptrdiff_t)argv[0];
   lua_State *const lstate = global_lstate;
   nlua_pushref(lstate, cb);
-  nlua_unref(lstate, cb);
+  nlua_unref_global(lstate, cb);
   if (nlua_pcall(lstate, 0, 0)) {
     nlua_error(lstate, _("Error executing vim.schedule lua callback: %.*s"));
   }
@@ -183,7 +325,7 @@ static int nlua_schedule(lua_State *const lstate)
     return lua_error(lstate);
   }
 
-  LuaRef cb = nlua_ref(lstate, 1);
+  LuaRef cb = nlua_ref_global(lstate, 1);
 
   multiqueue_put(main_loop.events, nlua_schedule_event,
                  1, (void *)(ptrdiff_t)cb);
@@ -192,8 +334,7 @@ static int nlua_schedule(lua_State *const lstate)
 
 // Dummy timer callback. Used by f_wait().
 static void dummy_timer_due_cb(TimeWatcher *tw, void *data)
-{
-}
+{}
 
 // Dummy timer close callback. Used by f_wait().
 static void dummy_timer_close_cb(TimeWatcher *tw, void *data)
@@ -219,7 +360,7 @@ static int nlua_wait(lua_State *lstate)
 {
   intptr_t timeout = luaL_checkinteger(lstate, 1);
   if (timeout < 0) {
-    return luaL_error(lstate, "timeout must be > 0");
+    return luaL_error(lstate, "timeout must be >= 0");
   }
 
   int lua_top = lua_gettop(lstate);
@@ -246,7 +387,7 @@ static int nlua_wait(lua_State *lstate)
   if (lua_top >= 3 && !lua_isnil(lstate, 3)) {
     interval = luaL_checkinteger(lstate, 3);
     if (interval < 0) {
-      return luaL_error(lstate, "interval must be > 0");
+      return luaL_error(lstate, "interval must be >= 0");
     }
   }
 
@@ -301,10 +442,154 @@ static int nlua_wait(lua_State *lstate)
   return 2;
 }
 
+static nlua_ref_state_t *nlua_new_ref_state(lua_State *lstate, bool is_thread)
+  FUNC_ATTR_NONNULL_ALL
+{
+  nlua_ref_state_t *ref_state = lua_newuserdata(lstate, sizeof(*ref_state));
+  memset(ref_state, 0, sizeof(*ref_state));
+  ref_state->nil_ref = LUA_NOREF;
+  ref_state->empty_dict_ref = LUA_NOREF;
+  if (!is_thread) {
+    nlua_global_refs = ref_state;
+  }
+  return ref_state;
+}
+
+static nlua_ref_state_t *nlua_get_ref_state(lua_State *lstate)
+  FUNC_ATTR_NONNULL_ALL
+{
+  lua_getfield(lstate, LUA_REGISTRYINDEX, "nlua.ref_state");
+  nlua_ref_state_t *ref_state = lua_touserdata(lstate, -1);
+  lua_pop(lstate, 1);
+
+  return ref_state;
+}
+
+LuaRef nlua_get_nil_ref(lua_State *lstate)
+  FUNC_ATTR_NONNULL_ALL
+{
+  nlua_ref_state_t *ref_state = nlua_get_ref_state(lstate);
+  return ref_state->nil_ref;
+}
+
+LuaRef nlua_get_empty_dict_ref(lua_State *lstate)
+  FUNC_ATTR_NONNULL_ALL
+{
+  nlua_ref_state_t *ref_state = nlua_get_ref_state(lstate);
+  return ref_state->empty_dict_ref;
+}
+
+int nlua_get_global_ref_count(void)
+{
+  return nlua_global_refs->ref_count;
+}
+
+static void nlua_common_vim_init(lua_State *lstate, bool is_thread)
+  FUNC_ATTR_NONNULL_ARG(1)
+{
+  nlua_ref_state_t *ref_state = nlua_new_ref_state(lstate, is_thread);
+  lua_setfield(lstate, LUA_REGISTRYINDEX, "nlua.ref_state");
+
+  // vim.is_thread
+  lua_pushboolean(lstate, is_thread);
+  lua_setfield(lstate, LUA_REGISTRYINDEX, "nvim.thread");
+  lua_pushcfunction(lstate, &nlua_is_thread);
+  lua_setfield(lstate, -2, "is_thread");
+
+  // vim.NIL
+  lua_newuserdata(lstate, 0);
+  lua_createtable(lstate, 0, 0);
+  lua_pushcfunction(lstate, &nlua_nil_tostring);
+  lua_setfield(lstate, -2, "__tostring");
+  lua_setmetatable(lstate, -2);
+  ref_state->nil_ref = nlua_ref(lstate,  ref_state, -1);
+  lua_pushvalue(lstate, -1);
+  lua_setfield(lstate, LUA_REGISTRYINDEX, "mpack.NIL");
+  lua_setfield(lstate, -2, "NIL");
+
+  // vim._empty_dict_mt
+  lua_createtable(lstate, 0, 0);
+  lua_pushcfunction(lstate, &nlua_empty_dict_tostring);
+  lua_setfield(lstate, -2, "__tostring");
+  ref_state->empty_dict_ref = nlua_ref(lstate, ref_state, -1);
+  lua_pushvalue(lstate, -1);
+  lua_setfield(lstate, LUA_REGISTRYINDEX, "mpack.empty_dict");
+  lua_setfield(lstate, -2, "_empty_dict_mt");
+
+  // vim.loop
+  if (is_thread) {
+    luv_set_callback(lstate, nlua_luv_thread_cb_cfpcall);
+    luv_set_thread(lstate, nlua_luv_thread_cfpcall);
+    luv_set_cthread(lstate, nlua_luv_thread_cfcpcall);
+  } else {
+    luv_set_loop(lstate, &main_loop.uv);
+    luv_set_callback(lstate, nlua_luv_cfpcall);
+  }
+  luaopen_luv(lstate);
+  lua_pushvalue(lstate, -1);
+  lua_setfield(lstate, -3, "loop");
+
+  // package.loaded.luv = vim.loop
+  // otherwise luv will be reinitialized when require'luv'
+  lua_getglobal(lstate, "package");
+  lua_getfield(lstate, -1, "loaded");
+  lua_pushvalue(lstate, -3);
+  lua_setfield(lstate, -2, "luv");
+  lua_pop(lstate, 3);
+}
+
+static int nlua_module_preloader(lua_State *lstate)
+{
+  size_t i = (size_t)lua_tointeger(lstate, lua_upvalueindex(1));
+  ModuleDef def = builtin_modules[i];
+  char name[256];
+  name[0] = '@';
+  size_t off = xstrlcpy(name + 1, def.name, (sizeof name) - 2);
+  strchrsub(name + 1, '.', '/');
+  xstrlcpy(name + 1 + off, ".lua", (sizeof name) - 2 - off);
+
+  if (luaL_loadbuffer(lstate, (const char *)def.data, def.size - 1, name)) {
+    return lua_error(lstate);
+  }
+
+  lua_call(lstate, 0, 1);  // propagates error to caller
+  return 1;
+}
+
+static bool nlua_init_packages(lua_State *lstate)
+  FUNC_ATTR_NONNULL_ALL
+{
+  // put builtin packages in preload
+  lua_getglobal(lstate, "package");  // [package]
+  lua_getfield(lstate, -1, "preload");  // [package, preload]
+  for (size_t i = 0; i < ARRAY_SIZE(builtin_modules); i++) {
+    ModuleDef def = builtin_modules[i];
+    lua_pushinteger(lstate, (long)i);  // [package, preload, i]
+    lua_pushcclosure(lstate, nlua_module_preloader, 1);  // [package, preload, cclosure]
+    lua_setfield(lstate, -2, def.name);  // [package, preload]
+
+    if (nlua_disable_preload && strequal(def.name, "vim.inspect")) {
+      break;
+    }
+  }
+
+  lua_pop(lstate, 2);  // []
+
+  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");
+    return false;
+  }
+
+  return true;
+}
+
 /// Initialize lua interpreter state
 ///
 /// Called by lua interpreter itself to initialize state.
-static int nlua_state_init(lua_State *const lstate) FUNC_ATTR_NONNULL_ALL
+static bool nlua_state_init(lua_State *const lstate) FUNC_ATTR_NONNULL_ALL
 {
   // print
   lua_pushcfunction(lstate, &nlua_print);
@@ -361,117 +646,30 @@ static int nlua_state_init(lua_State *const lstate) FUNC_ATTR_NONNULL_ALL
   lua_pushcfunction(lstate, &nlua_wait);
   lua_setfield(lstate, -2, "wait");
 
-  // vim.NIL
-  lua_newuserdata(lstate, 0);
-  lua_createtable(lstate, 0, 0);
-  lua_pushcfunction(lstate, &nlua_nil_tostring);
-  lua_setfield(lstate, -2, "__tostring");
-  lua_setmetatable(lstate, -2);
-  nlua_nil_ref = nlua_ref(lstate, -1);
-  lua_pushvalue(lstate, -1);
-  lua_setfield(lstate, LUA_REGISTRYINDEX, "mpack.NIL");
-  lua_setfield(lstate, -2, "NIL");
+  nlua_common_vim_init(lstate, false);
 
-  // vim._empty_dict_mt
-  lua_createtable(lstate, 0, 0);
-  lua_pushcfunction(lstate, &nlua_empty_dict_tostring);
-  lua_setfield(lstate, -2, "__tostring");
-  nlua_empty_dict_ref = nlua_ref(lstate, -1);
-  lua_pushvalue(lstate, -1);
-  lua_setfield(lstate, LUA_REGISTRYINDEX, "mpack.empty_dict");
-  lua_setfield(lstate, -2, "_empty_dict_mt");
+  // patch require() (only for --startuptime)
+  if (time_fd != NULL) {
+    lua_getglobal(lstate, "require");
+    // Must do this after nlua_common_vim_init where nlua_global_refs is initialized.
+    require_ref = nlua_ref_global(lstate, -1);
+    lua_pop(lstate, 1);
+    lua_pushcfunction(lstate, &nlua_require);
+    lua_setglobal(lstate, "require");
+  }
 
   // internal vim._treesitter... API
   nlua_add_treesitter(lstate);
 
-  // vim.loop
-  luv_set_loop(lstate, &main_loop.uv);
-  luv_set_callback(lstate, nlua_luv_cfpcall);
-  luaopen_luv(lstate);
-  lua_pushvalue(lstate, -1);
-  lua_setfield(lstate, -3, "loop");
-
-  // package.loaded.luv = vim.loop
-  // otherwise luv will be reinitialized when require'luv'
-  lua_getglobal(lstate, "package");
-  lua_getfield(lstate, -1, "loaded");
-  lua_pushvalue(lstate, -3);
-  lua_setfield(lstate, -2, "luv");
-  lua_pop(lstate, 3);
-
-  nlua_state_add_stdlib(lstate);
+  nlua_state_add_stdlib(lstate, false);
 
   lua_setglobal(lstate, "vim");
 
-  {
-    const char *code = (char *)&shared_module[0];
-    if (luaL_loadbuffer(lstate, code, sizeof(shared_module) - 1, "@vim/shared.lua")
-        || nlua_pcall(lstate, 0, 0)) {
-      nlua_error(lstate, _("E5106: Error while creating shared module: %.*s\n"));
-      return 1;
-    }
-  }
-
-  {
-    lua_getglobal(lstate, "package");  // [package]
-    lua_getfield(lstate, -1, "loaded");  // [package, loaded]
-
-    const char *code = (char *)&inspect_module[0];
-    if (luaL_loadbuffer(lstate, code, sizeof(inspect_module) - 1, "@vim/inspect.lua")
-        || nlua_pcall(lstate, 0, 1)) {
-      nlua_error(lstate, _("E5106: Error while creating inspect module: %.*s\n"));
-      return 1;
-    }
-    // [package, loaded, inspect]
-    lua_setfield(lstate, -2, "vim.inspect");  // [package, loaded]
-
-    code = (char *)&lua_F_module[0];
-    if (luaL_loadbuffer(lstate, code, sizeof(lua_F_module) - 1, "@vim/F.lua")
-        || nlua_pcall(lstate, 0, 1)) {
-      nlua_error(lstate, _("E5106: Error while creating vim.F module: %.*s\n"));
-      return 1;
-    }
-    // [package, loaded, module]
-    lua_setfield(lstate, -2, "vim.F");  // [package, loaded]
-
-    code = (char *)&lua_filetype_module[0];
-    if (luaL_loadbuffer(lstate, code, sizeof(lua_filetype_module) - 1, "@vim/filetype.lua")
-        || nlua_pcall(lstate, 0, 1)) {
-      nlua_error(lstate, _("E5106: Error while creating vim.filetype module: %.*s"));
-      return 1;
-    }
-    // [package, loaded, module]
-    lua_setfield(lstate, -2, "vim.filetype");  // [package, loaded]
-
-    lua_pop(lstate, 2);  // []
-  }
-
-  {
-    const char *code = (char *)&vim_module[0];
-    if (luaL_loadbuffer(lstate, code, sizeof(vim_module) - 1, "@vim.lua")
-        || nlua_pcall(lstate, 0, 0)) {
-      nlua_error(lstate, _("E5106: Error while creating vim module: %.*s\n"));
-      return 1;
-    }
-  }
-
-  {
-    lua_getglobal(lstate, "package");  // [package]
-    lua_getfield(lstate, -1, "loaded");  // [package, loaded]
-
-    const char *code = (char *)&lua_meta_module[0];
-    if (luaL_loadbuffer(lstate, code, sizeof(lua_meta_module) - 1, "@vim/_meta.lua")
-        || nlua_pcall(lstate, 0, 1)) {
-      nlua_error(lstate, _("E5106: Error while creating vim._meta module: %.*s\n"));
-      return 1;
-    }
-    // [package, loaded, module]
-    lua_setfield(lstate, -2, "vim._meta");  // [package, loaded]
-
-    lua_pop(lstate, 2);  // []
+  if (!nlua_init_packages(lstate)) {
+    return false;
   }
 
-  return 0;
+  return true;
 }
 
 /// Initialize global lua interpreter
@@ -488,15 +686,66 @@ void nlua_init(void)
 
   lua_State *lstate = luaL_newstate();
   if (lstate == NULL) {
-    emsg(_("E970: Failed to initialize lua interpreter"));
-    preserve_exit();
+    mch_errmsg(_("E970: Failed to initialize lua interpreter\n"));
+    os_exit(1);
   }
   luaL_openlibs(lstate);
-  nlua_state_init(lstate);
+  if (!nlua_state_init(lstate)) {
+    mch_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();
 }
 
+static lua_State *nlua_thread_acquire_vm(void)
+{
+  // If it is called from the main thread, it will attempt to rebuild the cache.
+  const uv_thread_t self = uv_thread_self();
+  if (uv_thread_equal(&main_thread, &self)) {
+    runtime_search_path_validate();
+  }
+
+  lua_State *lstate = luaL_newstate();
+
+  // Add in the lua standard libraries
+  luaL_openlibs(lstate);
+
+  // print
+  lua_pushcfunction(lstate, &nlua_print);
+  lua_setglobal(lstate, "print");
+
+  lua_pushinteger(lstate, 0);
+  lua_setfield(lstate, LUA_REGISTRYINDEX, "nlua.refcount");
+
+  // vim
+  lua_newtable(lstate);
+
+  nlua_common_vim_init(lstate, true);
+
+  nlua_state_add_stdlib(lstate, true);
+
+  lua_createtable(lstate, 0, 0);
+  lua_pushcfunction(lstate, nlua_thr_api_nvim__get_runtime);
+  lua_setfield(lstate, -2, "nvim__get_runtime");
+  lua_setfield(lstate, -2, "api");
+
+  lua_setglobal(lstate, "vim");
+
+  nlua_init_packages(lstate);
+
+  lua_getglobal(lstate, "package");
+  lua_getfield(lstate, -1, "loaded");
+  lua_getglobal(lstate, "vim");
+  lua_setfield(lstate, -2, "vim");
+  lua_pop(lstate, 2);
+
+  return lstate;
+}
 
 void nlua_free_all_mem(void)
 {
@@ -504,30 +753,35 @@ void nlua_free_all_mem(void)
     return;
   }
   lua_State *lstate = global_lstate;
+  nlua_unref_global(lstate, require_ref);
+  nlua_common_free_all_mem(lstate);
+}
 
-  nlua_unref(lstate, nlua_nil_ref);
-  nlua_unref(lstate, nlua_empty_dict_ref);
+static void nlua_common_free_all_mem(lua_State *lstate)
+  FUNC_ATTR_NONNULL_ALL
+{
+  nlua_ref_state_t *ref_state = nlua_get_ref_state(lstate);
+  nlua_unref(lstate, ref_state, ref_state->nil_ref);
+  nlua_unref(lstate, ref_state, ref_state->empty_dict_ref);
 
 #ifdef NLUA_TRACK_REFS
-  if (nlua_refcount) {
-    fprintf(stderr, "%d lua references were leaked!", nlua_refcount);
+  if (ref_state->ref_count) {
+    fprintf(stderr, "%d lua references were leaked!", ref_state->ref_count);
   }
 
   if (nlua_track_refs) {
     // in case there are leaked luarefs, leak the associated memory
     // to get LeakSanitizer stacktraces on exit
-    pmap_destroy(handle_T)(&nlua_ref_markers);
+    pmap_destroy(handle_T)(&ref_state->ref_markers);
   }
 #endif
 
-  nlua_refcount = 0;
   lua_close(lstate);
 }
-
 static void nlua_print_event(void **argv)
 {
   char *str = argv[0];
-  const size_t len = (size_t)(intptr_t)argv[1]-1;  // exclude final NUL
+  const size_t len = (size_t)(intptr_t)argv[1] - 1;  // exclude final NUL
 
   for (size_t i = 0; i < len;) {
     if (got_int) {
@@ -601,9 +855,18 @@ static int nlua_print(lua_State *const lstate)
 #undef PRINT_ERROR
   ga_append(&msg_ga, NUL);
 
-  if (in_fast_callback) {
+  lua_getfield(lstate, LUA_REGISTRYINDEX, "nvim.thread");
+  bool is_thread = lua_toboolean(lstate, -1);
+  lua_pop(lstate, 1);
+
+  if (is_thread) {
+    loop_schedule_deferred(&main_loop,
+                           event_create(nlua_print_event, 2,
+                                        msg_ga.ga_data,
+                                        (intptr_t)msg_ga.ga_len));
+  } else if (in_fast_callback) {
     multiqueue_put(main_loop.events, nlua_print_event,
-                   2, msg_ga.ga_data, msg_ga.ga_len);
+                   2, msg_ga.ga_data, (intptr_t)msg_ga.ga_len);
   } else {
     nlua_print_event((void *[]){ msg_ga.ga_data,
                                  (void *)(intptr_t)msg_ga.ga_len });
@@ -612,13 +875,71 @@ static int nlua_print(lua_State *const lstate)
 
 nlua_print_error:
   ga_clear(&msg_ga);
+  char *buff = xmalloc(IOSIZE);
   const char *fmt = _("E5114: Error while converting print argument #%i: %.*s");
-  size_t len = (size_t)vim_snprintf((char *)IObuff, IOSIZE, fmt, curargidx,
+  size_t len = (size_t)vim_snprintf(buff, IOSIZE, fmt, curargidx,
                                     (int)errmsg_len, errmsg);
-  lua_pushlstring(lstate, (char *)IObuff, len);
+  lua_pushlstring(lstate, buff, len);
+  xfree(buff);
   return lua_error(lstate);
 }
 
+/// require() for --startuptime
+///
+/// @param  lstate  Lua interpreter state.
+static int nlua_require(lua_State *const lstate)
+  FUNC_ATTR_NONNULL_ALL
+{
+  const char *name = luaL_checkstring(lstate, 1);
+  lua_settop(lstate, 1);
+  // [ name ]
+
+  // try cached module from package.loaded first
+  lua_getfield(lstate, LUA_REGISTRYINDEX, "_LOADED");
+  lua_getfield(lstate, 2, name);
+  // [ name package.loaded module ]
+  if (lua_toboolean(lstate, -1)) {
+    return 1;
+  }
+  lua_pop(lstate, 2);
+  // [ name ]
+
+  // push original require below the module name
+  nlua_pushref(lstate, require_ref);
+  lua_insert(lstate, 1);
+  // [ require name ]
+
+  if (time_fd == NULL) {
+    // after log file was closed, try to restore
+    // global require to the original function...
+    lua_getglobal(lstate, "require");
+    // ...only if it's still referencing this wrapper,
+    // to not overwrite it in case someone happened to
+    // patch it in the meantime...
+    if (lua_iscfunction(lstate, -1) && lua_tocfunction(lstate, -1) == nlua_require) {
+      lua_pushvalue(lstate, 1);
+      lua_setglobal(lstate, "require");
+    }
+    lua_pop(lstate, 1);
+
+    // ...and then call require directly.
+    lua_call(lstate, 1, 1);
+    return 1;
+  }
+
+  proftime_T rel_time;
+  proftime_T start_time;
+  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);
+  }
+  time_pop(rel_time);
+
+  return status == 0 ? 1 : lua_error(lstate);
+}
+
 /// debug.debug: interaction with user while debugging.
 ///
 /// @param  lstate  Lua interpreter state.
@@ -629,7 +950,7 @@ static int nlua_debug(lua_State *lstate)
     {
       .v_lock = VAR_FIXED,
       .v_type = VAR_STRING,
-      .vval.v_string = (char_u *)"lua_debug> ",
+      .vval.v_string = "lua_debug> ",
     },
     {
       .v_type = VAR_UNKNOWN,
@@ -664,16 +985,26 @@ int nlua_in_fast_event(lua_State *lstate)
   return 1;
 }
 
+static bool viml_func_is_fast(const char *name)
+{
+  const EvalFuncDef *const fdef = find_internal_func((const char *)name);
+  if (fdef) {
+    return fdef->fast;
+  }
+  // Not a vimL function
+  return false;
+}
+
 int nlua_call(lua_State *lstate)
 {
   Error err = ERROR_INIT;
   size_t name_len;
-  const char_u *name = (const char_u *)luaL_checklstring(lstate, 1, &name_len);
-  if (!nlua_is_deferred_safe()) {
+  const char *name = luaL_checklstring(lstate, 1, &name_len);
+  if (!nlua_is_deferred_safe() && !viml_func_is_fast(name)) {
     return luaL_error(lstate, e_luv_api_disabled, "vimL function");
   }
 
-  int nargs = lua_gettop(lstate)-1;
+  int nargs = lua_gettop(lstate) - 1;
   if (nargs > MAX_FUNC_ARGS) {
     return luaL_error(lstate, "Function called with too many arguments");
   }
@@ -681,10 +1012,10 @@ int nlua_call(lua_State *lstate)
   typval_T vim_args[MAX_FUNC_ARGS + 1];
   int i = 0;  // also used for freeing the variables
   for (; i < nargs; i++) {
-    lua_pushvalue(lstate, (int)i+2);
+    lua_pushvalue(lstate, i + 2);
     if (!nlua_pop_typval(lstate, &vim_args[i])) {
       api_set_error(&err, kErrorTypeException,
-                    "error converting argument %d", i+1);
+                    "error converting argument %d", i + 1);
       goto free_vim_args;
     }
   }
@@ -704,7 +1035,7 @@ int nlua_call(lua_State *lstate)
     funcexe.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(name, (int)name_len, &rettv, nargs, vim_args, &funcexe);
+    (void)call_func((char *)name, (int)name_len, &rettv, nargs, vim_args, &funcexe);
     if (!try_end(&err)) {
       nlua_push_typval(lstate, &rettv, false);
     }
@@ -741,12 +1072,12 @@ static int nlua_rpc(lua_State *lstate, bool request)
   size_t name_len;
   uint64_t chan_id = (uint64_t)luaL_checkinteger(lstate, 1);
   const char *name = luaL_checklstring(lstate, 2, &name_len);
-  int nargs = lua_gettop(lstate)-2;
+  int nargs = lua_gettop(lstate) - 2;
   Error err = ERROR_INIT;
   Array args = ARRAY_DICT_INIT;
 
   for (int i = 0; i < nargs; i++) {
-    lua_pushvalue(lstate, (int)i+3);
+    lua_pushvalue(lstate, i + 3);
     ADD(args, nlua_pop_Object(lstate, false, &err));
     if (ERROR_SET(&err)) {
       api_free_array(args);
@@ -755,10 +1086,11 @@ static int nlua_rpc(lua_State *lstate, bool request)
   }
 
   if (request) {
-    Object result = rpc_send_call(chan_id, name, args, &err);
+    ArenaMem res_mem = NULL;
+    Object result = rpc_send_call(chan_id, name, args, &res_mem, &err);
     if (!ERROR_SET(&err)) {
       nlua_push_Object(lstate, result, false);
-      api_free_object(result);
+      arena_mem_free(res_mem, NULL);
     }
   } else {
     if (!rpc_send_event(chan_id, name, args)) {
@@ -789,7 +1121,6 @@ static int nlua_empty_dict_tostring(lua_State *lstate)
   return 1;
 }
 
-
 #ifdef WIN32
 /// os.getenv: override os.getenv to maintain coherency. #9681
 ///
@@ -803,42 +1134,52 @@ static int nlua_getenv(lua_State *lstate)
 }
 #endif
 
-
 /// add the value to the registry
-LuaRef nlua_ref(lua_State *lstate, int index)
+/// The current implementation does not support calls from threads.
+LuaRef nlua_ref(lua_State *lstate, nlua_ref_state_t *ref_state, int index)
 {
   lua_pushvalue(lstate, index);
   LuaRef ref = luaL_ref(lstate, LUA_REGISTRYINDEX);
   if (ref > 0) {
-    nlua_refcount++;
+    ref_state->ref_count++;
 #ifdef NLUA_TRACK_REFS
     if (nlua_track_refs) {
       // dummy allocation to make LeakSanitizer track our luarefs
-      pmap_put(handle_T)(&nlua_ref_markers, ref, xmalloc(3));
+      pmap_put(handle_T)(&ref_state->ref_markers, ref, xmalloc(3));
     }
 #endif
   }
   return ref;
 }
 
+LuaRef nlua_ref_global(lua_State *lstate, int index)
+{
+  return nlua_ref(lstate, nlua_global_refs, index);
+}
+
 /// remove the value from the registry
-void nlua_unref(lua_State *lstate, LuaRef ref)
+void nlua_unref(lua_State *lstate, nlua_ref_state_t *ref_state, LuaRef ref)
 {
   if (ref > 0) {
-    nlua_refcount--;
+    ref_state->ref_count--;
 #ifdef NLUA_TRACK_REFS
     // NB: don't remove entry from map to track double-unref
     if (nlua_track_refs) {
-      xfree(pmap_get(handle_T)(&nlua_ref_markers, ref));
+      xfree(pmap_get(handle_T)(&ref_state->ref_markers, ref));
     }
 #endif
     luaL_unref(lstate, LUA_REGISTRYINDEX, ref);
   }
 }
 
+void nlua_unref_global(lua_State *lstate, LuaRef ref)
+{
+  nlua_unref(lstate, nlua_global_refs, ref);
+}
+
 void api_free_luaref(LuaRef ref)
 {
-  nlua_unref(global_lstate, ref);
+  nlua_unref_global(global_lstate, ref);
 }
 
 /// push a value referenced in the registry
@@ -847,7 +1188,6 @@ void nlua_pushref(lua_State *lstate, LuaRef ref)
   lua_rawgeti(lstate, LUA_REGISTRYINDEX, ref);
 }
 
-
 /// Gets a new reference to an object stored at original_ref
 ///
 /// NOTE: It does not copy the value, it creates a new ref to the lua object.
@@ -860,12 +1200,11 @@ LuaRef api_new_luaref(LuaRef original_ref)
 
   lua_State *const lstate = global_lstate;
   nlua_pushref(lstate, original_ref);
-  LuaRef new_ref = nlua_ref(lstate, -1);
+  LuaRef new_ref = nlua_ref_global(lstate,  -1);
   lua_pop(lstate, 1);
   return new_ref;
 }
 
-
 /// Evaluate lua string
 ///
 /// Used for luaeval().
@@ -930,8 +1269,8 @@ void nlua_call_user_expand_func(expand_T *xp, typval_T *ret_tv)
   lua_State *const lstate = global_lstate;
 
   nlua_pushref(lstate, xp->xp_luaref);
-  lua_pushstring(lstate, (char *)xp->xp_pattern);
-  lua_pushstring(lstate, (char *)xp->xp_line);
+  lua_pushstring(lstate, xp->xp_pattern);
+  lua_pushstring(lstate, xp->xp_line);
   lua_pushinteger(lstate, xp->xp_col);
 
   if (nlua_pcall(lstate, 3, 1)) {
@@ -984,7 +1323,7 @@ int nlua_source_using_linegetter(LineGetter fgetline, void *cookie, char *name)
   char_u *line = NULL;
 
   ga_init(&ga, (int)sizeof(char_u *), 10);
-  while ((line = fgetline(0, cookie, 0, false)) != NULL) {
+  while ((line = (char_u *)fgetline(0, cookie, 0, false)) != NULL) {
     GA_APPEND(char_u *, &ga, line);
   }
   char *code = ga_concat_strings_sep(&ga, "\n");
@@ -1062,6 +1401,19 @@ Object nlua_exec(const String str, const Array args, Error *err)
   return nlua_pop_Object(lstate, false, err);
 }
 
+bool nlua_ref_is_function(LuaRef ref)
+{
+  lua_State *const lstate = global_lstate;
+  nlua_pushref(lstate, ref);
+
+  // TODO(tjdevries): This should probably check for callable tables as well.
+  //                    We should put some work maybe into simplifying how all of that works
+  bool is_function = (lua_type(lstate, -1) == LUA_TFUNCTION);
+  lua_pop(lstate, 1);
+
+  return is_function;
+}
+
 /// call a LuaRef as a function (or table with __call metamethod)
 ///
 /// @param ref     the reference to call (not consumed)
@@ -1136,7 +1488,7 @@ void ex_lua(exarg_T *const eap)
     // lua nlua_typval_exec doesn't expect null terminated string so len
     // needs to end before null byte.
     char *code_buf = xmallocz(len);
-    vim_snprintf(code_buf, len+1, "vim.pretty_print(%s)", code+1);
+    vim_snprintf(code_buf, len + 1, "vim.pretty_print(%s)", code + 1);
     xfree(code);
     code = code_buf;
   }
@@ -1217,7 +1569,7 @@ void ex_luado(exarg_T *const eap)
           new_line_transformed[i] = '\n';
         }
       }
-      ml_replace(l, (char_u *)new_line_transformed, false);
+      ml_replace(l, new_line_transformed, false);
       inserted_bytes(l, 0, (int)old_line_len, (int)new_line_len);
     }
     lua_pop(lstate, 1);
@@ -1240,6 +1592,9 @@ void ex_luafile(exarg_T *const eap)
 
 /// execute lua code from a file.
 ///
+/// Note: we call the lua global loadfile as opposed to calling luaL_loadfile
+/// in case loadfile has been overridden in the users environment.
+///
 /// @param  path  path of the file
 ///
 /// @return  true if everything ok, false if there was an error (echoed)
@@ -1248,11 +1603,30 @@ bool nlua_exec_file(const char *path)
 {
   lua_State *const lstate = global_lstate;
 
-  if (luaL_loadfile(lstate, path)) {
+  lua_getglobal(lstate, "loadfile");
+  lua_pushstring(lstate, path);
+
+  if (nlua_pcall(lstate, 1, 2)) {
+    nlua_error(lstate, _("E5111: Error calling lua: %.*s"));
+    return false;
+  }
+
+  // loadstring() returns either:
+  //  1. nil, error
+  //  2. chunk, nil
+
+  if (lua_isnil(lstate, -2)) {
+    // 1
     nlua_error(lstate, _("E5112: Error while creating lua chunk: %.*s"));
+    assert(lua_isnil(lstate, -1));
+    lua_pop(lstate, 1);
     return false;
   }
 
+  // 2
+  assert(lua_isnil(lstate, -1));
+  lua_pop(lstate, 1);
+
   if (nlua_pcall(lstate, 0, 0)) {
     nlua_error(lstate, _("E5113: Error while calling lua chunk: %.*s"));
     return false;
@@ -1267,6 +1641,12 @@ int tslua_get_language_version(lua_State *L)
   return 1;
 }
 
+int tslua_get_minimum_language_version(lua_State *L)
+{
+  lua_pushnumber(L, TREE_SITTER_MIN_COMPATIBLE_LANGUAGE_VERSION);
+  return 1;
+}
+
 static void nlua_add_treesitter(lua_State *const lstate) FUNC_ATTR_NONNULL_ALL
 {
   tslua_init(lstate);
@@ -1288,6 +1668,9 @@ static void nlua_add_treesitter(lua_State *const lstate) FUNC_ATTR_NONNULL_ALL
 
   lua_pushcfunction(lstate, tslua_get_language_version);
   lua_setfield(lstate, -2, "_ts_get_language_version");
+
+  lua_pushcfunction(lstate, tslua_get_minimum_language_version);
+  lua_setfield(lstate, -2, "_ts_get_minimum_language_version");
 }
 
 int nlua_expand_pat(expand_T *xp, char_u *pat, int *num_results, char_u ***results)
@@ -1338,9 +1721,7 @@ int nlua_expand_pat(expand_T *xp, char_u *pat, int *num_results, char_u ***resul
       goto cleanup_array;
     }
 
-    GA_APPEND(char_u *,
-              &result_array,
-              vim_strsave((char_u *)v.data.string.data));
+    GA_APPEND(char_u *, &result_array, (char_u *)string_to_cstr(v.data.string));
   }
 
   xp->xp_pattern += prefix_len;
@@ -1359,6 +1740,13 @@ cleanup:
   return ret;
 }
 
+static int nlua_is_thread(lua_State *lstate)
+{
+  lua_getfield(lstate, LUA_REGISTRYINDEX, "nvim.thread");
+
+  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)
@@ -1375,7 +1763,7 @@ void nlua_CFunction_func_free(void *state)
   lua_State *const lstate = global_lstate;
   LuaCFunctionState *funcstate = (LuaCFunctionState *)state;
 
-  nlua_unref(lstate, funcstate->lua_callable.func_ref);
+  nlua_unref_global(lstate, funcstate->lua_callable.func_ref);
   xfree(funcstate);
 }
 
@@ -1425,12 +1813,11 @@ 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(lstate, -1);
+  state->lua_callable.func_ref = nlua_ref_global(lstate, -1);
 
   char_u *name = register_cfunc(&nlua_CFunction_func_call,
                                 &nlua_CFunction_func_free, state);
 
-
   lua_pop(lstate, 1);  // []
   assert(top == lua_gettop(lstate));
 
@@ -1458,10 +1845,13 @@ void nlua_execute_on_key(int c)
   // [ vim, vim._on_key, buf ]
   lua_pushlstring(lstate, (const char *)buf, buf_len);
 
+  int save_got_int = got_int;
+  got_int = false;  // avoid interrupts when the key typed is Ctrl-C
   if (nlua_pcall(lstate, 1, 0)) {
     nlua_error(lstate,
                _("Error executing  vim.on_key Lua callback: %.*s"));
   }
+  got_int |= save_got_int;
 
   // [ vim ]
   lua_pop(lstate, 1);
@@ -1472,11 +1862,64 @@ void nlua_execute_on_key(int c)
 #endif
 }
 
-void nlua_do_ucmd(ucmd_T *cmd, exarg_T *eap)
+// Sets the editor "script context" during Lua execution. Used by :verbose.
+// @param[out] current
+void nlua_set_sctx(sctx_T *current)
 {
+  if (p_verbose <= 0 || current->sc_sid != SID_LUA) {
+    return;
+  }
   lua_State *const lstate = global_lstate;
+  lua_Debug *info = (lua_Debug *)xmalloc(sizeof(lua_Debug));
+
+  // Files where internal wrappers are defined so we can ignore them
+  // like vim.o/opt etc are defined in _meta.lua
+  char *ignorelist[] = {
+    "vim/_meta.lua",
+    "vim/keymap.lua",
+  };
+  int ignorelist_size = sizeof(ignorelist) / sizeof(ignorelist[0]);
 
-  nlua_pushref(lstate, cmd->uc_luaref);
+  for (int level = 1; true; level++) {
+    if (lua_getstack(lstate, level, info) != 1) {
+      goto cleanup;
+    }
+    if (lua_getinfo(lstate, "nSl", info) == 0) {
+      goto cleanup;
+    }
+
+    bool is_ignored = false;
+    if (info->what[0] == 'C' || info->source[0] != '@') {
+      is_ignored = true;
+    } else {
+      for (int i = 0; i < ignorelist_size; i++) {
+        if (strncmp(ignorelist[i], info->source + 1, strlen(ignorelist[i])) == 0) {
+          is_ignored = true;
+          break;
+        }
+      }
+    }
+    if (is_ignored) {
+      continue;
+    }
+    break;
+  }
+  char *source_path = fix_fname(info->source + 1);
+  get_current_script_id((char_u *)source_path, current);
+  xfree(source_path);
+  current->sc_lnum = info->currentline;
+  current->sc_seq = -1;
+
+cleanup:
+  xfree(info);
+}
+
+/// @param preview Invoke the callback as a |:command-preview| handler.
+int nlua_do_ucmd(ucmd_T *cmd, exarg_T *eap, bool preview)
+{
+  lua_State *const lstate = global_lstate;
+
+  nlua_pushref(lstate, preview ? cmd->uc_preview_luaref : cmd->uc_luaref);
 
   lua_newtable(lstate);
   lua_pushboolean(lstate, eap->forceit == 1);
@@ -1488,8 +1931,42 @@ void nlua_do_ucmd(ucmd_T *cmd, exarg_T *eap)
   lua_pushinteger(lstate, eap->line2);
   lua_setfield(lstate, -2, "line2");
 
+  lua_newtable(lstate);  // f-args table
   lua_pushstring(lstate, (const char *)eap->arg);
-  lua_setfield(lstate, -2, "args");
+  lua_pushvalue(lstate, -1);  // Reference for potential use on f-args
+  lua_setfield(lstate, -4, "args");
+
+  // Split args by unescaped whitespace |<f-args>| (nargs dependent)
+  if (cmd->uc_argt & EX_NOSPC) {
+    // Commands where nargs = 1 or "?" fargs is the same as args
+    lua_rawseti(lstate, -2, 1);
+  } 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 end = 0;
+    size_t len = 0;
+    int i = 1;
+    char *buf = xcalloc(length, sizeof(char));
+    bool done = false;
+    while (!done) {
+      done = uc_split_args_iter(eap->arg, length, &end, buf, &len);
+      if (len > 0) {
+        lua_pushlstring(lstate, buf, len);
+        lua_rawseti(lstate, -2, i);
+        i++;
+      }
+    }
+    xfree(buf);
+  } else {
+    // If argument list is available, just use it.
+    lua_pop(lstate, 1);
+    for (size_t i = 0; i < eap->argc; i++) {
+      lua_pushlstring(lstate, eap->args[i], eap->arglens[i]);
+      lua_rawseti(lstate, -2, (int)i + 1);
+    }
+  }
+  lua_setfield(lstate, -2, "fargs");
 
   lua_pushstring(lstate, (const char *)&eap->regname);
   lua_setfield(lstate, -2, "reg");
@@ -1508,12 +1985,93 @@ void nlua_do_ucmd(ucmd_T *cmd, exarg_T *eap)
   // every possible modifier (with room to spare). If the list of possible
   // modifiers grows this may need to be updated.
   char buf[200] = { 0 };
-  (void)uc_mods(buf);
+  (void)uc_mods(buf, &cmdmod, false);
   lua_pushstring(lstate, buf);
   lua_setfield(lstate, -2, "mods");
 
-  if (nlua_pcall(lstate, 1, 0)) {
+  lua_newtable(lstate);  // smods table
+
+  lua_pushinteger(lstate, cmdmod.cmod_tab);
+  lua_setfield(lstate, -2, "tab");
+
+  lua_pushinteger(lstate, cmdmod.cmod_verbose - 1);
+  lua_setfield(lstate, -2, "verbose");
+
+  if (cmdmod.cmod_split & WSP_ABOVE) {
+    lua_pushstring(lstate, "aboveleft");
+  } else if (cmdmod.cmod_split & WSP_BELOW) {
+    lua_pushstring(lstate, "belowright");
+  } else if (cmdmod.cmod_split & WSP_TOP) {
+    lua_pushstring(lstate, "topleft");
+  } else if (cmdmod.cmod_split & WSP_BOT) {
+    lua_pushstring(lstate, "botright");
+  } else {
+    lua_pushstring(lstate, "");
+  }
+  lua_setfield(lstate, -2, "split");
+
+  lua_pushboolean(lstate, cmdmod.cmod_split & WSP_VERT);
+  lua_setfield(lstate, -2, "vertical");
+  lua_pushboolean(lstate, cmdmod.cmod_flags & CMOD_SILENT);
+  lua_setfield(lstate, -2, "silent");
+  lua_pushboolean(lstate, cmdmod.cmod_flags & CMOD_ERRSILENT);
+  lua_setfield(lstate, -2, "emsg_silent");
+  lua_pushboolean(lstate, cmdmod.cmod_flags & CMOD_UNSILENT);
+  lua_setfield(lstate, -2, "unsilent");
+  lua_pushboolean(lstate, cmdmod.cmod_flags & CMOD_SANDBOX);
+  lua_setfield(lstate, -2, "sandbox");
+  lua_pushboolean(lstate, cmdmod.cmod_flags & CMOD_NOAUTOCMD);
+  lua_setfield(lstate, -2, "noautocmd");
+
+  typedef struct {
+    int flag;
+    char *name;
+  } mod_entry_T;
+  static mod_entry_T mod_entries[] = {
+    { CMOD_BROWSE, "browse" },
+    { CMOD_CONFIRM, "confirm" },
+    { CMOD_HIDE, "hide" },
+    { CMOD_KEEPALT, "keepalt" },
+    { CMOD_KEEPJUMPS, "keepjumps" },
+    { CMOD_KEEPMARKS, "keepmarks" },
+    { CMOD_KEEPPATTERNS, "keeppatterns" },
+    { CMOD_LOCKMARKS, "lockmarks" },
+    { CMOD_NOSWAPFILE, "noswapfile" }
+  };
+
+  // The modifiers that are simple flags
+  for (size_t i = 0; i < ARRAY_SIZE(mod_entries); i++) {
+    lua_pushboolean(lstate, cmdmod.cmod_flags & mod_entries[i].flag);
+    lua_setfield(lstate, -2, mod_entries[i].name);
+  }
+
+  lua_setfield(lstate, -2, "smods");
+
+  if (preview) {
+    lua_pushinteger(lstate, cmdpreview_get_ns());
+
+    handle_T cmdpreview_bufnr = cmdpreview_get_bufnr();
+    if (cmdpreview_bufnr != 0) {
+      lua_pushinteger(lstate, cmdpreview_bufnr);
+    } else {
+      lua_pushnil(lstate);
+    }
+  }
+
+  if (nlua_pcall(lstate, preview ? 3 : 1, preview ? 1 : 0)) {
     nlua_error(lstate, _("Error executing Lua callback: %.*s"));
+    return 0;
+  }
+
+  int retv = 0;
+
+  if (preview) {
+    if (lua_isnumber(lstate, -1) && (retv = (int)lua_tointeger(lstate, -1)) >= 0 && retv <= 2) {
+      lua_pop(lstate, 1);
+    } else {
+      retv = 0;
+    }
   }
-}
 
+  return retv;
+}
diff --git a/src/nvim/lua/executor.h b/src/nvim/lua/executor.h
index bf78f7ec5e..e96494ec5a 100644
--- a/src/nvim/lua/executor.h
+++ b/src/nvim/lua/executor.h
@@ -5,6 +5,7 @@
 #include <lua.h>
 
 #include "nvim/api/private/defs.h"
+#include "nvim/assert.h"
 #include "nvim/eval/typval.h"
 #include "nvim/ex_cmds_defs.h"
 #include "nvim/ex_docmd.h"
@@ -14,18 +15,14 @@
 // Generated by msgpack-gen.lua
 void nlua_add_api_functions(lua_State *lstate) REAL_FATTR_NONNULL_ALL;
 
-EXTERN LuaRef nlua_nil_ref INIT(= LUA_NOREF);
-EXTERN LuaRef nlua_empty_dict_ref INIT(= LUA_NOREF);
-
-EXTERN int nlua_refcount INIT(= 0);
-
-#define set_api_error(s, err) \
-  do { \
-    Error *err_ = (err); \
-    err_->type = kErrorTypeException; \
-    err_->set = true; \
-    memcpy(&err_->msg[0], s, sizeof(s)); \
-  } while (0)
+typedef struct {
+  LuaRef nil_ref;
+  LuaRef empty_dict_ref;
+  int ref_count;
+#if __has_feature(address_sanitizer)
+  PMap(handle_T) ref_markers;
+#endif
+} nlua_ref_state_t;
 
 #define NLUA_CLEAR_REF(x) \
   do { \
@@ -39,4 +36,8 @@ EXTERN int nlua_refcount INIT(= 0);
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "lua/executor.h.generated.h"
 #endif
+
+EXTERN nlua_ref_state_t *nlua_global_refs INIT(= NULL);
+EXTERN bool nlua_disable_preload INIT(= false);
+
 #endif  // NVIM_LUA_EXECUTOR_H
diff --git a/src/nvim/lua/spell.c b/src/nvim/lua/spell.c
index 3a63f61200..31a2b2d19f 100644
--- a/src/nvim/lua/spell.c
+++ b/src/nvim/lua/spell.c
@@ -1,12 +1,12 @@
 // 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 <lua.h>
 #include <lauxlib.h>
+#include <lua.h>
 
+#include "nvim/lua/spell.h"
 #include "nvim/spell.h"
 #include "nvim/vim.h"
-#include "nvim/lua/spell.h"
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "lua/spell.c.generated.h"
@@ -45,7 +45,7 @@ int nlua_spell_check(lua_State *lstate)
   size_t pos = 0;
   int capcol = -1;
   int no_res = 0;
-  const char * result;
+  const char *result;
 
   lua_createtable(lstate, 0, 0);
 
@@ -90,7 +90,7 @@ int nlua_spell_check(lua_State *lstate)
 
 static const luaL_Reg spell_functions[] = {
   { "check", nlua_spell_check },
-  { NULL   , NULL }
+  { NULL, NULL }
 };
 
 int luaopen_spell(lua_State *L)
diff --git a/src/nvim/lua/stdlib.c b/src/nvim/lua/stdlib.c
index 18a579ed0f..8fde85b163 100644
--- a/src/nvim/lua/stdlib.c
+++ b/src/nvim/lua/stdlib.c
@@ -25,12 +25,13 @@
 #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/lua/spell.h"
 #include "nvim/macros.h"
 #include "nvim/map.h"
 #include "nvim/memline.h"
@@ -54,12 +55,12 @@ static int regex_match(lua_State *lstate, regprog_T **prog, char_u *str)
   regmatch_T rm;
   rm.regprog = *prog;
   rm.rm_ic = false;
-  bool match = vim_regexec(&rm, str, 0);
+  bool match = vim_regexec(&rm, (char *)str, 0);
   *prog = rm.regprog;
 
   if (match) {
-    lua_pushinteger(lstate, (lua_Integer)(rm.startp[0]-str));
-    lua_pushinteger(lstate, (lua_Integer)(rm.endp[0]-str));
+    lua_pushinteger(lstate, (lua_Integer)(rm.startp[0] - str));
+    lua_pushinteger(lstate, (lua_Integer)(rm.endp[0] - str));
     return 2;
   }
   return 0;
@@ -88,7 +89,7 @@ static int regex_match_line(lua_State *lstate)
   }
 
   long bufnr = luaL_checkinteger(lstate, 2);
-  long rownr = luaL_checkinteger(lstate, 3);
+  linenr_T rownr = (linenr_T)luaL_checkinteger(lstate, 3);
   long start = 0, end = -1;
   if (narg >= 4) {
     start = luaL_checkinteger(lstate, 4);
@@ -109,7 +110,7 @@ static int regex_match_line(lua_State *lstate)
     return luaL_error(lstate, "invalid row");
   }
 
-  char_u *line = ml_get_buf(buf, rownr+1, false);
+  char_u *line = ml_get_buf(buf, rownr + 1, false);
   size_t len = STRLEN(line);
 
   if (start < 0 || (size_t)start > len) {
@@ -125,7 +126,7 @@ static int regex_match_line(lua_State *lstate)
     line[end] = NUL;
   }
 
-  int nret = regex_match(lstate, prog, line+start);
+  int nret = regex_match(lstate, prog, line + start);
 
   if (end >= 0) {
     line[end] = save;
@@ -207,7 +208,7 @@ 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((const char_u *)(s1) + i, (int)(s1_len - i));
     lua_pushinteger(lstate, (long)i + 1);
     lua_rawseti(lstate, -2, (int)idx);
     idx++;
@@ -251,7 +252,7 @@ static int nlua_str_utf_end(lua_State *const lstate) FUNC_ATTR_NONNULL_ALL
   if (offset < 0 || offset > (intptr_t)s1_len) {
     return luaL_error(lstate, "index out of range");
   }
-  int tail_offset = mb_tail_off((char_u *)s1, (char_u *)s1 + offset - 1);
+  int tail_offset = mb_tail_off(s1, s1 + offset - 1);
   lua_pushinteger(lstate, tail_offset);
   return 1;
 }
@@ -294,12 +295,14 @@ int nlua_regex(lua_State *lstate)
 
   TRY_WRAP({
     try_start();
-    prog = vim_regcomp((char_u *)text, RE_AUTO | RE_MAGIC | RE_STRICT);
+    prog = vim_regcomp((char *)text, RE_AUTO | RE_MAGIC | RE_STRICT);
     try_end(&err);
   });
 
   if (ERROR_SET(&err)) {
-    return luaL_error(lstate, "couldn't parse regex: %s", err.msg);
+    nlua_push_errstr(lstate, "couldn't parse regex: %s", err.msg);
+    api_clear_error(&err);
+    return lua_error(lstate);
   }
   assert(prog);
 
@@ -337,18 +340,19 @@ static dict_T *nlua_get_var_scope(lua_State *lstate)
       dict = tabpage->tp_vars;
     }
   } else {
-    luaL_error(lstate, "invalid scope", err.msg);
+    luaL_error(lstate, "invalid scope");
     return NULL;
   }
 
   if (ERROR_SET(&err)) {
-    luaL_error(lstate, "FAIL: %s", err.msg);
+    nlua_push_errstr(lstate, "scoped variable: %s", err.msg);
+    api_clear_error(&err);
+    lua_error(lstate);
     return NULL;
   }
   return dict;
 }
 
-
 int nlua_setvar(lua_State *lstate)
 {
   // non-local return if not found
@@ -408,6 +412,12 @@ int nlua_getvar(lua_State *lstate)
   const char *name = luaL_checklstring(lstate, 3, &len);
 
   dictitem_T *di = tv_dict_find(dict, name, (ptrdiff_t)len);
+  if (di == NULL && dict == &globvardict) {  // try to autoload script
+    if (!script_autoload(name, len, false) || aborting()) {
+      return 0;  // nil
+    }
+    di = tv_dict_find(dict, name, (ptrdiff_t)len);
+  }
   if (di == NULL) {
     return 0;  // nil
   }
@@ -463,44 +473,52 @@ static int nlua_stricmp(lua_State *const lstate) FUNC_ATTR_NONNULL_ALL
   return 1;
 }
 
-
-void nlua_state_add_stdlib(lua_State *const lstate)
+void nlua_state_add_stdlib(lua_State *const lstate, bool is_thread)
 {
-  // stricmp
-  lua_pushcfunction(lstate, &nlua_stricmp);
-  lua_setfield(lstate, -2, "stricmp");
-  // str_utfindex
-  lua_pushcfunction(lstate, &nlua_str_utfindex);
-  lua_setfield(lstate, -2, "str_utfindex");
-  // str_byteindex
-  lua_pushcfunction(lstate, &nlua_str_byteindex);
-  lua_setfield(lstate, -2, "str_byteindex");
-  // str_utf_pos
-  lua_pushcfunction(lstate, &nlua_str_utf_pos);
-  lua_setfield(lstate, -2, "str_utf_pos");
-  // str_utf_start
-  lua_pushcfunction(lstate, &nlua_str_utf_start);
-  lua_setfield(lstate, -2, "str_utf_start");
-  // str_utf_end
-  lua_pushcfunction(lstate, &nlua_str_utf_end);
-  lua_setfield(lstate, -2, "str_utf_end");
-  // regex
-  lua_pushcfunction(lstate, &nlua_regex);
-  lua_setfield(lstate, -2, "regex");
-  luaL_newmetatable(lstate, "nvim_regex");
-  luaL_register(lstate, NULL, regex_meta);
-
-  lua_pushvalue(lstate, -1);  // [meta, meta]
-  lua_setfield(lstate, -2, "__index");  // [meta]
-  lua_pop(lstate, 1);  // don't use metatable now
-
-  // _getvar
-  lua_pushcfunction(lstate, &nlua_getvar);
-  lua_setfield(lstate, -2, "_getvar");
-
-  // _setvar
-  lua_pushcfunction(lstate, &nlua_setvar);
-  lua_setfield(lstate, -2, "_setvar");
+  if (!is_thread) {
+    // TODO(bfredl): some of basic string functions should already be
+    // (or be easy to make) threadsafe
+
+    // stricmp
+    lua_pushcfunction(lstate, &nlua_stricmp);
+    lua_setfield(lstate, -2, "stricmp");
+    // str_utfindex
+    lua_pushcfunction(lstate, &nlua_str_utfindex);
+    lua_setfield(lstate, -2, "str_utfindex");
+    // str_byteindex
+    lua_pushcfunction(lstate, &nlua_str_byteindex);
+    lua_setfield(lstate, -2, "str_byteindex");
+    // str_utf_pos
+    lua_pushcfunction(lstate, &nlua_str_utf_pos);
+    lua_setfield(lstate, -2, "str_utf_pos");
+    // str_utf_start
+    lua_pushcfunction(lstate, &nlua_str_utf_start);
+    lua_setfield(lstate, -2, "str_utf_start");
+    // str_utf_end
+    lua_pushcfunction(lstate, &nlua_str_utf_end);
+    lua_setfield(lstate, -2, "str_utf_end");
+    // regex
+    lua_pushcfunction(lstate, &nlua_regex);
+    lua_setfield(lstate, -2, "regex");
+    luaL_newmetatable(lstate, "nvim_regex");
+    luaL_register(lstate, NULL, regex_meta);
+
+    lua_pushvalue(lstate, -1);  // [meta, meta]
+    lua_setfield(lstate, -2, "__index");  // [meta]
+    lua_pop(lstate, 1);  // don't use metatable now
+
+    // _getvar
+    lua_pushcfunction(lstate, &nlua_getvar);
+    lua_setfield(lstate, -2, "_getvar");
+
+    // _setvar
+    lua_pushcfunction(lstate, &nlua_setvar);
+    lua_setfield(lstate, -2, "_setvar");
+
+    // vim.spell
+    luaopen_spell(lstate);
+    lua_setfield(lstate, -2, "spell");
+  }
 
   // vim.mpack
   luaopen_mpack(lstate);
@@ -519,10 +537,18 @@ void nlua_state_add_stdlib(lua_State *const lstate)
   lua_pushcfunction(lstate, &nlua_xdl_diff);
   lua_setfield(lstate, -2, "diff");
 
-  // vim.spell
-  luaopen_spell(lstate);
-  lua_setfield(lstate, -2, "spell");
-
+  // vim.json
   lua_cjson_new(lstate);
   lua_setfield(lstate, -2, "json");
 }
+
+/// like luaL_error, but allow cleanup
+void nlua_push_errstr(lua_State *L, const char *fmt, ...)
+{
+  va_list argp;
+  va_start(argp, fmt);
+  luaL_where(L, 1);
+  lua_pushvfstring(L, fmt, argp);
+  va_end(argp);
+  lua_concat(L, 2);
+}
diff --git a/src/nvim/lua/treesitter.c b/src/nvim/lua/treesitter.c
index f4067ad02f..b96193d199 100644
--- a/src/nvim/lua/treesitter.c
+++ b/src/nvim/lua/treesitter.c
@@ -16,6 +16,7 @@
 
 #include "nvim/api/private/helpers.h"
 #include "nvim/buffer.h"
+#include "nvim/lib/kvec.h"
 #include "nvim/lua/treesitter.h"
 #include "nvim/memline.h"
 #include "tree_sitter/api.h"
@@ -104,6 +105,7 @@ static struct luaL_Reg treecursor_meta[] = {
   { NULL, NULL }
 };
 
+static kvec_t(TSQueryCursor *) cursors = KV_INITIAL_VALUE;
 static PMap(cstr_t) langs = MAP_INIT;
 
 static void build_meta(lua_State *L, const char *tname, const luaL_Reg *meta)
@@ -208,7 +210,7 @@ int tslua_inspect_lang(lua_State *L)
 
   size_t nsymbols = (size_t)ts_language_symbol_count(lang);
 
-  lua_createtable(L, nsymbols-1, 1);  // [retval, symbols]
+  lua_createtable(L, nsymbols - 1, 1);  // [retval, symbols]
   for (size_t i = 0; i < nsymbols; i++) {
     TSSymbolType t = ts_language_symbol_type(lang, i);
     if (t == TSSymbolTypeAuxiliary) {
@@ -298,15 +300,15 @@ static const char *input_cb(void *payload, uint32_t byte_index, TSPoint position
     *bytes_read = 0;
     return "";
   }
-  char_u *line = ml_get_buf(bp, position.row+1, false);
+  char_u *line = ml_get_buf(bp, position.row + 1, false);
   size_t len = STRLEN(line);
   if (position.column > len) {
     *bytes_read = 0;
     return "";
   }
-  size_t tocopy = MIN(len-position.column, BUFSIZE);
+  size_t tocopy = MIN(len - position.column, BUFSIZE);
 
-  memcpy(buf, line+position.column, tocopy);
+  memcpy(buf, line + position.column, tocopy);
   // Translate embedded \n to NUL
   memchrsub(buf, '\n', '\0', tocopy);
   *bytes_read = (uint32_t)tocopy;
@@ -334,7 +336,7 @@ static void push_ranges(lua_State *L, const TSRange *ranges, const unsigned int
     lua_pushinteger(L, ranges[i].end_point.column);
     lua_rawseti(L, -2, 4);
 
-    lua_rawseti(L, -2, i+1);
+    lua_rawseti(L, -2, i + 1);
   }
 }
 
@@ -389,7 +391,7 @@ static int parser_parse(lua_State *L)
     return luaL_error(L, "An error occurred when parsing.");
   }
 
-  // The new tree will be pushed to the stack, without copy, owwership is now to
+  // The new tree will be pushed to the stack, without copy, ownership is now to
   // the lua GC.
   // Old tree is still owned by the lua GC.
   uint32_t n_ranges = 0;
@@ -527,7 +529,6 @@ static int parser_set_ranges(lua_State *L)
   size_t tbl_len = lua_objlen(L, 2);
   TSRange *ranges = xmalloc(sizeof(TSRange) * tbl_len);
 
-
   // [ parser, ranges ]
   for (size_t index = 0; index < tbl_len; index++) {
     lua_rawgeti(L, 2, index + 1);  // [ parser, ranges, range ]
@@ -556,7 +557,6 @@ static int parser_get_ranges(lua_State *L)
   return 1;
 }
 
-
 // Tree methods
 
 /// push tree interface on lua stack.
@@ -654,7 +654,6 @@ static bool node_check(lua_State *L, int index, TSNode *res)
   return false;
 }
 
-
 static int node_tostring(lua_State *L)
 {
   TSNode node;
@@ -1037,7 +1036,7 @@ static void set_match(lua_State *L, TSQueryMatch *match, int nodeidx)
 {
   for (int i = 0; i < match->capture_count; i++) {
     push_node(L, match->captures[i].node, nodeidx);
-    lua_rawseti(L, -2, match->captures[i].index+1);
+    lua_rawseti(L, -2, match->captures[i].index + 1);
   }
 }
 
@@ -1049,7 +1048,7 @@ static int query_next_match(lua_State *L)
   TSQuery *query = query_check(L, lua_upvalueindex(3));
   TSQueryMatch match;
   if (ts_query_cursor_next_match(cursor, &match)) {
-    lua_pushinteger(L, match.pattern_index+1);  // [index]
+    lua_pushinteger(L, match.pattern_index + 1);  // [index]
     lua_createtable(L, ts_query_capture_count(query), 2);  // [index, match]
     set_match(L, &match, lua_upvalueindex(2));
     return 2;
@@ -1057,7 +1056,6 @@ static int query_next_match(lua_State *L)
   return 0;
 }
 
-
 static int query_next_capture(lua_State *L)
 {
   // Upvalues are:
@@ -1082,7 +1080,7 @@ static int query_next_capture(lua_State *L)
   if (ts_query_cursor_next_capture(cursor, &match, &capture_index)) {
     TSQueryCapture capture = match.captures[capture_index];
 
-    lua_pushinteger(L, capture.index+1);  // [index]
+    lua_pushinteger(L, capture.index + 1);  // [index]
     push_node(L, capture.node, lua_upvalueindex(2));  // [index, node]
 
     // Now check if we need to run the predicates
@@ -1094,7 +1092,7 @@ static int query_next_capture(lua_State *L)
 
       lua_pushvalue(L, lua_upvalueindex(4));  // [index, node, match]
       set_match(L, &match, lua_upvalueindex(2));
-      lua_pushinteger(L, match.pattern_index+1);
+      lua_pushinteger(L, match.pattern_index + 1);
       lua_setfield(L, -2, "pattern");
 
       if (match.capture_count > 1) {
@@ -1116,13 +1114,17 @@ static int node_rawquery(lua_State *L)
     return 0;
   }
   TSQuery *query = query_check(L, 2);
-  // TODO(bfredl): these are expensive allegedly,
-  // use a reuse list later on?
-  TSQueryCursor *cursor = ts_query_cursor_new();
+
+  TSQueryCursor *cursor;
+  if (kv_size(cursors) > 0) {
+    cursor = kv_pop(cursors);
+  } else {
+    cursor = ts_query_cursor_new();
+  }
   // TODO(clason): API introduced after tree-sitter release 0.19.5
   // remove guard when minimum ts version is bumped to 0.19.6+
 #ifdef NVIM_TS_HAS_SET_MATCH_LIMIT
-  ts_query_cursor_set_match_limit(cursor, 32);
+  ts_query_cursor_set_match_limit(cursor, 64);
 #endif
   ts_query_cursor_exec(cursor, query, node);
 
@@ -1161,7 +1163,8 @@ static int node_rawquery(lua_State *L)
 static int querycursor_gc(lua_State *L)
 {
   TSLua_cursor *ud = luaL_checkudata(L, 1, TS_META_QUERYCURSOR);
-  ts_query_cursor_delete(ud->cursor);
+  kv_push(cursors, ud->cursor);
+  ud->cursor = NULL;
   return 0;
 }
 
@@ -1198,7 +1201,6 @@ int tslua_parse_query(lua_State *L)
   return 1;
 }
 
-
 static const char *query_err_string(TSQueryError err)
 {
   switch (err) {
@@ -1273,7 +1275,7 @@ static int query_inspect(lua_State *L)
                                                        &strlen);
         lua_pushlstring(L, str, strlen);  // [retval, patterns, pat, pred, item]
       } else if (step[k].type == TSQueryPredicateStepTypeCapture) {
-        lua_pushnumber(L, step[k].value_id+1);  // [..., pat, pred, item]
+        lua_pushnumber(L, step[k].value_id + 1);  // [..., pat, pred, item]
       } else {
         abort();
       }
@@ -1281,7 +1283,7 @@ static int query_inspect(lua_State *L)
     }
     // last predicate should have ended with TypeDone
     lua_pop(L, 1);  // [retval, patters, pat]
-    lua_rawseti(L, -2, i+1);  // [retval, patterns]
+    lua_rawseti(L, -2, i + 1);  // [retval, patterns]
   }
   lua_setfield(L, -2, "patterns");  // [retval]
 
@@ -1291,7 +1293,7 @@ static int query_inspect(lua_State *L)
     uint32_t strlen;
     const char *str = ts_query_capture_name_for_id(query, i, &strlen);
     lua_pushlstring(L, str, strlen);  // [retval, captures, capture]
-    lua_rawseti(L, -2, i+1);
+    lua_rawseti(L, -2, i + 1);
   }
   lua_setfield(L, -2, "captures");  // [retval]
 
diff --git a/src/nvim/lua/vim.lua b/src/nvim/lua/vim.lua
deleted file mode 100644
index 731e7d8d36..0000000000
--- a/src/nvim/lua/vim.lua
+++ /dev/null
@@ -1,711 +0,0 @@
--- Nvim-Lua stdlib: the `vim` module (:help lua-stdlib)
---
--- Lua code lives in one of three places:
---    1. runtime/lua/vim/ (the runtime): For "nice to have" features, e.g. the
---       `inspect` and `lpeg` modules.
---    2. runtime/lua/vim/shared.lua: Code shared between Nvim and tests.
---       (This will go away if we migrate to nvim as the test-runner.)
---    3. src/nvim/lua/: Compiled-into Nvim itself.
---
--- Guideline: "If in doubt, put it in the runtime".
---
--- Most functions should live directly in `vim.`, not in submodules.
--- The only "forbidden" names are those claimed by legacy `if_lua`:
---    $ vim
---    :lua for k,v in pairs(vim) do print(k) end
---    buffer
---    open
---    window
---    lastline
---    firstline
---    type
---    line
---    eval
---    dict
---    beep
---    list
---    command
---
--- Reference (#6580):
---    - https://github.com/luafun/luafun
---    - https://github.com/rxi/lume
---    - http://leafo.net/lapis/reference/utilities.html
---    - https://github.com/torch/paths
---    - https://github.com/bakpakin/Fennel (pretty print, repl)
---    - https://github.com/howl-editor/howl/tree/master/lib/howl/util
-
-local vim = vim
-assert(vim)
-
-vim.inspect = package.loaded['vim.inspect']
-assert(vim.inspect)
-
-vim.filetype = package.loaded['vim.filetype']
-assert(vim.filetype)
-
-local pathtrails = {}
-vim._so_trails = {}
-for s in  (package.cpath..';'):gmatch('[^;]*;') do
-    s = s:sub(1, -2)  -- Strip trailing semicolon
-  -- Find out path patterns. pathtrail should contain something like
-  -- /?.so, \?.dll. This allows not to bother determining what correct
-  -- suffixes are.
-  local pathtrail = s:match('[/\\][^/\\]*%?.*$')
-  if pathtrail and not pathtrails[pathtrail] then
-    pathtrails[pathtrail] = true
-    table.insert(vim._so_trails, pathtrail)
-  end
-end
-
-function vim._load_package(name)
-  local basename = name:gsub('%.', '/')
-  local paths = {"lua/"..basename..".lua", "lua/"..basename.."/init.lua"}
-  local found = vim.api.nvim__get_runtime(paths, false, {is_lua=true})
-  if #found > 0 then
-    local f, err = loadfile(found[1])
-    return f or error(err)
-  end
-
-  local so_paths = {}
-  for _,trail in ipairs(vim._so_trails) do
-    local path = "lua"..trail:gsub('?', basename) -- so_trails contains a leading slash
-    table.insert(so_paths, path)
-  end
-
-  found = vim.api.nvim__get_runtime(so_paths, false, {is_lua=true})
-  if #found > 0 then
-    -- Making function name in Lua 5.1 (see src/loadlib.c:mkfuncname) is
-    -- a) strip prefix up to and including the first dash, if any
-    -- b) replace all dots by underscores
-    -- c) prepend "luaopen_"
-    -- So "foo-bar.baz" should result in "luaopen_bar_baz"
-    local dash = name:find("-", 1, true)
-    local modname = dash and name:sub(dash + 1) or name
-    local f, err = package.loadlib(found[1], "luaopen_"..modname:gsub("%.", "_"))
-    return f or error(err)
-  end
-  return nil
-end
-
-table.insert(package.loaders, 1, vim._load_package)
-
--- These are for loading runtime modules lazily since they aren't available in
--- the nvim binary as specified in executor.c
-setmetatable(vim, {
-  __index = function(t, key)
-    if key == 'treesitter' then
-      t.treesitter = require('vim.treesitter')
-      return t.treesitter
-    elseif key == 'F' then
-      t.F = require('vim.F')
-      return t.F
-    elseif require('vim.uri')[key] ~= nil then
-      -- Expose all `vim.uri` functions on the `vim` module.
-      t[key] = require('vim.uri')[key]
-      return t[key]
-    elseif key == 'lsp' then
-      t.lsp = require('vim.lsp')
-      return t.lsp
-    elseif key == 'highlight' then
-      t.highlight = require('vim.highlight')
-      return t.highlight
-    elseif key == 'diagnostic' then
-      t.diagnostic = require('vim.diagnostic')
-      return t.diagnostic
-    elseif key == 'ui' then
-      t.ui = require('vim.ui')
-      return t.ui
-    elseif key == 'keymap' then
-      t.keymap = require('vim.keymap')
-      return t.keymap
-    end
-  end
-})
-
-vim.log = {
-  levels = {
-    TRACE = 0;
-    DEBUG = 1;
-    INFO  = 2;
-    WARN  = 3;
-    ERROR = 4;
-  }
-}
-
--- Internal-only until comments in #8107 are addressed.
--- Returns:
---    {errcode}, {output}
-function vim._system(cmd)
-  local out = vim.fn.system(cmd)
-  local err = vim.v.shell_error
-  return err, out
-end
-
--- Gets process info from the `ps` command.
--- Used by nvim_get_proc() as a fallback.
-function vim._os_proc_info(pid)
-  if pid == nil or pid <= 0 or type(pid) ~= 'number' then
-    error('invalid pid')
-  end
-  local cmd = { 'ps', '-p', pid, '-o', 'comm=', }
-  local err, name = vim._system(cmd)
-  if 1 == err and vim.trim(name) == '' then
-    return {}  -- Process not found.
-  elseif 0 ~= err then
-    error('command failed: '..vim.fn.string(cmd))
-  end
-  local _, ppid = vim._system({ 'ps', '-p', pid, '-o', 'ppid=', })
-  -- Remove trailing whitespace.
-  name = vim.trim(name):gsub('^.*/', '')
-  ppid = tonumber(ppid) or -1
-  return {
-    name = name,
-    pid = pid,
-    ppid = ppid,
-  }
-end
-
--- Gets process children from the `pgrep` command.
--- Used by nvim_get_proc_children() as a fallback.
-function vim._os_proc_children(ppid)
-  if ppid == nil or ppid <= 0 or type(ppid) ~= 'number' then
-    error('invalid ppid')
-  end
-  local cmd = { 'pgrep', '-P', ppid, }
-  local err, rv = vim._system(cmd)
-  if 1 == err and vim.trim(rv) == '' then
-    return {}  -- Process not found.
-  elseif 0 ~= err then
-    error('command failed: '..vim.fn.string(cmd))
-  end
-  local children = {}
-  for s in rv:gmatch('%S+') do
-    local i = tonumber(s)
-    if i ~= nil then
-      table.insert(children, i)
-    end
-  end
-  return children
-end
-
--- TODO(ZyX-I): Create compatibility layer.
-
---- Return a human-readable representation of the given object.
----
----@see https://github.com/kikito/inspect.lua
----@see https://github.com/mpeterv/vinspect
-local function inspect(object, options)  -- luacheck: no unused
-  error(object, options)  -- Stub for gen_vimdoc.py
-end
-
-do
-  local tdots, tick, got_line1 = 0, 0, false
-
-  --- Paste handler, invoked by |nvim_paste()| when a conforming UI
-  --- (such as the |TUI|) pastes text into the editor.
-  ---
-  --- Example: To remove ANSI color codes when pasting:
-  --- <pre>
-  --- vim.paste = (function(overridden)
-  ---   return function(lines, phase)
-  ---     for i,line in ipairs(lines) do
-  ---       -- Scrub ANSI color codes from paste input.
-  ---       lines[i] = line:gsub('\27%[[0-9;mK]+', '')
-  ---     end
-  ---     overridden(lines, phase)
-  ---   end
-  --- end)(vim.paste)
-  --- </pre>
-  ---
-  ---@see |paste|
-  ---
-  ---@param lines  |readfile()|-style list of lines to paste. |channel-lines|
-  ---@param phase  -1: "non-streaming" paste: the call contains all lines.
-  ---              If paste is "streamed", `phase` indicates the stream state:
-  ---                - 1: starts the paste (exactly once)
-  ---                - 2: continues the paste (zero or more times)
-  ---                - 3: ends the paste (exactly once)
-  ---@returns false if client should cancel the paste.
-  function vim.paste(lines, phase)
-    local call = vim.api.nvim_call_function
-    local now = vim.loop.now()
-    local mode = call('mode', {}):sub(1,1)
-    if phase < 2 then  -- Reset flags.
-      tdots, tick, got_line1 = now, 0, false
-    elseif mode ~= 'c' then
-      vim.api.nvim_command('undojoin')
-    end
-    if mode == 'c' and not got_line1 then  -- cmdline-mode: paste only 1 line.
-      got_line1 = (#lines > 1)
-      vim.api.nvim_set_option('paste', true)  -- For nvim_input().
-      local line1 = lines[1]:gsub('<', '<lt>'):gsub('[\r\n\012\027]', ' ')  -- Scrub.
-      vim.api.nvim_input(line1)
-      vim.api.nvim_set_option('paste', false)
-    elseif mode ~= 'c' then
-      if phase < 2 and mode:find('^[vV\22sS\19]') then
-        vim.api.nvim_command([[exe "normal! \<Del>"]])
-        vim.api.nvim_put(lines, 'c', false, true)
-      elseif phase < 2 and not mode:find('^[iRt]') then
-        vim.api.nvim_put(lines, 'c', true, true)
-        -- XXX: Normal-mode: workaround bad cursor-placement after first chunk.
-        vim.api.nvim_command('normal! a')
-      elseif phase < 2 and mode == 'R' then
-        local nchars = 0
-        for _, line in ipairs(lines) do
-            nchars = nchars + line:len()
-        end
-        local row, col = unpack(vim.api.nvim_win_get_cursor(0))
-        local bufline = vim.api.nvim_buf_get_lines(0, row-1, row, true)[1]
-        local firstline = lines[1]
-        firstline = bufline:sub(1, col)..firstline
-        lines[1] = firstline
-        lines[#lines] = lines[#lines]..bufline:sub(col + nchars + 1, bufline:len())
-        vim.api.nvim_buf_set_lines(0, row-1, row, false, lines)
-      else
-        vim.api.nvim_put(lines, 'c', false, true)
-      end
-    end
-    if phase ~= -1 and (now - tdots >= 100) then
-      local dots = ('.'):rep(tick % 4)
-      tdots = now
-      tick = tick + 1
-      -- Use :echo because Lua print('') is a no-op, and we want to clear the
-      -- message when there are zero dots.
-      vim.api.nvim_command(('echo "%s"'):format(dots))
-    end
-    if phase == -1 or phase == 3 then
-      vim.api.nvim_command('redraw'..(tick > 1 and '|echo ""' or ''))
-    end
-    return true  -- Paste will not continue if not returning `true`.
-  end
-end
-
---- Defers callback `cb` until the Nvim API is safe to call.
----
----@see |lua-loop-callbacks|
----@see |vim.schedule()|
----@see |vim.in_fast_event()|
-function vim.schedule_wrap(cb)
-  return (function (...)
-    local args = vim.F.pack_len(...)
-    vim.schedule(function() cb(vim.F.unpack_len(args)) end)
-  end)
-end
-
---- <Docs described in |vim.empty_dict()| >
----@private
-function vim.empty_dict()
-  return setmetatable({}, vim._empty_dict_mt)
-end
-
--- vim.fn.{func}(...)
-vim.fn = setmetatable({}, {
-  __index = function(t, key)
-    local _fn
-    if vim.api[key] ~= nil then
-      _fn = function()
-        error(string.format("Tried to call API function with vim.fn: use vim.api.%s instead", key))
-      end
-    else
-      _fn = function(...)
-        return vim.call(key, ...)
-      end
-    end
-    t[key] = _fn
-    return _fn
-  end
-})
-
-vim.funcref = function(viml_func_name)
-  return vim.fn[viml_func_name]
-end
-
--- An easier alias for commands.
-vim.cmd = function(command)
-  return vim.api.nvim_exec(command, false)
-end
-
--- These are the vim.env/v/g/o/bo/wo variable magic accessors.
-do
-  local validate = vim.validate
-
-  --@private
-  local function make_dict_accessor(scope, handle)
-    validate {
-      scope = {scope, 's'};
-    }
-    local mt = {}
-    function mt:__newindex(k, v)
-      return vim._setvar(scope, handle or 0, k, v)
-    end
-    function mt:__index(k)
-      if handle == nil and type(k) == 'number' then
-        return make_dict_accessor(scope, k)
-      end
-      return vim._getvar(scope, handle or 0, k)
-    end
-    return setmetatable({}, mt)
-  end
-
-  vim.g = make_dict_accessor('g', false)
-  vim.v = make_dict_accessor('v', false)
-  vim.b = make_dict_accessor('b')
-  vim.w = make_dict_accessor('w')
-  vim.t = make_dict_accessor('t')
-end
-
---- Get a table of lines with start, end columns for a region marked by two points
----
----@param bufnr number of buffer
----@param pos1 (line, column) tuple marking beginning of region
----@param pos2 (line, column) tuple marking end of region
----@param regtype type of selection (:help setreg)
----@param inclusive boolean indicating whether the selection is end-inclusive
----@return region lua table of the form {linenr = {startcol,endcol}}
-function vim.region(bufnr, pos1, pos2, regtype, inclusive)
-  if not vim.api.nvim_buf_is_loaded(bufnr) then
-    vim.fn.bufload(bufnr)
-  end
-
-  -- check that region falls within current buffer
-  local buf_line_count = vim.api.nvim_buf_line_count(bufnr)
-  pos1[1] = math.min(pos1[1], buf_line_count - 1)
-  pos2[1] = math.min(pos2[1], buf_line_count - 1)
-
-  -- in case of block selection, columns need to be adjusted for non-ASCII characters
-  -- TODO: handle double-width characters
-  local bufline
-  if regtype:byte() == 22 then
-    bufline = vim.api.nvim_buf_get_lines(bufnr, pos1[1], pos1[1] + 1, true)[1]
-    pos1[2] = vim.str_utfindex(bufline, pos1[2])
-  end
-
-  local region = {}
-  for l = pos1[1], pos2[1] do
-    local c1, c2
-    if regtype:byte() == 22 then  -- block selection: take width from regtype
-      c1 = pos1[2]
-      c2 = c1 + regtype:sub(2)
-      -- and adjust for non-ASCII characters
-      bufline = vim.api.nvim_buf_get_lines(bufnr, l, l + 1, true)[1]
-      if c1 < #bufline then
-        c1 = vim.str_byteindex(bufline, c1)
-      end
-      if c2 < #bufline then
-        c2 = vim.str_byteindex(bufline, c2)
-      end
-    else
-      c1 = (l == pos1[1]) and (pos1[2]) or 0
-      c2 = (l == pos2[1]) and (pos2[2] + (inclusive and 1 or 0)) or -1
-    end
-    table.insert(region, l, {c1, c2})
-  end
-  return region
-end
-
---- Defers calling `fn` until `timeout` ms passes.
----
---- Use to do a one-shot timer that calls `fn`
---- Note: The {fn} is |schedule_wrap|ped automatically, so API functions are
---- safe to call.
----@param fn Callback to call once `timeout` expires
----@param timeout Number of milliseconds to wait before calling `fn`
----@return timer luv timer object
-function vim.defer_fn(fn, timeout)
-  vim.validate { fn = { fn, 'c', true}; }
-  local timer = vim.loop.new_timer()
-  timer:start(timeout, 0, vim.schedule_wrap(function()
-    timer:stop()
-    timer:close()
-
-    fn()
-  end))
-
-  return timer
-end
-
-
---- Display a notification to the user.
----
---- This function can be overridden by plugins to display notifications using a
---- custom provider (such as the system notification provider). By default,
---- writes to |:messages|.
----
----@param msg string Content of the notification to show to the user.
----@param level number|nil One of the values from |vim.log.levels|.
----@param opts table|nil Optional parameters. Unused by default.
-function vim.notify(msg, level, opts) -- luacheck: no unused args
-  if level == vim.log.levels.ERROR then
-    vim.api.nvim_err_writeln(msg)
-  elseif level == vim.log.levels.WARN then
-    vim.api.nvim_echo({{msg, 'WarningMsg'}}, true, {})
-  else
-    vim.api.nvim_echo({{msg}}, true, {})
-  end
-end
-
-do
-  local notified = {}
-
-  --- Display a notification only one time.
-  ---
-  --- Like |vim.notify()|, but subsequent calls with the same message will not
-  --- display a notification.
-  ---
-  ---@param msg string Content of the notification to show to the user.
-  ---@param level number|nil One of the values from |vim.log.levels|.
-  ---@param opts table|nil Optional parameters. Unused by default.
-  function vim.notify_once(msg, level, opts) -- luacheck: no unused args
-    if not notified[msg] then
-      vim.notify(msg, level, opts)
-      notified[msg] = true
-    end
-  end
-end
-
----@private
-function vim.register_keystroke_callback()
-  error('vim.register_keystroke_callback is deprecated, instead use: vim.on_key')
-end
-
-local on_key_cbs = {}
-
---- Adds Lua function {fn} with namespace id {ns_id} as a listener to every,
---- yes every, input key.
----
---- The Nvim command-line option |-w| is related but does not support callbacks
---- and cannot be toggled dynamically.
----
----@param fn function: Callback function. It should take one string argument.
----                   On each key press, Nvim passes the key char to fn(). |i_CTRL-V|
----                   If {fn} is nil, it removes the callback for the associated {ns_id}
----@param ns_id number? Namespace ID. If nil or 0, generates and returns a new
----                    |nvim_create_namespace()| id.
----
----@return number Namespace id associated with {fn}. Or count of all callbacks
----if on_key() is called without arguments.
----
----@note {fn} will be removed if an error occurs while calling.
----@note {fn} will not be cleared by |nvim_buf_clear_namespace()|
----@note {fn} will receive the keys after mappings have been evaluated
-function vim.on_key(fn, ns_id)
-  if fn == nil and ns_id == nil then
-    return #on_key_cbs
-  end
-
-  vim.validate {
-    fn = { fn, 'c', true},
-    ns_id = { ns_id, 'n', true }
-  }
-
-  if ns_id == nil or ns_id == 0 then
-    ns_id = vim.api.nvim_create_namespace('')
-  end
-
-  on_key_cbs[ns_id] = fn
-  return ns_id
-end
-
---- Executes the on_key callbacks.
----@private
-function vim._on_key(char)
-  local failed_ns_ids = {}
-  local failed_messages = {}
-  for k, v in pairs(on_key_cbs) do
-    local ok, err_msg = pcall(v, char)
-    if not ok then
-      vim.on_key(nil, k)
-      table.insert(failed_ns_ids, k)
-      table.insert(failed_messages, err_msg)
-    end
-  end
-
-  if failed_ns_ids[1] then
-    error(string.format(
-      "Error executing 'on_key' with ns_ids '%s'\n    Messages: %s",
-      table.concat(failed_ns_ids, ", "),
-      table.concat(failed_messages, "\n")))
-  end
-end
-
---- Generate a list of possible completions for the string.
---- String starts with ^ and then has the pattern.
----
----     1. Can we get it to just return things in the global namespace with that name prefix
----     2. Can we get it to return things from global namespace even with `print(` in front.
-function vim._expand_pat(pat, env)
-  env = env or _G
-
-  pat = string.sub(pat, 2, #pat)
-
-  if pat == '' then
-    local result = vim.tbl_keys(env)
-    table.sort(result)
-    return result, 0
-  end
-
-  -- TODO: We can handle spaces in [] ONLY.
-  --    We should probably do that at some point, just for cooler completion.
-  -- TODO: We can suggest the variable names to go in []
-  --    This would be difficult as well.
-  --    Probably just need to do a smarter match than just `:match`
-
-  -- Get the last part of the pattern
-  local last_part = pat:match("[%w.:_%[%]'\"]+$")
-  if not last_part then return {}, 0 end
-
-  local parts, search_index = vim._expand_pat_get_parts(last_part)
-
-  local match_part = string.sub(last_part, search_index, #last_part)
-  local prefix_match_pat = string.sub(pat, 1, #pat - #match_part) or ''
-
-  local final_env = env
-
-  for _, part in ipairs(parts) do
-    if type(final_env) ~= 'table' then
-      return {}, 0
-    end
-    local key
-
-    -- Normally, we just have a string
-    -- Just attempt to get the string directly from the environment
-    if type(part) == "string" then
-      key = part
-    else
-      -- However, sometimes you want to use a variable, and complete on it
-      --    With this, you have the power.
-
-      -- MY_VAR = "api"
-      -- vim[MY_VAR]
-      -- -> _G[MY_VAR] -> "api"
-      local result_key = part[1]
-      if not result_key then
-        return {}, 0
-      end
-
-      local result = rawget(env, result_key)
-
-      if result == nil then
-        return {}, 0
-      end
-
-      key = result
-    end
-    local field = rawget(final_env, key)
-    if field == nil then
-      local mt = getmetatable(final_env)
-      if mt and type(mt.__index) == "table" then
-        field = rawget(mt.__index, key)
-      end
-    end
-    final_env = field
-
-    if not final_env then
-      return {}, 0
-    end
-  end
-
-  local keys = {}
-  ---@private
-  local function insert_keys(obj)
-    for k,_ in pairs(obj) do
-      if type(k) == "string" and string.sub(k,1,string.len(match_part)) == match_part then
-        table.insert(keys,k)
-      end
-    end
-  end
-
-  if type(final_env) == "table" then
-    insert_keys(final_env)
-  end
-  local mt = getmetatable(final_env)
-  if mt and type(mt.__index) == "table" then
-    insert_keys(mt.__index)
-  end
-
-  table.sort(keys)
-
-  return keys, #prefix_match_pat
-end
-
-vim._expand_pat_get_parts = function(lua_string)
-  local parts = {}
-
-  local accumulator, search_index = '', 1
-  local in_brackets, bracket_end = false, -1
-  local string_char = nil
-  for idx = 1, #lua_string do
-    local s = lua_string:sub(idx, idx)
-
-    if not in_brackets and (s == "." or s == ":") then
-      table.insert(parts, accumulator)
-      accumulator = ''
-
-      search_index = idx + 1
-    elseif s == "[" then
-      in_brackets = true
-
-      table.insert(parts, accumulator)
-      accumulator = ''
-
-      search_index = idx + 1
-    elseif in_brackets then
-      if idx == bracket_end then
-        in_brackets = false
-        search_index = idx + 1
-
-        if string_char == "VAR" then
-          table.insert(parts, { accumulator })
-          accumulator = ''
-
-          string_char = nil
-        end
-      elseif not string_char then
-        bracket_end = string.find(lua_string, ']', idx, true)
-
-        if s == '"' or s == "'" then
-          string_char = s
-        elseif s ~= ' ' then
-          string_char = "VAR"
-          accumulator = s
-        end
-      elseif string_char then
-        if string_char ~= s then
-          accumulator = accumulator .. s
-        else
-          table.insert(parts, accumulator)
-          accumulator = ''
-
-          string_char = nil
-        end
-      end
-    else
-      accumulator = accumulator .. s
-    end
-  end
-
-  parts = vim.tbl_filter(function(val) return #val > 0 end, parts)
-
-  return parts, search_index
-end
-
----Prints given arguments in human-readable format.
----Example:
----<pre>
----  -- Print highlight group Normal and store it's contents in a variable.
----  local hl_normal = vim.pretty_print(vim.api.nvim_get_hl_by_name("Normal", true))
----</pre>
----@see |vim.inspect()|
----@return given arguments.
-function vim.pretty_print(...)
-  local objects = {}
-  for i = 1, select('#', ...) do
-    local v = select(i, ...)
-    table.insert(objects, vim.inspect(v))
-  end
-
-  print(table.concat(objects, '    '))
-  return ...
-end
-
-return module
diff --git a/src/nvim/lua/xdiff.c b/src/nvim/lua/xdiff.c
index b2e971f9f3..71f85385b6 100644
--- a/src/nvim/lua/xdiff.c
+++ b/src/nvim/lua/xdiff.c
@@ -74,7 +74,7 @@ static int hunk_locations_cb(long start_a, long count_a, long start_b, long coun
   lua_pushinteger(lstate, count_b);
   lua_rawseti(lstate, -2, 4);
 
-  lua_rawseti(lstate, -2, (signed)lua_objlen(lstate, -2)+1);
+  lua_rawseti(lstate, -2, (signed)lua_objlen(lstate, -2) + 1);
 
   return 0;
 }
@@ -171,6 +171,7 @@ static NluaXdiffMode process_xdl_diff_opts(lua_State *lstate, xdemitconf_t *cfg,
         goto exit_1;
       }
       if (strequal("unified", v->data.string.data)) {
+        // the default
       } else if (strequal("indices", v->data.string.data)) {
         had_result_type_indices = true;
       } else {
@@ -184,11 +185,11 @@ static NluaXdiffMode process_xdl_diff_opts(lua_State *lstate, xdemitconf_t *cfg,
       if (strequal("myers", v->data.string.data)) {
         // default
       } else if (strequal("minimal", v->data.string.data)) {
-        cfg->flags |= XDF_NEED_MINIMAL;
+        params->flags |= XDF_NEED_MINIMAL;
       } else if (strequal("patience", v->data.string.data)) {
-        cfg->flags |= XDF_PATIENCE_DIFF;
+        params->flags |= XDF_PATIENCE_DIFF;
       } else if (strequal("histogram", v->data.string.data)) {
-        cfg->flags |= XDF_HISTOGRAM_DIFF;
+        params->flags |= XDF_HISTOGRAM_DIFF;
       } else {
         api_set_error(err, kErrorTypeValidation, "not a valid algorithm");
         goto exit_1;