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

1 files changed, 354 insertions, 334 deletions

diff --git a/src/nvim/api/vim.c b/src/nvim/api/vim.c
index a53b30dd8a..d631b10af9 100644
--- a/src/nvim/api/vim.c
+++ b/src/nvim/api/vim.c
@@ -1,8 +1,6 @@
-// This is an open source non-commercial project. Dear PVS-Studio, please check
-// it. PVS-Studio Static Code Analyzer for C, C++ and C#: http://www.viva64.com
-
 #include <assert.h>
 #include <inttypes.h>
+#include <lauxlib.h>
 #include <limits.h>
 #include <stdbool.h>
 #include <stddef.h>
@@ -11,25 +9,29 @@
 #include <string.h>
 
 #include "klib/kvec.h"
-#include "lauxlib.h"
 #include "nvim/api/buffer.h"
 #include "nvim/api/deprecated.h"
+#include "nvim/api/keysets_defs.h"
 #include "nvim/api/private/converter.h"
 #include "nvim/api/private/defs.h"
 #include "nvim/api/private/dispatch.h"
 #include "nvim/api/private/helpers.h"
+#include "nvim/api/private/validate.h"
 #include "nvim/api/vim.h"
-#include "nvim/ascii.h"
+#include "nvim/ascii_defs.h"
 #include "nvim/autocmd.h"
 #include "nvim/buffer.h"
 #include "nvim/channel.h"
 #include "nvim/context.h"
+#include "nvim/cursor.h"
+#include "nvim/decoration.h"
 #include "nvim/drawscreen.h"
 #include "nvim/eval.h"
 #include "nvim/eval/typval.h"
-#include "nvim/eval/typval_defs.h"
 #include "nvim/ex_docmd.h"
 #include "nvim/ex_eval.h"
+#include "nvim/fold.h"
+#include "nvim/func_attr.h"
 #include "nvim/getchar.h"
 #include "nvim/globals.h"
 #include "nvim/grid.h"
@@ -38,7 +40,7 @@
 #include "nvim/keycodes.h"
 #include "nvim/log.h"
 #include "nvim/lua/executor.h"
-#include "nvim/macros.h"
+#include "nvim/macros_defs.h"
 #include "nvim/mapping.h"
 #include "nvim/mark.h"
 #include "nvim/mbyte.h"
@@ -47,24 +49,24 @@
 #include "nvim/message.h"
 #include "nvim/move.h"
 #include "nvim/msgpack_rpc/channel.h"
-#include "nvim/msgpack_rpc/channel_defs.h"
 #include "nvim/msgpack_rpc/unpacker.h"
 #include "nvim/ops.h"
 #include "nvim/option.h"
+#include "nvim/option_vars.h"
 #include "nvim/optionstr.h"
 #include "nvim/os/input.h"
-#include "nvim/os/os_defs.h"
 #include "nvim/os/process.h"
 #include "nvim/popupmenu.h"
-#include "nvim/pos.h"
+#include "nvim/pos_defs.h"
 #include "nvim/runtime.h"
+#include "nvim/sign.h"
 #include "nvim/state.h"
 #include "nvim/statusline.h"
 #include "nvim/strings.h"
 #include "nvim/terminal.h"
-#include "nvim/types.h"
+#include "nvim/types_defs.h"
 #include "nvim/ui.h"
-#include "nvim/vim.h"
+#include "nvim/vim_defs.h"
 #include "nvim/window.h"
 
 #define LINE_BUFFER_MIN_SIZE 4096
@@ -73,44 +75,6 @@
 # include "api/vim.c.generated.h"
 #endif
 
-/// Gets a highlight definition by name.
-///
-/// @param name Highlight group name
-/// @param rgb Export RGB colors
-/// @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, 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);
-    return result;
-  }
-  return nvim_get_hl_by_id(id, rgb, arena, err);
-}
-
-/// Gets a highlight definition by id. |hlID()|
-/// @param hl_id Highlight id as returned by |hlID()|
-/// @param rgb Export RGB colors
-/// @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, 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);
-    return dic;
-  }
-  int attrcode = syn_id2attr((int)hl_id);
-  return hl_get_attr_by_id(attrcode, rgb, arena, err);
-}
-
 /// Gets a highlight group by name
 ///
 /// similar to |hlID()|, but allocates a new ID if not present.
@@ -120,12 +84,26 @@ 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, Arena *arena, Error *err)
+/// Gets all or specific highlight groups in a namespace.
+///
+/// @note When the `link` attribute is defined in the highlight definition
+///       map, other attributes will not be taking effect (see |:hi-link|).
+///
+/// @param ns_id Get highlight groups for namespace ns_id |nvim_get_namespaces()|.
+///              Use 0 to get global highlight groups |:highlight|.
+/// @param opts  Options dict:
+///                 - name: (string) Get a highlight definition by name.
+///                 - id: (integer) Get a highlight definition by id.
+///                 - link: (boolean, default true) Show linked group name instead of effective definition |:hi-link|.
+///                 - create: (boolean, default true) When highlight group doesn't exist create it.
+///
+/// @param[out] err Error details, if any.
+/// @return Highlight groups as a map from group name to a highlight definition map as in |nvim_set_hl()|,
+///                   or only a single highlight definition map if requested by name or id.
+Dictionary nvim_get_hl(Integer ns_id, Dict(get_highlight) *opts, Arena *arena, Error *err)
+  FUNC_API_SINCE(11)
 {
-  if (ns_id == 0) {
-    return get_global_hl_defs(arena);
-  }
-  abort();
+  return ns_get_hl_defs((NS)ns_id, opts, arena, err);
 }
 
 /// Sets a highlight group.
@@ -140,8 +118,14 @@ Dictionary nvim__get_hl_defs(Integer ns_id, Arena *arena, Error *err)
 ///       values of the Normal group. If the Normal group has not been defined,
 ///       using these values results in an error.
 ///
+///
+/// @note If `link` is used in combination with other attributes; only the
+///       `link` will take effect (see |:hi-link|).
+///
 /// @param ns_id Namespace id for this highlight |nvim_create_namespace()|.
 ///              Use 0 to set a highlight group globally |:highlight|.
+///              Highlights from non-global namespaces are not active by default, use
+///              |nvim_set_hl_ns()| or |nvim_win_set_hl_ns()| to activate them.
 /// @param name  Highlight group name, e.g. "ErrorMsg"
 /// @param val   Highlight definition map, accepts the following keys:
 ///                - fg (or foreground): color name or "#RRGGBB", see note.
@@ -166,6 +150,7 @@ Dictionary nvim__get_hl_defs(Integer ns_id, Arena *arena, Error *err)
 ///                - cterm: cterm attribute map, like |highlight-args|. If not set,
 ///                         cterm attributes will match those from the attribute map
 ///                         documented above.
+///                - force: if true force update the highlight group when it exists.
 /// @param[out] err Error details, if any
 ///
 // TODO(bfredl): val should take update vs reset flag
@@ -173,10 +158,9 @@ 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);
+  VALIDATE_S((hl_id != 0), "highlight name", name.data, {
     return;
-  }
+  });
   int link_id = -1;
 
   HlAttrs attrs = dict2hlattrs(val, true, &link_id, err);
@@ -185,25 +169,47 @@ 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()|.
+/// Gets the active highlight namespace.
+///
+/// @param opts Optional parameters
+///           - winid: (number) |window-ID| for retrieving a window's highlight
+///             namespace. A value of -1 is returned when |nvim_win_set_hl_ns()|
+///             has not been called for the window (or was called with a namespace
+///             of -1).
+/// @param[out] err Error details, if any
+/// @return Namespace id, or -1
+Integer nvim_get_hl_ns(Dict(get_ns) *opts, Error *err)
+  FUNC_API_SINCE(12)
+{
+  if (HAS_KEY(opts, get_ns, winid)) {
+    win_T *win = find_window_by_handle(opts->winid, err);
+    if (!win) {
+      return 0;
+    }
+    return win->w_ns_hl;
+  } else {
+    return ns_hl_global;
+  }
+}
+
+/// Set active namespace for highlights defined with |nvim_set_hl()|. This can be set for
+/// a single window, see |nvim_win_set_hl_ns()|.
 ///
 /// @param ns_id the namespace to use
 /// @param[out] err Error details, if any
 void nvim_set_hl_ns(Integer ns_id, Error *err)
   FUNC_API_SINCE(10)
 {
-  if (ns_id < 0) {
-    api_set_error(err, kErrorTypeValidation, "no such namespace");
+  VALIDATE_INT((ns_id >= 0), "namespace", ns_id, {
     return;
-  }
+  });
 
   ns_hl_global = (NS)ns_id;
   hl_check_ns();
   redraw_all_later(UPD_NOT_VALID);
 }
 
-/// Set active namespace for highlights while redrawing.
+/// Set active namespace for highlights defined with |nvim_set_hl()| while redrawing.
 ///
 /// This function meant to be called while redrawing, primarily from
 /// |nvim_set_decoration_provider()| on_win and on_line callbacks, which
@@ -229,10 +235,11 @@ void nvim_set_hl_ns_fast(Integer ns_id, Error *err)
 /// nvim_feedkeys().
 ///
 /// Example:
-/// <pre>vim
-///     :let key = nvim_replace_termcodes("<C-o>", v:true, v:false, v:true)
-///     :call nvim_feedkeys(key, 'n', v:false)
-/// </pre>
+///
+/// ```vim
+/// :let key = nvim_replace_termcodes("<C-o>", v:true, v:false, v:true)
+/// :call nvim_feedkeys(key, 'n', v:false)
+/// ```
 ///
 /// @param keys         to be typed
 /// @param mode         behavior flags, see |feedkeys()|
@@ -323,6 +330,7 @@ void nvim_feedkeys(String keys, String mode, Boolean escape_ks)
 Integer nvim_input(String keys)
   FUNC_API_SINCE(1) FUNC_API_FAST
 {
+  may_trigger_vim_suspend_resume(false);
   return (Integer)input_enqueue(keys);
 }
 
@@ -352,6 +360,8 @@ void nvim_input_mouse(String button, String action, String modifier, Integer gri
                       Integer col, Error *err)
   FUNC_API_SINCE(6) FUNC_API_FAST
 {
+  may_trigger_vim_suspend_resume(false);
+
   if (button.data == NULL || action.data == NULL) {
     goto error;
   }
@@ -403,11 +413,9 @@ void nvim_input_mouse(String button, String action, String modifier, Integer gri
       continue;
     }
     int mod = name_to_mod_mask(byte);
-    if (mod == 0) {
-      api_set_error(err, kErrorTypeValidation,
-                    "invalid modifier %c", byte);
+    VALIDATE((mod != 0), "Invalid modifier: %c", byte, {
       return;
-    }
+    });
     modmask |= mod;
   }
 
@@ -448,7 +456,7 @@ String nvim_replace_termcodes(String str, Boolean from_part, Boolean do_lt, Bool
   }
 
   char *ptr = NULL;
-  replace_termcodes(str.data, str.size, &ptr, flags, NULL, CPO_TO_CPO_FLAGS);
+  replace_termcodes(str.data, str.size, &ptr, 0, flags, NULL, CPO_TO_CPO_FLAGS);
   return cstr_as_string(ptr);
 }
 
@@ -500,15 +508,14 @@ Object nvim_notify(String msg, Integer log_level, Dictionary opts, Error *err)
 Integer nvim_strwidth(String text, Error *err)
   FUNC_API_SINCE(1)
 {
-  if (text.size > INT_MAX) {
-    api_set_error(err, kErrorTypeValidation, "String is too long");
+  VALIDATE_S((text.size <= INT_MAX), "text length", "(too long)", {
     return 0;
-  }
+  });
 
   return (Integer)mb_string2cells(text.data);
 }
 
-/// Gets the paths contained in 'runtimepath'.
+/// Gets the paths contained in |runtime-search-path|.
 ///
 /// @return List of paths
 ArrayOf(String) nvim_list_runtime_paths(Error *err)
@@ -542,20 +549,23 @@ ArrayOf(String) nvim_get_runtime_file(String name, Boolean all, Error *err)
 
   int flags = DIP_DIRFILE | (all ? DIP_ALL : 0);
 
-  TRY_WRAP({
-    try_start();
+  TRY_WRAP(err, {
     do_in_runtimepath((name.size ? name.data : ""), flags, find_runtime_cb, &rv);
-    try_end(err);
   });
   return rv;
 }
 
-static void find_runtime_cb(char *fname, void *cookie)
+static bool find_runtime_cb(int num_fnames, char **fnames, bool all, void *cookie)
 {
   Array *rv = (Array *)cookie;
-  if (fname != NULL) {
-    ADD(*rv, STRING_OBJ(cstr_to_string((char *)fname)));
+  for (int i = 0; i < num_fnames; i++) {
+    ADD(*rv, CSTR_TO_OBJ(fnames[i]));
+    if (!all) {
+      return true;
+    }
   }
+
+  return num_fnames > 0;
 }
 
 String nvim__get_lib_dir(void)
@@ -567,28 +577,24 @@ String nvim__get_lib_dir(void)
 ///
 /// @param pat pattern of files to search for
 /// @param all whether to return all matches or only the first
-/// @param opts is_lua: only search lua subdirs
+/// @param opts is_lua: only search Lua subdirs
 /// @return list of absolute paths to the found files
 ArrayOf(String) nvim__get_runtime(Array pat, Boolean all, Dict(runtime) *opts, Error *err)
   FUNC_API_SINCE(8)
   FUNC_API_FAST
 {
-  bool is_lua = api_object_to_bool(opts->is_lua, "is_lua", false, err);
-  bool source = api_object_to_bool(opts->do_source, "do_source", false, err);
-  if (source && !nlua_is_deferred_safe()) {
-    api_set_error(err, kErrorTypeValidation, "'do_source' cannot be used in fast callback");
-  }
-
+  VALIDATE(!opts->do_source || nlua_is_deferred_safe(), "%s", "'do_source' used in fast callback",
+           {});
   if (ERROR_SET(err)) {
     return (Array)ARRAY_DICT_INIT;
   }
 
-  ArrayOf(String) res = runtime_get_named(is_lua, pat, all);
+  ArrayOf(String) res = runtime_get_named(opts->is_lua, pat, all);
 
-  if (source) {
+  if (opts->do_source) {
     for (size_t i = 0; i < res.size; i++) {
       String name = res.items[i].data.string;
-      (void)do_source(name.data, false, DOSO_NONE);
+      (void)do_source(name.data, false, DOSO_NONE, NULL);
     }
   }
 
@@ -602,10 +608,9 @@ ArrayOf(String) nvim__get_runtime(Array pat, Boolean all, Dict(runtime) *opts, E
 void nvim_set_current_dir(String dir, Error *err)
   FUNC_API_SINCE(1)
 {
-  if (dir.size >= MAXPATHL) {
-    api_set_error(err, kErrorTypeValidation, "Directory name is too long");
+  VALIDATE_S((dir.size < MAXPATHL), "directory name", "(too long)", {
     return;
-  }
+  });
 
   char string[MAXPATHL];
   memcpy(string, dir.data, dir.size);
@@ -639,7 +644,7 @@ String nvim_get_current_line(Error *err)
 /// @param[out] err Error details, if any
 void nvim_set_current_line(String line, Error *err)
   FUNC_API_SINCE(1)
-  FUNC_API_CHECK_TEXTLOCK
+  FUNC_API_TEXTLOCK_ALLOW_CMDWIN
 {
   buffer_set_line(curbuf->handle, curwin->w_cursor.lnum - 1, line, err);
 }
@@ -649,7 +654,7 @@ void nvim_set_current_line(String line, Error *err)
 /// @param[out] err Error details, if any
 void nvim_del_current_line(Error *err)
   FUNC_API_SINCE(1)
-  FUNC_API_CHECK_TEXTLOCK
+  FUNC_API_TEXTLOCK_ALLOW_CMDWIN
 {
   buffer_del_line(curbuf->handle, curwin->w_cursor.lnum - 1, err);
 }
@@ -664,16 +669,15 @@ Object nvim_get_var(String name, Error *err)
 {
   dictitem_T *di = tv_dict_find(&globvardict, name.data, (ptrdiff_t)name.size);
   if (di == NULL) {  // try to autoload script
-    if (!script_autoload(name.data, name.size, false) || aborting()) {
-      api_set_error(err, kErrorTypeValidation, "Key not found: %s", name.data);
+    bool found = script_autoload(name.data, name.size, false) && !aborting();
+    VALIDATE(found, "Key not found: %s", name.data, {
       return (Object)OBJECT_INIT;
-    }
+    });
     di = tv_dict_find(&globvardict, name.data, (ptrdiff_t)name.size);
   }
-  if (di == NULL) {
-    api_set_error(err, kErrorTypeValidation, "Key not found: %s", name.data);
+  VALIDATE((di != NULL), "Key not found: %s", name.data, {
     return (Object)OBJECT_INIT;
-  }
+  });
   return vim_to_object(&di->di_tv);
 }
 
@@ -738,15 +742,13 @@ void nvim_echo(Array chunks, Boolean history, Dict(echo_opts) *opts, Error *err)
     goto error;
   }
 
-  bool verbose = api_object_to_bool(opts->verbose, "verbose", false, err);
-
-  if (verbose) {
+  if (opts->verbose) {
     verbose_enter();
   }
 
   msg_multiattr(hl_msg, history ? "echomsg" : "echo", history);
 
-  if (verbose) {
+  if (opts->verbose) {
     verbose_leave();
     verbose_stop();  // flush now
   }
@@ -767,7 +769,7 @@ error:
 void nvim_out_write(String str)
   FUNC_API_SINCE(1)
 {
-  write_msg(str, false);
+  write_msg(str, false, false);
 }
 
 /// Writes a message to the Vim error buffer. Does not append "\n", the
@@ -777,7 +779,7 @@ void nvim_out_write(String str)
 void nvim_err_write(String str)
   FUNC_API_SINCE(1)
 {
-  write_msg(str, true);
+  write_msg(str, true, false);
 }
 
 /// Writes a message to the Vim error buffer. Appends "\n", so the buffer is
@@ -788,8 +790,7 @@ void nvim_err_write(String str)
 void nvim_err_writeln(String str)
   FUNC_API_SINCE(1)
 {
-  nvim_err_write(str);
-  nvim_err_write((String) { .data = "\n", .size = 1 });
+  write_msg(str, true, true);
 }
 
 /// Gets the current list of buffer handles
@@ -832,7 +833,7 @@ Buffer nvim_get_current_buf(void)
 /// @param[out] err Error details, if any
 void nvim_set_current_buf(Buffer buffer, Error *err)
   FUNC_API_SINCE(1)
-  FUNC_API_CHECK_TEXTLOCK
+  FUNC_API_TEXTLOCK
 {
   buf_T *buf = find_buffer_by_handle(buffer, err);
 
@@ -887,7 +888,7 @@ Window nvim_get_current_win(void)
 /// @param[out] err Error details, if any
 void nvim_set_current_win(Window window, Error *err)
   FUNC_API_SINCE(1)
-  FUNC_API_CHECK_TEXTLOCK
+  FUNC_API_TEXTLOCK
 {
   win_T *win = find_window_by_handle(window, err);
 
@@ -918,7 +919,7 @@ Buffer nvim_create_buf(Boolean listed, Boolean scratch, Error *err)
   FUNC_API_SINCE(6)
 {
   try_start();
-  buf_T *buf = buflist_new(NULL, NULL, (linenr_T)0,
+  buf_T *buf = buflist_new(NULL, NULL, 0,
                            BLN_NOOPT | BLN_NEW | (listed ? BLN_LISTED : 0));
   try_end(err);
   if (buf == NULL) {
@@ -936,14 +937,23 @@ Buffer nvim_create_buf(Boolean listed, Boolean scratch, Error *err)
     goto fail;
   }
 
+  // Set last_changedtick to avoid triggering a TextChanged autocommand right
+  // after it was added.
+  buf->b_last_changedtick = buf_get_changedtick(buf);
+  buf->b_last_changedtick_i = buf_get_changedtick(buf);
+  buf->b_last_changedtick_pum = buf_get_changedtick(buf);
+
+  // Only strictly needed for scratch, but could just as well be consistent
+  // and do this now. buffer is created NOW, not when it latter first happen
+  // to reach a window or aucmd_prepbuf() ..
+  buf_copy_options(buf, BCO_ENTER | BCO_NOHELP);
+
   if (scratch) {
-    aco_save_T aco;
-    aucmd_prepbuf(&aco, buf);
-    set_option_value("bufhidden", 0L, "hide", OPT_LOCAL);
-    set_option_value("buftype", 0L, "nofile", OPT_LOCAL);
-    set_option_value("swapfile", 0L, NULL, OPT_LOCAL);
-    set_option_value("modeline", 0L, NULL, OPT_LOCAL);  // 'nomodeline'
-    aucmd_restbuf(&aco);
+    set_string_option_direct_in_buf(buf, "bufhidden", -1, "hide", OPT_LOCAL, 0);
+    set_string_option_direct_in_buf(buf, "buftype", -1, "nofile", OPT_LOCAL, 0);
+    assert(buf->b_ml.ml_mfp->mf_fd < 0);  // ml_open() should not have opened swapfile already
+    buf->b_p_swf = false;
+    buf->b_p_ml = false;
   }
   return buf->b_fnum;
 
@@ -970,7 +980,7 @@ fail:
 ///
 /// @param buffer the buffer to use (expected to be empty)
 /// @param opts   Optional parameters.
-///          - on_input: lua callback for input sent, i e keypresses in terminal
+///          - on_input: Lua callback for input sent, i e keypresses in terminal
 ///            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
@@ -980,27 +990,31 @@ fail:
 /// @return Channel id, or 0 on error
 Integer nvim_open_term(Buffer buffer, DictionaryOf(LuaRef) opts, Error *err)
   FUNC_API_SINCE(7)
+  FUNC_API_TEXTLOCK_ALLOW_CMDWIN
 {
   buf_T *buf = find_buffer_by_handle(buffer, err);
   if (!buf) {
     return 0;
   }
 
+  if (cmdwin_type != 0 && buf == curbuf) {
+    api_set_error(err, kErrorTypeException, "%s", e_cmdwin);
+    return 0;
+  }
+
   LuaRef cb = LUA_NOREF;
   for (size_t i = 0; i < opts.size; i++) {
     String k = opts.items[i].key;
     Object *v = &opts.items[i].value;
     if (strequal("on_input", k.data)) {
-      if (v->type != kObjectTypeLuaRef) {
-        api_set_error(err, kErrorTypeValidation,
-                      "%s is not a function", "on_input");
+      VALIDATE_T("on_input", kObjectTypeLuaRef, v->type, {
         return 0;
-      }
+      });
       cb = v->data.luaref;
       v->data.luaref = LUA_NOREF;
       break;
     } else {
-      api_set_error(err, kErrorTypeValidation, "unexpected key: %s", k.data);
+      VALIDATE_S(false, "'opts' key", k.data, {});
     }
   }
 
@@ -1016,9 +1030,12 @@ Integer nvim_open_term(Buffer buffer, DictionaryOf(LuaRef) opts, Error *err)
   topts.write_cb = term_write;
   topts.resize_cb = term_resize;
   topts.close_cb = term_close;
-  Terminal *term = terminal_open(buf, topts);
-  terminal_check_size(term);
-  chan->term = term;
+  channel_incref(chan);
+  terminal_open(&chan->term, buf, topts);
+  if (chan->term != NULL) {
+    terminal_check_size(chan->term);
+  }
+  channel_decref(chan);
   return (Integer)chan->id;
 }
 
@@ -1040,7 +1057,7 @@ static void term_write(char *buf, size_t size, void *data)  // NOLINT(readabilit
 
 static void term_resize(uint16_t width, uint16_t height, void *data)
 {
-  // TODO(bfredl): lua callback
+  // TODO(bfredl): Lua callback
 }
 
 static void term_close(void *data)
@@ -1075,9 +1092,7 @@ void nvim_chan_send(Integer chan, String data, Error *err)
 
   channel_send((uint64_t)chan, data.data, data.size,
                false, &error);
-  if (error) {
-    api_set_error(err, kErrorTypeValidation, "%s", error);
-  }
+  VALIDATE(!error, "%s", error, {});
 }
 
 /// Gets the current list of tabpage handles.
@@ -1117,7 +1132,7 @@ Tabpage nvim_get_current_tabpage(void)
 /// @param[out] err Error details, if any
 void nvim_set_current_tabpage(Tabpage tabpage, Error *err)
   FUNC_API_SINCE(1)
-  FUNC_API_CHECK_TEXTLOCK
+  FUNC_API_TEXTLOCK
 {
   tabpage_T *tp = find_tab_by_handle(tabpage, err);
 
@@ -1159,15 +1174,14 @@ void nvim_set_current_tabpage(Tabpage tabpage, Error *err)
 ///     - false: Client must cancel the paste.
 Boolean nvim_paste(String data, Boolean crlf, Integer phase, Error *err)
   FUNC_API_SINCE(6)
-  FUNC_API_CHECK_TEXTLOCK
+  FUNC_API_TEXTLOCK_ALLOW_CMDWIN
 {
   static bool draining = false;
   bool cancel = false;
 
-  if (phase < -1 || phase > 3) {
-    api_set_error(err, kErrorTypeValidation, "Invalid phase: %" PRId64, phase);
+  VALIDATE_INT((phase >= -1 && phase <= 3), "phase", phase, {
     return false;
-  }
+  });
   Array args = ARRAY_DICT_INIT;
   Object rv = OBJECT_INIT;
   if (phase == -1 || phase == 1) {  // Start of paste-stream.
@@ -1231,23 +1245,20 @@ theend:
 /// @param[out] err Error details, if any
 void nvim_put(ArrayOf(String) lines, String type, Boolean after, Boolean follow, Error *err)
   FUNC_API_SINCE(6)
-  FUNC_API_CHECK_TEXTLOCK
+  FUNC_API_TEXTLOCK_ALLOW_CMDWIN
 {
   yankreg_T *reg = xcalloc(1, sizeof(yankreg_T));
-  if (!prepare_yankreg_from_object(reg, type, lines.size)) {
-    api_set_error(err, kErrorTypeValidation, "Invalid type: '%s'", type.data);
+  VALIDATE_S((prepare_yankreg_from_object(reg, type, lines.size)), "type", type.data, {
     goto cleanup;
-  }
+  });
   if (lines.size == 0) {
     goto cleanup;  // Nothing to do.
   }
 
   for (size_t i = 0; i < lines.size; i++) {
-    if (lines.items[i].type != kObjectTypeString) {
-      api_set_error(err, kErrorTypeValidation,
-                    "Invalid lines (expected array of strings)");
+    VALIDATE_T("line", kObjectTypeString, lines.items[i].type, {
       goto cleanup;
-    }
+    });
     String line = lines.items[i].data.string;
     reg->y_array[i] = xmemdupz(line.data, line.size);
     memchrsub(reg->y_array[i], NUL, NL, line.size);
@@ -1255,14 +1266,12 @@ void nvim_put(ArrayOf(String) lines, String type, Boolean after, Boolean follow,
 
   finish_yankreg_from_object(reg, false);
 
-  TRY_WRAP({
-    try_start();
+  TRY_WRAP(err, {
     bool VIsual_was_active = VIsual_active;
     msg_silent++;  // Avoid "N more lines" message.
     do_put(0, reg, after ? FORWARD : BACKWARD, 1, follow ? PUT_CURSEND : 0);
     msg_silent--;
     VIsual_active = VIsual_was_active;
-    try_end(err);
   });
 
 cleanup:
@@ -1291,9 +1300,9 @@ void nvim_subscribe(uint64_t channel_id, String event)
 void nvim_unsubscribe(uint64_t channel_id, String event)
   FUNC_API_SINCE(1) FUNC_API_REMOTE_ONLY
 {
-  size_t length = (event.size < METHOD_MAXLEN ?
-                   event.size :
-                   METHOD_MAXLEN);
+  size_t length = (event.size < METHOD_MAXLEN
+                   ? event.size
+                   : METHOD_MAXLEN);
   char e[METHOD_MAXLEN + 1];
   memcpy(e, event.data, length);
   e[length] = NUL;
@@ -1304,10 +1313,11 @@ void nvim_unsubscribe(uint64_t channel_id, String event)
 /// "#rrggbb" hexadecimal string.
 ///
 /// Example:
-/// <pre>vim
-///     :echo nvim_get_color_by_name("Pink")
-///     :echo nvim_get_color_by_name("#cbcbcb")
-/// </pre>
+///
+/// ```vim
+/// :echo nvim_get_color_by_name("Pink")
+/// :echo nvim_get_color_by_name("#cbcbcb")
+/// ```
 ///
 /// @param name Color name or "#rrggbb" string
 /// @return 24-bit RGB value, or -1 for invalid argument.
@@ -1348,11 +1358,8 @@ Dictionary nvim_get_context(Dict(context) *opts, Error *err)
   FUNC_API_SINCE(6)
 {
   Array types = ARRAY_DICT_INIT;
-  if (opts->types.type == kObjectTypeArray) {
-    types = opts->types.data.array;
-  } else if (opts->types.type != kObjectTypeNil) {
-    api_set_error(err, kErrorTypeValidation, "invalid value for key: types");
-    return (Dictionary)ARRAY_DICT_INIT;
+  if (HAS_KEY(opts, context, types)) {
+    types = opts->types;
   }
 
   int int_types = types.size > 0 ? 0 : kCtxAll;
@@ -1373,8 +1380,9 @@ Dictionary nvim_get_context(Dict(context) *opts, Error *err)
         } else if (strequal(s, "funcs")) {
           int_types |= kCtxFuncs;
         } else {
-          api_set_error(err, kErrorTypeValidation, "unexpected type: %s", s);
-          return (Dictionary)ARRAY_DICT_INIT;
+          VALIDATE_S(false, "type", s, {
+            return (Dictionary)ARRAY_DICT_INIT;
+          });
         }
       }
     }
@@ -1390,7 +1398,7 @@ Dictionary nvim_get_context(Dict(context) *opts, Error *err)
 /// Sets the current editor state from the given |context| map.
 ///
 /// @param  dict  |Context| map.
-Object nvim_load_context(Dictionary dict)
+Object nvim_load_context(Dictionary dict, Error *err)
   FUNC_API_SINCE(6)
 {
   Context ctx = CONTEXT_INIT;
@@ -1398,8 +1406,8 @@ Object nvim_load_context(Dictionary dict)
   int save_did_emsg = did_emsg;
   did_emsg = false;
 
-  ctx_from_dict(dict, &ctx);
-  if (!did_emsg) {
+  ctx_from_dict(dict, &ctx, err);
+  if (!ERROR_SET(err)) {
     ctx_restore(&ctx, kCtxAll);
   }
 
@@ -1421,7 +1429,7 @@ Dictionary nvim_get_mode(void)
   get_mode(modestr);
   bool blocked = input_blocking();
 
-  PUT(rv, "mode", STRING_OBJ(cstr_to_string(modestr)));
+  PUT(rv, "mode", CSTR_TO_OBJ(modestr));
   PUT(rv, "blocking", BOOLEAN_OBJ(blocked));
 
   return rv;
@@ -1446,29 +1454,31 @@ ArrayOf(Dictionary) nvim_get_keymap(String mode)
 /// Empty {rhs} is |<Nop>|. |keycodes| are replaced as usual.
 ///
 /// Example:
-/// <pre>vim
-///     call nvim_set_keymap('n', ' <NL>', '', {'nowait': v:true})
-/// </pre>
+///
+/// ```vim
+/// call nvim_set_keymap('n', ' <NL>', '', {'nowait': v:true})
+/// ```
 ///
 /// is equivalent to:
-/// <pre>vim
-///     nmap <nowait> <Space><NL> <Nop>
-/// </pre>
+///
+/// ```vim
+/// nmap <nowait> <Space><NL> <Nop>
+/// ```
 ///
 /// @param channel_id
 /// @param  mode  Mode short-name (map command prefix: "n", "i", "v", "x", …)
 ///               or "!" for |:map!|, or empty string for |:map|.
+///               "ia", "ca" or "!a" for abbreviation in Insert mode, Cmdline mode, or both, respectively
 /// @param  lhs   Left-hand-side |{lhs}| of the mapping.
 /// @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.
-///               "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.
-///               When "expr" is true, "replace_keycodes" (boolean) can be used to replace keycodes
-///               in the resulting string (see |nvim_replace_termcodes()|), and a Lua callback
-///               returning `nil` is equivalent to returning an empty string.
+/// @param  opts  Optional parameters map: Accepts all |:map-arguments| as keys except |<buffer>|,
+///               values are booleans (default false). Also:
+///               - "noremap" disables |recursive_mapping|, like |:noremap|
+///               - "desc" human-readable description.
+///               - "callback" Lua function called in place of {rhs}.
+///               - "replace_keycodes" (boolean) When "expr" is true, replace keycodes in the
+///                 resulting string (see |nvim_replace_termcodes()|). Returning nil from the Lua
+///                 "callback" is equivalent to returning an empty string.
 /// @param[out]   err   Error details, if any.
 void nvim_set_keymap(uint64_t channel_id, String mode, String lhs, String rhs, Dict(keymap) *opts,
                      Error *err)
@@ -1527,7 +1537,10 @@ Array nvim_get_api_info(uint64_t channel_id, Arena *arena)
 ///     - "commit" hash or similar identifier of commit
 /// @param type Must be one of the following values. Client libraries should
 ///             default to "remote" unless overridden by the user.
-///     - "remote" remote client connected to Nvim.
+///     - "remote" remote client connected "Nvim flavored" MessagePack-RPC (responses
+///                must be in reverse order of requests). |msgpack-rpc|
+///     - "msgpack-rpc" remote client connected to Nvim via fully MessagePack-RPC
+///                     compliant protocol.
 ///     - "ui" gui frontend
 ///     - "embedder" application using Nvim as a component (for example,
 ///                  IDE/editor implementing a vim mode).
@@ -1651,34 +1664,20 @@ Array nvim_call_atomic(uint64_t channel_id, Array calls, Arena *arena, Error *er
 
   size_t i;  // also used for freeing the variables
   for (i = 0; i < calls.size; i++) {
-    if (calls.items[i].type != kObjectTypeArray) {
-      api_set_error(err,
-                    kErrorTypeValidation,
-                    "Items in calls array must be arrays");
+    VALIDATE_T("'calls' item", kObjectTypeArray, calls.items[i].type, {
       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");
+    VALIDATE_EXP((call.size == 2), "'calls' item", "2-item Array", NULL, {
       goto theend;
-    }
-
-    if (call.items[0].type != kObjectTypeString) {
-      api_set_error(err,
-                    kErrorTypeValidation,
-                    "Name must be String");
+    });
+    VALIDATE_T("name", kObjectTypeString, call.items[0].type, {
       goto theend;
-    }
+    });
     String name = call.items[0].data.string;
-
-    if (call.items[1].type != kObjectTypeArray) {
-      api_set_error(err,
-                    kErrorTypeValidation,
-                    "Args must be Array");
+    VALIDATE_T("call args", kObjectTypeArray, call.items[1].type, {
       goto theend;
-    }
+    });
     Array args = call.items[1].data.array;
 
     MsgpackRpcRequestHandler handler =
@@ -1726,34 +1725,44 @@ theend:
 ///
 /// @param message  Message to write
 /// @param to_err   true: message is an error (uses `emsg` instead of `msg`)
-static void write_msg(String message, bool to_err)
+/// @param writeln  Append a trailing newline
+static void write_msg(String message, bool to_err, bool writeln)
 {
   static StringBuilder out_line_buf = KV_INITIAL_VALUE;
   static StringBuilder err_line_buf = KV_INITIAL_VALUE;
+  StringBuilder *line_buf = to_err ? &err_line_buf : &out_line_buf;
 
-#define PUSH_CHAR(i, line_buf, msg) \
-  if (kv_max(line_buf) == 0) { \
-    kv_resize(line_buf, LINE_BUFFER_MIN_SIZE); \
+#define PUSH_CHAR(c) \
+  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; \
-  } \
-  kv_push(line_buf, message.data[i]);
+  if (c == NL) { \
+    kv_push(*line_buf, NUL); \
+    if (to_err) { \
+      emsg(line_buf->items); \
+    } else { \
+      msg(line_buf->items, 0); \
+    } \
+    if (msg_silent == 0) { \
+      msg_didout = true; \
+    } \
+    kv_drop(*line_buf, kv_size(*line_buf)); \
+    kv_resize(*line_buf, LINE_BUFFER_MIN_SIZE); \
+  } else if (c == NUL) { \
+    kv_push(*line_buf, NL); \
+  } else { \
+    kv_push(*line_buf, c); \
+  }
 
   no_wait_return++;
   for (uint32_t i = 0; i < message.size; i++) {
     if (got_int) {
       break;
     }
-    if (to_err) {
-      PUSH_CHAR(i, err_line_buf, emsg);
-    } else {
-      PUSH_CHAR(i, out_line_buf, msg);
-    }
+    PUSH_CHAR(message.data[i]);
+  }
+  if (writeln) {
+    PUSH_CHAR(NL);
   }
   no_wait_return--;
   msg_end();
@@ -1850,10 +1859,9 @@ Array nvim_get_proc_children(Integer pid, Error *err)
   Array rvobj = ARRAY_DICT_INIT;
   int *proc_list = NULL;
 
-  if (pid <= 0 || pid > INT_MAX) {
-    api_set_error(err, kErrorTypeException, "Invalid pid: %" PRId64, pid);
+  VALIDATE_INT((pid > 0 && pid <= INT_MAX), "pid", pid, {
     goto end;
-  }
+  });
 
   size_t proc_count;
   int rv = os_proc_children((int)pid, &proc_list, &proc_count);
@@ -1892,10 +1900,10 @@ Object nvim_get_proc(Integer pid, Error *err)
   rvobj.data.dictionary = (Dictionary)ARRAY_DICT_INIT;
   rvobj.type = kObjectTypeDictionary;
 
-  if (pid <= 0 || pid > INT_MAX) {
-    api_set_error(err, kErrorTypeException, "Invalid pid: %" PRId64, pid);
+  VALIDATE_INT((pid > 0 && pid <= INT_MAX), "pid", pid, {
     return NIL;
-  }
+  });
+
 #ifdef MSWIN
   rvobj.data.dictionary = os_proc_info((int)pid);
   if (rvobj.data.dictionary.size == 0) {  // Process not found.
@@ -1937,10 +1945,9 @@ void nvim_select_popupmenu_item(Integer item, Boolean insert, Boolean finish, Di
                                 Error *err)
   FUNC_API_SINCE(6)
 {
-  if (opts.size > 0) {
-    api_set_error(err, kErrorTypeValidation, "opts dict isn't empty");
+  VALIDATE((opts.size == 0), "%s", "opts dict isn't empty", {
     return;
-  }
+  });
 
   if (finish) {
     insert = true;
@@ -1961,13 +1968,10 @@ Array nvim__inspect_cell(Integer grid, Integer row, Integer col, Arena *arena, E
     g = &pum_grid;
   } else if (grid > 1) {
     win_T *wp = get_win_by_grid_handle((handle_T)grid);
-    if (wp != NULL && wp->w_grid_alloc.chars != NULL) {
-      g = &wp->w_grid_alloc;
-    } else {
-      api_set_error(err, kErrorTypeValidation,
-                    "No grid with the given handle");
+    VALIDATE_INT((wp != NULL && wp->w_grid_alloc.chars != NULL), "grid handle", grid, {
       return ret;
-    }
+    });
+    g = &wp->w_grid_alloc;
   }
 
   if (row < 0 || row >= g->rows
@@ -1976,7 +1980,9 @@ Array nvim__inspect_cell(Integer grid, Integer row, Integer col, Arena *arena, E
   }
   ret = arena_array(arena, 3);
   size_t off = g->line_offset[(size_t)row] + (size_t)col;
-  ADD_C(ret, STRING_OBJ(cstr_as_string((char *)g->chars[off])));
+  char *sc_buf = arena_alloc(arena, MAX_SCHAR_SIZE, false);
+  schar_get(sc_buf, g->chars[off]);
+  ADD_C(ret, CSTR_AS_OBJ(sc_buf));
   int attr = g->attrs[off];
   ADD_C(ret, DICTIONARY_OBJ(hl_get_attr_by_id(attr, true, arena, err)));
   // will not work first time
@@ -1992,6 +1998,14 @@ void nvim__screenshot(String path)
   ui_call_screenshot(path);
 }
 
+/// For testing. The condition in schar_cache_clear_if_full is hard to
+/// reach, so this function can be used to force a cache clear in a test.
+void nvim__invalidate_glyph_cache(void)
+{
+  schar_cache_clear();
+  must_redraw = UPD_CLEAR;
+}
+
 Object nvim__unpack(String str, Error *err)
   FUNC_API_FAST
 {
@@ -2000,7 +2014,7 @@ Object nvim__unpack(String str, Error *err)
 
 /// Deletes an uppercase/file named mark. See |mark-motions|.
 ///
-/// @note fails with error if a lowercase or buffer local named mark is used.
+/// @note Lowercase name (or other buffer-local mark) is an error.
 /// @param name       Mark name
 /// @return true if the mark was deleted, else false.
 /// @see |nvim_buf_del_mark()|
@@ -2009,29 +2023,26 @@ Boolean nvim_del_mark(String name, Error *err)
   FUNC_API_SINCE(8)
 {
   bool res = false;
-  if (name.size != 1) {
-    api_set_error(err, kErrorTypeValidation,
-                  "Mark name must be a single character");
+  VALIDATE_S((name.size == 1), "mark name (must be a single char)", name.data, {
     return res;
-  }
+  });
   // Only allow file/uppercase marks
   // TODO(muniter): Refactor this ASCII_ISUPPER macro to a proper function
-  if (ASCII_ISUPPER(*name.data) || ascii_isdigit(*name.data)) {
-    res = set_mark(NULL, name, 0, 0, err);
-  } else {
-    api_set_error(err, kErrorTypeValidation,
-                  "Only file/uppercase marks allowed, invalid mark name: '%c'",
-                  *name.data);
-  }
+  VALIDATE_S((ASCII_ISUPPER(*name.data) || ascii_isdigit(*name.data)),
+             "mark name (must be file/uppercase)", name.data, {
+    return res;
+  });
+  res = set_mark(NULL, name, 0, 0, err);
   return res;
 }
 
-/// Return a tuple (row, col, buffer, buffername) representing the position of
-/// the uppercase/file named mark. See |mark-motions|.
+/// Returns a `(row, col, buffer, buffername)` tuple representing the position
+/// of the uppercase/file named mark. "End of line" column position is returned
+/// as |v:maxcol| (big number). See |mark-motions|.
 ///
 /// Marks are (1,0)-indexed. |api-indexing|
 ///
-/// @note fails with error if a lowercase or buffer local named mark is used.
+/// @note Lowercase name (or other buffer-local mark) is an error.
 /// @param name       Mark name
 /// @param opts       Optional parameters. Reserved for future use.
 /// @return 4-tuple (row, col, buffer, buffername), (0, 0, 0, '') if the mark is
@@ -2043,16 +2054,13 @@ Array nvim_get_mark(String name, Dictionary opts, Error *err)
 {
   Array rv = ARRAY_DICT_INIT;
 
-  if (name.size != 1) {
-    api_set_error(err, kErrorTypeValidation,
-                  "Mark name must be a single character");
+  VALIDATE_S((name.size == 1), "mark name (must be a single char)", name.data, {
     return rv;
-  } else if (!(ASCII_ISUPPER(*name.data) || ascii_isdigit(*name.data))) {
-    api_set_error(err, kErrorTypeValidation,
-                  "Only file/uppercase marks allowed, invalid mark name: '%c'",
-                  *name.data);
+  });
+  VALIDATE_S((ASCII_ISUPPER(*name.data) || ascii_isdigit(*name.data)),
+             "mark name (must be file/uppercase)", name.data, {
     return rv;
-  }
+  });
 
   xfmark_T *mark = mark_get_global(false, *name.data);  // false avoids loading the mark buffer
   pos_T pos = mark->fmark.mark;
@@ -2092,7 +2100,7 @@ Array nvim_get_mark(String name, Dictionary opts, Error *err)
   ADD(rv, INTEGER_OBJ(row));
   ADD(rv, INTEGER_OBJ(col));
   ADD(rv, INTEGER_OBJ(bufnr));
-  ADD(rv, STRING_OBJ(cstr_to_string(filename)));
+  ADD(rv, CSTR_TO_OBJ(filename));
 
   if (allocated) {
     xfree(filename);
@@ -2113,6 +2121,7 @@ Array nvim_get_mark(String name, Dictionary opts, Error *err)
 ///           - use_winbar: (boolean) Evaluate winbar instead of statusline.
 ///           - use_tabline: (boolean) Evaluate tabline instead of statusline. When true, {winid}
 ///                                    is ignored. Mutually exclusive with {use_winbar}.
+///           - use_statuscol_lnum: (number) Evaluate statuscolumn for this line number instead of statusline.
 ///
 /// @param[out] err Error details, if any.
 /// @return Dictionary containing statusline information, with these keys:
@@ -2130,106 +2139,117 @@ Dictionary nvim_eval_statusline(String str, Dict(eval_statusline) *opts, Error *
 
   int maxwidth;
   int fillchar = 0;
+  int statuscol_lnum = 0;
   Window window = 0;
-  bool use_winbar = false;
-  bool use_tabline = false;
-  bool highlights = false;
 
   if (str.size < 2 || memcmp(str.data, "%!", 2) != 0) {
     const char *const errmsg = check_stl_option(str.data);
-    if (errmsg) {
-      api_set_error(err, kErrorTypeValidation, "%s", errmsg);
+    VALIDATE(!errmsg, "%s", errmsg, {
       return result;
-    }
+    });
   }
 
-  if (HAS_KEY(opts->winid)) {
-    if (opts->winid.type != kObjectTypeInteger) {
-      api_set_error(err, kErrorTypeValidation, "winid must be an integer");
-      return result;
-    }
-
-    window = (Window)opts->winid.data.integer;
+  if (HAS_KEY(opts, eval_statusline, winid)) {
+    window = opts->winid;
   }
-  if (HAS_KEY(opts->fillchar)) {
-    if (opts->fillchar.type != kObjectTypeString || opts->fillchar.data.string.size == 0
-        || ((size_t)utf_ptr2len(opts->fillchar.data.string.data)
-            != opts->fillchar.data.string.size)) {
-      api_set_error(err, kErrorTypeValidation, "fillchar must be a single character");
+  if (HAS_KEY(opts, eval_statusline, fillchar)) {
+    VALIDATE_EXP((*opts->fillchar.data != 0
+                  && ((size_t)utf_ptr2len(opts->fillchar.data) == opts->fillchar.size)),
+                 "fillchar", "single character", NULL, {
       return result;
-    }
-    fillchar = utf_ptr2char(opts->fillchar.data.string.data);
+    });
+    fillchar = utf_ptr2char(opts->fillchar.data);
   }
-  if (HAS_KEY(opts->highlights)) {
-    highlights = api_object_to_bool(opts->highlights, "highlights", false, err);
 
-    if (ERROR_SET(err)) {
-      return result;
-    }
-  }
-  if (HAS_KEY(opts->use_winbar)) {
-    use_winbar = api_object_to_bool(opts->use_winbar, "use_winbar", false, err);
+  int use_bools = (int)opts->use_winbar + (int)opts->use_tabline;
 
-    if (ERROR_SET(err)) {
-      return result;
-    }
+  win_T *wp = opts->use_tabline ? curwin : find_window_by_handle(window, err);
+  if (wp == NULL) {
+    api_set_error(err, kErrorTypeException, "unknown winid %d", window);
+    return result;
   }
-  if (HAS_KEY(opts->use_tabline)) {
-    use_tabline = api_object_to_bool(opts->use_tabline, "use_tabline", false, err);
 
-    if (ERROR_SET(err)) {
+  if (HAS_KEY(opts, eval_statusline, use_statuscol_lnum)) {
+    statuscol_lnum = (int)opts->use_statuscol_lnum;
+    VALIDATE_RANGE(statuscol_lnum > 0 && statuscol_lnum <= wp->w_buffer->b_ml.ml_line_count,
+                   "use_statuscol_lnum", {
       return result;
-    }
+    });
+    use_bools++;
   }
-  if (use_winbar && use_tabline) {
-    api_set_error(err, kErrorTypeValidation, "use_winbar and use_tabline are mutually exclusive");
+  VALIDATE(use_bools <= 1, "%s",
+           "Can only use one of 'use_winbar', 'use_tabline' and 'use_statuscol_lnum'", {
     return result;
-  }
+  });
 
-  win_T *wp, *ewp;
+  int stc_hl_id = 0;
+  statuscol_T statuscol = { 0 };
+  SignTextAttrs sattrs[SIGN_SHOW_MAX] = { 0 };
 
-  if (use_tabline) {
-    wp = NULL;
-    ewp = curwin;
+  if (opts->use_tabline) {
     fillchar = ' ';
   } else {
-    wp = find_window_by_handle(window, err);
-    if (wp == NULL) {
-      api_set_error(err, kErrorTypeException, "unknown winid %d", window);
-      return result;
-    }
-    ewp = wp;
-
     if (fillchar == 0) {
-      if (use_winbar) {
+      if (opts->use_winbar) {
         fillchar = wp->w_p_fcs_chars.wbr;
       } else {
         int attr;
         fillchar = fillchar_status(&attr, wp);
       }
     }
-  }
+    if (statuscol_lnum) {
+      int line_id = 0;
+      int cul_id = 0;
+      int num_id = 0;
+      linenr_T lnum = statuscol_lnum;
+      wp->w_scwidth = win_signcol_count(wp);
+      decor_redraw_signs(wp, wp->w_buffer, lnum - 1, sattrs, &line_id, &cul_id, &num_id);
+
+      statuscol.sattrs = sattrs;
+      statuscol.foldinfo = fold_info(wp, lnum);
+      wp->w_cursorline = win_cursorline_standout(wp) ? wp->w_cursor.lnum : 0;
+
+      if (wp->w_p_cul) {
+        if (statuscol.foldinfo.fi_level != 0 && statuscol.foldinfo.fi_lines > 0) {
+          wp->w_cursorline = statuscol.foldinfo.fi_lnum;
+        }
+        statuscol.use_cul = lnum == wp->w_cursorline && (wp->w_p_culopt_flags & CULOPT_NBR);
+      }
 
-  if (HAS_KEY(opts->maxwidth)) {
-    if (opts->maxwidth.type != kObjectTypeInteger) {
-      api_set_error(err, kErrorTypeValidation, "maxwidth must be an integer");
-      return result;
+      statuscol.sign_cul_id = statuscol.use_cul ? cul_id : 0;
+      if (num_id) {
+        stc_hl_id = num_id;
+      } else if (statuscol.use_cul) {
+        stc_hl_id = HLF_CLN + 1;
+      } else if (wp->w_p_rnu) {
+        stc_hl_id = (lnum < wp->w_cursor.lnum ? HLF_LNA : HLF_LNB) + 1;
+      } else {
+        stc_hl_id = HLF_N + 1;
+      }
+
+      set_vim_var_nr(VV_LNUM, lnum);
+      set_vim_var_nr(VV_RELNUM, labs(get_cursor_rel_lnum(wp, lnum)));
+      set_vim_var_nr(VV_VIRTNUM, 0);
     }
+  }
 
-    maxwidth = (int)opts->maxwidth.data.integer;
+  if (HAS_KEY(opts, eval_statusline, maxwidth)) {
+    maxwidth = (int)opts->maxwidth;
   } else {
-    maxwidth = (use_tabline || (!use_winbar && global_stl_height() > 0)) ? Columns : wp->w_width;
+    maxwidth = statuscol_lnum ? win_col_off(wp)
+                              : (opts->use_tabline
+                                 || (!opts->use_winbar
+                                     && global_stl_height() > 0)) ? Columns : wp->w_width;
   }
 
   char buf[MAXPATHL];
   stl_hlrec_t *hltab;
-  stl_hlrec_t **hltab_ptr = highlights ? &hltab : NULL;
 
   // Temporarily reset 'cursorbind' to prevent side effects from moving the cursor away and back.
-  int p_crb_save = ewp->w_p_crb;
-  ewp->w_p_crb = false;
+  int p_crb_save = wp->w_p_crb;
+  wp->w_p_crb = false;
 
-  int width = build_stl_str_hl(ewp,
+  int width = build_stl_str_hl(wp,
                                buf,
                                sizeof(buf),
                                str.data,
@@ -2237,25 +2257,25 @@ Dictionary nvim_eval_statusline(String str, Dict(eval_statusline) *opts, Error *
                                0,
                                fillchar,
                                maxwidth,
-                               hltab_ptr,
+                               opts->highlights ? &hltab : NULL,
                                NULL,
-                               NULL);
+                               statuscol_lnum ? &statuscol : NULL);
 
   PUT(result, "width", INTEGER_OBJ(width));
 
   // Restore original value of 'cursorbind'
-  ewp->w_p_crb = p_crb_save;
+  wp->w_p_crb = p_crb_save;
 
-  if (highlights) {
+  if (opts->highlights) {
     Array hl_values = ARRAY_DICT_INIT;
     const char *grpname;
-    char user_group[6];
+    char user_group[15];  // strlen("User") + strlen("2147483647") + NUL
 
     // If first character doesn't have a defined highlight,
     // add the default highlight at the beginning of the highlight list
     if (hltab->start == NULL || (hltab->start - buf) != 0) {
       Dictionary hl_info = ARRAY_DICT_INIT;
-      grpname = get_default_stl_hl(wp, use_winbar);
+      grpname = get_default_stl_hl(opts->use_tabline ? NULL : wp, opts->use_winbar, stc_hl_id);
 
       PUT(hl_info, "start", INTEGER_OBJ(0));
       PUT(hl_info, "group", CSTR_TO_OBJ(grpname));
@@ -2266,10 +2286,10 @@ Dictionary nvim_eval_statusline(String str, Dict(eval_statusline) *opts, Error *
     for (stl_hlrec_t *sp = hltab; sp->start != NULL; sp++) {
       Dictionary hl_info = ARRAY_DICT_INIT;
 
-      PUT(hl_info, "start", INTEGER_OBJ((char *)sp->start - buf));
+      PUT(hl_info, "start", INTEGER_OBJ(sp->start - buf));
 
       if (sp->userhl == 0) {
-        grpname = get_default_stl_hl(wp, use_winbar);
+        grpname = get_default_stl_hl(opts->use_tabline ? NULL : wp, opts->use_winbar, stc_hl_id);
       } else if (sp->userhl < 0) {
         grpname = syn_id2name(-sp->userhl);
       } else {
@@ -2281,7 +2301,7 @@ Dictionary nvim_eval_statusline(String str, Dict(eval_statusline) *opts, Error *
     }
     PUT(result, "highlights", ARRAY_OBJ(hl_values));
   }
-  PUT(result, "str", CSTR_TO_OBJ((char *)buf));
+  PUT(result, "str", CSTR_TO_OBJ(buf));
 
   return result;
 }