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

17 files changed, 376 insertions, 272 deletions

diff --git a/src/nvim/api/autocmd.c b/src/nvim/api/autocmd.c
index 79ae7994f7..b5c695b9ce 100644
--- a/src/nvim/api/autocmd.c
+++ b/src/nvim/api/autocmd.c
@@ -59,6 +59,9 @@ static int64_t next_autocmd_id = 1;
 ///             - group (string|integer): the autocommand group name or id to match against.
 ///             - event (string|array): event or events to match against |autocmd-events|.
 ///             - pattern (string|array): pattern or patterns to match against |autocmd-pattern|.
+///             Cannot be used with {buffer}
+///             - buffer: Buffer number or list of buffer numbers for buffer local autocommands
+///             |autocmd-buflocal|. Cannot be used with {pattern}
 /// @return Array of autocommands matching the criteria, with each item
 ///         containing the following fields:
 ///             - id (number): the autocommand id (only when defined with the API).
@@ -240,7 +243,7 @@ Array nvim_get_autocmds(Dict(get_autocmds) *opts, Error *err)
           assert(pattern_filters[i]);
 
           char *pat = pattern_filters[i];
-          int patlen = (int)STRLEN(pat);
+          int patlen = (int)strlen(pat);
 
           if (aupat_is_buflocal(pat, patlen)) {
             aupat_normalize_buflocal_pat(pattern_buflocal,
@@ -596,7 +599,7 @@ void nvim_del_autocmd(Integer id, Error *err)
 }
 
 /// Clear all autocommands that match the corresponding {opts}. To delete
-/// a particular autocmd, see |nvim_del_autocmd|.
+/// a particular autocmd, see |nvim_del_autocmd()|.
 /// @param opts Parameters
 ///         - event: (string|table)
 ///              Examples:
@@ -725,7 +728,7 @@ Integer nvim_create_augroup(uint64_t channel_id, String name, Dict(create_augrou
 ///
 /// To get a group id one can use |nvim_get_autocmds()|.
 ///
-/// NOTE: behavior differs from |augroup-delete|. When deleting a group, autocommands contained in
+/// NOTE: behavior differs from |:augroup-delete|. When deleting a group, autocommands contained in
 /// this group will also be deleted and cleared. This group will no longer exist.
 /// @param id Integer The id of the group.
 /// @see |nvim_del_augroup_by_name()|
@@ -743,10 +746,10 @@ void nvim_del_augroup_by_id(Integer id, Error *err)
 
 /// Delete an autocommand group by name.
 ///
-/// NOTE: behavior differs from |augroup-delete|. When deleting a group, autocommands contained in
+/// NOTE: behavior differs from |:augroup-delete|. When deleting a group, autocommands contained in
 /// this group will also be deleted and cleared. This group will no longer exist.
 /// @param name String The name of the group.
-/// @see |autocommand-groups|
+/// @see |autocmd-groups|
 void nvim_del_augroup_by_name(String name, Error *err)
   FUNC_API_SINCE(9)
 {
@@ -887,12 +890,12 @@ static bool check_autocmd_string_array(Array arr, char *k, Error *err)
 static bool unpack_string_or_array(Array *array, Object *v, char *k, bool required, Error *err)
 {
   if (v->type == kObjectTypeString) {
-    ADD(*array, copy_object(*v));
+    ADD(*array, copy_object(*v, NULL));
   } else if (v->type == kObjectTypeArray) {
     if (!check_autocmd_string_array(v->data.array, k, err)) {
       return false;
     }
-    *array = copy_array(v->data.array);
+    *array = copy_array(v->data.array, NULL);
   } else {
     if (required) {
       api_set_error(err,
diff --git a/src/nvim/api/buffer.c b/src/nvim/api/buffer.c
index 5e90e40dd3..51fedb302a 100644
--- a/src/nvim/api/buffer.c
+++ b/src/nvim/api/buffer.c
@@ -355,6 +355,8 @@ static bool check_string_array(Array arr, bool disallow_nl, Error *err)
 /// Out-of-bounds indices are clamped to the nearest valid value, unless
 /// `strict_indexing` is set.
 ///
+/// @see |nvim_buf_set_text()|
+///
 /// @param channel_id
 /// @param buffer           Buffer handle, or 0 for current buffer
 /// @param start            First line index
@@ -527,6 +529,8 @@ end:
 ///
 /// Prefer |nvim_buf_set_lines()| if you are only adding or deleting entire lines.
 ///
+/// @see |nvim_buf_set_lines()|
+///
 /// @param channel_id
 /// @param buffer           Buffer handle, or 0 for current buffer
 /// @param start_row        First line index
@@ -570,7 +574,7 @@ void nvim_buf_set_text(uint64_t channel_id, Buffer buffer, Integer start_row, In
   char *str_at_end = NULL;
 
   // Another call to ml_get_buf() may free the line, so make a copy.
-  str_at_start = xstrdup((char *)ml_get_buf(buf, (linenr_T)start_row, false));
+  str_at_start = xstrdup(ml_get_buf(buf, (linenr_T)start_row, false));
   size_t len_at_start = strlen(str_at_start);
   if (start_col < 0 || (size_t)start_col > len_at_start) {
     api_set_error(err, kErrorTypeValidation, "start_col out of bounds");
@@ -578,7 +582,7 @@ void nvim_buf_set_text(uint64_t channel_id, Buffer buffer, Integer start_row, In
   }
 
   // Another call to ml_get_buf() may free the line, so make a copy.
-  str_at_end = xstrdup((char *)ml_get_buf(buf, (linenr_T)end_row, false));
+  str_at_end = xstrdup(ml_get_buf(buf, (linenr_T)end_row, false));
   size_t len_at_end = strlen(str_at_end);
   if (end_col < 0 || (size_t)end_col > len_at_end) {
     api_set_error(err, kErrorTypeValidation, "end_col out of bounds");
@@ -608,7 +612,7 @@ void nvim_buf_set_text(uint64_t channel_id, Buffer buffer, Integer start_row, In
     for (int64_t i = 1; i < end_row - start_row; i++) {
       int64_t lnum = start_row + i;
 
-      const char *bufline = (char *)ml_get_buf(buf, (linenr_T)lnum, false);
+      const char *bufline = ml_get_buf(buf, (linenr_T)lnum, false);
       old_byte += (bcount_t)(strlen(bufline)) + 1;
     }
     old_byte += (bcount_t)end_col + 1;
@@ -945,7 +949,7 @@ Integer nvim_buf_get_changedtick(Buffer buffer, Error *err)
 /// @param[out]  err   Error details, if any
 /// @returns Array of |maparg()|-like dictionaries describing mappings.
 ///          The "buffer" key holds the associated buffer handle.
-ArrayOf(Dictionary) nvim_buf_get_keymap(uint64_t channel_id, Buffer buffer, String mode, Error *err)
+ArrayOf(Dictionary) nvim_buf_get_keymap(Buffer buffer, String mode, Error *err)
   FUNC_API_SINCE(3)
 {
   buf_T *buf = find_buffer_by_handle(buffer, err);
@@ -954,7 +958,7 @@ ArrayOf(Dictionary) nvim_buf_get_keymap(uint64_t channel_id, Buffer buffer, Stri
     return (Array)ARRAY_DICT_INIT;
   }
 
-  return keymap_array(mode, buf, channel_id == LUA_INTERNAL_CALL);
+  return keymap_array(mode, buf);
 }
 
 /// Sets a buffer-local |mapping| for the given mode.
@@ -1021,7 +1025,7 @@ void nvim_buf_del_var(Buffer buffer, String name, Error *err)
 /// @param buffer     Buffer handle, or 0 for current buffer
 /// @param[out] err   Error details, if any
 /// @return Buffer name
-String nvim_buf_get_name(Buffer buffer, Error *err)
+String nvim_buf_get_name(Buffer buffer, Arena *arena, Error *err)
   FUNC_API_SINCE(1)
 {
   String rv = STRING_INIT;
@@ -1031,7 +1035,7 @@ String nvim_buf_get_name(Buffer buffer, Error *err)
     return rv;
   }
 
-  return cstr_to_string((char *)buf->b_ffname);
+  return cstr_as_string(buf->b_ffname);
 }
 
 /// Sets the full file name for a buffer
diff --git a/src/nvim/api/command.c b/src/nvim/api/command.c
index 1323fc347b..8cd2c0f8b8 100644
--- a/src/nvim/api/command.c
+++ b/src/nvim/api/command.c
@@ -31,14 +31,15 @@
 /// @param[out] err  Error details, if any.
 /// @return Dictionary containing command information, with these keys:
 ///         - cmd: (string) Command name.
-///         - range: (array) Command <range>. Can have 0-2 elements depending on how many items the
-///                          range contains. Has no elements if command doesn't accept a range or if
-///                          no range was specified, one element if only a single range item was
-///                          specified and two elements if both range items were specified.
-///         - count: (number) Any |<count>| that was supplied to the command. -1 if command cannot
-///                           take a count.
-///         - reg: (number) The optional command |<register>|, if specified. Empty string if not
-///                         specified or if command cannot take a register.
+///         - range: (array) (optional) Command range (|<line1>| |<line2>|).
+///                          Omitted if command doesn't accept a range.
+///                          Otherwise, has no elements if no range was specified, one element if
+///                          only a single range item was specified, or two elements if both range
+///                          items were specified.
+///         - count: (number) (optional) Command |<count>|.
+///                           Omitted if command cannot take a count.
+///         - reg: (string) (optional) Command |<register>|.
+///                         Omitted if command cannot take a register.
 ///         - bang: (boolean) Whether command contains a |<bang>| (!) modifier.
 ///         - args: (array) Command arguments.
 ///         - addr: (string) Value of |:command-addr|. Uses short name.
@@ -62,13 +63,14 @@
 ///             - browse: (boolean) |:browse|.
 ///             - confirm: (boolean) |:confirm|.
 ///             - hide: (boolean) |:hide|.
+///             - horizontal: (boolean) |:horizontal|.
 ///             - keepalt: (boolean) |:keepalt|.
 ///             - keepjumps: (boolean) |:keepjumps|.
 ///             - keepmarks: (boolean) |:keepmarks|.
 ///             - keeppatterns: (boolean) |:keeppatterns|.
 ///             - lockmarks: (boolean) |:lockmarks|.
 ///             - noswapfile: (boolean) |:noswapfile|.
-///             - tab: (integer) |:tab|.
+///             - tab: (integer) |:tab|. -1 when omitted.
 ///             - verbose: (integer) |:verbose|. -1 when omitted.
 ///             - vertical: (boolean) |:vertical|.
 ///             - split: (string) Split modifier string, is an empty string when there's no split
@@ -104,7 +106,7 @@ Dictionary nvim_parse_cmd(String str, Dictionary opts, Error *err)
 
   // Parse arguments
   Array args = ARRAY_DICT_INIT;
-  size_t length = STRLEN(ea.arg);
+  size_t length = strlen(ea.arg);
 
   // For nargs = 1 or '?', pass the entire argument list as a single argument,
   // otherwise split arguments by whitespace.
@@ -141,15 +143,15 @@ Dictionary nvim_parse_cmd(String str, Dictionary opts, Error *err)
     PUT(result, "cmd", CSTR_TO_OBJ((char *)get_command_name(NULL, ea.cmdidx)));
   }
 
-  if ((ea.argt & EX_RANGE) && ea.addr_count > 0) {
+  if (ea.argt & EX_RANGE) {
     Array range = ARRAY_DICT_INIT;
-    if (ea.addr_count > 1) {
-      ADD(range, INTEGER_OBJ(ea.line1));
+    if (ea.addr_count > 0) {
+      if (ea.addr_count > 1) {
+        ADD(range, INTEGER_OBJ(ea.line1));
+      }
+      ADD(range, INTEGER_OBJ(ea.line2));
     }
-    ADD(range, INTEGER_OBJ(ea.line2));
     PUT(result, "range", ARRAY_OBJ(range));
-  } else {
-    PUT(result, "range", ARRAY_OBJ(ARRAY_DICT_INIT));
   }
 
   if (ea.argt & EX_COUNT) {
@@ -160,14 +162,12 @@ Dictionary nvim_parse_cmd(String str, Dictionary opts, Error *err)
     } else {
       PUT(result, "count", INTEGER_OBJ(0));
     }
-  } else {
-    PUT(result, "count", INTEGER_OBJ(-1));
   }
 
-  char reg[2];
-  reg[0] = (char)ea.regname;
-  reg[1] = '\0';
-  PUT(result, "reg", CSTR_TO_OBJ(reg));
+  if (ea.argt & EX_REGSTR) {
+    char reg[2] = { (char)ea.regname, NUL };
+    PUT(result, "reg", CSTR_TO_OBJ(reg));
+  }
 
   PUT(result, "bang", BOOLEAN_OBJ(ea.forceit));
   PUT(result, "args", ARRAY_OBJ(args));
@@ -238,7 +238,7 @@ Dictionary nvim_parse_cmd(String str, Dictionary opts, Error *err)
   PUT(mods, "unsilent", BOOLEAN_OBJ(cmdinfo.cmdmod.cmod_flags & CMOD_UNSILENT));
   PUT(mods, "sandbox", BOOLEAN_OBJ(cmdinfo.cmdmod.cmod_flags & CMOD_SANDBOX));
   PUT(mods, "noautocmd", BOOLEAN_OBJ(cmdinfo.cmdmod.cmod_flags & CMOD_NOAUTOCMD));
-  PUT(mods, "tab", INTEGER_OBJ(cmdinfo.cmdmod.cmod_tab));
+  PUT(mods, "tab", INTEGER_OBJ(cmdinfo.cmdmod.cmod_tab - 1));
   PUT(mods, "verbose", INTEGER_OBJ(cmdinfo.cmdmod.cmod_verbose - 1));
   PUT(mods, "browse", BOOLEAN_OBJ(cmdinfo.cmdmod.cmod_flags & CMOD_BROWSE));
   PUT(mods, "confirm", BOOLEAN_OBJ(cmdinfo.cmdmod.cmod_flags & CMOD_CONFIRM));
@@ -250,6 +250,7 @@ Dictionary nvim_parse_cmd(String str, Dictionary opts, Error *err)
   PUT(mods, "lockmarks", BOOLEAN_OBJ(cmdinfo.cmdmod.cmod_flags & CMOD_LOCKMARKS));
   PUT(mods, "noswapfile", BOOLEAN_OBJ(cmdinfo.cmdmod.cmod_flags & CMOD_NOSWAPFILE));
   PUT(mods, "vertical", BOOLEAN_OBJ(cmdinfo.cmdmod.cmod_split & WSP_VERT));
+  PUT(mods, "horizontal", BOOLEAN_OBJ(cmdinfo.cmdmod.cmod_split & WSP_HOR));
 
   const char *split;
   if (cmdinfo.cmdmod.cmod_split & WSP_BOT) {
@@ -283,7 +284,11 @@ end:
 /// Unlike |nvim_command()| this command takes a structured Dictionary instead of a String. This
 /// allows for easier construction and manipulation of an Ex command. This also allows for things
 /// such as having spaces inside a command argument, expanding filenames in a command that otherwise
-/// doesn't expand filenames, etc.
+/// doesn't expand filenames, etc. Command arguments may also be Number, Boolean or String.
+///
+/// The first argument may also be used instead of count for commands that support it in order to
+/// make their usage simpler with |vim.cmd()|. For example, instead of
+/// `vim.cmd.bdelete{ count = 2 }`, you may do `vim.cmd.bdelete(2)`.
 ///
 /// On execution error: fails with VimL error, updates v:errmsg.
 ///
@@ -308,8 +313,7 @@ String nvim_cmd(uint64_t channel_id, Dict(cmd) *cmd, Dict(cmd_opts) *opts, Error
 
   char *cmdline = NULL;
   char *cmdname = NULL;
-  ArrayOf(String) args;
-  size_t argc = 0;
+  ArrayOf(String) args = ARRAY_DICT_INIT;
 
   String retv = (String)STRING_INIT;
 
@@ -381,48 +385,70 @@ String nvim_cmd(uint64_t channel_id, Dict(cmd) *cmd, Dict(cmd_opts) *opts, Error
     if (cmd->args.type != kObjectTypeArray) {
       VALIDATION_ERROR("'args' must be an Array");
     }
-    // Check if every argument is valid
+
+    // Process all arguments. Convert non-String arguments to String and check if String arguments
+    // have non-whitespace characters.
     for (size_t i = 0; i < cmd->args.data.array.size; i++) {
       Object elem = cmd->args.data.array.items[i];
-      if (elem.type != kObjectTypeString) {
-        VALIDATION_ERROR("Command argument must be a String");
-      } else if (string_iswhite(elem.data.string)) {
-        VALIDATION_ERROR("Command argument must have non-whitespace characters");
+      char *data_str;
+
+      switch (elem.type) {
+      case kObjectTypeBoolean:
+        data_str = xcalloc(2, sizeof(char));
+        data_str[0] = elem.data.boolean ? '1' : '0';
+        data_str[1] = '\0';
+        break;
+      case kObjectTypeBuffer:
+      case kObjectTypeWindow:
+      case kObjectTypeTabpage:
+      case kObjectTypeInteger:
+        data_str = xcalloc(NUMBUFLEN, sizeof(char));
+        snprintf(data_str, NUMBUFLEN, "%" PRId64, elem.data.integer);
+        break;
+      case kObjectTypeString:
+        if (string_iswhite(elem.data.string)) {
+          VALIDATION_ERROR("String command argument must have at least one non-whitespace "
+                           "character");
+        }
+        data_str = xstrndup(elem.data.string.data, elem.data.string.size);
+        break;
+      default:
+        VALIDATION_ERROR("Invalid type for command argument");
+        break;
       }
+
+      ADD(args, STRING_OBJ(cstr_as_string(data_str)));
     }
 
-    argc = cmd->args.data.array.size;
     bool argc_valid;
 
     // Check if correct number of arguments is used.
     switch (ea.argt & (EX_EXTRA | EX_NOSPC | EX_NEEDARG)) {
     case EX_EXTRA | EX_NOSPC | EX_NEEDARG:
-      argc_valid = argc == 1;
+      argc_valid = args.size == 1;
       break;
     case EX_EXTRA | EX_NOSPC:
-      argc_valid = argc <= 1;
+      argc_valid = args.size <= 1;
       break;
     case EX_EXTRA | EX_NEEDARG:
-      argc_valid = argc >= 1;
+      argc_valid = args.size >= 1;
       break;
     case EX_EXTRA:
       argc_valid = true;
       break;
     default:
-      argc_valid = argc == 0;
+      argc_valid = args.size == 0;
       break;
     }
 
     if (!argc_valid) {
       VALIDATION_ERROR("Incorrect number of arguments supplied");
     }
-
-    args = cmd->args.data.array;
   }
 
   // Simply pass the first argument (if it exists) as the arg pointer to `set_cmd_addr_type()`
   // since it only ever checks the first argument.
-  set_cmd_addr_type(&ea, argc > 0 ? args.items[0].data.string.data : NULL);
+  set_cmd_addr_type(&ea, args.size > 0 ? args.items[0].data.string.data : NULL);
 
   if (HAS_KEY(cmd->range)) {
     if (!(ea.argt & EX_RANGE)) {
@@ -557,15 +583,17 @@ String nvim_cmd(uint64_t channel_id, Dict(cmd) *cmd, Dict(cmd_opts) *opts, Error
     }
 
     if (HAS_KEY(mods.tab)) {
-      if (mods.tab.type != kObjectTypeInteger || mods.tab.data.integer < 0) {
-        VALIDATION_ERROR("'mods.tab' must be a non-negative Integer");
+      if (mods.tab.type != kObjectTypeInteger) {
+        VALIDATION_ERROR("'mods.tab' must be an Integer");
+      } else if ((int)mods.tab.data.integer >= 0) {
+        // Silently ignore negative integers to allow mods.tab to be set to -1.
+        cmdinfo.cmdmod.cmod_tab = (int)mods.tab.data.integer + 1;
       }
-      cmdinfo.cmdmod.cmod_tab = (int)mods.tab.data.integer + 1;
     }
 
     if (HAS_KEY(mods.verbose)) {
       if (mods.verbose.type != kObjectTypeInteger) {
-        VALIDATION_ERROR("'mods.verbose' must be a Integer");
+        VALIDATION_ERROR("'mods.verbose' must be an Integer");
       } else if ((int)mods.verbose.data.integer >= 0) {
         // Silently ignore negative integers to allow mods.verbose to be set to -1.
         cmdinfo.cmdmod.cmod_verbose = (int)mods.verbose.data.integer + 1;
@@ -576,6 +604,10 @@ String nvim_cmd(uint64_t channel_id, Dict(cmd) *cmd, Dict(cmd_opts) *opts, Error
     OBJ_TO_BOOL(vertical, mods.vertical, false, "'mods.vertical'");
     cmdinfo.cmdmod.cmod_split |= (vertical ? WSP_VERT : 0);
 
+    bool horizontal;
+    OBJ_TO_BOOL(horizontal, mods.horizontal, false, "'mods.horizontal'");
+    cmdinfo.cmdmod.cmod_split |= (horizontal ? WSP_HOR : 0);
+
     if (HAS_KEY(mods.split)) {
       if (mods.split.type != kObjectTypeString) {
         VALIDATION_ERROR("'mods.split' must be a String");
@@ -583,15 +615,15 @@ String nvim_cmd(uint64_t channel_id, Dict(cmd) *cmd, Dict(cmd_opts) *opts, Error
 
       if (*mods.split.data.string.data == NUL) {
         // Empty string, do nothing.
-      } else if (STRCMP(mods.split.data.string.data, "aboveleft") == 0
-                 || STRCMP(mods.split.data.string.data, "leftabove") == 0) {
+      } else if (strcmp(mods.split.data.string.data, "aboveleft") == 0
+                 || strcmp(mods.split.data.string.data, "leftabove") == 0) {
         cmdinfo.cmdmod.cmod_split |= WSP_ABOVE;
-      } else if (STRCMP(mods.split.data.string.data, "belowright") == 0
-                 || STRCMP(mods.split.data.string.data, "rightbelow") == 0) {
+      } else if (strcmp(mods.split.data.string.data, "belowright") == 0
+                 || strcmp(mods.split.data.string.data, "rightbelow") == 0) {
         cmdinfo.cmdmod.cmod_split |= WSP_BELOW;
-      } else if (STRCMP(mods.split.data.string.data, "topleft") == 0) {
+      } else if (strcmp(mods.split.data.string.data, "topleft") == 0) {
         cmdinfo.cmdmod.cmod_split |= WSP_TOP;
-      } else if (STRCMP(mods.split.data.string.data, "botright") == 0) {
+      } else if (strcmp(mods.split.data.string.data, "botright") == 0) {
         cmdinfo.cmdmod.cmod_split |= WSP_BOT;
       } else {
         VALIDATION_ERROR("Invalid value for 'mods.split'");
@@ -620,7 +652,7 @@ String nvim_cmd(uint64_t channel_id, Dict(cmd) *cmd, Dict(cmd_opts) *opts, Error
 
   // Finally, build the command line string that will be stored inside ea.cmdlinep.
   // This also sets the values of ea.cmd, ea.arg, ea.args and ea.arglens.
-  build_cmdline_str(&cmdline, &ea, &cmdinfo, args, argc);
+  build_cmdline_str(&cmdline, &ea, &cmdinfo, args);
   ea.cmdlinep = &cmdline;
 
   garray_T capture_local;
@@ -676,6 +708,7 @@ clear_ga:
     ga_clear(&capture_local);
   }
 end:
+  api_free_array(args);
   xfree(cmdline);
   xfree(cmdname);
   xfree(ea.args);
@@ -705,8 +738,9 @@ static bool string_iswhite(String str)
 
 /// Build cmdline string for command, used by `nvim_cmd()`.
 static void build_cmdline_str(char **cmdlinep, exarg_T *eap, CmdParseInfo *cmdinfo,
-                              ArrayOf(String) args, size_t argc)
+                              ArrayOf(String) args)
 {
+  size_t argc = args.size;
   StringBuilder cmdline = KV_INITIAL_VALUE;
   kv_resize(cmdline, 32);  // Make it big enough to handle most typical commands
 
@@ -753,6 +787,7 @@ static void build_cmdline_str(char **cmdlinep, exarg_T *eap, CmdParseInfo *cmdin
   } while (0)
 
   CMDLINE_APPEND_IF(cmdinfo->cmdmod.cmod_split & WSP_VERT, "vertical ");
+  CMDLINE_APPEND_IF(cmdinfo->cmdmod.cmod_split & WSP_HOR, "horizontal ");
   CMDLINE_APPEND_IF(cmdinfo->cmdmod.cmod_flags & CMOD_SANDBOX, "sandbox ");
   CMDLINE_APPEND_IF(cmdinfo->cmdmod.cmod_flags & CMOD_NOAUTOCMD, "noautocmd ");
   CMDLINE_APPEND_IF(cmdinfo->cmdmod.cmod_flags & CMOD_BROWSE, "browse ");
@@ -791,7 +826,7 @@ static void build_cmdline_str(char **cmdlinep, exarg_T *eap, CmdParseInfo *cmdin
   }
 
   eap->argc = argc;
-  eap->arglens = xcalloc(argc, sizeof(size_t));
+  eap->arglens = eap->argc > 0 ? xcalloc(argc, sizeof(size_t)) : NULL;
   size_t argstart_idx = cmdline.size;
   for (size_t i = 0; i < argc; i++) {
     String s = args.items[i].data.string;
@@ -806,7 +841,7 @@ static void build_cmdline_str(char **cmdlinep, exarg_T *eap, CmdParseInfo *cmdin
   // Now that all the arguments are appended, use the command index and argument indices to set the
   // values of eap->cmd, eap->arg and eap->args.
   eap->cmd = cmdline.items + cmdname_idx;
-  eap->args = xcalloc(argc, sizeof(char *));
+  eap->args = eap->argc > 0 ? xcalloc(argc, sizeof(char *)) : NULL;
   size_t offset = argstart_idx;
   for (size_t i = 0; i < argc; i++) {
     offset++;  // Account for space
@@ -823,13 +858,12 @@ static void build_cmdline_str(char **cmdlinep, exarg_T *eap, CmdParseInfo *cmdin
   // Replace, :make and :grep with 'makeprg' and 'grepprg'.
   char *p = replace_makeprg(eap, eap->arg, cmdlinep);
   if (p != eap->arg) {
-    // If replace_makeprg modified the cmdline string, correct the argument pointers.
+    // If replace_makeprg() modified the cmdline string, correct the eap->arg pointer.
     eap->arg = p;
-    // We can only know the position of the first argument because the argument list can be used
-    // multiple times in makeprg / grepprg.
-    if (argc >= 1) {
-      eap->args[0] = p;
-    }
+    // This cannot be a user command, so eap->args will not be used.
+    XFREE_CLEAR(eap->args);
+    XFREE_CLEAR(eap->arglens);
+    eap->argc = 0;
   }
 }
 
@@ -929,7 +963,7 @@ void nvim_buf_del_user_command(Buffer buffer, String name, Error *err)
 
   for (int i = 0; i < gap->ga_len; i++) {
     ucmd_T *cmd = USER_CMD_GA(gap, i);
-    if (!STRCMP(name.data, cmd->uc_name)) {
+    if (!strcmp(name.data, cmd->uc_name)) {
       free_ucmd(cmd);
 
       gap->ga_len -= 1;
diff --git a/src/nvim/api/extmark.c b/src/nvim/api/extmark.c
index 933aa85530..3b1b470629 100644
--- a/src/nvim/api/extmark.c
+++ b/src/nvim/api/extmark.c
@@ -51,7 +51,7 @@ Integer nvim_create_namespace(String name)
   }
   id = next_namespace_id++;
   if (name.size > 0) {
-    String name_alloc = copy_string(name);
+    String name_alloc = copy_string(name, NULL);
     map_put(String, handle_T)(&namespace_ids, name_alloc, id);
   }
   return (Integer)id;
@@ -87,7 +87,7 @@ const char *describe_ns(NS ns_id)
 }
 
 // Is the Namespace in use?
-static bool ns_initialized(uint32_t ns)
+bool ns_initialized(uint32_t ns)
 {
   if (ns < 1) {
     return false;
@@ -389,11 +389,11 @@ Array nvim_buf_get_extmarks(Buffer buffer, Integer ns_id, Object start, Object e
 ///               - virt_text : virtual text to link to this mark.
 ///                   A list of [text, highlight] tuples, each representing a
 ///                   text chunk with specified highlight. `highlight` element
-///                   can either be a a single highlight group, or an array of
+///                   can either be a single highlight group, or an array of
 ///                   multiple highlight groups that will be stacked
 ///                   (highest priority last). A highlight group can be supplied
 ///                   either as a string or as an integer, the latter which
-///                   can be obtained using |nvim_get_hl_id_by_name|.
+///                   can be obtained using |nvim_get_hl_id_by_name()|.
 ///               - virt_text_pos : position of virtual text. Possible values:
 ///                 - "eol": right after eol character (default)
 ///                 - "overlay": display over the specified column, without
@@ -430,7 +430,7 @@ Array nvim_buf_get_extmarks(Buffer buffer, Integer ns_id, Object start, Object e
 ///                                     column of the window, bypassing
 ///                                     sign and number columns.
 ///
-///               - ephemeral : for use with |nvim_set_decoration_provider|
+///               - ephemeral : for use with |nvim_set_decoration_provider()|
 ///                   callbacks. The mark will only be used for the current
 ///                   redraw cycle, and not be permantently stored in the
 ///                   buffer.
@@ -473,6 +473,8 @@ Array nvim_buf_get_extmarks(Buffer buffer, Integer ns_id, Object start, Object e
 ///                   When a character is supplied it is used as |:syn-cchar|.
 ///                   "hl_group" is used as highlight for the cchar if provided,
 ///                   otherwise it defaults to |hl-Conceal|.
+///               - spell: boolean indicating that spell checking should be
+///                   performed within this extmark
 ///               - ui_watched: boolean that indicates the mark should be drawn
 ///                   by a UI. When set, the UI will receive win_extmark events.
 ///                   Note: the mark is positioned by virt_text attributes. Can be
@@ -719,6 +721,11 @@ Integer nvim_buf_set_extmark(Buffer buffer, Integer ns_id, Integer line, Integer
   bool ephemeral = false;
   OPTION_TO_BOOL(ephemeral, ephemeral, false);
 
+  OPTION_TO_BOOL(decor.spell, spell, false);
+  if (decor.spell) {
+    has_decor = true;
+  }
+
   OPTION_TO_BOOL(decor.ui_watched, ui_watched, false);
   if (decor.ui_watched) {
     has_decor = true;
@@ -735,7 +742,7 @@ Integer nvim_buf_set_extmark(Buffer buffer, Integer ns_id, Integer line, Integer
       line = buf->b_ml.ml_line_count;
     }
   } else if (line < buf->b_ml.ml_line_count) {
-    len = ephemeral ? MAXCOL : STRLEN(ml_get_buf(buf, (linenr_T)line + 1, false));
+    len = ephemeral ? MAXCOL : strlen(ml_get_buf(buf, (linenr_T)line + 1, false));
   }
 
   if (col == -1) {
@@ -754,7 +761,7 @@ Integer nvim_buf_set_extmark(Buffer buffer, Integer ns_id, Integer line, Integer
 
   if (col2 >= 0) {
     if (line2 >= 0 && line2 < buf->b_ml.ml_line_count) {
-      len = ephemeral ? MAXCOL : STRLEN(ml_get_buf(buf, (linenr_T)line2 + 1, false));
+      len = ephemeral ? MAXCOL : strlen(ml_get_buf(buf, (linenr_T)line2 + 1, false));
     } else if (line2 == buf->b_ml.ml_line_count) {
       // We are trying to add an extmark past final newline
       len = 0;
@@ -951,7 +958,7 @@ void nvim_buf_clear_namespace(Buffer buffer, Integer ns_id, Integer line_start,
 /// being triggered during the redraw code.
 ///
 /// The expected usage is to set extmarks for the currently
-/// redrawn buffer. |nvim_buf_set_extmark| can be called to add marks
+/// redrawn buffer. |nvim_buf_set_extmark()| can be called to add marks
 /// on a per-window or per-lines basis. Use the `ephemeral` key to only
 /// use the mark for the current screen redraw (the callback will be called
 /// again for the next redraw ).
@@ -972,20 +979,21 @@ void nvim_buf_clear_namespace(Buffer buffer, Integer ns_id, Integer line_start,
 /// for the moment.
 ///
 /// @param ns_id  Namespace id from |nvim_create_namespace()|
-/// @param opts   Callbacks invoked during redraw:
+/// @param opts  Table of callbacks:
 ///             - on_start: called first on each screen redraw
 ///                 ["start", tick]
-///             - on_buf: called for each buffer being redrawn (before window
-///                 callbacks)
+///             - on_buf: called for each buffer being redrawn (before
+///                 window callbacks)
 ///                 ["buf", bufnr, tick]
-///             - on_win: called when starting to redraw a specific window.
+///             - on_win: called when starting to redraw a
+///                 specific window.
 ///                 ["win", winid, bufnr, topline, botline_guess]
-///             - on_line: called for each buffer line being redrawn. (The
-///                 interaction with fold lines is subject to change)
+///             - on_line: called for each buffer line being redrawn.
+///                 (The interaction with fold lines is subject to change)
 ///                 ["win", winid, bufnr, row]
 ///             - on_end: called at the end of a redraw cycle
 ///                 ["end", tick]
-void nvim_set_decoration_provider(Integer ns_id, DictionaryOf(LuaRef) opts, Error *err)
+void nvim_set_decoration_provider(Integer ns_id, Dict(set_decoration_provider) *opts, Error *err)
   FUNC_API_SINCE(7) FUNC_API_LUA_ONLY
 {
   DecorProvider *p = get_decor_provider((NS)ns_id, true);
@@ -993,41 +1001,36 @@ void nvim_set_decoration_provider(Integer ns_id, DictionaryOf(LuaRef) opts, Erro
   decor_provider_clear(p);
 
   // regardless of what happens, it seems good idea to redraw
-  redraw_all_later(NOT_VALID);  // TODO(bfredl): too soon?
+  redraw_all_later(UPD_NOT_VALID);  // TODO(bfredl): too soon?
 
   struct {
     const char *name;
+    Object *source;
     LuaRef *dest;
   } cbs[] = {
-    { "on_start", &p->redraw_start },
-    { "on_buf", &p->redraw_buf },
-    { "on_win", &p->redraw_win },
-    { "on_line", &p->redraw_line },
-    { "on_end", &p->redraw_end },
-    { "_on_hl_def", &p->hl_def },
-    { NULL, NULL },
+    { "on_start", &opts->on_start, &p->redraw_start },
+    { "on_buf", &opts->on_buf, &p->redraw_buf },
+    { "on_win", &opts->on_win, &p->redraw_win },
+    { "on_line", &opts->on_line, &p->redraw_line },
+    { "on_end", &opts->on_end, &p->redraw_end },
+    { "_on_hl_def", &opts->_on_hl_def, &p->hl_def },
+    { "_on_spell_nav", &opts->_on_spell_nav, &p->spell_nav },
+    { NULL, NULL, NULL },
   };
 
-  for (size_t i = 0; i < opts.size; i++) {
-    String k = opts.items[i].key;
-    Object *v = &opts.items[i].value;
-    size_t j;
-    for (j = 0; cbs[j].name && cbs[j].dest; j++) {
-      if (strequal(cbs[j].name, k.data)) {
-        if (v->type != kObjectTypeLuaRef) {
-          api_set_error(err, kErrorTypeValidation,
-                        "%s is not a function", cbs[j].name);
-          goto error;
-        }
-        *(cbs[j].dest) = v->data.luaref;
-        v->data.luaref = LUA_NOREF;
-        break;
-      }
+  for (size_t i = 0; cbs[i].source && cbs[i].dest && cbs[i].name; i++) {
+    Object *v = cbs[i].source;
+    if (v->type == kObjectTypeNil) {
+      continue;
     }
-    if (!cbs[j].name) {
-      api_set_error(err, kErrorTypeValidation, "unexpected key: %s", k.data);
+
+    if (v->type != kObjectTypeLuaRef) {
+      api_set_error(err, kErrorTypeValidation,
+                    "%s is not a function", cbs[i].name);
       goto error;
     }
+    *(cbs[i].dest) = v->data.luaref;
+    v->data.luaref = LUA_NOREF;
   }
 
   p->active = true;
@@ -1103,7 +1106,7 @@ static int init_sign_text(char **sign_text, char *text)
 {
   char *s;
 
-  char *endp = text + (int)STRLEN(text);
+  char *endp = text + (int)strlen(text);
 
   // Count cells and check for non-printable chars
   int cells = 0;
diff --git a/src/nvim/api/keysets.lua b/src/nvim/api/keysets.lua
index 32104ef6dc..d9d9c7ee1d 100644
--- a/src/nvim/api/keysets.lua
+++ b/src/nvim/api/keysets.lua
@@ -2,6 +2,15 @@ return {
   context = {
     "types";
   };
+  set_decoration_provider = {
+    "on_start";
+    "on_buf";
+    "on_win";
+    "on_line";
+    "on_end";
+    "_on_hl_def";
+    "_on_spell_nav";
+  };
   set_extmark = {
     "id";
     "end_line";
@@ -28,6 +37,7 @@ return {
     "line_hl_group";
     "cursorline_hl_group";
     "conceal";
+    "spell";
     "ui_watched";
   };
   keymap = {
@@ -190,6 +200,7 @@ return {
     "browse";
     "confirm";
     "hide";
+    "horizontal";
     "keepalt";
     "keepjumps";
     "keepmarks";
diff --git a/src/nvim/api/options.c b/src/nvim/api/options.c
index 867584dd71..ec1f19cf6a 100644
--- a/src/nvim/api/options.c
+++ b/src/nvim/api/options.c
@@ -147,7 +147,7 @@ Object nvim_get_option_value(String name, Dict(option) *opts, Error *err)
 /// @param name      Option name
 /// @param value     New option value
 /// @param opts      Optional parameters
-///                  - scope: One of 'global' or 'local'. Analogous to
+///                  - scope: One of "global" or "local". Analogous to
 ///                  |:setglobal| and |:setlocal|, respectively.
 ///                  - win: |window-ID|. Used for setting window local option.
 ///                  - buf: Buffer number. Used for setting buffer local option.
@@ -202,7 +202,7 @@ void nvim_set_option_value(String name, Object value, Dict(option) *opts, Error
 /// Gets the option information for all options.
 ///
 /// The dictionary has the full option names as keys and option metadata
-/// dictionaries as detailed at |nvim_get_option_info|.
+/// dictionaries as detailed at |nvim_get_option_info()|.
 ///
 /// @return dictionary of all options
 Dictionary nvim_get_all_options_info(Error *err)
diff --git a/src/nvim/api/private/converter.c b/src/nvim/api/private/converter.c
index 8724ef4432..b6b3c83f3c 100644
--- a/src/nvim/api/private/converter.c
+++ b/src/nvim/api/private/converter.c
@@ -65,8 +65,8 @@ typedef struct {
 #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) { \
-      LuaRef ref = api_new_luaref(((LuaCFunctionState *)fp->uf_cb_state)->lua_callable.func_ref); \
+    if (fp != NULL && (fp->uf_flags & FC_LUAREF)) { \
+      LuaRef ref = api_new_luaref(fp->uf_luaref); \
       kvi_push(edata->stack, LUAREF_OBJ(ref)); \
     } else { \
       TYPVAL_ENCODE_CONV_NIL(tv); \
@@ -351,10 +351,7 @@ bool object_to_vim(Object obj, typval_T *tv, Error *err)
   }
 
   case kObjectTypeLuaRef: {
-    LuaCFunctionState *state = xmalloc(sizeof(LuaCFunctionState));
-    state->lua_callable.func_ref = api_new_luaref(obj.data.luaref);
-    char *name =
-      (char *)register_cfunc(&nlua_CFunction_func_call, &nlua_CFunction_func_free, state);
+    char *name = (char *)register_luafunc(api_new_luaref(obj.data.luaref));
     tv->v_type = VAR_FUNC;
     tv->vval.v_string = xstrdup(name);
     break;
diff --git a/src/nvim/api/private/defs.h b/src/nvim/api/private/defs.h
index 9c7e59e4b3..2ae3ee6c7c 100644
--- a/src/nvim/api/private/defs.h
+++ b/src/nvim/api/private/defs.h
@@ -5,8 +5,8 @@
 #include <stdint.h>
 #include <string.h>
 
+#include "klib/kvec.h"
 #include "nvim/func_attr.h"
-#include "nvim/lib/kvec.h"
 #include "nvim/types.h"
 
 #define ARRAY_DICT_INIT KV_INITIAL_VALUE
diff --git a/src/nvim/api/private/dispatch.h b/src/nvim/api/private/dispatch.h
index 4b7c394944..f92b205531 100644
--- a/src/nvim/api/private/dispatch.h
+++ b/src/nvim/api/private/dispatch.h
@@ -5,18 +5,23 @@
 
 typedef Object (*ApiDispatchWrapper)(uint64_t channel_id,
                                      Array args,
+                                     Arena *arena,
                                      Error *error);
 
 /// The rpc_method_handlers table, used in msgpack_rpc_dispatch(), stores
 /// functions of this type.
-typedef struct {
+struct MsgpackRpcRequestHandler {
   const char *name;
   ApiDispatchWrapper fn;
   bool fast;  // Function is safe to be executed immediately while running the
               // uv loop (the loop is run very frequently due to breakcheck).
               // If "fast" is false, the function is deferred, i e the call will
               // be put in the event queue, for safe handling later.
-} MsgpackRpcRequestHandler;
+  bool arena_return;  // return value is allocated in the arena (or statically)
+                      // and should not be freed as such.
+};
+
+extern const MsgpackRpcRequestHandler method_handlers[];
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "api/private/dispatch.h.generated.h"
diff --git a/src/nvim/api/private/helpers.c b/src/nvim/api/private/helpers.c
index c466fc53e1..73b5489d5c 100644
--- a/src/nvim/api/private/helpers.c
+++ b/src/nvim/api/private/helpers.c
@@ -8,6 +8,7 @@
 #include <stdlib.h>
 #include <string.h>
 
+#include "klib/kvec.h"
 #include "nvim/api/private/converter.h"
 #include "nvim/api/private/defs.h"
 #include "nvim/api/private/helpers.h"
@@ -22,7 +23,6 @@
 #include "nvim/ex_eval.h"
 #include "nvim/extmark.h"
 #include "nvim/highlight_group.h"
-#include "nvim/lib/kvec.h"
 #include "nvim/lua/executor.h"
 #include "nvim/map.h"
 #include "nvim/map_defs.h"
@@ -58,6 +58,7 @@ void try_enter(TryState *const tstate)
     .private_msg_list = NULL,
     .trylevel = trylevel,
     .got_int = got_int,
+    .did_throw = did_throw,
     .need_rethrow = need_rethrow,
     .did_emsg = did_emsg,
   };
@@ -65,6 +66,7 @@ void try_enter(TryState *const tstate)
   current_exception = NULL;
   trylevel = 1;
   got_int = false;
+  did_throw = false;
   need_rethrow = false;
   did_emsg = false;
 }
@@ -85,6 +87,7 @@ bool try_leave(const TryState *const tstate, Error *const err)
   assert(trylevel == 0);
   assert(!need_rethrow);
   assert(!got_int);
+  assert(!did_throw);
   assert(!did_emsg);
   assert(msg_list == &tstate->private_msg_list);
   assert(*msg_list == NULL);
@@ -93,6 +96,7 @@ bool try_leave(const TryState *const tstate, Error *const err)
   current_exception = tstate->current_exception;
   trylevel = tstate->trylevel;
   got_int = tstate->got_int;
+  did_throw = tstate->did_throw;
   need_rethrow = tstate->need_rethrow;
   did_emsg = tstate->did_emsg;
   return ret;
@@ -127,7 +131,7 @@ bool try_end(Error *err)
   force_abort = false;
 
   if (got_int) {
-    if (current_exception) {
+    if (did_throw) {
       // If we got an interrupt, discard the current exception
       discard_current_exception();
     }
@@ -146,7 +150,7 @@ bool try_end(Error *err)
     if (should_free) {
       xfree(msg);
     }
-  } else if (current_exception) {
+  } else if (did_throw) {
     api_set_error(err, kErrorTypeException, "%s", current_exception->value);
     discard_current_exception();
   }
@@ -214,6 +218,8 @@ Object dict_set_var(dict_T *dict, String key, Object value, bool del, bool retva
     return rv;
   }
 
+  bool watched = tv_dict_is_watched(dict);
+
   if (del) {
     // Delete the key
     if (di == NULL) {
@@ -221,6 +227,10 @@ Object dict_set_var(dict_T *dict, String key, Object value, bool del, bool retva
       api_set_error(err, kErrorTypeValidation, "Key not found: %s",
                     key.data);
     } else {
+      // Notify watchers
+      if (watched) {
+        tv_dict_watcher_notify(dict, key.data, NULL, &di->di_tv);
+      }
       // Return the old value
       if (retval) {
         rv = vim_to_object(&di->di_tv);
@@ -237,11 +247,16 @@ Object dict_set_var(dict_T *dict, String key, Object value, bool del, bool retva
       return rv;
     }
 
+    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);
+      }
       // Return the old value
       if (retval) {
         rv = vim_to_object(&di->di_tv);
@@ -251,6 +266,13 @@ Object dict_set_var(dict_T *dict, String key, Object value, bool del, bool retva
 
     // 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);
   }
@@ -462,7 +484,7 @@ bool buf_collect_lines(buf_T *buf, size_t n, int64_t start, bool replace_nl, Arr
       return false;
     }
 
-    const char *bufstr = (char *)ml_get_buf(buf, (linenr_T)lnum, false);
+    const char *bufstr = ml_get_buf(buf, (linenr_T)lnum, false);
     Object str = STRING_OBJ(cstr_to_string(bufstr));
 
     if (replace_nl) {
@@ -495,7 +517,7 @@ String buf_get_text(buf_T *buf, int64_t lnum, int64_t start_col, int64_t end_col
     return rv;
   }
 
-  const char *bufstr = (char *)ml_get_buf(buf, (linenr_T)lnum, false);
+  const char *bufstr = ml_get_buf(buf, (linenr_T)lnum, false);
   size_t line_length = strlen(bufstr);
 
   start_col = start_col < 0 ? (int64_t)line_length + start_col + 1 : start_col;
@@ -618,6 +640,7 @@ void api_clear_error(Error *value)
   value->type = kErrorTypeNone;
 }
 
+/// @returns a shared value. caller must not modify it!
 Dictionary api_metadata(void)
 {
   static Dictionary metadata = ARRAY_DICT_INIT;
@@ -630,7 +653,7 @@ Dictionary api_metadata(void)
     init_type_metadata(&metadata);
   }
 
-  return copy_object(DICTIONARY_OBJ(metadata)).data.dictionary;
+  return metadata;
 }
 
 static void init_function_metadata(Dictionary *metadata)
@@ -715,36 +738,40 @@ static void init_type_metadata(Dictionary *metadata)
   PUT(*metadata, "types", DICTIONARY_OBJ(types));
 }
 
-String copy_string(String str)
+// all the copy_[object] functions allow arena=NULL,
+// then global allocations are used, and the resulting object
+// should be freed with an api_free_[object] function
+
+String copy_string(String str, Arena *arena)
 {
   if (str.data != NULL) {
-    return (String){ .data = xmemdupz(str.data, str.size), .size = str.size };
+    return (String){ .data = arena_memdupz(arena, str.data, str.size), .size = str.size };
   } else {
     return (String)STRING_INIT;
   }
 }
 
-Array copy_array(Array array)
+Array copy_array(Array array, Arena *arena)
 {
-  Array rv = ARRAY_DICT_INIT;
+  Array rv = arena_array(arena, array.size);
   for (size_t i = 0; i < array.size; i++) {
-    ADD(rv, copy_object(array.items[i]));
+    ADD(rv, copy_object(array.items[i], arena));
   }
   return rv;
 }
 
-Dictionary copy_dictionary(Dictionary dict)
+Dictionary copy_dictionary(Dictionary dict, Arena *arena)
 {
-  Dictionary rv = ARRAY_DICT_INIT;
+  Dictionary rv = arena_dict(arena, dict.size);
   for (size_t i = 0; i < dict.size; i++) {
     KeyValuePair item = dict.items[i];
-    PUT(rv, item.key.data, copy_object(item.value));
+    PUT_C(rv, copy_string(item.key, arena).data, copy_object(item.value, arena));
   }
   return rv;
 }
 
 /// Creates a deep clone of an object
-Object copy_object(Object obj)
+Object copy_object(Object obj, Arena *arena)
 {
   switch (obj.type) {
   case kObjectTypeBuffer:
@@ -757,13 +784,13 @@ Object copy_object(Object obj)
     return obj;
 
   case kObjectTypeString:
-    return STRING_OBJ(copy_string(obj.data.string));
+    return STRING_OBJ(copy_string(obj.data.string, arena));
 
   case kObjectTypeArray:
-    return ARRAY_OBJ(copy_array(obj.data.array));
+    return ARRAY_OBJ(copy_array(obj.data.array, arena));
 
   case kObjectTypeDictionary:
-    return DICTIONARY_OBJ(copy_dictionary(obj.data.dictionary));
+    return DICTIONARY_OBJ(copy_dictionary(obj.data.dictionary, arena));
 
   case kObjectTypeLuaRef:
     return LUAREF_OBJ(api_new_luaref(obj.data.luaref));
@@ -844,7 +871,7 @@ HlMessage parse_hl_msg(Array chunks, Error *err)
       goto free_exit;
     }
 
-    String str = copy_string(chunk.items[0].data.string);
+    String str = copy_string(chunk.items[0].data.string, NULL);
 
     int attr = 0;
     if (chunk.size == 2) {
diff --git a/src/nvim/api/private/helpers.h b/src/nvim/api/private/helpers.h
index 4608554448..65215fa8c8 100644
--- a/src/nvim/api/private/helpers.h
+++ b/src/nvim/api/private/helpers.h
@@ -1,11 +1,11 @@
 #ifndef NVIM_API_PRIVATE_HELPERS_H
 #define NVIM_API_PRIVATE_HELPERS_H
 
+#include "klib/kvec.h"
 #include "nvim/api/private/defs.h"
 #include "nvim/decoration.h"
 #include "nvim/ex_eval_defs.h"
 #include "nvim/getchar.h"
-#include "nvim/lib/kvec.h"
 #include "nvim/memory.h"
 #include "nvim/vim.h"
 
@@ -134,6 +134,7 @@ typedef struct {
   const msglist_T *const *msg_list;
   int trylevel;
   int got_int;
+  bool did_throw;
   int need_rethrow;
   int did_emsg;
 } TryState;
diff --git a/src/nvim/api/ui.c b/src/nvim/api/ui.c
index 6f7bfa244a..e6d8cb2fdb 100644
--- a/src/nvim/api/ui.c
+++ b/src/nvim/api/ui.c
@@ -122,7 +122,7 @@ static char *mpack_array_dyn16(char **buf)
 static void mpack_str(char **buf, const char *str)
 {
   assert(sizeof(schar_T) - 1 < 0x20);
-  size_t len = STRLEN(str);
+  size_t len = strlen(str);
   mpack_w(buf, 0xa0 | len);
   memcpy(*buf, str, len);
   *buf += len;
@@ -223,6 +223,7 @@ void nvim_ui_attach(uint64_t channel_id, Integer width, Integer height, Dictiona
   ui->msg_set_pos = remote_ui_msg_set_pos;
   ui->event = remote_ui_event;
   ui->inspect = remote_ui_inspect;
+  ui->win_viewport = remote_ui_win_viewport;
 
   CLEAR_FIELD(ui->ui_ext);
 
@@ -452,7 +453,7 @@ void nvim_ui_try_resize_grid(uint64_t channel_id, Integer grid, Integer width, I
   }
 }
 
-/// Tells Nvim the number of elements displaying in the popumenu, to decide
+/// Tells Nvim the number of elements displaying in the popupmenu, to decide
 /// <PageUp> and <PageDown> movement.
 ///
 /// @param channel_id
@@ -482,7 +483,7 @@ void nvim_ui_pum_set_height(uint64_t channel_id, Integer height, Error *err)
   ui->pum_nlines = (int)height;
 }
 
-/// Tells Nvim the geometry of the popumenu, to align floating windows with an
+/// Tells Nvim the geometry of the popupmenu, to align floating windows with an
 /// external popup menu.
 ///
 /// Note that this method is not to be confused with |nvim_ui_pum_set_height()|,
@@ -748,10 +749,12 @@ static void remote_ui_hl_attr_define(UI *ui, Integer id, HlAttrs rgb_attrs, HlAt
   UIData *data = ui->data;
   Array args = data->call_buf;
   ADD_C(args, INTEGER_OBJ(id));
-  MAXSIZE_TEMP_DICT(rgb, 16);
-  MAXSIZE_TEMP_DICT(cterm, 16);
-  ADD_C(args, DICTIONARY_OBJ(hlattrs2dict(&rgb, rgb_attrs, true)));
-  ADD_C(args, DICTIONARY_OBJ(hlattrs2dict(&cterm, cterm_attrs, false)));
+  MAXSIZE_TEMP_DICT(rgb, HLATTRS_DICT_SIZE);
+  MAXSIZE_TEMP_DICT(cterm, HLATTRS_DICT_SIZE);
+  hlattrs2dict(&rgb, rgb_attrs, true);
+  hlattrs2dict(&cterm, rgb_attrs, false);
+  ADD_C(args, DICTIONARY_OBJ(rgb));
+  ADD_C(args, DICTIONARY_OBJ(cterm));
 
   if (ui->ui_ext[kUIHlState]) {
     ADD_C(args, ARRAY_OBJ(info));
@@ -771,8 +774,9 @@ static void remote_ui_highlight_set(UI *ui, int id)
     return;
   }
   data->hl_id = id;
-  MAXSIZE_TEMP_DICT(dict, 16);
-  ADD_C(args, DICTIONARY_OBJ(hlattrs2dict(&dict, syn_attr2entry(id), ui->rgb)));
+  MAXSIZE_TEMP_DICT(dict, HLATTRS_DICT_SIZE);
+  hlattrs2dict(&dict, syn_attr2entry(id), ui->rgb);
+  ADD_C(args, DICTIONARY_OBJ(dict));
   push_call(ui, "highlight_set", args);
 }
 
@@ -841,7 +845,7 @@ static void remote_ui_raw_line(UI *ui, Integer grid, Integer row, Integer startc
     for (size_t i = 0; i < ncells; i++) {
       repeat++;
       if (i == ncells - 1 || attrs[i] != attrs[i + 1]
-          || STRCMP(chunk[i], chunk[i + 1])) {
+          || strcmp(chunk[i], chunk[i + 1])) {
         if (UI_BUF_SIZE - BUF_POS(data) < 2 * (1 + 2 + sizeof(schar_T) + 5 + 5)) {
           // close to overflowing the redraw buffer. finish this event,
           // flush, and start a new "grid_line" event at the current position.
@@ -952,65 +956,63 @@ static void remote_ui_flush(UI *ui)
   }
 }
 
-static Array translate_contents(UI *ui, Array contents)
+static Array translate_contents(UI *ui, Array contents, Arena *arena)
 {
-  Array new_contents = ARRAY_DICT_INIT;
+  Array new_contents = arena_array(arena, contents.size);
   for (size_t i = 0; i < contents.size; i++) {
     Array item = contents.items[i].data.array;
-    Array new_item = ARRAY_DICT_INIT;
+    Array new_item = arena_array(arena, 2);
     int attr = (int)item.items[0].data.integer;
     if (attr) {
-      Dictionary rgb_attrs = hlattrs2dict(NULL, syn_attr2entry(attr), ui->rgb);
+      Dictionary rgb_attrs = arena_dict(arena, HLATTRS_DICT_SIZE);
+      hlattrs2dict(&rgb_attrs, syn_attr2entry(attr), ui->rgb);
       ADD(new_item, DICTIONARY_OBJ(rgb_attrs));
     } else {
       ADD(new_item, DICTIONARY_OBJ((Dictionary)ARRAY_DICT_INIT));
     }
-    ADD(new_item, copy_object(item.items[1]));
+    ADD(new_item, item.items[1]);
     ADD(new_contents, ARRAY_OBJ(new_item));
   }
   return new_contents;
 }
 
-static Array translate_firstarg(UI *ui, Array args)
+static Array translate_firstarg(UI *ui, Array args, Arena *arena)
 {
-  Array new_args = ARRAY_DICT_INIT;
+  Array new_args = arena_array(arena, args.size);
   Array contents = args.items[0].data.array;
 
-  ADD(new_args, ARRAY_OBJ(translate_contents(ui, contents)));
+  ADD_C(new_args, ARRAY_OBJ(translate_contents(ui, contents, arena)));
   for (size_t i = 1; i < args.size; i++) {
-    ADD(new_args, copy_object(args.items[i]));
+    ADD(new_args, args.items[i]);
   }
   return new_args;
 }
 
 static void remote_ui_event(UI *ui, char *name, Array args)
 {
+  Arena arena = ARENA_EMPTY;
   UIData *data = ui->data;
   if (!ui->ui_ext[kUILinegrid]) {
     // the representation of highlights in cmdline changed, translate back
     // never consumes args
     if (strequal(name, "cmdline_show")) {
-      Array new_args = translate_firstarg(ui, args);
+      Array new_args = translate_firstarg(ui, args, &arena);
       push_call(ui, name, new_args);
-      api_free_array(new_args);
-      return;
+      goto free_ret;
     } else if (strequal(name, "cmdline_block_show")) {
       Array new_args = data->call_buf;
       Array block = args.items[0].data.array;
-      Array new_block = ARRAY_DICT_INIT;
+      Array new_block = arena_array(&arena, block.size);
       for (size_t i = 0; i < block.size; i++) {
-        ADD(new_block,
-            ARRAY_OBJ(translate_contents(ui, block.items[i].data.array)));
+        ADD_C(new_block, ARRAY_OBJ(translate_contents(ui, block.items[i].data.array, &arena)));
       }
       ADD_C(new_args, ARRAY_OBJ(new_block));
       push_call(ui, name, new_args);
-      api_free_array(new_block);
-      return;
+      goto free_ret;
     } else if (strequal(name, "cmdline_block_append")) {
-      Array new_args = translate_firstarg(ui, args);
+      Array new_args = translate_firstarg(ui, args, &arena);
       push_call(ui, name, new_args);
-      api_free_array(new_args);
-      return;
+      goto free_ret;
     }
   }
 
@@ -1022,19 +1024,18 @@ static void remote_ui_event(UI *ui, char *name, Array args)
       if (data->wildmenu_active) {
         Array new_args = data->call_buf;
         Array items = args.items[0].data.array;
-        Array new_items = ARRAY_DICT_INIT;
+        Array new_items = arena_array(&arena, items.size);
         for (size_t i = 0; i < items.size; i++) {
-          ADD(new_items, copy_object(items.items[i].data.array.items[0]));
+          ADD_C(new_items, items.items[i].data.array.items[0]);
         }
         ADD_C(new_args, ARRAY_OBJ(new_items));
         push_call(ui, "wildmenu_show", new_args);
-        api_free_array(new_items);
         if (args.items[1].data.integer != -1) {
           Array new_args2 = data->call_buf;
           ADD_C(new_args2, args.items[1]);
           push_call(ui, "wildmenu_select", new_args2);
         }
-        return;
+        goto free_ret;
       }
     } else if (strequal(name, "popupmenu_select")) {
       if (data->wildmenu_active) {
@@ -1048,6 +1049,10 @@ static void remote_ui_event(UI *ui, char *name, Array args)
   }
 
   push_call(ui, name, args);
+  return;
+
+free_ret:
+  arena_mem_free(arena_finish(&arena));
 }
 
 static void remote_ui_inspect(UI *ui, Dictionary *info)
diff --git a/src/nvim/api/ui_events.in.h b/src/nvim/api/ui_events.in.h
index 8b7e01e1c3..17930dca85 100644
--- a/src/nvim/api/ui_events.in.h
+++ b/src/nvim/api/ui_events.in.h
@@ -100,7 +100,7 @@ void raw_line(Integer grid, Integer row, Integer startcol,
   FUNC_API_NOEXPORT FUNC_API_COMPOSITOR_IMPL;
 
 void event(char *name, Array args)
-  FUNC_API_NOEXPORT;
+  FUNC_API_NOEXPORT FUNC_API_COMPOSITOR_IMPL;
 
 void win_pos(Integer grid, Window win, Integer startrow,
              Integer startcol, Integer width, Integer height)
@@ -121,7 +121,7 @@ void msg_set_pos(Integer grid, Integer row, Boolean scrolled, String sep_char)
 void win_viewport(Integer grid, Window win, Integer topline,
                   Integer botline, Integer curline, Integer curcol,
                   Integer line_count)
-  FUNC_API_SINCE(7) FUNC_API_REMOTE_ONLY;
+  FUNC_API_SINCE(7) FUNC_API_BRIDGE_IMPL;
 
 void win_extmark(Integer grid, Window win, Integer ns_id, Integer mark_id,
                  Integer row, Integer col)
diff --git a/src/nvim/api/vim.c b/src/nvim/api/vim.c
index ce91c1b4af..fa8d26914a 100644
--- a/src/nvim/api/vim.c
+++ b/src/nvim/api/vim.c
@@ -66,7 +66,7 @@
 #include "nvim/viml/parser/parser.h"
 #include "nvim/window.h"
 
-#define LINE_BUFFER_SIZE 4096
+#define LINE_BUFFER_MIN_SIZE 4096
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "api/vim.c.generated.h"
@@ -79,19 +79,17 @@
 /// @param[out] err Error details, if any
 /// @return Highlight definition map
 /// @see nvim_get_hl_by_id
-Dictionary nvim_get_hl_by_name(String name, Boolean rgb, Error *err)
+Dictionary nvim_get_hl_by_name(String name, Boolean rgb, Arena *arena, Error *err)
   FUNC_API_SINCE(3)
 {
   Dictionary result = ARRAY_DICT_INIT;
   int id = syn_name2id(name.data);
 
   if (id == 0) {
-    api_set_error(err, kErrorTypeException, "Invalid highlight name: %s",
-                  name.data);
+    api_set_error(err, kErrorTypeException, "Invalid highlight name: %s", name.data);
     return result;
   }
-  result = nvim_get_hl_by_id(id, rgb, err);
-  return result;
+  return nvim_get_hl_by_id(id, rgb, arena, err);
 }
 
 /// Gets a highlight definition by id. |hlID()|
@@ -100,17 +98,16 @@ Dictionary nvim_get_hl_by_name(String name, Boolean rgb, Error *err)
 /// @param[out] err Error details, if any
 /// @return Highlight definition map
 /// @see nvim_get_hl_by_name
-Dictionary nvim_get_hl_by_id(Integer hl_id, Boolean rgb, Error *err)
+Dictionary nvim_get_hl_by_id(Integer hl_id, Boolean rgb, Arena *arena, Error *err)
   FUNC_API_SINCE(3)
 {
   Dictionary dic = ARRAY_DICT_INIT;
   if (syn_get_final_id((int)hl_id) == 0) {
-    api_set_error(err, kErrorTypeException,
-                  "Invalid highlight id: %" PRId64, hl_id);
+    api_set_error(err, kErrorTypeException, "Invalid highlight id: %" PRId64, hl_id);
     return dic;
   }
   int attrcode = syn_id2attr((int)hl_id);
-  return hl_get_attr_by_id(attrcode, rgb, err);
+  return hl_get_attr_by_id(attrcode, rgb, arena, err);
 }
 
 /// Gets a highlight group by name
@@ -122,10 +119,10 @@ Integer nvim_get_hl_id_by_name(String name)
   return syn_check_group(name.data, name.size);
 }
 
-Dictionary nvim__get_hl_defs(Integer ns_id, Error *err)
+Dictionary nvim__get_hl_defs(Integer ns_id, Arena *arena, Error *err)
 {
   if (ns_id == 0) {
-    return get_global_hl_defs();
+    return get_global_hl_defs(arena);
   }
   abort();
 }
@@ -163,8 +160,8 @@ Dictionary nvim__get_hl_defs(Integer ns_id, Error *err)
 ///                - nocombine: boolean
 ///                - link: name of another highlight group to link to, see |:hi-link|.
 ///                - default: Don't override existing definition |:hi-default|
-///                - ctermfg: Sets foreground of cterm color |highlight-ctermfg|
-///                - ctermbg: Sets background of cterm color |highlight-ctermbg|
+///                - ctermfg: Sets foreground of cterm color |ctermfg|
+///                - ctermbg: Sets background of cterm color |ctermbg|
 ///                - cterm: cterm attribute map, like |highlight-args|. If not set,
 ///                         cterm attributes will match those from the attribute map
 ///                         documented above.
@@ -175,6 +172,10 @@ void nvim_set_hl(Integer ns_id, String name, Dict(highlight) *val, Error *err)
   FUNC_API_SINCE(7)
 {
   int hl_id = syn_check_group(name.data, name.size);
+  if (hl_id == 0) {
+    api_set_error(err, kErrorTypeException, "Invalid highlight name: %s", name.data);
+    return;
+  }
   int link_id = -1;
 
   HlAttrs attrs = dict2hlattrs(val, true, &link_id, err);
@@ -184,7 +185,7 @@ void nvim_set_hl(Integer ns_id, String name, Dict(highlight) *val, Error *err)
 }
 
 /// Set active namespace for highlights. This can be set for a single window,
-/// see |nvim_win_set_hl_ns|.
+/// see |nvim_win_set_hl_ns()|.
 ///
 /// @param ns_id the namespace to use
 /// @param[out] err Error details, if any
@@ -198,13 +199,13 @@ void nvim_set_hl_ns(Integer ns_id, Error *err)
 
   ns_hl_global = (NS)ns_id;
   hl_check_ns();
-  redraw_all_later(NOT_VALID);
+  redraw_all_later(UPD_NOT_VALID);
 }
 
 /// Set active namespace for highlights while redrawing.
 ///
 /// This function meant to be called while redrawing, primarily from
-/// |nvim_set_decoration_provider| on_win and on_line callbacks, which
+/// |nvim_set_decoration_provider()| on_win and on_line callbacks, which
 /// are allowed to change the namespace during a redraw cycle.
 ///
 /// @param ns_id the namespace to activate
@@ -335,9 +336,9 @@ Integer nvim_input(String keys)
 ///       mouse input in a GUI. The deprecated pseudokey form
 ///       ("<LeftMouse><col,row>") of |nvim_input()| has the same limitation.
 ///
-/// @param button Mouse button: one of "left", "right", "middle", "wheel".
+/// @param button Mouse button: one of "left", "right", "middle", "wheel", "move".
 /// @param action For ordinary buttons, one of "press", "drag", "release".
-///               For the wheel, one of "up", "down", "left", "right".
+///               For the wheel, one of "up", "down", "left", "right". Ignored for "move".
 /// @param modifier String of modifiers each represented by a single char.
 ///                 The same specifiers are used as for a key press, except
 ///                 that the "-" separator is optional, so "C-A-", "c-a"
@@ -364,6 +365,8 @@ void nvim_input_mouse(String button, String action, String modifier, Integer gri
     code = KE_RIGHTMOUSE;
   } else if (strequal(button.data, "wheel")) {
     code = KE_MOUSEDOWN;
+  } else if (strequal(button.data, "move")) {
+    code = KE_MOUSEMOVE;
   } else {
     goto error;
   }
@@ -380,7 +383,7 @@ void nvim_input_mouse(String button, String action, String modifier, Integer gri
     } else {
       goto error;
     }
-  } else {
+  } else if (code != KE_MOUSEMOVE) {
     if (strequal(action.data, "press")) {
       // pass
     } else if (strequal(action.data, "drag")) {
@@ -520,7 +523,7 @@ Array nvim__runtime_inspect(void)
 
 /// Find files in runtime directories
 ///
-/// 'name' can contain wildcards. For example
+/// "name" can contain wildcards. For example
 /// nvim_get_runtime_file("colors/*.vim", true) will return all color
 /// scheme files. Always use forward slashes (/) in the search pattern for
 /// subdirectories regardless of platform.
@@ -961,7 +964,7 @@ fail:
 ///            mode. Note: keypresses are sent raw as they would be to the pty
 ///            master end. For instance, a carriage return is sent
 ///            as a "\r", not as a "\n". |textlock| applies. It is possible
-///            to call |nvim_chan_send| directly in the callback however.
+///            to call |nvim_chan_send()| directly in the callback however.
 ///                 ["input", term, bufnr, data]
 /// @param[out] err Error details, if any
 /// @return Channel id, or 0 on error
@@ -1419,10 +1422,10 @@ Dictionary nvim_get_mode(void)
 /// @param  mode       Mode short-name ("n", "i", "v", ...)
 /// @returns Array of |maparg()|-like dictionaries describing mappings.
 ///          The "buffer" key is always zero.
-ArrayOf(Dictionary) nvim_get_keymap(uint64_t channel_id, String mode)
+ArrayOf(Dictionary) nvim_get_keymap(String mode)
   FUNC_API_SINCE(3)
 {
-  return keymap_array(mode, NULL, channel_id == LUA_INTERNAL_CALL);
+  return keymap_array(mode, NULL);
 }
 
 /// Sets a global |mapping| for the given mode.
@@ -1449,7 +1452,7 @@ ArrayOf(Dictionary) nvim_get_keymap(uint64_t channel_id, String mode)
 /// @param  rhs   Right-hand-side |{rhs}| of the mapping.
 /// @param  opts  Optional parameters map: keys are |:map-arguments|, values are booleans (default
 ///               false). Accepts all |:map-arguments| as keys excluding |<buffer>| but including
-///               |noremap| and "desc". Unknown key is an error.
+///               |:noremap| and "desc". Unknown key is an error.
 ///               "desc" can be used to give a description to the mapping.
 ///               When called from Lua, also accepts a "callback" key that takes a Lua function to
 ///               call when the mapping is executed.
@@ -1479,14 +1482,14 @@ void nvim_del_keymap(uint64_t channel_id, String mode, String lhs, Error *err)
 /// 1 is the |api-metadata| map (Dictionary).
 ///
 /// @returns 2-tuple [{channel-id}, {api-metadata}]
-Array nvim_get_api_info(uint64_t channel_id)
+Array nvim_get_api_info(uint64_t channel_id, Arena *arena)
   FUNC_API_SINCE(1) FUNC_API_FAST FUNC_API_REMOTE_ONLY
 {
-  Array rv = ARRAY_DICT_INIT;
+  Array rv = arena_array(arena, 2);
 
   assert(channel_id <= INT64_MAX);
-  ADD(rv, INTEGER_OBJ((int64_t)channel_id));
-  ADD(rv, DICTIONARY_OBJ(api_metadata()));
+  ADD_C(rv, INTEGER_OBJ((int64_t)channel_id));
+  ADD_C(rv, DICTIONARY_OBJ(api_metadata()));
 
   return rv;
 }
@@ -1545,9 +1548,9 @@ void nvim_set_client_info(uint64_t channel_id, String name, Dictionary version,
   FUNC_API_SINCE(4) FUNC_API_REMOTE_ONLY
 {
   Dictionary info = ARRAY_DICT_INIT;
-  PUT(info, "name", copy_object(STRING_OBJ(name)));
+  PUT(info, "name", copy_object(STRING_OBJ(name), NULL));
 
-  version = copy_dictionary(version);
+  version = copy_dictionary(version, NULL);
   bool has_major = false;
   for (size_t i = 0; i < version.size; i++) {
     if (strequal(version.items[i].key.data, "major")) {
@@ -1560,9 +1563,9 @@ void nvim_set_client_info(uint64_t channel_id, String name, Dictionary version,
   }
   PUT(info, "version", DICTIONARY_OBJ(version));
 
-  PUT(info, "type", copy_object(STRING_OBJ(type)));
-  PUT(info, "methods", DICTIONARY_OBJ(copy_dictionary(methods)));
-  PUT(info, "attributes", DICTIONARY_OBJ(copy_dictionary(attributes)));
+  PUT(info, "type", copy_object(STRING_OBJ(type), NULL));
+  PUT(info, "methods", DICTIONARY_OBJ(copy_dictionary(methods, NULL)));
+  PUT(info, "attributes", DICTIONARY_OBJ(copy_dictionary(attributes, NULL)));
 
   rpc_set_client_info(channel_id, info);
 }
@@ -1629,11 +1632,11 @@ Array nvim_list_chans(void)
 /// an error, it is a three-element array with the zero-based index of the call
 /// which resulted in an error, the error type and the error message. If an
 /// error occurred, the values from all preceding calls will still be returned.
-Array nvim_call_atomic(uint64_t channel_id, Array calls, Error *err)
+Array nvim_call_atomic(uint64_t channel_id, Array calls, Arena *arena, Error *err)
   FUNC_API_SINCE(1) FUNC_API_REMOTE_ONLY
 {
-  Array rv = ARRAY_DICT_INIT;
-  Array results = ARRAY_DICT_INIT;
+  Array rv = arena_array(arena, 2);
+  Array results = arena_array(arena, calls.size);
   Error nested_error = ERROR_INIT;
 
   size_t i;  // also used for freeing the variables
@@ -1642,21 +1645,21 @@ Array nvim_call_atomic(uint64_t channel_id, Array calls, Error *err)
       api_set_error(err,
                     kErrorTypeValidation,
                     "Items in calls array must be arrays");
-      goto validation_error;
+      goto theend;
     }
     Array call = calls.items[i].data.array;
     if (call.size != 2) {
       api_set_error(err,
                     kErrorTypeValidation,
                     "Items in calls array must be arrays of size 2");
-      goto validation_error;
+      goto theend;
     }
 
     if (call.items[0].type != kObjectTypeString) {
       api_set_error(err,
                     kErrorTypeValidation,
                     "Name must be String");
-      goto validation_error;
+      goto theend;
     }
     String name = call.items[0].data.string;
 
@@ -1664,7 +1667,7 @@ Array nvim_call_atomic(uint64_t channel_id, Array calls, Error *err)
       api_set_error(err,
                     kErrorTypeValidation,
                     "Args must be Array");
-      goto validation_error;
+      goto theend;
     }
     Array args = call.items[1].data.array;
 
@@ -1676,29 +1679,32 @@ Array nvim_call_atomic(uint64_t channel_id, Array calls, Error *err)
     if (ERROR_SET(&nested_error)) {
       break;
     }
-    Object result = handler.fn(channel_id, args, &nested_error);
+
+    Object result = handler.fn(channel_id, args, arena, &nested_error);
     if (ERROR_SET(&nested_error)) {
       // error handled after loop
       break;
     }
-
-    ADD(results, result);
+    // TODO(bfredl): wastefull copy. It could be avoided to encoding to msgpack
+    // directly here. But `result` might become invalid when next api function
+    // is called in the loop.
+    ADD_C(results, copy_object(result, arena));
+    if (!handler.arena_return) {
+      api_free_object(result);
+    }
   }
 
-  ADD(rv, ARRAY_OBJ(results));
+  ADD_C(rv, ARRAY_OBJ(results));
   if (ERROR_SET(&nested_error)) {
-    Array errval = ARRAY_DICT_INIT;
-    ADD(errval, INTEGER_OBJ((Integer)i));
-    ADD(errval, INTEGER_OBJ(nested_error.type));
-    ADD(errval, STRING_OBJ(cstr_to_string(nested_error.msg)));
-    ADD(rv, ARRAY_OBJ(errval));
+    Array errval = arena_array(arena, 3);
+    ADD_C(errval, INTEGER_OBJ((Integer)i));
+    ADD_C(errval, INTEGER_OBJ(nested_error.type));
+    ADD_C(errval, STRING_OBJ(copy_string(cstr_as_string(nested_error.msg), arena)));
+    ADD_C(rv, ARRAY_OBJ(errval));
   } else {
-    ADD(rv, NIL);
+    ADD_C(rv, NIL);
   }
-  goto theend;
 
-validation_error:
-  api_free_array(results);
 theend:
   api_clear_error(&nested_error);
   return rv;
@@ -1712,17 +1718,21 @@ theend:
 /// @param to_err   true: message is an error (uses `emsg` instead of `msg`)
 static void write_msg(String message, bool to_err)
 {
-  static size_t out_pos = 0, err_pos = 0;
-  static char out_line_buf[LINE_BUFFER_SIZE], err_line_buf[LINE_BUFFER_SIZE];
+  static StringBuilder out_line_buf = KV_INITIAL_VALUE;
+  static StringBuilder err_line_buf = KV_INITIAL_VALUE;
 
-#define PUSH_CHAR(i, pos, line_buf, msg) \
-  if (message.data[i] == NL || (pos) == LINE_BUFFER_SIZE - 1) { \
-    (line_buf)[pos] = NUL; \
-    msg(line_buf); \
-    (pos) = 0; \
+#define PUSH_CHAR(i, line_buf, msg) \
+  if (kv_max(line_buf) == 0) { \
+    kv_resize(line_buf, LINE_BUFFER_MIN_SIZE); \
+  } \
+  if (message.data[i] == NL) { \
+    kv_push(line_buf, NUL); \
+    msg(line_buf.items); \
+    kv_drop(line_buf, kv_size(line_buf)); \
+    kv_resize(line_buf, LINE_BUFFER_MIN_SIZE); \
     continue; \
   } \
-  (line_buf)[(pos)++] = message.data[i];
+  kv_push(line_buf, message.data[i]);
 
   no_wait_return++;
   for (uint32_t i = 0; i < message.size; i++) {
@@ -1730,9 +1740,9 @@ static void write_msg(String message, bool to_err)
       break;
     }
     if (to_err) {
-      PUSH_CHAR(i, err_pos, err_line_buf, emsg);
+      PUSH_CHAR(i, err_line_buf, emsg);
     } else {
-      PUSH_CHAR(i, out_pos, out_line_buf, msg);
+      PUSH_CHAR(i, out_line_buf, msg);
     }
   }
   no_wait_return--;
@@ -1751,7 +1761,7 @@ static void write_msg(String message, bool to_err)
 /// @return its argument.
 Object nvim__id(Object obj)
 {
-  return copy_object(obj);
+  return copy_object(obj, NULL);
 }
 
 /// Returns array given as argument.
@@ -1764,7 +1774,7 @@ Object nvim__id(Object obj)
 /// @return its argument.
 Array nvim__id_array(Array arr)
 {
-  return copy_object(ARRAY_OBJ(arr)).data.array;
+  return copy_array(arr, NULL);
 }
 
 /// Returns dictionary given as argument.
@@ -1777,7 +1787,7 @@ Array nvim__id_array(Array arr)
 /// @return its argument.
 Dictionary nvim__id_dictionary(Dictionary dct)
 {
-  return copy_object(DICTIONARY_OBJ(dct)).data.dictionary;
+  return copy_dictionary(dct, NULL);
 }
 
 /// Returns floating-point value given as argument.
@@ -1803,6 +1813,7 @@ Dictionary nvim__stats(void)
   PUT(rv, "log_skip", INTEGER_OBJ(g_stats.log_skip));
   PUT(rv, "lua_refcount", INTEGER_OBJ(nlua_get_global_ref_count()));
   PUT(rv, "redraw", INTEGER_OBJ(g_stats.redraw));
+  PUT(rv, "arena_alloc_count", INTEGER_OBJ((Integer)arena_alloc_count));
   return rv;
 }
 
@@ -1875,7 +1886,7 @@ Object nvim_get_proc(Integer pid, Error *err)
     api_set_error(err, kErrorTypeException, "Invalid pid: %" PRId64, pid);
     return NIL;
   }
-#ifdef WIN32
+#ifdef MSWIN
   rvobj.data.dictionary = os_proc_info((int)pid);
   if (rvobj.data.dictionary.size == 0) {  // Process not found.
     return NIL;
@@ -1928,7 +1939,7 @@ void nvim_select_popupmenu_item(Integer item, Boolean insert, Boolean finish, Di
 }
 
 /// NB: if your UI doesn't use hlstate, this will not return hlstate first time
-Array nvim__inspect_cell(Integer grid, Integer row, Integer col, Error *err)
+Array nvim__inspect_cell(Integer grid, Integer row, Integer col, Arena *arena, Error *err)
 {
   Array ret = ARRAY_DICT_INIT;
 
@@ -1952,13 +1963,14 @@ Array nvim__inspect_cell(Integer grid, Integer row, Integer col, Error *err)
       || col < 0 || col >= g->cols) {
     return ret;
   }
+  ret = arena_array(arena, 3);
   size_t off = g->line_offset[(size_t)row] + (size_t)col;
-  ADD(ret, STRING_OBJ(cstr_to_string((char *)g->chars[off])));
+  ADD_C(ret, STRING_OBJ(cstr_as_string((char *)g->chars[off])));
   int attr = g->attrs[off];
-  ADD(ret, DICTIONARY_OBJ(hl_get_attr_by_id(attr, true, err)));
+  ADD_C(ret, DICTIONARY_OBJ(hl_get_attr_by_id(attr, true, arena, err)));
   // will not work first time
   if (!highlight_use_hlstate()) {
-    ADD(ret, ARRAY_OBJ(hl_inspect(attr)));
+    ADD_C(ret, ARRAY_OBJ(hl_inspect(attr)));
   }
   return ret;
 }
@@ -2040,7 +2052,7 @@ Array nvim_get_mark(String name, Dictionary opts, Error *err)
   // Marks are from an open buffer it fnum is non zero
   if (mark->fmark.fnum != 0) {
     bufnr = mark->fmark.fnum;
-    filename = (char *)buflist_nr2name(bufnr, true, true);
+    filename = buflist_nr2name(bufnr, true, true);
     allocated = true;
     // Marks comes from shada
   } else {
@@ -2088,7 +2100,7 @@ Array nvim_get_mark(String name, Dictionary opts, Error *err)
 ///                                'fillchars'). Treated as single-width even if it isn't.
 ///           - highlights: (boolean) Return highlight information.
 ///           - use_winbar: (boolean) Evaluate winbar instead of statusline.
-///           - use_tabline: (boolean) Evaluate tabline instead of statusline. When |TRUE|, {winid}
+///           - use_tabline: (boolean) Evaluate tabline instead of statusline. When true, {winid}
 ///                                    is ignored. Mutually exclusive with {use_winbar}.
 ///
 /// @param[out] err Error details, if any.
@@ -2096,7 +2108,7 @@ Array nvim_get_mark(String name, Dictionary opts, Error *err)
 ///       - str: (string) Characters that will be displayed on the statusline.
 ///       - width: (number) Display width of the statusline.
 ///       - highlights: Array containing highlight information of the statusline. Only included when
-///                     the "highlights" key in {opts} is |TRUE|. Each element of the array is a
+///                     the "highlights" key in {opts} is true. Each element of the array is a
 ///                     |Dictionary| with these keys:
 ///           - start: (number) Byte index (0-based) of first character that uses the highlight.
 ///           - group: (string) Name of highlight group.
@@ -2228,7 +2240,7 @@ Dictionary nvim_eval_statusline(String str, Dict(eval_statusline) *opts, Error *
 
     // If first character doesn't have a defined highlight,
     // add the default highlight at the beginning of the highlight list
-    if (hltab->start == NULL || ((char *)hltab->start - buf) != 0) {
+    if (hltab->start == NULL || (hltab->start - buf) != 0) {
       Dictionary hl_info = ARRAY_DICT_INIT;
       grpname = get_default_stl_hl(wp, use_winbar);
 
diff --git a/src/nvim/api/vimscript.c b/src/nvim/api/vimscript.c
index a28bfd2ab9..71209c9ab6 100644
--- a/src/nvim/api/vimscript.c
+++ b/src/nvim/api/vimscript.c
@@ -137,7 +137,7 @@ Object nvim_eval(String expr, Error *err)
     if (!recursive) {
       force_abort = false;
       suppress_errthrow = false;
-      current_exception = NULL;
+      did_throw = false;
       // `did_emsg` is set by emsg(), which cancels execution.
       did_emsg = false;
     }
@@ -196,7 +196,7 @@ static Object _call_function(String fn, Array args, dict_T *self, Error *err)
     if (!recursive) {
       force_abort = false;
       suppress_errthrow = false;
-      current_exception = NULL;
+      did_throw = false;
       // `did_emsg` is set by emsg(), which cancels execution.
       did_emsg = false;
     }
@@ -204,10 +204,10 @@ static Object _call_function(String fn, Array args, dict_T *self, Error *err)
     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.selfdict = self;
+    funcexe.fe_firstline = curwin->w_cursor.lnum;
+    funcexe.fe_lastline = curwin->w_cursor.lnum;
+    funcexe.fe_evaluate = true;
+    funcexe.fe_selfdict = self;
     // call_func() retval is deceptive, ignore it.  Instead we set `msg_list`
     // (see above) to capture abort-causing non-exception errors.
     (void)call_func(fn.data, (int)fn.size, &rettv, (int)args.size,
@@ -304,7 +304,7 @@ Object nvim_call_dict_function(Object dict, String fn, Array args, Error *err)
     }
     fn = (String) {
       .data = di->di_tv.vval.v_string,
-      .size = STRLEN(di->di_tv.vval.v_string),
+      .size = strlen(di->di_tv.vval.v_string),
     };
   }
 
diff --git a/src/nvim/api/win_config.c b/src/nvim/api/win_config.c
index 0c89726d71..7523ff301d 100644
--- a/src/nvim/api/win_config.c
+++ b/src/nvim/api/win_config.c
@@ -109,7 +109,7 @@
 ///                    is changed to `auto` and 'colorcolumn' is cleared. The
 ///                    end-of-buffer region is hidden by setting `eob` flag of
 ///                    'fillchars' to a space char, and clearing the
-///                    |EndOfBuffer| region in 'winhighlight'.
+///                    |hl-EndOfBuffer| region in 'winhighlight'.
 ///   - border: Style of (optional) window border. This can either be a string
 ///      or an array. The string values are
 ///     - "none": No border (default).
@@ -202,7 +202,7 @@ void nvim_win_set_config(Window window, Dict(float_config) *config, Error *err)
     if (!win_new_float(win, false, fconfig, err)) {
       return;
     }
-    redraw_later(win, NOT_VALID);
+    redraw_later(win, UPD_NOT_VALID);
   } else {
     win_config_float(win, fconfig);
     win->w_pos_changed = true;
diff --git a/src/nvim/api/window.c b/src/nvim/api/window.c
index 580dfd8639..08dcc113da 100644
--- a/src/nvim/api/window.c
+++ b/src/nvim/api/window.c
@@ -51,7 +51,9 @@ void nvim_win_set_buf(Window window, Buffer buffer, Error *err)
   win_set_buf(window, buffer, false, err);
 }
 
-/// Gets the (1,0)-indexed cursor position in the window. |api-indexing|
+/// Gets the (1,0)-indexed, buffer-relative cursor position for a given window
+/// (different windows showing the same buffer have independent cursor
+/// positions). |api-indexing|
 ///
 /// @param window   Window handle, or 0 for current window
 /// @param[out] err Error details, if any
@@ -118,7 +120,7 @@ void nvim_win_set_cursor(Window window, ArrayOf(Integer, 2) pos, Error *err)
   // make sure cursor is in visible range even if win != curwin
   update_topline_win(win);
 
-  redraw_later(win, VALID);
+  redraw_later(win, UPD_VALID);
   win->w_redr_status = true;
 }
 
@@ -340,7 +342,7 @@ Boolean nvim_win_is_valid(Window window)
 ///
 /// Like |:hide| the buffer becomes hidden unless another window is editing it,
 /// or 'bufhidden' is `unload`, `delete` or `wipe` as opposed to |:close| or
-/// |nvim_win_close|, which will close the buffer.
+/// |nvim_win_close()|, which will close the buffer.
 ///
 /// @param window   Window handle, or 0 for current window
 /// @param[out] err Error details, if any
@@ -430,7 +432,7 @@ Object nvim_win_call(Window window, LuaRef fun, Error *err)
 /// Set highlight namespace for a window. This will use highlights defined in
 /// this namespace, but fall back to global highlights (ns=0) when missing.
 ///
-/// This takes predecence over the 'winhighlight' option.
+/// This takes precedence over the 'winhighlight' option.
 ///
 /// @param ns_id the namespace to use
 /// @param[out] err Error details, if any
@@ -449,5 +451,5 @@ void nvim_win_set_hl_ns(Window window, Integer ns_id, Error *err)
 
   win->w_ns_hl = (NS)ns_id;
   win->w_hl_needs_update = true;
-  redraw_later(win, NOT_VALID);
+  redraw_later(win, UPD_NOT_VALID);
 }