vim-patch:8.1.1933: the eval.c file is too big (#19462)

Problem:    The eval.c file is too big.
Solution:   Move code related to variables to evalvars.c. (Yegappan
            Lakshmanan, closes vim/vim#4868)
https://github.com/vim/vim/commit/0522ba0359c96a8c2a4fc8fca0d3b58e49dda759

Name the new file eval/vars.c instead.

18 files changed, 1775 insertions, 1726 deletions

diff --git a/scripts/vim-patch.sh b/scripts/vim-patch.sh
index d5424f51ab..f1bc07c249 100755
--- a/scripts/vim-patch.sh
+++ b/scripts/vim-patch.sh
@@ -229,6 +229,10 @@ preprocess_patch() {
   LC_ALL=C sed -e 's/\( [ab]\/src\/nvim\)\/evalfunc\.c/\1\/eval\/funcs\.c/g' \
     "$file" > "$file".tmp && mv "$file".tmp "$file"
 
+  # Rename evalvars.c to eval/vars.c
+  LC_ALL=C sed -e 's/\( [ab]\/src\/nvim\)\/evalfunc\.c/\1\/eval\/vars\.c/g' \
+    "$file" > "$file".tmp && mv "$file".tmp "$file"
+
   # Rename userfunc.c to eval/userfunc.c
   LC_ALL=C sed -e 's/\( [ab]\/src\/nvim\)\/userfunc\.c/\1\/eval\/userfunc\.c/g' \
     "$file" > "$file".tmp && mv "$file".tmp "$file"
diff --git a/src/nvim/autocmd.c b/src/nvim/autocmd.c
index d364881084..73c2cda92b 100644
--- a/src/nvim/autocmd.c
+++ b/src/nvim/autocmd.c
@@ -14,6 +14,7 @@
 #include "nvim/edit.h"
 #include "nvim/eval.h"
 #include "nvim/eval/userfunc.h"
+#include "nvim/eval/vars.h"
 #include "nvim/ex_docmd.h"
 #include "nvim/ex_getln.h"
 #include "nvim/fileio.h"
diff --git a/src/nvim/buffer.c b/src/nvim/buffer.c
index f937450107..4830b200af 100644
--- a/src/nvim/buffer.c
+++ b/src/nvim/buffer.c
@@ -37,6 +37,7 @@
 #include "nvim/diff.h"
 #include "nvim/digraph.h"
 #include "nvim/eval.h"
+#include "nvim/eval/vars.h"
 #include "nvim/ex_cmds.h"
 #include "nvim/ex_cmds2.h"
 #include "nvim/ex_docmd.h"
diff --git a/src/nvim/eval.c b/src/nvim/eval.c
index 096fcba981..fb12214e59 100644
--- a/src/nvim/eval.c
+++ b/src/nvim/eval.c
@@ -27,6 +27,7 @@
 #include "nvim/eval/gc.h"
 #include "nvim/eval/typval.h"
 #include "nvim/eval/userfunc.h"
+#include "nvim/eval/vars.h"
 #include "nvim/ex_cmds2.h"
 #include "nvim/ex_getln.h"
 #include "nvim/ex_session.h"
@@ -58,20 +59,13 @@
 
 #define DICT_MAXNEST 100        // maximum nesting of lists and dicts
 
-static char *e_letunexp = N_("E18: Unexpected characters in :let");
 static char *e_missbrac = N_("E111: Missing ']'");
 static char *e_dictrange = N_("E719: Cannot use [:] with a Dictionary");
-static char *e_illvar = N_("E461: Illegal variable name: %s");
-static char *e_cannot_mod = N_("E995: Cannot modify existing variable");
 static char *e_nowhitespace
   = N_("E274: No white space allowed before parenthesis");
-static char *e_lock_unlock = N_("E940: Cannot lock or unlock variable %s");
 static char *e_write2 = N_("E80: Error while writing: %s");
 static char *e_string_list_or_blob_required = N_("E1098: String, List or Blob required");
 
-// TODO(ZyX-I): move to eval/executor
-static char *e_letwrong = N_("E734: Wrong variable type for %s=");
-
 static char * const namespace_char = "abglstvw";
 
 /// Variable used for g:
@@ -967,6 +961,30 @@ typval_T *eval_expr(char *arg)
   return tv;
 }
 
+/// List Vim variables.
+void list_vim_vars(int *first)
+{
+  list_hashtable_vars(&vimvarht, "v:", false, first);
+}
+
+/// List script-local variables, if there is a script.
+void list_script_vars(int *first)
+{
+  if (current_sctx.sc_sid > 0 && current_sctx.sc_sid <= ga_scripts.ga_len) {
+    list_hashtable_vars(&SCRIPT_VARS(current_sctx.sc_sid), "s:", false, first);
+  }
+}
+
+bool is_vimvarht(const hashtab_T *ht)
+{
+  return ht == &vimvarht;
+}
+
+bool is_compatht(const hashtab_T *ht)
+{
+  return ht == &compat_hashtab;
+}
+
 /// Prepare v: variable "idx" to be used.
 /// Save the current typeval in "save_tv".
 /// When not used yet add the variable to the v: hashtable.
@@ -1251,718 +1269,6 @@ int eval_foldexpr(char *arg, int *cp)
   return (int)retval;
 }
 
-/// ":cons[t] var = expr1" define constant
-/// ":cons[t] [name1, name2, ...] = expr1" define constants unpacking list
-/// ":cons[t] [name, ..., ; lastname] = expr" define constants unpacking list
-void ex_const(exarg_T *eap)
-{
-  ex_let_const(eap, true);
-}
-
-/// Get a list of lines from a HERE document. The here document is a list of
-/// lines surrounded by a marker.
-///     cmd << {marker}
-///       {line1}
-///       {line2}
-///       ....
-///     {marker}
-///
-/// The {marker} is a string. If the optional 'trim' word is supplied before the
-/// marker, then the leading indentation before the lines (matching the
-/// indentation in the 'cmd' line) is stripped.
-///
-/// @return  a List with {lines} or NULL.
-static list_T *heredoc_get(exarg_T *eap, char *cmd)
-{
-  char *marker;
-  char *p;
-  int marker_indent_len = 0;
-  int text_indent_len = 0;
-  char *text_indent = NULL;
-
-  if (eap->getline == NULL) {
-    emsg(_("E991: cannot use =<< here"));
-    return NULL;
-  }
-
-  // Check for the optional 'trim' word before the marker
-  cmd = skipwhite(cmd);
-  if (STRNCMP(cmd, "trim", 4) == 0
-      && (cmd[4] == NUL || ascii_iswhite(cmd[4]))) {
-    cmd = skipwhite(cmd + 4);
-
-    // Trim the indentation from all the lines in the here document.
-    // The amount of indentation trimmed is the same as the indentation of
-    // the first line after the :let command line.  To find the end marker
-    // the indent of the :let command line is trimmed.
-    p = *eap->cmdlinep;
-    while (ascii_iswhite(*p)) {
-      p++;
-      marker_indent_len++;
-    }
-    text_indent_len = -1;
-  }
-
-  // The marker is the next word.
-  if (*cmd != NUL && *cmd != '"') {
-    marker = skipwhite(cmd);
-    p = (char *)skiptowhite((char_u *)marker);
-    if (*skipwhite(p) != NUL && *skipwhite(p) != '"') {
-      emsg(_(e_trailing));
-      return NULL;
-    }
-    *p = NUL;
-    if (islower(*marker)) {
-      emsg(_("E221: Marker cannot start with lower case letter"));
-      return NULL;
-    }
-  } else {
-    emsg(_("E172: Missing marker"));
-    return NULL;
-  }
-
-  list_T *l = tv_list_alloc(0);
-  for (;;) {
-    int mi = 0;
-    int ti = 0;
-
-    char *theline = eap->getline(NUL, eap->cookie, 0, false);
-    if (theline == NULL) {
-      semsg(_("E990: Missing end marker '%s'"), marker);
-      break;
-    }
-
-    // with "trim": skip the indent matching the :let line to find the
-    // marker
-    if (marker_indent_len > 0
-        && STRNCMP(theline, *eap->cmdlinep, marker_indent_len) == 0) {
-      mi = marker_indent_len;
-    }
-    if (STRCMP(marker, theline + mi) == 0) {
-      xfree(theline);
-      break;
-    }
-    if (text_indent_len == -1 && *theline != NUL) {
-      // set the text indent from the first line.
-      p = theline;
-      text_indent_len = 0;
-      while (ascii_iswhite(*p)) {
-        p++;
-        text_indent_len++;
-      }
-      text_indent = xstrnsave(theline, (size_t)text_indent_len);
-    }
-    // with "trim": skip the indent matching the first line
-    if (text_indent != NULL) {
-      for (ti = 0; ti < text_indent_len; ti++) {
-        if (theline[ti] != text_indent[ti]) {
-          break;
-        }
-      }
-    }
-
-    tv_list_append_string(l, theline + ti, -1);
-    xfree(theline);
-  }
-  xfree(text_indent);
-
-  return l;
-}
-
-/// ":let" list all variable values
-/// ":let var1 var2" list variable values
-/// ":let var = expr" assignment command.
-/// ":let var += expr" assignment command.
-/// ":let var -= expr" assignment command.
-/// ":let var *= expr" assignment command.
-/// ":let var /= expr" assignment command.
-/// ":let var %= expr" assignment command.
-/// ":let var .= expr" assignment command.
-/// ":let var ..= expr" assignment command.
-/// ":let [var1, var2] = expr" unpack list.
-/// ":let [name, ..., ; lastname] = expr" unpack list.
-void ex_let(exarg_T *eap)
-{
-  ex_let_const(eap, false);
-}
-
-static void ex_let_const(exarg_T *eap, const bool is_const)
-{
-  char *arg = eap->arg;
-  char *expr = NULL;
-  typval_T rettv;
-  int i;
-  int var_count = 0;
-  int semicolon = 0;
-  char op[2];
-  char *argend;
-  int first = true;
-
-  argend = (char *)skip_var_list(arg, &var_count, &semicolon);
-  if (argend == NULL) {
-    return;
-  }
-  if (argend > arg && argend[-1] == '.') {  // For var.='str'.
-    argend--;
-  }
-  expr = skipwhite(argend);
-  if (*expr != '=' && !((vim_strchr("+-*/%.", *expr) != NULL
-                         && expr[1] == '=') || STRNCMP(expr, "..=", 3) == 0)) {
-    // ":let" without "=": list variables
-    if (*arg == '[') {
-      emsg(_(e_invarg));
-    } else if (!ends_excmd(*arg)) {
-      // ":let var1 var2"
-      arg = (char *)list_arg_vars(eap, (const char *)arg, &first);
-    } else if (!eap->skip) {
-      // ":let"
-      list_glob_vars(&first);
-      list_buf_vars(&first);
-      list_win_vars(&first);
-      list_tab_vars(&first);
-      list_script_vars(&first);
-      list_func_vars(&first);
-      list_vim_vars(&first);
-    }
-    eap->nextcmd = (char *)check_nextcmd((char_u *)arg);
-  } else if (expr[0] == '=' && expr[1] == '<' && expr[2] == '<') {
-    // HERE document
-    list_T *l = heredoc_get(eap, expr + 3);
-    if (l != NULL) {
-      tv_list_set_ret(&rettv, l);
-      if (!eap->skip) {
-        op[0] = '=';
-        op[1] = NUL;
-        (void)ex_let_vars(eap->arg, &rettv, false, semicolon, var_count,
-                          is_const, (char *)op);
-      }
-      tv_clear(&rettv);
-    }
-  } else {
-    op[0] = '=';
-    op[1] = NUL;
-    if (*expr != '=') {
-      if (vim_strchr("+-*/%.", *expr) != NULL) {
-        op[0] = *expr;  // +=, -=, *=, /=, %= or .=
-        if (expr[0] == '.' && expr[1] == '.') {  // ..=
-          expr++;
-        }
-      }
-      expr = skipwhite(expr + 2);
-    } else {
-      expr = skipwhite(expr + 1);
-    }
-
-    if (eap->skip) {
-      ++emsg_skip;
-    }
-    i = eval0(expr, &rettv, &eap->nextcmd, !eap->skip);
-    if (eap->skip) {
-      if (i != FAIL) {
-        tv_clear(&rettv);
-      }
-      emsg_skip--;
-    } else if (i != FAIL) {
-      (void)ex_let_vars(eap->arg, &rettv, false, semicolon, var_count,
-                        is_const, (char *)op);
-      tv_clear(&rettv);
-    }
-  }
-}
-
-/// Assign the typevalue "tv" to the variable or variables at "arg_start".
-/// Handles both "var" with any type and "[var, var; var]" with a list type.
-/// When "op" is not NULL it points to a string with characters that
-/// must appear after the variable(s).  Use "+", "-" or "." for add, subtract
-/// or concatenate.
-///
-/// @param copy  copy values from "tv", don't move
-/// @param semicolon  from skip_var_list()
-/// @param var_count  from skip_var_list()
-/// @param is_const  lock variables for :const
-///
-/// @return  OK or FAIL;
-static int ex_let_vars(char *arg_start, typval_T *tv, int copy, int semicolon, int var_count,
-                       int is_const, char *op)
-{
-  char *arg = arg_start;
-  typval_T ltv;
-
-  if (*arg != '[') {
-    /*
-     * ":let var = expr" or ":for var in list"
-     */
-    if (ex_let_one(arg, tv, copy, is_const, op, op) == NULL) {
-      return FAIL;
-    }
-    return OK;
-  }
-
-  // ":let [v1, v2] = list" or ":for [v1, v2] in listlist"
-  if (tv->v_type != VAR_LIST) {
-    emsg(_(e_listreq));
-    return FAIL;
-  }
-  list_T *const l = tv->vval.v_list;
-
-  const int len = tv_list_len(l);
-  if (semicolon == 0 && var_count < len) {
-    emsg(_("E687: Less targets than List items"));
-    return FAIL;
-  }
-  if (var_count - semicolon > len) {
-    emsg(_("E688: More targets than List items"));
-    return FAIL;
-  }
-  // List l may actually be NULL, but it should fail with E688 or even earlier
-  // if you try to do ":let [] = v:_null_list".
-  assert(l != NULL);
-
-  listitem_T *item = tv_list_first(l);
-  size_t rest_len = (size_t)tv_list_len(l);
-  while (*arg != ']') {
-    arg = skipwhite(arg + 1);
-    arg = ex_let_one(arg, TV_LIST_ITEM_TV(item), true, is_const, ",;]", op);
-    if (arg == NULL) {
-      return FAIL;
-    }
-    rest_len--;
-
-    item = TV_LIST_ITEM_NEXT(l, item);
-    arg = skipwhite(arg);
-    if (*arg == ';') {
-      /* Put the rest of the list (may be empty) in the var after ';'.
-       * Create a new list for this. */
-      list_T *const rest_list = tv_list_alloc((ptrdiff_t)rest_len);
-      while (item != NULL) {
-        tv_list_append_tv(rest_list, TV_LIST_ITEM_TV(item));
-        item = TV_LIST_ITEM_NEXT(l, item);
-      }
-
-      ltv.v_type = VAR_LIST;
-      ltv.v_lock = VAR_UNLOCKED;
-      ltv.vval.v_list = rest_list;
-      tv_list_ref(rest_list);
-
-      arg = ex_let_one(skipwhite(arg + 1), &ltv, false, is_const, "]", op);
-      tv_clear(&ltv);
-      if (arg == NULL) {
-        return FAIL;
-      }
-      break;
-    } else if (*arg != ',' && *arg != ']') {
-      internal_error("ex_let_vars()");
-      return FAIL;
-    }
-  }
-
-  return OK;
-}
-
-/// Skip over assignable variable "var" or list of variables "[var, var]".
-/// Used for ":let varvar = expr" and ":for varvar in expr".
-/// For "[var, var]" increment "*var_count" for each variable.
-/// for "[var, var; var]" set "semicolon".
-///
-/// @return  NULL for an error.
-static const char *skip_var_list(const char *arg, int *var_count, int *semicolon)
-{
-  const char *p;
-  const char *s;
-
-  if (*arg == '[') {
-    // "[var, var]": find the matching ']'.
-    p = arg;
-    for (;;) {
-      p = skipwhite(p + 1);             // skip whites after '[', ';' or ','
-      s = skip_var_one((char *)p);
-      if (s == p) {
-        semsg(_(e_invarg2), p);
-        return NULL;
-      }
-      ++*var_count;
-
-      p = skipwhite(s);
-      if (*p == ']') {
-        break;
-      } else if (*p == ';') {
-        if (*semicolon == 1) {
-          emsg(_("E452: Double ; in list of variables"));
-          return NULL;
-        }
-        *semicolon = 1;
-      } else if (*p != ',') {
-        semsg(_(e_invarg2), p);
-        return NULL;
-      }
-    }
-    return p + 1;
-  } else {
-    return skip_var_one((char *)arg);
-  }
-}
-
-/// Skip one (assignable) variable name, including @r, $VAR, &option, d.key,
-/// l[idx].
-static const char *skip_var_one(const char *arg)
-{
-  if (*arg == '@' && arg[1] != NUL) {
-    return arg + 2;
-  }
-  return (char *)find_name_end(*arg == '$' || *arg == '&' ? arg + 1 : arg,
-                               NULL, NULL, FNE_INCL_BR | FNE_CHECK_START);
-}
-
-/// List variables for hashtab "ht" with prefix "prefix".
-///
-/// @param empty  if TRUE also list NULL strings as empty strings.
-void list_hashtable_vars(hashtab_T *ht, const char *prefix, int empty, int *first)
-{
-  hashitem_T *hi;
-  dictitem_T *di;
-  int todo;
-
-  todo = (int)ht->ht_used;
-  for (hi = ht->ht_array; todo > 0 && !got_int; ++hi) {
-    if (!HASHITEM_EMPTY(hi)) {
-      todo--;
-      di = TV_DICT_HI2DI(hi);
-      char buf[IOSIZE];
-
-      // apply :filter /pat/ to variable name
-      xstrlcpy(buf, prefix, IOSIZE);
-      xstrlcat(buf, (char *)di->di_key, IOSIZE);
-      if (message_filtered((char_u *)buf)) {
-        continue;
-      }
-
-      if (empty || di->di_tv.v_type != VAR_STRING
-          || di->di_tv.vval.v_string != NULL) {
-        list_one_var(di, prefix, first);
-      }
-    }
-  }
-}
-
-/// List global variables.
-static void list_glob_vars(int *first)
-{
-  list_hashtable_vars(&globvarht, "", true, first);
-}
-
-/// List buffer variables.
-static void list_buf_vars(int *first)
-{
-  list_hashtable_vars(&curbuf->b_vars->dv_hashtab, "b:", true, first);
-}
-
-/// List window variables.
-static void list_win_vars(int *first)
-{
-  list_hashtable_vars(&curwin->w_vars->dv_hashtab, "w:", true, first);
-}
-
-/// List tab page variables.
-static void list_tab_vars(int *first)
-{
-  list_hashtable_vars(&curtab->tp_vars->dv_hashtab, "t:", true, first);
-}
-
-/// List Vim variables.
-static void list_vim_vars(int *first)
-{
-  list_hashtable_vars(&vimvarht, "v:", false, first);
-}
-
-/// List script-local variables, if there is a script.
-static void list_script_vars(int *first)
-{
-  if (current_sctx.sc_sid > 0 && current_sctx.sc_sid <= ga_scripts.ga_len) {
-    list_hashtable_vars(&SCRIPT_VARS(current_sctx.sc_sid), "s:", false, first);
-  }
-}
-
-/// List variables in "arg".
-static const char *list_arg_vars(exarg_T *eap, const char *arg, int *first)
-{
-  int error = FALSE;
-  int len;
-  const char *name;
-  const char *name_start;
-  typval_T tv;
-
-  while (!ends_excmd(*arg) && !got_int) {
-    if (error || eap->skip) {
-      arg = find_name_end(arg, NULL, NULL, FNE_INCL_BR | FNE_CHECK_START);
-      if (!ascii_iswhite(*arg) && !ends_excmd(*arg)) {
-        emsg_severe = true;
-        emsg(_(e_trailing));
-        break;
-      }
-    } else {
-      // get_name_len() takes care of expanding curly braces
-      name_start = name = arg;
-      char *tofree;
-      len = get_name_len(&arg, &tofree, true, true);
-      if (len <= 0) {
-        /* This is mainly to keep test 49 working: when expanding
-         * curly braces fails overrule the exception error message. */
-        if (len < 0 && !aborting()) {
-          emsg_severe = true;
-          semsg(_(e_invarg2), arg);
-          break;
-        }
-        error = TRUE;
-      } else {
-        if (tofree != NULL) {
-          name = tofree;
-        }
-        if (get_var_tv(name, len, &tv, NULL, true, false)
-            == FAIL) {
-          error = true;
-        } else {
-          // handle d.key, l[idx], f(expr)
-          const char *const arg_subsc = arg;
-          if (handle_subscript(&arg, &tv, true, true, name, &name) == FAIL) {
-            error = true;
-          } else {
-            if (arg == arg_subsc && len == 2 && name[1] == ':') {
-              switch (*name) {
-              case 'g':
-                list_glob_vars(first); break;
-              case 'b':
-                list_buf_vars(first); break;
-              case 'w':
-                list_win_vars(first); break;
-              case 't':
-                list_tab_vars(first); break;
-              case 'v':
-                list_vim_vars(first); break;
-              case 's':
-                list_script_vars(first); break;
-              case 'l':
-                list_func_vars(first); break;
-              default:
-                semsg(_("E738: Can't list variables for %s"), name);
-              }
-            } else {
-              char *const s = encode_tv2echo(&tv, NULL);
-              const char *const used_name = (arg == arg_subsc
-                                             ? name
-                                             : name_start);
-              const ptrdiff_t name_size = (used_name == tofree
-                                           ? (ptrdiff_t)strlen(used_name)
-                                           : (arg - used_name));
-              list_one_var_a("", used_name, name_size,
-                             tv.v_type, s == NULL ? "" : s, first);
-              xfree(s);
-            }
-            tv_clear(&tv);
-          }
-        }
-      }
-
-      xfree(tofree);
-    }
-
-    arg = (const char *)skipwhite(arg);
-  }
-
-  return arg;
-}
-
-// TODO(ZyX-I): move to eval/ex_cmds
-
-/// Set one item of `:let var = expr` or `:let [v1, v2] = list` to its value
-///
-/// @param[in]  arg  Start of the variable name.
-/// @param[in]  tv  Value to assign to the variable.
-/// @param[in]  copy  If true, copy value from `tv`.
-/// @param[in]  endchars  Valid characters after variable name or NULL.
-/// @param[in]  op  Operation performed: *op is `+`, `-`, `.` for `+=`, etc.
-///                 NULL for `=`.
-///
-/// @return a pointer to the char just after the var name or NULL in case of
-///         error.
-static char *ex_let_one(char *arg, typval_T *const tv, const bool copy, const bool is_const,
-                        const char *const endchars, const char *const op)
-  FUNC_ATTR_NONNULL_ARG(1, 2) FUNC_ATTR_WARN_UNUSED_RESULT
-{
-  char *arg_end = NULL;
-  int len;
-  int opt_flags;
-  char *tofree = NULL;
-
-  /*
-   * ":let $VAR = expr": Set environment variable.
-   */
-  if (*arg == '$') {
-    if (is_const) {
-      emsg(_("E996: Cannot lock an environment variable"));
-      return NULL;
-    }
-    // Find the end of the name.
-    arg++;
-    char *name = arg;
-    len = get_env_len((const char **)&arg);
-    if (len == 0) {
-      semsg(_(e_invarg2), name - 1);
-    } else {
-      if (op != NULL && vim_strchr("+-*/%", *op) != NULL) {
-        semsg(_(e_letwrong), op);
-      } else if (endchars != NULL
-                 && vim_strchr(endchars, *skipwhite(arg)) == NULL) {
-        emsg(_(e_letunexp));
-      } else if (!check_secure()) {
-        const char c1 = name[len];
-        name[len] = NUL;
-        const char *p = tv_get_string_chk(tv);
-        if (p != NULL && op != NULL && *op == '.') {
-          char *s = vim_getenv(name);
-
-          if (s != NULL) {
-            tofree = (char *)concat_str((const char_u *)s, (const char_u *)p);
-            p = (const char *)tofree;
-            xfree(s);
-          }
-        }
-        if (p != NULL) {
-          os_setenv(name, p, 1);
-          if (STRICMP(name, "HOME") == 0) {
-            init_homedir();
-          } else if (didset_vim && STRICMP(name, "VIM") == 0) {
-            didset_vim = false;
-          } else if (didset_vimruntime
-                     && STRICMP(name, "VIMRUNTIME") == 0) {
-            didset_vimruntime = false;
-          }
-          arg_end = arg;
-        }
-        name[len] = c1;
-        xfree(tofree);
-      }
-    }
-    // ":let &option = expr": Set option value.
-    // ":let &l:option = expr": Set local option value.
-    // ":let &g:option = expr": Set global option value.
-  } else if (*arg == '&') {
-    if (is_const) {
-      emsg(_("E996: Cannot lock an option"));
-      return NULL;
-    }
-    // Find the end of the name.
-    char *const p = (char *)find_option_end((const char **)&arg, &opt_flags);
-    if (p == NULL
-        || (endchars != NULL
-            && vim_strchr(endchars, *skipwhite(p)) == NULL)) {
-      emsg(_(e_letunexp));
-    } else {
-      int opt_type;
-      long numval;
-      char *stringval = NULL;
-      const char *s = NULL;
-
-      const char c1 = *p;
-      *p = NUL;
-
-      varnumber_T n = tv_get_number(tv);
-      if (tv->v_type != VAR_BOOL && tv->v_type != VAR_SPECIAL) {
-        s = tv_get_string_chk(tv);  // != NULL if number or string.
-      }
-      if (s != NULL && op != NULL && *op != '=') {
-        opt_type = get_option_value(arg, &numval, &stringval, opt_flags);
-        if ((opt_type == 1 && *op == '.')
-            || (opt_type == 0 && *op != '.')) {
-          semsg(_(e_letwrong), op);
-          s = NULL;  // don't set the value
-        } else {
-          if (opt_type == 1) {  // number
-            switch (*op) {
-            case '+':
-              n = numval + n; break;
-            case '-':
-              n = numval - n; break;
-            case '*':
-              n = numval * n; break;
-            case '/':
-              n = num_divide(numval, n); break;
-            case '%':
-              n = num_modulus(numval, n); break;
-            }
-          } else if (opt_type == 0 && stringval != NULL) {  // string
-            char *const oldstringval = stringval;
-            stringval = (char *)concat_str((const char_u *)stringval,
-                                           (const char_u *)s);
-            xfree(oldstringval);
-            s = stringval;
-          }
-        }
-      }
-      if (s != NULL || tv->v_type == VAR_BOOL
-          || tv->v_type == VAR_SPECIAL) {
-        set_option_value((const char *)arg, n, s, opt_flags);
-        arg_end = p;
-      }
-      *p = c1;
-      xfree(stringval);
-    }
-    // ":let @r = expr": Set register contents.
-  } else if (*arg == '@') {
-    if (is_const) {
-      emsg(_("E996: Cannot lock a register"));
-      return NULL;
-    }
-    arg++;
-    if (op != NULL && vim_strchr("+-*/%", *op) != NULL) {
-      semsg(_(e_letwrong), op);
-    } else if (endchars != NULL
-               && vim_strchr(endchars, *skipwhite(arg + 1)) == NULL) {
-      emsg(_(e_letunexp));
-    } else {
-      char *s;
-
-      char *ptofree = NULL;
-      const char *p = tv_get_string_chk(tv);
-      if (p != NULL && op != NULL && *op == '.') {
-        s = get_reg_contents(*arg == '@' ? '"' : *arg, kGRegExprSrc);
-        if (s != NULL) {
-          ptofree = (char *)concat_str((char_u *)s, (const char_u *)p);
-          p = (const char *)ptofree;
-          xfree(s);
-        }
-      }
-      if (p != NULL) {
-        write_reg_contents(*arg == '@' ? '"' : *arg,
-                           (const char_u *)p, (ssize_t)STRLEN(p), false);
-        arg_end = arg + 1;
-      }
-      xfree(ptofree);
-    }
-  }
-  /*
-   * ":let var = expr": Set internal variable.
-   * ":let {expr} = expr": Idem, name made with curly braces
-   */
-  else if (eval_isnamec1(*arg) || *arg == '{') {
-    lval_T lv;
-
-    char *const p = get_lval(arg, tv, &lv, false, false, 0, FNE_CHECK_START);
-    if (p != NULL && lv.ll_name != NULL) {
-      if (endchars != NULL && vim_strchr(endchars, *skipwhite(p)) == NULL) {
-        emsg(_(e_letunexp));
-      } else {
-        set_var_lval(&lv, p, tv, copy, is_const, op);
-        arg_end = p;
-      }
-    }
-    clear_lval(&lv);
-  } else {
-    semsg(_(e_invarg2), arg);
-  }
-
-  return arg_end;
-}
-
 // TODO(ZyX-I): move to eval/executor
 
 /// Get an lvalue
@@ -2352,8 +1658,8 @@ void clear_lval(lval_T *lp)
 /// @param endp  points to just after the parsed name.
 /// @param op    NULL, "+" for "+=", "-" for "-=", "*" for "*=", "/" for "/=",
 ///              "%" for "%=", "." for ".=" or "=" for "=".
-static void set_var_lval(lval_T *lp, char *endp, typval_T *rettv, int copy, const bool is_const,
-                         const char *op)
+void set_var_lval(lval_T *lp, char *endp, typval_T *rettv, int copy, const bool is_const,
+                  const char *op)
 {
   int cc;
   listitem_T *ri;
@@ -2805,327 +2111,6 @@ void set_context_for_expression(expand_T *xp, char *arg, cmdidx_T cmdidx)
   xp->xp_pattern = arg;
 }
 
-/// ":unlet[!] var1 ... " command.
-void ex_unlet(exarg_T *eap)
-{
-  ex_unletlock(eap, eap->arg, 0, do_unlet_var);
-}
-
-// TODO(ZyX-I): move to eval/ex_cmds
-
-/// ":lockvar" and ":unlockvar" commands
-void ex_lockvar(exarg_T *eap)
-{
-  char *arg = eap->arg;
-  int deep = 2;
-
-  if (eap->forceit) {
-    deep = -1;
-  } else if (ascii_isdigit(*arg)) {
-    deep = getdigits_int(&arg, false, -1);
-    arg = skipwhite(arg);
-  }
-
-  ex_unletlock(eap, arg, deep, do_lock_var);
-}
-
-// TODO(ZyX-I): move to eval/ex_cmds
-
-/// Common parsing logic for :unlet, :lockvar and :unlockvar.
-///
-/// Invokes `callback` afterwards if successful and `eap->skip == false`.
-///
-/// @param[in]  eap  Ex command arguments for the command.
-/// @param[in]  argstart  Start of the string argument for the command.
-/// @param[in]  deep  Levels to (un)lock for :(un)lockvar, -1 to (un)lock
-///                   everything.
-/// @param[in]  callback  Appropriate handler for the command.
-static void ex_unletlock(exarg_T *eap, char *argstart, int deep, ex_unletlock_callback callback)
-  FUNC_ATTR_NONNULL_ALL
-{
-  char *arg = argstart;
-  char *name_end;
-  bool error = false;
-  lval_T lv;
-
-  do {
-    if (*arg == '$') {
-      lv.ll_name = (const char *)arg;
-      lv.ll_tv = NULL;
-      arg++;
-      if (get_env_len((const char **)&arg) == 0) {
-        semsg(_(e_invarg2), arg - 1);
-        return;
-      }
-      if (!error && !eap->skip && callback(&lv, arg, eap, deep) == FAIL) {
-        error = true;
-      }
-      name_end = arg;
-    } else {
-      // Parse the name and find the end.
-      name_end = get_lval(arg, NULL, &lv, true, eap->skip || error,
-                          0, FNE_CHECK_START);
-      if (lv.ll_name == NULL) {
-        error = true;  // error, but continue parsing.
-      }
-      if (name_end == NULL
-          || (!ascii_iswhite(*name_end) && !ends_excmd(*name_end))) {
-        if (name_end != NULL) {
-          emsg_severe = true;
-          emsg(_(e_trailing));
-        }
-        if (!(eap->skip || error)) {
-          clear_lval(&lv);
-        }
-        break;
-      }
-
-      if (!error && !eap->skip && callback(&lv, name_end, eap, deep) == FAIL) {
-        error = true;
-      }
-
-      if (!eap->skip) {
-        clear_lval(&lv);
-      }
-    }
-    arg = skipwhite(name_end);
-  } while (!ends_excmd(*arg));
-
-  eap->nextcmd = (char *)check_nextcmd((char_u *)arg);
-}
-
-// TODO(ZyX-I): move to eval/ex_cmds
-
-/// Unlet a variable indicated by `lp`.
-///
-/// @param[in]  lp  The lvalue.
-/// @param[in]  name_end  End of the string argument for the command.
-/// @param[in]  eap  Ex command arguments for :unlet.
-/// @param[in]  deep  Unused.
-///
-/// @return OK on success, or FAIL on failure.
-static int do_unlet_var(lval_T *lp, char *name_end, exarg_T *eap, int deep FUNC_ATTR_UNUSED)
-  FUNC_ATTR_NONNULL_ALL
-{
-  int forceit = eap->forceit;
-  int ret = OK;
-  int cc;
-
-  if (lp->ll_tv == NULL) {
-    cc = (char_u)(*name_end);
-    *name_end = NUL;
-
-    // Environment variable, normal name or expanded name.
-    if (*lp->ll_name == '$') {
-      os_unsetenv(lp->ll_name + 1);
-    } else if (do_unlet(lp->ll_name, lp->ll_name_len, forceit) == FAIL) {
-      ret = FAIL;
-    }
-    *name_end = (char)cc;
-  } else if ((lp->ll_list != NULL
-              // ll_list is not NULL when lvalue is not in a list, NULL lists
-              // yield E689.
-              && var_check_lock(tv_list_locked(lp->ll_list),
-                                lp->ll_name,
-                                lp->ll_name_len))
-             || (lp->ll_dict != NULL
-                 && var_check_lock(lp->ll_dict->dv_lock,
-                                   lp->ll_name,
-                                   lp->ll_name_len))) {
-    return FAIL;
-  } else if (lp->ll_range) {
-    assert(lp->ll_list != NULL);
-    // Delete a range of List items.
-    listitem_T *const first_li = lp->ll_li;
-    listitem_T *last_li = first_li;
-    for (;;) {
-      listitem_T *const li = TV_LIST_ITEM_NEXT(lp->ll_list, lp->ll_li);
-      if (var_check_lock(TV_LIST_ITEM_TV(lp->ll_li)->v_lock,
-                         lp->ll_name,
-                         lp->ll_name_len)) {
-        return false;
-      }
-      lp->ll_li = li;
-      lp->ll_n1++;
-      if (lp->ll_li == NULL || (!lp->ll_empty2 && lp->ll_n2 < lp->ll_n1)) {
-        break;
-      } else {
-        last_li = lp->ll_li;
-      }
-    }
-    tv_list_remove_items(lp->ll_list, first_li, last_li);
-  } else {
-    if (lp->ll_list != NULL) {
-      // unlet a List item.
-      tv_list_item_remove(lp->ll_list, lp->ll_li);
-    } else {
-      // unlet a Dictionary item.
-      dict_T *d = lp->ll_dict;
-      assert(d != NULL);
-      dictitem_T *di = lp->ll_di;
-      bool watched = tv_dict_is_watched(d);
-      char *key = NULL;
-      typval_T oldtv;
-
-      if (watched) {
-        tv_copy(&di->di_tv, &oldtv);
-        // need to save key because dictitem_remove will free it
-        key = xstrdup((char *)di->di_key);
-      }
-
-      tv_dict_item_remove(d, di);
-
-      if (watched) {
-        tv_dict_watcher_notify(d, key, NULL, &oldtv);
-        tv_clear(&oldtv);
-        xfree(key);
-      }
-    }
-  }
-
-  return ret;
-}
-
-// TODO(ZyX-I): move to eval/ex_cmds
-
-/// unlet a variable
-///
-/// @param[in]  name  Variable name to unlet.
-/// @param[in]  name_len  Variable name length.
-/// @param[in]  forceit  If true, do not complain if variable doesn’t exist.
-///
-/// @return OK if it existed, FAIL otherwise.
-int do_unlet(const char *const name, const size_t name_len, const bool forceit)
-  FUNC_ATTR_NONNULL_ALL
-{
-  const char *varname;
-  dict_T *dict;
-  hashtab_T *ht = find_var_ht_dict(name, name_len, &varname, &dict);
-
-  if (ht != NULL && *varname != NUL) {
-    dict_T *d = get_current_funccal_dict(ht);
-    if (d == NULL) {
-      if (ht == &globvarht) {
-        d = &globvardict;
-      } else if (ht == &compat_hashtab) {
-        d = &vimvardict;
-      } else {
-        dictitem_T *const di = find_var_in_ht(ht, *name, "", 0, false);
-        d = di->di_tv.vval.v_dict;
-      }
-      if (d == NULL) {
-        internal_error("do_unlet()");
-        return FAIL;
-      }
-    }
-
-    hashitem_T *hi = hash_find(ht, varname);
-    if (HASHITEM_EMPTY(hi)) {
-      hi = find_hi_in_scoped_ht(name, &ht);
-    }
-    if (hi != NULL && !HASHITEM_EMPTY(hi)) {
-      dictitem_T *const di = TV_DICT_HI2DI(hi);
-      if (var_check_fixed(di->di_flags, name, TV_CSTRING)
-          || var_check_ro(di->di_flags, name, TV_CSTRING)
-          || var_check_lock(d->dv_lock, name, TV_CSTRING)) {
-        return FAIL;
-      }
-
-      if (var_check_lock(d->dv_lock, name, TV_CSTRING)) {
-        return FAIL;
-      }
-
-      typval_T oldtv;
-      bool watched = tv_dict_is_watched(dict);
-
-      if (watched) {
-        tv_copy(&di->di_tv, &oldtv);
-      }
-
-      delete_var(ht, hi);
-
-      if (watched) {
-        tv_dict_watcher_notify(dict, varname, NULL, &oldtv);
-        tv_clear(&oldtv);
-      }
-      return OK;
-    }
-  }
-  if (forceit) {
-    return OK;
-  }
-  semsg(_("E108: No such variable: \"%s\""), name);
-  return FAIL;
-}
-
-// TODO(ZyX-I): move to eval/ex_cmds
-
-/// Lock or unlock variable indicated by `lp`.
-///
-/// Locks if `eap->cmdidx == CMD_lockvar`, unlocks otherwise.
-///
-/// @param[in]  lp  The lvalue.
-/// @param[in]  name_end  Unused.
-/// @param[in]  eap  Ex command arguments for :(un)lockvar.
-/// @param[in]  deep  Levels to (un)lock, -1 to (un)lock everything.
-///
-/// @return OK on success, or FAIL on failure.
-static int do_lock_var(lval_T *lp, char *name_end FUNC_ATTR_UNUSED, exarg_T *eap, int deep)
-  FUNC_ATTR_NONNULL_ARG(1, 3)
-{
-  bool lock = eap->cmdidx == CMD_lockvar;
-  int ret = OK;
-
-  if (deep == 0) {  // Nothing to do.
-    return OK;
-  }
-
-  if (lp->ll_tv == NULL) {
-    if (*lp->ll_name == '$') {
-      semsg(_(e_lock_unlock), lp->ll_name);
-      ret = FAIL;
-    } else {
-      // Normal name or expanded name.
-      dictitem_T *const di = find_var(lp->ll_name, lp->ll_name_len, NULL,
-                                      true);
-      if (di == NULL) {
-        ret = FAIL;
-      } else if ((di->di_flags & DI_FLAGS_FIX)
-                 && di->di_tv.v_type != VAR_DICT
-                 && di->di_tv.v_type != VAR_LIST) {
-        // For historical reasons this error is not given for Lists and
-        // Dictionaries. E.g. b: dictionary may be locked/unlocked.
-        semsg(_(e_lock_unlock), lp->ll_name);
-        ret = FAIL;
-      } else {
-        if (lock) {
-          di->di_flags |= DI_FLAGS_LOCK;
-        } else {
-          di->di_flags &= (uint8_t)(~DI_FLAGS_LOCK);
-        }
-        tv_item_lock(&di->di_tv, deep, lock, false);
-      }
-    }
-  } else if (lp->ll_range) {
-    listitem_T *li = lp->ll_li;
-
-    // (un)lock a range of List items.
-    while (li != NULL && (lp->ll_empty2 || lp->ll_n2 >= lp->ll_n1)) {
-      tv_item_lock(TV_LIST_ITEM_TV(li), deep, lock, false);
-      li = TV_LIST_ITEM_NEXT(lp->ll_list, li);
-      lp->ll_n1++;
-    }
-  } else if (lp->ll_list != NULL) {
-    // (un)lock a List item.
-    tv_item_lock(TV_LIST_ITEM_TV(lp->ll_li), deep, lock, false);
-  } else {
-    // (un)lock a Dictionary item.
-    tv_item_lock(&lp->ll_di->di_tv, deep, lock, false);
-  }
-
-  return ret;
-}
-
 /// Delete all "menutrans_" variables.
 void del_menutrans_vars(void)
 {
@@ -6474,73 +5459,6 @@ win_T *find_tabwin(typval_T *wvp, typval_T *tvp)
   return wp;
 }
 
-/// getwinvar() and gettabwinvar()
-///
-/// @param off  1 for gettabwinvar()
-void getwinvar(typval_T *argvars, typval_T *rettv, int off)
-{
-  win_T *win;
-  dictitem_T *v;
-  tabpage_T *tp = NULL;
-  bool done = false;
-
-  if (off == 1) {
-    tp = find_tabpage((int)tv_get_number_chk(&argvars[0], NULL));
-  } else {
-    tp = curtab;
-  }
-  win = find_win_by_nr(&argvars[off], tp);
-  const char *varname = tv_get_string_chk(&argvars[off + 1]);
-
-  rettv->v_type = VAR_STRING;
-  rettv->vval.v_string = NULL;
-
-  emsg_off++;
-  if (win != NULL && varname != NULL) {
-    // Set curwin to be our win, temporarily.  Also set the tabpage,
-    // otherwise the window is not valid. Only do this when needed,
-    // autocommands get blocked.
-    bool need_switch_win = tp != curtab || win != curwin;
-    switchwin_T switchwin;
-    if (!need_switch_win || switch_win(&switchwin, win, tp, true) == OK) {
-      if (*varname == '&') {
-        if (varname[1] == NUL) {
-          // get all window-local options in a dict
-          dict_T *opts = get_winbuf_options(false);
-
-          if (opts != NULL) {
-            tv_dict_set_ret(rettv, opts);
-            done = true;
-          }
-        } else if (get_option_tv(&varname, rettv, 1) == OK) {
-          // window-local-option
-          done = true;
-        }
-      } else {
-        // Look up the variable.
-        // Let getwinvar({nr}, "") return the "w:" dictionary.
-        v = find_var_in_ht(&win->w_vars->dv_hashtab, 'w', varname,
-                           strlen(varname), false);
-        if (v != NULL) {
-          tv_copy(&v->di_tv, rettv);
-          done = true;
-        }
-      }
-    }
-
-    if (need_switch_win) {
-      // restore previous notion of curwin
-      restore_win(&switchwin, true);
-    }
-  }
-  emsg_off--;
-
-  if (!done && argvars[off + 2].v_type != VAR_UNKNOWN) {
-    // use the default return value
-    tv_copy(&argvars[off + 2], rettv);
-  }
-}
-
 /// This function is used by f_input() and f_inputdialog() functions. The third
 /// argument to f_input() specifies the type of completion to use at the
 /// prompt. The third argument to f_inputdialog() specifies the value to return
@@ -6934,56 +5852,6 @@ void set_buffer_lines(buf_T *buf, linenr_T lnum_arg, bool append, const typval_T
   }
 }
 
-/*
- * "setwinvar()" and "settabwinvar()" functions
- */
-
-void setwinvar(typval_T *argvars, typval_T *rettv, int off)
-{
-  if (check_secure()) {
-    return;
-  }
-
-  tabpage_T *tp = NULL;
-  if (off == 1) {
-    tp = find_tabpage((int)tv_get_number_chk(&argvars[0], NULL));
-  } else {
-    tp = curtab;
-  }
-  win_T *const win = find_win_by_nr(&argvars[off], tp);
-  const char *varname = tv_get_string_chk(&argvars[off + 1]);
-  typval_T *varp = &argvars[off + 2];
-
-  if (win != NULL && varname != NULL && varp != NULL) {
-    bool need_switch_win = tp != curtab || win != curwin;
-    switchwin_T switchwin;
-    if (!need_switch_win || switch_win(&switchwin, win, tp, true) == OK) {
-      if (*varname == '&') {
-        long numval;
-        bool error = false;
-
-        varname++;
-        numval = tv_get_number_chk(varp, &error);
-        char nbuf[NUMBUFLEN];
-        const char *const strval = tv_get_string_buf_chk(varp, nbuf);
-        if (!error && strval != NULL) {
-          set_option_value(varname, numval, strval, OPT_LOCAL);
-        }
-      } else {
-        const size_t varname_len = strlen(varname);
-        char *const winvarname = xmalloc(varname_len + 3);
-        memcpy(winvarname, "w:", 2);
-        memcpy(winvarname + 2, varname, varname_len + 1);
-        set_var(winvarname, varname_len + 2, varp, true);
-        xfree(winvarname);
-      }
-    }
-    if (need_switch_win) {
-      restore_win(&switchwin, true);
-    }
-  }
-}
-
 /// "stdpath()" helper for list results
 void get_xdg_var_list(const XDGVarType xdg, typval_T *rettv)
   FUNC_ATTR_NONNULL_ALL
@@ -7871,7 +6739,7 @@ int list2fpos(typval_T *arg, pos_T *posp, int *fnump, colnr_T *curswantp, bool c
 /// Advance "arg" to the first character after the name.
 ///
 /// @return  0 for error.
-static int get_env_len(const char **arg)
+int get_env_len(const char **arg)
 {
   int len;
 
@@ -8404,41 +7272,6 @@ char *set_cmdarg(exarg_T *eap, char *oldarg)
   return oldval;
 }
 
-/// Get the value of internal variable "name".
-/// Return OK or FAIL.  If OK is returned "rettv" must be cleared.
-///
-/// @param len  length of "name"
-/// @param rettv  NULL when only checking existence
-/// @param dip  non-NULL when typval's dict item is needed
-/// @param verbose  may give error message
-/// @param no_autoload  do not use script autoloading
-int get_var_tv(const char *name, int len, typval_T *rettv, dictitem_T **dip, int verbose,
-               int no_autoload)
-{
-  int ret = OK;
-  typval_T *tv = NULL;
-  dictitem_T *v;
-
-  v = find_var(name, (size_t)len, NULL, no_autoload);
-  if (v != NULL) {
-    tv = &v->di_tv;
-    if (dip != NULL) {
-      *dip = v;
-    }
-  }
-
-  if (tv == NULL) {
-    if (rettv != NULL && verbose) {
-      semsg(_("E121: Undefined variable: %.*s"), len, name);
-    }
-    ret = FAIL;
-  } else if (rettv != NULL) {
-    tv_copy(tv, rettv);
-  }
-
-  return ret;
-}
-
 /// Check if variable "name[len]" is a local variable or an argument.
 /// If so, "*eval_lavars_used" is set to true.
 static void check_vars(const char *name, size_t len)
@@ -8704,8 +7537,8 @@ dictitem_T *find_var_in_ht(hashtab_T *const ht, int htname, const char *const va
 /// @param[out]  d  Scope dictionary.
 ///
 /// @return Scope hashtab, NULL if name is not valid.
-static hashtab_T *find_var_ht_dict(const char *name, const size_t name_len, const char **varname,
-                                   dict_T **d)
+hashtab_T *find_var_ht_dict(const char *name, const size_t name_len, const char **varname,
+                            dict_T **d)
 {
   hashitem_T *hi;
   funccall_T *funccal = get_funccal();
@@ -8808,21 +7641,6 @@ hashtab_T *find_var_ht(const char *name, const size_t name_len, const char **var
   return find_var_ht_dict(name, name_len, varname, &d);
 }
 
-/// @return  the string value of a (global/local) variable or
-///          NULL when it doesn't exist.
-///
-/// @see  tv_get_string() for how long the pointer remains valid.
-char_u *get_var_value(const char *const name)
-{
-  dictitem_T *v;
-
-  v = find_var(name, strlen(name), NULL, false);
-  if (v == NULL) {
-    return NULL;
-  }
-  return (char_u *)tv_get_string(&v->di_tv);
-}
-
 /// Allocate a new hashtab for a sourced script.  It will be used while
 /// sourcing this script and when executing functions defined in the script.
 void new_script_vars(scid_T id)
@@ -8878,391 +7696,6 @@ void unref_var_dict(dict_T *dict)
   tv_dict_unref(dict);
 }
 
-/// Clean up a list of internal variables.
-/// Frees all allocated variables and the value they contain.
-/// Clears hashtab "ht", does not free it.
-void vars_clear(hashtab_T *ht)
-{
-  vars_clear_ext(ht, TRUE);
-}
-
-/// Like vars_clear(), but only free the value if "free_val" is TRUE.
-void vars_clear_ext(hashtab_T *ht, int free_val)
-{
-  int todo;
-  hashitem_T *hi;
-  dictitem_T *v;
-
-  hash_lock(ht);
-  todo = (int)ht->ht_used;
-  for (hi = ht->ht_array; todo > 0; ++hi) {
-    if (!HASHITEM_EMPTY(hi)) {
-      --todo;
-
-      // Free the variable.  Don't remove it from the hashtab,
-      // ht_array might change then.  hash_clear() takes care of it
-      // later.
-      v = TV_DICT_HI2DI(hi);
-      if (free_val) {
-        tv_clear(&v->di_tv);
-      }
-      if (v->di_flags & DI_FLAGS_ALLOC) {
-        xfree(v);
-      }
-    }
-  }
-  hash_clear(ht);
-  ht->ht_used = 0;
-}
-
-/// Delete a variable from hashtab "ht" at item "hi".
-/// Clear the variable value and free the dictitem.
-static void delete_var(hashtab_T *ht, hashitem_T *hi)
-{
-  dictitem_T *di = TV_DICT_HI2DI(hi);
-
-  hash_remove(ht, hi);
-  tv_clear(&di->di_tv);
-  xfree(di);
-}
-
-/// List the value of one internal variable.
-static void list_one_var(dictitem_T *v, const char *prefix, int *first)
-{
-  char *const s = encode_tv2echo(&v->di_tv, NULL);
-  list_one_var_a(prefix, (const char *)v->di_key, (ptrdiff_t)STRLEN(v->di_key),
-                 v->di_tv.v_type, (s == NULL ? "" : s), first);
-  xfree(s);
-}
-
-/// @param[in]  name_len  Length of the name. May be -1, in this case strlen()
-///                       will be used.
-/// @param[in,out]  first  When true clear rest of screen and set to false.
-static void list_one_var_a(const char *prefix, const char *name, const ptrdiff_t name_len,
-                           const VarType type, const char *string, int *first)
-{
-  // don't use msg() or msg_attr() to avoid overwriting "v:statusmsg"
-  msg_start();
-  msg_puts(prefix);
-  if (name != NULL) {  // "a:" vars don't have a name stored
-    msg_puts_attr_len(name, name_len, 0);
-  }
-  msg_putchar(' ');
-  msg_advance(22);
-  if (type == VAR_NUMBER) {
-    msg_putchar('#');
-  } else if (type == VAR_FUNC || type == VAR_PARTIAL) {
-    msg_putchar('*');
-  } else if (type == VAR_LIST) {
-    msg_putchar('[');
-    if (*string == '[') {
-      ++string;
-    }
-  } else if (type == VAR_DICT) {
-    msg_putchar('{');
-    if (*string == '{') {
-      ++string;
-    }
-  } else {
-    msg_putchar(' ');
-  }
-
-  msg_outtrans((char *)string);
-
-  if (type == VAR_FUNC || type == VAR_PARTIAL) {
-    msg_puts("()");
-  }
-  if (*first) {
-    msg_clr_eos();
-    *first = FALSE;
-  }
-}
-
-/// Set variable to the given value
-///
-/// If the variable already exists, the value is updated. Otherwise the variable
-/// is created.
-///
-/// @param[in]  name  Variable name to set.
-/// @param[in]  name_len  Length of the variable name.
-/// @param  tv  Variable value.
-/// @param[in]  copy  True if value in tv is to be copied.
-void set_var(const char *name, const size_t name_len, typval_T *const tv, const bool copy)
-  FUNC_ATTR_NONNULL_ALL
-{
-  set_var_const(name, name_len, tv, copy, false);
-}
-
-/// Set variable to the given value
-///
-/// If the variable already exists, the value is updated. Otherwise the variable
-/// is created.
-///
-/// @param[in]  name  Variable name to set.
-/// @param[in]  name_len  Length of the variable name.
-/// @param  tv  Variable value.
-/// @param[in]  copy  True if value in tv is to be copied.
-/// @param[in]  is_const  True if value in tv is to be locked.
-static void set_var_const(const char *name, const size_t name_len, typval_T *const tv,
-                          const bool copy, const bool is_const)
-  FUNC_ATTR_NONNULL_ALL
-{
-  dictitem_T *v;
-  hashtab_T *ht;
-  dict_T *dict;
-
-  const char *varname;
-  ht = find_var_ht_dict(name, name_len, &varname, &dict);
-  const bool watched = tv_dict_is_watched(dict);
-
-  if (ht == NULL || *varname == NUL) {
-    semsg(_(e_illvar), name);
-    return;
-  }
-  v = find_var_in_ht(ht, 0, varname, name_len - (size_t)(varname - name), true);
-
-  // Search in parent scope which is possible to reference from lambda
-  if (v == NULL) {
-    v = find_var_in_scoped_ht(name, name_len, true);
-  }
-
-  if (tv_is_func(*tv) && !var_check_func_name(name, v == NULL)) {
-    return;
-  }
-
-  typval_T oldtv = TV_INITIAL_VALUE;
-  if (v != NULL) {
-    if (is_const) {
-      emsg(_(e_cannot_mod));
-      return;
-    }
-
-    // existing variable, need to clear the value
-    if (var_check_ro(v->di_flags, name, name_len)
-        || var_check_lock(v->di_tv.v_lock, name, name_len)) {
-      return;
-    }
-
-    // Handle setting internal v: variables separately where needed to
-    // prevent changing the type.
-    if (ht == &vimvarht) {
-      if (v->di_tv.v_type == VAR_STRING) {
-        XFREE_CLEAR(v->di_tv.vval.v_string);
-        if (copy || tv->v_type != VAR_STRING) {
-          const char *const val = tv_get_string(tv);
-
-          // Careful: when assigning to v:errmsg and tv_get_string()
-          // causes an error message the variable will already be set.
-          if (v->di_tv.vval.v_string == NULL) {
-            v->di_tv.vval.v_string = xstrdup(val);
-          }
-        } else {
-          // Take over the string to avoid an extra alloc/free.
-          v->di_tv.vval.v_string = tv->vval.v_string;
-          tv->vval.v_string = NULL;
-        }
-        return;
-      } else if (v->di_tv.v_type == VAR_NUMBER) {
-        v->di_tv.vval.v_number = tv_get_number(tv);
-        if (strcmp(varname, "searchforward") == 0) {
-          set_search_direction(v->di_tv.vval.v_number ? '/' : '?');
-        } else if (strcmp(varname, "hlsearch") == 0) {
-          no_hlsearch = !v->di_tv.vval.v_number;
-          redraw_all_later(SOME_VALID);
-        }
-        return;
-      } else if (v->di_tv.v_type != tv->v_type) {
-        semsg(_("E963: setting %s to value with wrong type"), name);
-        return;
-      }
-    }
-
-    if (watched) {
-      tv_copy(&v->di_tv, &oldtv);
-    }
-    tv_clear(&v->di_tv);
-  } else {  // Add a new variable.
-    // Can't add "v:" or "a:" variable.
-    if (ht == &vimvarht || ht == get_funccal_args_ht()) {
-      semsg(_(e_illvar), name);
-      return;
-    }
-
-    // Make sure the variable name is valid.
-    if (!valid_varname(varname)) {
-      return;
-    }
-
-    // Make sure dict is valid
-    assert(dict != NULL);
-
-    v = xmalloc(sizeof(dictitem_T) + strlen(varname));
-    STRCPY(v->di_key, varname);
-    if (tv_dict_add(dict, v) == FAIL) {
-      xfree(v);
-      return;
-    }
-    v->di_flags = DI_FLAGS_ALLOC;
-    if (is_const) {
-      v->di_flags |= DI_FLAGS_LOCK;
-    }
-  }
-
-  if (copy || tv->v_type == VAR_NUMBER || tv->v_type == VAR_FLOAT) {
-    tv_copy(tv, &v->di_tv);
-  } else {
-    v->di_tv = *tv;
-    v->di_tv.v_lock = VAR_UNLOCKED;
-    tv_init(tv);
-  }
-
-  if (watched) {
-    if (oldtv.v_type == VAR_UNKNOWN) {
-      tv_dict_watcher_notify(dict, (char *)v->di_key, &v->di_tv, NULL);
-    } else {
-      tv_dict_watcher_notify(dict, (char *)v->di_key, &v->di_tv, &oldtv);
-      tv_clear(&oldtv);
-    }
-  }
-
-  if (is_const) {
-    // Like :lockvar! name: lock the value and what it contains, but only
-    // if the reference count is up to one.  That locks only literal
-    // values.
-    tv_item_lock(&v->di_tv, DICT_MAXNEST, true, true);
-  }
-}
-
-/// Check whether variable is read-only (DI_FLAGS_RO, DI_FLAGS_RO_SBX)
-///
-/// Also gives an error message.
-///
-/// @param[in]  flags  di_flags attribute value.
-/// @param[in]  name  Variable name, for use in error message.
-/// @param[in]  name_len  Variable name length. Use #TV_TRANSLATE to translate
-///                       variable name and compute the length. Use #TV_CSTRING
-///                       to compute the length with strlen() without
-///                       translating.
-///
-///                       Both #TV_… values are used for optimization purposes:
-///                       variable name with its length is needed only in case
-///                       of error, when no error occurs computing them is
-///                       a waste of CPU resources. This especially applies to
-///                       gettext.
-///
-/// @return True if variable is read-only: either always or in sandbox when
-///         sandbox is enabled, false otherwise.
-bool var_check_ro(const int flags, const char *name, size_t name_len)
-  FUNC_ATTR_WARN_UNUSED_RESULT FUNC_ATTR_NONNULL_ALL
-{
-  const char *error_message = NULL;
-  if (flags & DI_FLAGS_RO) {
-    error_message = _(e_readonlyvar);
-  } else if ((flags & DI_FLAGS_RO_SBX) && sandbox) {
-    error_message = N_("E794: Cannot set variable in the sandbox: \"%.*s\"");
-  }
-
-  if (error_message == NULL) {
-    return false;
-  }
-  if (name_len == TV_TRANSLATE) {
-    name = _(name);
-    name_len = strlen(name);
-  } else if (name_len == TV_CSTRING) {
-    name_len = strlen(name);
-  }
-
-  semsg(_(error_message), (int)name_len, name);
-
-  return true;
-}
-
-/// Check whether variable is fixed (DI_FLAGS_FIX)
-///
-/// Also gives an error message.
-///
-/// @param[in]  flags  di_flags attribute value.
-/// @param[in]  name  Variable name, for use in error message.
-/// @param[in]  name_len  Variable name length. Use #TV_TRANSLATE to translate
-///                       variable name and compute the length. Use #TV_CSTRING
-///                       to compute the length with strlen() without
-///                       translating.
-///
-///                       Both #TV_… values are used for optimization purposes:
-///                       variable name with its length is needed only in case
-///                       of error, when no error occurs computing them is
-///                       a waste of CPU resources. This especially applies to
-///                       gettext.
-///
-/// @return True if variable is fixed, false otherwise.
-bool var_check_fixed(const int flags, const char *name, size_t name_len)
-  FUNC_ATTR_WARN_UNUSED_RESULT FUNC_ATTR_NONNULL_ALL
-{
-  if (flags & DI_FLAGS_FIX) {
-    if (name_len == TV_TRANSLATE) {
-      name = _(name);
-      name_len = strlen(name);
-    } else if (name_len == TV_CSTRING) {
-      name_len = strlen(name);
-    }
-    semsg(_("E795: Cannot delete variable %.*s"), (int)name_len, name);
-    return true;
-  }
-  return false;
-}
-
-// TODO(ZyX-I): move to eval/expressions
-
-/// Check if name is a valid name to assign funcref to
-///
-/// @param[in]  name  Possible function/funcref name.
-/// @param[in]  new_var  True if it is a name for a variable.
-///
-/// @return false in case of error, true in case of success. Also gives an
-///         error message if appropriate.
-bool var_check_func_name(const char *const name, const bool new_var)
-  FUNC_ATTR_NONNULL_ALL FUNC_ATTR_WARN_UNUSED_RESULT
-{
-  // Allow for w: b: s: and t:.
-  if (!(vim_strchr("wbst", name[0]) != NULL && name[1] == ':')
-      && !ASCII_ISUPPER((name[0] != NUL && name[1] == ':')
-                        ? name[2] : name[0])) {
-    semsg(_("E704: Funcref variable name must start with a capital: %s"), name);
-    return false;
-  }
-  // Don't allow hiding a function.  When "v" is not NULL we might be
-  // assigning another function to the same var, the type is checked
-  // below.
-  if (new_var && function_exists(name, false)) {
-    semsg(_("E705: Variable name conflicts with existing function: %s"),
-          name);
-    return false;
-  }
-  return true;
-}
-
-// TODO(ZyX-I): move to eval/expressions
-
-/// Check if a variable name is valid
-///
-/// @param[in]  varname  Variable name to check.
-///
-/// @return false when variable name is not valid, true when it is. Also gives
-///         an error message if appropriate.
-bool valid_varname(const char *varname)
-  FUNC_ATTR_NONNULL_ALL FUNC_ATTR_WARN_UNUSED_RESULT
-{
-  for (const char *p = varname; *p != NUL; p++) {
-    if (!eval_isnamec1((int)(uint8_t)(*p))
-        && (p == varname || !ascii_isdigit(*p))
-        && *p != AUTOLOAD_CHAR) {
-      semsg(_(e_illvar), varname);
-      return false;
-    }
-  }
-  return true;
-}
-
 /// Make a copy of an item
 ///
 /// Lists and Dictionaries are also copied.
@@ -9527,7 +7960,7 @@ void ex_execute(exarg_T *eap)
 ///
 /// @return  NULL when no option name found.  Otherwise pointer to the char
 ///          after the option name.
-static const char *find_option_end(const char **const arg, int *const opt_flags)
+const char *find_option_end(const char **const arg, int *const opt_flags)
 {
   const char *p = *arg;
 
@@ -10889,35 +9322,3 @@ char *typval_tostring(typval_T *arg)
   }
   return encode_tv2string(arg, NULL);
 }
-
-bool var_exists(const char *var)
-  FUNC_ATTR_NONNULL_ALL
-{
-  char *tofree;
-  bool n = false;
-
-  // get_name_len() takes care of expanding curly braces
-  const char *name = var;
-  const int len = get_name_len(&var, &tofree, true, false);
-  if (len > 0) {
-    typval_T tv;
-
-    if (tofree != NULL) {
-      name = tofree;
-    }
-    n = get_var_tv(name, len, &tv, NULL, false, true) == OK;
-    if (n) {
-      // Handle d.key, l[idx], f(expr).
-      n = handle_subscript(&var, &tv, true, false, name, &name) == OK;
-      if (n) {
-        tv_clear(&tv);
-      }
-    }
-  }
-  if (*var != NUL) {
-    n = false;
-  }
-
-  xfree(tofree);
-  return n;
-}
diff --git a/src/nvim/eval/executor.c b/src/nvim/eval/executor.c
index 3e66150180..b461456a3a 100644
--- a/src/nvim/eval/executor.c
+++ b/src/nvim/eval/executor.c
@@ -12,8 +12,6 @@
 # include "eval/executor.c.generated.h"
 #endif
 
-static char *e_letwrong = N_("E734: Wrong variable type for %s=");
-
 char *e_listidx = N_("E684: list index out of range: %" PRId64);
 
 /// Handle tv1 += tv2, -=, *=, /=,  %=, .=
diff --git a/src/nvim/eval/funcs.c b/src/nvim/eval/funcs.c
index c58dbcd620..6dcdccf773 100644
--- a/src/nvim/eval/funcs.c
+++ b/src/nvim/eval/funcs.c
@@ -25,6 +25,7 @@
 #include "nvim/eval/funcs.h"
 #include "nvim/eval/typval.h"
 #include "nvim/eval/userfunc.h"
+#include "nvim/eval/vars.h"
 #include "nvim/ex_docmd.h"
 #include "nvim/ex_getln.h"
 #include "nvim/file_search.h"
@@ -3707,50 +3708,6 @@ static void f_gettabinfo(typval_T *argvars, typval_T *rettv, FunPtr fptr)
   }
 }
 
-/// "gettabvar()" function
-static void f_gettabvar(typval_T *argvars, typval_T *rettv, FunPtr fptr)
-{
-  bool done = false;
-
-  rettv->v_type = VAR_STRING;
-  rettv->vval.v_string = NULL;
-
-  const char *const varname = tv_get_string_chk(&argvars[1]);
-  tabpage_T *const tp = find_tabpage((int)tv_get_number_chk(&argvars[0], NULL));
-  if (tp != NULL && varname != NULL) {
-    // Set tp to be our tabpage, temporarily.  Also set the window to the
-    // first window in the tabpage, otherwise the window is not valid.
-    win_T *const window = tp == curtab || tp->tp_firstwin == NULL
-        ? firstwin
-        : tp->tp_firstwin;
-    switchwin_T switchwin;
-    if (switch_win(&switchwin, window, tp, true) == OK) {
-      // look up the variable
-      // Let gettabvar({nr}, "") return the "t:" dictionary.
-      const dictitem_T *const v = find_var_in_ht(&tp->tp_vars->dv_hashtab, 't',
-                                                 varname, strlen(varname),
-                                                 false);
-      if (v != NULL) {
-        tv_copy(&v->di_tv, rettv);
-        done = true;
-      }
-    }
-
-    // restore previous notion of curwin
-    restore_win(&switchwin, true);
-  }
-
-  if (!done && argvars[2].v_type != VAR_UNKNOWN) {
-    tv_copy(&argvars[2], rettv);
-  }
-}
-
-/// "gettabwinvar()" function
-static void f_gettabwinvar(typval_T *argvars, typval_T *rettv, FunPtr fptr)
-{
-  getwinvar(argvars, rettv, 1);
-}
-
 /// "gettagstack()" function
 static void f_gettagstack(typval_T *argvars, typval_T *rettv, FunPtr fptr)
 {
@@ -3974,12 +3931,6 @@ static void f_getwinposy(typval_T *argvars, typval_T *rettv, FunPtr fptr)
   rettv->vval.v_number = -1;
 }
 
-/// "getwinvar()" function
-static void f_getwinvar(typval_T *argvars, typval_T *rettv, FunPtr fptr)
-{
-  getwinvar(argvars, rettv, 0);
-}
-
 /// "glob()" function
 static void f_glob(typval_T *argvars, typval_T *rettv, FunPtr fptr)
 {
@@ -8856,43 +8807,6 @@ free_lstval:
   }
 }
 
-/// "settabvar()" function
-static void f_settabvar(typval_T *argvars, typval_T *rettv, FunPtr fptr)
-{
-  rettv->vval.v_number = 0;
-
-  if (check_secure()) {
-    return;
-  }
-
-  tabpage_T *const tp = find_tabpage((int)tv_get_number_chk(&argvars[0], NULL));
-  const char *const varname = tv_get_string_chk(&argvars[1]);
-  typval_T *const varp = &argvars[2];
-
-  if (varname != NULL && tp != NULL) {
-    tabpage_T *const save_curtab = curtab;
-    goto_tabpage_tp(tp, false, false);
-
-    const size_t varname_len = strlen(varname);
-    char *const tabvarname = xmalloc(varname_len + 3);
-    memcpy(tabvarname, "t:", 2);
-    memcpy(tabvarname + 2, varname, varname_len + 1);
-    set_var(tabvarname, varname_len + 2, varp, true);
-    xfree(tabvarname);
-
-    // Restore current tabpage.
-    if (valid_tabpage(save_curtab)) {
-      goto_tabpage_tp(save_curtab, false, false);
-    }
-  }
-}
-
-/// "settabwinvar()" function
-static void f_settabwinvar(typval_T *argvars, typval_T *rettv, FunPtr fptr)
-{
-  setwinvar(argvars, rettv, 1);
-}
-
 /// "settagstack()" function
 static void f_settagstack(typval_T *argvars, typval_T *rettv, FunPtr fptr)
 {
@@ -8946,12 +8860,6 @@ static void f_settagstack(typval_T *argvars, typval_T *rettv, FunPtr fptr)
   }
 }
 
-/// "setwinvar()" function
-static void f_setwinvar(typval_T *argvars, typval_T *rettv, FunPtr fptr)
-{
-  setwinvar(argvars, rettv, 0);
-}
-
 /// f_sha256 - sha256({string}) function
 static void f_sha256(typval_T *argvars, typval_T *rettv, FunPtr fptr)
 {
diff --git a/src/nvim/eval/typval.c b/src/nvim/eval/typval.c
index e19cf411c0..63458e7e69 100644
--- a/src/nvim/eval/typval.c
+++ b/src/nvim/eval/typval.c
@@ -19,6 +19,7 @@
 #include "nvim/eval/typval.h"
 #include "nvim/eval/typval_encode.h"
 #include "nvim/eval/userfunc.h"
+#include "nvim/eval/vars.h"
 #include "nvim/garray.h"
 #include "nvim/gettext.h"
 #include "nvim/globals.h"
diff --git a/src/nvim/eval/userfunc.c b/src/nvim/eval/userfunc.c
index d9102c07a5..b01415f052 100644
--- a/src/nvim/eval/userfunc.c
+++ b/src/nvim/eval/userfunc.c
@@ -10,6 +10,7 @@
 #include "nvim/eval.h"
 #include "nvim/eval/encode.h"
 #include "nvim/eval/userfunc.h"
+#include "nvim/eval/vars.h"
 #include "nvim/ex_cmds2.h"
 #include "nvim/ex_docmd.h"
 #include "nvim/ex_getln.h"
diff --git a/src/nvim/eval/vars.c b/src/nvim/eval/vars.c
new file mode 100644
index 0000000000..021d2764a6
--- /dev/null
+++ b/src/nvim/eval/vars.c
@@ -0,0 +1,1715 @@
+// 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
+
+// eval/vars.c: functions for dealing with variables
+
+#include "nvim/ascii.h"
+#include "nvim/buffer.h"
+#include "nvim/charset.h"
+#include "nvim/eval.h"
+#include "nvim/eval/encode.h"
+#include "nvim/eval/typval.h"
+#include "nvim/eval/userfunc.h"
+#include "nvim/eval/vars.h"
+#include "nvim/ex_cmds.h"
+#include "nvim/ex_docmd.h"
+#include "nvim/ops.h"
+#include "nvim/option.h"
+#include "nvim/search.h"
+#include "nvim/window.h"
+
+#ifdef INCLUDE_GENERATED_DECLARATIONS
+# include "eval/vars.c.generated.h"
+#endif
+
+// TODO(ZyX-I): Remove DICT_MAXNEST, make users be non-recursive instead
+
+#define DICT_MAXNEST 100        // maximum nesting of lists and dicts
+
+static char *e_letunexp = N_("E18: Unexpected characters in :let");
+static char *e_lock_unlock = N_("E940: Cannot lock or unlock variable %s");
+
+/// Get a list of lines from a HERE document. The here document is a list of
+/// lines surrounded by a marker.
+///     cmd << {marker}
+///       {line1}
+///       {line2}
+///       ....
+///     {marker}
+///
+/// The {marker} is a string. If the optional 'trim' word is supplied before the
+/// marker, then the leading indentation before the lines (matching the
+/// indentation in the 'cmd' line) is stripped.
+///
+/// @return  a List with {lines} or NULL.
+static list_T *heredoc_get(exarg_T *eap, char *cmd)
+{
+  char *marker;
+  char *p;
+  int marker_indent_len = 0;
+  int text_indent_len = 0;
+  char *text_indent = NULL;
+
+  if (eap->getline == NULL) {
+    emsg(_("E991: cannot use =<< here"));
+    return NULL;
+  }
+
+  // Check for the optional 'trim' word before the marker
+  cmd = skipwhite(cmd);
+  if (STRNCMP(cmd, "trim", 4) == 0
+      && (cmd[4] == NUL || ascii_iswhite(cmd[4]))) {
+    cmd = skipwhite(cmd + 4);
+
+    // Trim the indentation from all the lines in the here document.
+    // The amount of indentation trimmed is the same as the indentation of
+    // the first line after the :let command line.  To find the end marker
+    // the indent of the :let command line is trimmed.
+    p = *eap->cmdlinep;
+    while (ascii_iswhite(*p)) {
+      p++;
+      marker_indent_len++;
+    }
+    text_indent_len = -1;
+  }
+
+  // The marker is the next word.
+  if (*cmd != NUL && *cmd != '"') {
+    marker = skipwhite(cmd);
+    p = (char *)skiptowhite((char_u *)marker);
+    if (*skipwhite(p) != NUL && *skipwhite(p) != '"') {
+      emsg(_(e_trailing));
+      return NULL;
+    }
+    *p = NUL;
+    if (islower(*marker)) {
+      emsg(_("E221: Marker cannot start with lower case letter"));
+      return NULL;
+    }
+  } else {
+    emsg(_("E172: Missing marker"));
+    return NULL;
+  }
+
+  list_T *l = tv_list_alloc(0);
+  for (;;) {
+    int mi = 0;
+    int ti = 0;
+
+    char *theline = eap->getline(NUL, eap->cookie, 0, false);
+    if (theline == NULL) {
+      semsg(_("E990: Missing end marker '%s'"), marker);
+      break;
+    }
+
+    // with "trim": skip the indent matching the :let line to find the
+    // marker
+    if (marker_indent_len > 0
+        && STRNCMP(theline, *eap->cmdlinep, marker_indent_len) == 0) {
+      mi = marker_indent_len;
+    }
+    if (STRCMP(marker, theline + mi) == 0) {
+      xfree(theline);
+      break;
+    }
+    if (text_indent_len == -1 && *theline != NUL) {
+      // set the text indent from the first line.
+      p = theline;
+      text_indent_len = 0;
+      while (ascii_iswhite(*p)) {
+        p++;
+        text_indent_len++;
+      }
+      text_indent = xstrnsave(theline, (size_t)text_indent_len);
+    }
+    // with "trim": skip the indent matching the first line
+    if (text_indent != NULL) {
+      for (ti = 0; ti < text_indent_len; ti++) {
+        if (theline[ti] != text_indent[ti]) {
+          break;
+        }
+      }
+    }
+
+    tv_list_append_string(l, theline + ti, -1);
+    xfree(theline);
+  }
+  xfree(text_indent);
+
+  return l;
+}
+
+/// ":let" list all variable values
+/// ":let var1 var2" list variable values
+/// ":let var = expr" assignment command.
+/// ":let var += expr" assignment command.
+/// ":let var -= expr" assignment command.
+/// ":let var *= expr" assignment command.
+/// ":let var /= expr" assignment command.
+/// ":let var %= expr" assignment command.
+/// ":let var .= expr" assignment command.
+/// ":let var ..= expr" assignment command.
+/// ":let [var1, var2] = expr" unpack list.
+/// ":let [name, ..., ; lastname] = expr" unpack list.
+void ex_let(exarg_T *eap)
+{
+  ex_let_const(eap, false);
+}
+
+/// ":cons[t] var = expr1" define constant
+/// ":cons[t] [name1, name2, ...] = expr1" define constants unpacking list
+/// ":cons[t] [name, ..., ; lastname] = expr" define constants unpacking list
+void ex_const(exarg_T *eap)
+{
+  ex_let_const(eap, true);
+}
+
+static void ex_let_const(exarg_T *eap, const bool is_const)
+{
+  char *arg = eap->arg;
+  char *expr = NULL;
+  typval_T rettv;
+  int i;
+  int var_count = 0;
+  int semicolon = 0;
+  char op[2];
+  char *argend;
+  int first = true;
+
+  argend = (char *)skip_var_list(arg, &var_count, &semicolon);
+  if (argend == NULL) {
+    return;
+  }
+  if (argend > arg && argend[-1] == '.') {  // For var.='str'.
+    argend--;
+  }
+  expr = skipwhite(argend);
+  if (*expr != '=' && !((vim_strchr("+-*/%.", *expr) != NULL
+                         && expr[1] == '=') || STRNCMP(expr, "..=", 3) == 0)) {
+    // ":let" without "=": list variables
+    if (*arg == '[') {
+      emsg(_(e_invarg));
+    } else if (!ends_excmd(*arg)) {
+      // ":let var1 var2"
+      arg = (char *)list_arg_vars(eap, (const char *)arg, &first);
+    } else if (!eap->skip) {
+      // ":let"
+      list_glob_vars(&first);
+      list_buf_vars(&first);
+      list_win_vars(&first);
+      list_tab_vars(&first);
+      list_script_vars(&first);
+      list_func_vars(&first);
+      list_vim_vars(&first);
+    }
+    eap->nextcmd = (char *)check_nextcmd((char_u *)arg);
+  } else if (expr[0] == '=' && expr[1] == '<' && expr[2] == '<') {
+    // HERE document
+    list_T *l = heredoc_get(eap, expr + 3);
+    if (l != NULL) {
+      tv_list_set_ret(&rettv, l);
+      if (!eap->skip) {
+        op[0] = '=';
+        op[1] = NUL;
+        (void)ex_let_vars(eap->arg, &rettv, false, semicolon, var_count,
+                          is_const, (char *)op);
+      }
+      tv_clear(&rettv);
+    }
+  } else {
+    op[0] = '=';
+    op[1] = NUL;
+    if (*expr != '=') {
+      if (vim_strchr("+-*/%.", *expr) != NULL) {
+        op[0] = *expr;  // +=, -=, *=, /=, %= or .=
+        if (expr[0] == '.' && expr[1] == '.') {  // ..=
+          expr++;
+        }
+      }
+      expr = skipwhite(expr + 2);
+    } else {
+      expr = skipwhite(expr + 1);
+    }
+
+    if (eap->skip) {
+      emsg_skip++;
+    }
+    i = eval0(expr, &rettv, &eap->nextcmd, !eap->skip);
+    if (eap->skip) {
+      if (i != FAIL) {
+        tv_clear(&rettv);
+      }
+      emsg_skip--;
+    } else if (i != FAIL) {
+      (void)ex_let_vars(eap->arg, &rettv, false, semicolon, var_count,
+                        is_const, (char *)op);
+      tv_clear(&rettv);
+    }
+  }
+}
+
+/// Assign the typevalue "tv" to the variable or variables at "arg_start".
+/// Handles both "var" with any type and "[var, var; var]" with a list type.
+/// When "op" is not NULL it points to a string with characters that
+/// must appear after the variable(s).  Use "+", "-" or "." for add, subtract
+/// or concatenate.
+///
+/// @param copy  copy values from "tv", don't move
+/// @param semicolon  from skip_var_list()
+/// @param var_count  from skip_var_list()
+/// @param is_const  lock variables for :const
+///
+/// @return  OK or FAIL;
+int ex_let_vars(char *arg_start, typval_T *tv, int copy, int semicolon, int var_count, int is_const,
+                char *op)
+{
+  char *arg = arg_start;
+  typval_T ltv;
+
+  if (*arg != '[') {
+    // ":let var = expr" or ":for var in list"
+    if (ex_let_one(arg, tv, copy, is_const, op, op) == NULL) {
+      return FAIL;
+    }
+    return OK;
+  }
+
+  // ":let [v1, v2] = list" or ":for [v1, v2] in listlist"
+  if (tv->v_type != VAR_LIST) {
+    emsg(_(e_listreq));
+    return FAIL;
+  }
+  list_T *const l = tv->vval.v_list;
+
+  const int len = tv_list_len(l);
+  if (semicolon == 0 && var_count < len) {
+    emsg(_("E687: Less targets than List items"));
+    return FAIL;
+  }
+  if (var_count - semicolon > len) {
+    emsg(_("E688: More targets than List items"));
+    return FAIL;
+  }
+  // List l may actually be NULL, but it should fail with E688 or even earlier
+  // if you try to do ":let [] = v:_null_list".
+  assert(l != NULL);
+
+  listitem_T *item = tv_list_first(l);
+  size_t rest_len = (size_t)tv_list_len(l);
+  while (*arg != ']') {
+    arg = skipwhite(arg + 1);
+    arg = ex_let_one(arg, TV_LIST_ITEM_TV(item), true, is_const, ",;]", op);
+    if (arg == NULL) {
+      return FAIL;
+    }
+    rest_len--;
+
+    item = TV_LIST_ITEM_NEXT(l, item);
+    arg = skipwhite(arg);
+    if (*arg == ';') {
+      // Put the rest of the list (may be empty) in the var after ';'.
+      // Create a new list for this.
+      list_T *const rest_list = tv_list_alloc((ptrdiff_t)rest_len);
+      while (item != NULL) {
+        tv_list_append_tv(rest_list, TV_LIST_ITEM_TV(item));
+        item = TV_LIST_ITEM_NEXT(l, item);
+      }
+
+      ltv.v_type = VAR_LIST;
+      ltv.v_lock = VAR_UNLOCKED;
+      ltv.vval.v_list = rest_list;
+      tv_list_ref(rest_list);
+
+      arg = ex_let_one(skipwhite(arg + 1), &ltv, false, is_const, "]", op);
+      tv_clear(&ltv);
+      if (arg == NULL) {
+        return FAIL;
+      }
+      break;
+    } else if (*arg != ',' && *arg != ']') {
+      internal_error("ex_let_vars()");
+      return FAIL;
+    }
+  }
+
+  return OK;
+}
+
+/// Skip over assignable variable "var" or list of variables "[var, var]".
+/// Used for ":let varvar = expr" and ":for varvar in expr".
+/// For "[var, var]" increment "*var_count" for each variable.
+/// for "[var, var; var]" set "semicolon".
+///
+/// @return  NULL for an error.
+const char *skip_var_list(const char *arg, int *var_count, int *semicolon)
+{
+  const char *p;
+  const char *s;
+
+  if (*arg == '[') {
+    // "[var, var]": find the matching ']'.
+    p = arg;
+    for (;;) {
+      p = skipwhite(p + 1);             // skip whites after '[', ';' or ','
+      s = skip_var_one((char *)p);
+      if (s == p) {
+        semsg(_(e_invarg2), p);
+        return NULL;
+      }
+      (*var_count)++;
+
+      p = skipwhite(s);
+      if (*p == ']') {
+        break;
+      } else if (*p == ';') {
+        if (*semicolon == 1) {
+          emsg(_("E452: Double ; in list of variables"));
+          return NULL;
+        }
+        *semicolon = 1;
+      } else if (*p != ',') {
+        semsg(_(e_invarg2), p);
+        return NULL;
+      }
+    }
+    return p + 1;
+  } else {
+    return skip_var_one((char *)arg);
+  }
+}
+
+/// Skip one (assignable) variable name, including @r, $VAR, &option, d.key,
+/// l[idx].
+static const char *skip_var_one(const char *arg)
+{
+  if (*arg == '@' && arg[1] != NUL) {
+    return arg + 2;
+  }
+  return (char *)find_name_end(*arg == '$' || *arg == '&' ? arg + 1 : arg,
+                               NULL, NULL, FNE_INCL_BR | FNE_CHECK_START);
+}
+
+/// List variables for hashtab "ht" with prefix "prefix".
+///
+/// @param empty  if true also list NULL strings as empty strings.
+void list_hashtable_vars(hashtab_T *ht, const char *prefix, int empty, int *first)
+{
+  hashitem_T *hi;
+  dictitem_T *di;
+  int todo;
+
+  todo = (int)ht->ht_used;
+  for (hi = ht->ht_array; todo > 0 && !got_int; hi++) {
+    if (!HASHITEM_EMPTY(hi)) {
+      todo--;
+      di = TV_DICT_HI2DI(hi);
+      char buf[IOSIZE];
+
+      // apply :filter /pat/ to variable name
+      xstrlcpy(buf, prefix, IOSIZE);
+      xstrlcat(buf, (char *)di->di_key, IOSIZE);
+      if (message_filtered((char_u *)buf)) {
+        continue;
+      }
+
+      if (empty || di->di_tv.v_type != VAR_STRING
+          || di->di_tv.vval.v_string != NULL) {
+        list_one_var(di, prefix, first);
+      }
+    }
+  }
+}
+
+/// List global variables.
+static void list_glob_vars(int *first)
+{
+  list_hashtable_vars(&globvarht, "", true, first);
+}
+
+/// List buffer variables.
+static void list_buf_vars(int *first)
+{
+  list_hashtable_vars(&curbuf->b_vars->dv_hashtab, "b:", true, first);
+}
+
+/// List window variables.
+static void list_win_vars(int *first)
+{
+  list_hashtable_vars(&curwin->w_vars->dv_hashtab, "w:", true, first);
+}
+
+/// List tab page variables.
+static void list_tab_vars(int *first)
+{
+  list_hashtable_vars(&curtab->tp_vars->dv_hashtab, "t:", true, first);
+}
+
+/// List variables in "arg".
+static const char *list_arg_vars(exarg_T *eap, const char *arg, int *first)
+{
+  int error = false;
+  int len;
+  const char *name;
+  const char *name_start;
+  typval_T tv;
+
+  while (!ends_excmd(*arg) && !got_int) {
+    if (error || eap->skip) {
+      arg = find_name_end(arg, NULL, NULL, FNE_INCL_BR | FNE_CHECK_START);
+      if (!ascii_iswhite(*arg) && !ends_excmd(*arg)) {
+        emsg_severe = true;
+        emsg(_(e_trailing));
+        break;
+      }
+    } else {
+      // get_name_len() takes care of expanding curly braces
+      name_start = name = arg;
+      char *tofree;
+      len = get_name_len(&arg, &tofree, true, true);
+      if (len <= 0) {
+        // This is mainly to keep test 49 working: when expanding
+        // curly braces fails overrule the exception error message.
+        if (len < 0 && !aborting()) {
+          emsg_severe = true;
+          semsg(_(e_invarg2), arg);
+          break;
+        }
+        error = true;
+      } else {
+        if (tofree != NULL) {
+          name = tofree;
+        }
+        if (get_var_tv(name, len, &tv, NULL, true, false)
+            == FAIL) {
+          error = true;
+        } else {
+          // handle d.key, l[idx], f(expr)
+          const char *const arg_subsc = arg;
+          if (handle_subscript(&arg, &tv, true, true, name, &name) == FAIL) {
+            error = true;
+          } else {
+            if (arg == arg_subsc && len == 2 && name[1] == ':') {
+              switch (*name) {
+              case 'g':
+                list_glob_vars(first); break;
+              case 'b':
+                list_buf_vars(first); break;
+              case 'w':
+                list_win_vars(first); break;
+              case 't':
+                list_tab_vars(first); break;
+              case 'v':
+                list_vim_vars(first); break;
+              case 's':
+                list_script_vars(first); break;
+              case 'l':
+                list_func_vars(first); break;
+              default:
+                semsg(_("E738: Can't list variables for %s"), name);
+              }
+            } else {
+              char *const s = encode_tv2echo(&tv, NULL);
+              const char *const used_name = (arg == arg_subsc
+                                             ? name
+                                             : name_start);
+              const ptrdiff_t name_size = (used_name == tofree
+                                           ? (ptrdiff_t)strlen(used_name)
+                                           : (arg - used_name));
+              list_one_var_a("", used_name, name_size,
+                             tv.v_type, s == NULL ? "" : s, first);
+              xfree(s);
+            }
+            tv_clear(&tv);
+          }
+        }
+      }
+
+      xfree(tofree);
+    }
+
+    arg = (const char *)skipwhite(arg);
+  }
+
+  return arg;
+}
+
+// TODO(ZyX-I): move to eval/ex_cmds
+
+/// Set one item of `:let var = expr` or `:let [v1, v2] = list` to its value
+///
+/// @param[in]  arg  Start of the variable name.
+/// @param[in]  tv  Value to assign to the variable.
+/// @param[in]  copy  If true, copy value from `tv`.
+/// @param[in]  endchars  Valid characters after variable name or NULL.
+/// @param[in]  op  Operation performed: *op is `+`, `-`, `.` for `+=`, etc.
+///                 NULL for `=`.
+///
+/// @return a pointer to the char just after the var name or NULL in case of
+///         error.
+static char *ex_let_one(char *arg, typval_T *const tv, const bool copy, const bool is_const,
+                        const char *const endchars, const char *const op)
+  FUNC_ATTR_NONNULL_ARG(1, 2) FUNC_ATTR_WARN_UNUSED_RESULT
+{
+  char *arg_end = NULL;
+  int len;
+  int opt_flags;
+  char *tofree = NULL;
+
+  // ":let $VAR = expr": Set environment variable.
+  if (*arg == '$') {
+    if (is_const) {
+      emsg(_("E996: Cannot lock an environment variable"));
+      return NULL;
+    }
+    // Find the end of the name.
+    arg++;
+    char *name = arg;
+    len = get_env_len((const char **)&arg);
+    if (len == 0) {
+      semsg(_(e_invarg2), name - 1);
+    } else {
+      if (op != NULL && vim_strchr("+-*/%", *op) != NULL) {
+        semsg(_(e_letwrong), op);
+      } else if (endchars != NULL
+                 && vim_strchr(endchars, *skipwhite(arg)) == NULL) {
+        emsg(_(e_letunexp));
+      } else if (!check_secure()) {
+        const char c1 = name[len];
+        name[len] = NUL;
+        const char *p = tv_get_string_chk(tv);
+        if (p != NULL && op != NULL && *op == '.') {
+          char *s = vim_getenv(name);
+
+          if (s != NULL) {
+            tofree = (char *)concat_str((const char_u *)s, (const char_u *)p);
+            p = (const char *)tofree;
+            xfree(s);
+          }
+        }
+        if (p != NULL) {
+          os_setenv(name, p, 1);
+          if (STRICMP(name, "HOME") == 0) {
+            init_homedir();
+          } else if (didset_vim && STRICMP(name, "VIM") == 0) {
+            didset_vim = false;
+          } else if (didset_vimruntime
+                     && STRICMP(name, "VIMRUNTIME") == 0) {
+            didset_vimruntime = false;
+          }
+          arg_end = arg;
+        }
+        name[len] = c1;
+        xfree(tofree);
+      }
+    }
+    // ":let &option = expr": Set option value.
+    // ":let &l:option = expr": Set local option value.
+    // ":let &g:option = expr": Set global option value.
+  } else if (*arg == '&') {
+    if (is_const) {
+      emsg(_("E996: Cannot lock an option"));
+      return NULL;
+    }
+    // Find the end of the name.
+    char *const p = (char *)find_option_end((const char **)&arg, &opt_flags);
+    if (p == NULL
+        || (endchars != NULL
+            && vim_strchr(endchars, *skipwhite(p)) == NULL)) {
+      emsg(_(e_letunexp));
+    } else {
+      int opt_type;
+      long numval;
+      char *stringval = NULL;
+      const char *s = NULL;
+
+      const char c1 = *p;
+      *p = NUL;
+
+      varnumber_T n = tv_get_number(tv);
+      if (tv->v_type != VAR_BOOL && tv->v_type != VAR_SPECIAL) {
+        s = tv_get_string_chk(tv);  // != NULL if number or string.
+      }
+      if (s != NULL && op != NULL && *op != '=') {
+        opt_type = get_option_value(arg, &numval, &stringval, opt_flags);
+        if ((opt_type == 1 && *op == '.')
+            || (opt_type == 0 && *op != '.')) {
+          semsg(_(e_letwrong), op);
+          s = NULL;  // don't set the value
+        } else {
+          if (opt_type == 1) {  // number
+            switch (*op) {
+            case '+':
+              n = numval + n; break;
+            case '-':
+              n = numval - n; break;
+            case '*':
+              n = numval * n; break;
+            case '/':
+              n = num_divide(numval, n); break;
+            case '%':
+              n = num_modulus(numval, n); break;
+            }
+          } else if (opt_type == 0 && stringval != NULL) {  // string
+            char *const oldstringval = stringval;
+            stringval = (char *)concat_str((const char_u *)stringval,
+                                           (const char_u *)s);
+            xfree(oldstringval);
+            s = stringval;
+          }
+        }
+      }
+      if (s != NULL || tv->v_type == VAR_BOOL
+          || tv->v_type == VAR_SPECIAL) {
+        set_option_value((const char *)arg, n, s, opt_flags);
+        arg_end = p;
+      }
+      *p = c1;
+      xfree(stringval);
+    }
+    // ":let @r = expr": Set register contents.
+  } else if (*arg == '@') {
+    if (is_const) {
+      emsg(_("E996: Cannot lock a register"));
+      return NULL;
+    }
+    arg++;
+    if (op != NULL && vim_strchr("+-*/%", *op) != NULL) {
+      semsg(_(e_letwrong), op);
+    } else if (endchars != NULL
+               && vim_strchr(endchars, *skipwhite(arg + 1)) == NULL) {
+      emsg(_(e_letunexp));
+    } else {
+      char *s;
+
+      char *ptofree = NULL;
+      const char *p = tv_get_string_chk(tv);
+      if (p != NULL && op != NULL && *op == '.') {
+        s = get_reg_contents(*arg == '@' ? '"' : *arg, kGRegExprSrc);
+        if (s != NULL) {
+          ptofree = (char *)concat_str((char_u *)s, (const char_u *)p);
+          p = (const char *)ptofree;
+          xfree(s);
+        }
+      }
+      if (p != NULL) {
+        write_reg_contents(*arg == '@' ? '"' : *arg,
+                           (const char_u *)p, (ssize_t)STRLEN(p), false);
+        arg_end = arg + 1;
+      }
+      xfree(ptofree);
+    }
+    // ":let var = expr": Set internal variable.
+    // ":let {expr} = expr": Idem, name made with curly braces
+  } else if (eval_isnamec1(*arg) || *arg == '{') {
+    lval_T lv;
+
+    char *const p = get_lval(arg, tv, &lv, false, false, 0, FNE_CHECK_START);
+    if (p != NULL && lv.ll_name != NULL) {
+      if (endchars != NULL && vim_strchr(endchars, *skipwhite(p)) == NULL) {
+        emsg(_(e_letunexp));
+      } else {
+        set_var_lval(&lv, p, tv, copy, is_const, op);
+        arg_end = p;
+      }
+    }
+    clear_lval(&lv);
+  } else {
+    semsg(_(e_invarg2), arg);
+  }
+
+  return arg_end;
+}
+
+/// ":unlet[!] var1 ... " command.
+void ex_unlet(exarg_T *eap)
+{
+  ex_unletlock(eap, eap->arg, 0, do_unlet_var);
+}
+
+// TODO(ZyX-I): move to eval/ex_cmds
+
+/// ":lockvar" and ":unlockvar" commands
+void ex_lockvar(exarg_T *eap)
+{
+  char *arg = eap->arg;
+  int deep = 2;
+
+  if (eap->forceit) {
+    deep = -1;
+  } else if (ascii_isdigit(*arg)) {
+    deep = getdigits_int(&arg, false, -1);
+    arg = skipwhite(arg);
+  }
+
+  ex_unletlock(eap, arg, deep, do_lock_var);
+}
+
+// TODO(ZyX-I): move to eval/ex_cmds
+
+/// Common parsing logic for :unlet, :lockvar and :unlockvar.
+///
+/// Invokes `callback` afterwards if successful and `eap->skip == false`.
+///
+/// @param[in]  eap  Ex command arguments for the command.
+/// @param[in]  argstart  Start of the string argument for the command.
+/// @param[in]  deep  Levels to (un)lock for :(un)lockvar, -1 to (un)lock
+///                   everything.
+/// @param[in]  callback  Appropriate handler for the command.
+static void ex_unletlock(exarg_T *eap, char *argstart, int deep, ex_unletlock_callback callback)
+  FUNC_ATTR_NONNULL_ALL
+{
+  char *arg = argstart;
+  char *name_end;
+  bool error = false;
+  lval_T lv;
+
+  do {
+    if (*arg == '$') {
+      lv.ll_name = (const char *)arg;
+      lv.ll_tv = NULL;
+      arg++;
+      if (get_env_len((const char **)&arg) == 0) {
+        semsg(_(e_invarg2), arg - 1);
+        return;
+      }
+      if (!error && !eap->skip && callback(&lv, arg, eap, deep) == FAIL) {
+        error = true;
+      }
+      name_end = arg;
+    } else {
+      // Parse the name and find the end.
+      name_end = get_lval(arg, NULL, &lv, true, eap->skip || error,
+                          0, FNE_CHECK_START);
+      if (lv.ll_name == NULL) {
+        error = true;  // error, but continue parsing.
+      }
+      if (name_end == NULL
+          || (!ascii_iswhite(*name_end) && !ends_excmd(*name_end))) {
+        if (name_end != NULL) {
+          emsg_severe = true;
+          emsg(_(e_trailing));
+        }
+        if (!(eap->skip || error)) {
+          clear_lval(&lv);
+        }
+        break;
+      }
+
+      if (!error && !eap->skip && callback(&lv, name_end, eap, deep) == FAIL) {
+        error = true;
+      }
+
+      if (!eap->skip) {
+        clear_lval(&lv);
+      }
+    }
+    arg = skipwhite(name_end);
+  } while (!ends_excmd(*arg));
+
+  eap->nextcmd = (char *)check_nextcmd((char_u *)arg);
+}
+
+// TODO(ZyX-I): move to eval/ex_cmds
+
+/// Unlet a variable indicated by `lp`.
+///
+/// @param[in]  lp  The lvalue.
+/// @param[in]  name_end  End of the string argument for the command.
+/// @param[in]  eap  Ex command arguments for :unlet.
+/// @param[in]  deep  Unused.
+///
+/// @return OK on success, or FAIL on failure.
+static int do_unlet_var(lval_T *lp, char *name_end, exarg_T *eap, int deep FUNC_ATTR_UNUSED)
+  FUNC_ATTR_NONNULL_ALL
+{
+  int forceit = eap->forceit;
+  int ret = OK;
+  int cc;
+
+  if (lp->ll_tv == NULL) {
+    cc = (char_u)(*name_end);
+    *name_end = NUL;
+
+    // Environment variable, normal name or expanded name.
+    if (*lp->ll_name == '$') {
+      os_unsetenv(lp->ll_name + 1);
+    } else if (do_unlet(lp->ll_name, lp->ll_name_len, forceit) == FAIL) {
+      ret = FAIL;
+    }
+    *name_end = (char)cc;
+  } else if ((lp->ll_list != NULL
+              // ll_list is not NULL when lvalue is not in a list, NULL lists
+              // yield E689.
+              && var_check_lock(tv_list_locked(lp->ll_list),
+                                lp->ll_name,
+                                lp->ll_name_len))
+             || (lp->ll_dict != NULL
+                 && var_check_lock(lp->ll_dict->dv_lock,
+                                   lp->ll_name,
+                                   lp->ll_name_len))) {
+    return FAIL;
+  } else if (lp->ll_range) {
+    assert(lp->ll_list != NULL);
+    // Delete a range of List items.
+    listitem_T *const first_li = lp->ll_li;
+    listitem_T *last_li = first_li;
+    for (;;) {
+      listitem_T *const li = TV_LIST_ITEM_NEXT(lp->ll_list, lp->ll_li);
+      if (var_check_lock(TV_LIST_ITEM_TV(lp->ll_li)->v_lock,
+                         lp->ll_name,
+                         lp->ll_name_len)) {
+        return false;
+      }
+      lp->ll_li = li;
+      lp->ll_n1++;
+      if (lp->ll_li == NULL || (!lp->ll_empty2 && lp->ll_n2 < lp->ll_n1)) {
+        break;
+      } else {
+        last_li = lp->ll_li;
+      }
+    }
+    tv_list_remove_items(lp->ll_list, first_li, last_li);
+  } else {
+    if (lp->ll_list != NULL) {
+      // unlet a List item.
+      tv_list_item_remove(lp->ll_list, lp->ll_li);
+    } else {
+      // unlet a Dictionary item.
+      dict_T *d = lp->ll_dict;
+      assert(d != NULL);
+      dictitem_T *di = lp->ll_di;
+      bool watched = tv_dict_is_watched(d);
+      char *key = NULL;
+      typval_T oldtv;
+
+      if (watched) {
+        tv_copy(&di->di_tv, &oldtv);
+        // need to save key because dictitem_remove will free it
+        key = xstrdup((char *)di->di_key);
+      }
+
+      tv_dict_item_remove(d, di);
+
+      if (watched) {
+        tv_dict_watcher_notify(d, key, NULL, &oldtv);
+        tv_clear(&oldtv);
+        xfree(key);
+      }
+    }
+  }
+
+  return ret;
+}
+
+// TODO(ZyX-I): move to eval/ex_cmds
+
+/// unlet a variable
+///
+/// @param[in]  name  Variable name to unlet.
+/// @param[in]  name_len  Variable name length.
+/// @param[in]  forceit  If true, do not complain if variable doesn’t exist.
+///
+/// @return OK if it existed, FAIL otherwise.
+int do_unlet(const char *const name, const size_t name_len, const bool forceit)
+  FUNC_ATTR_NONNULL_ALL
+{
+  const char *varname;
+  dict_T *dict;
+  hashtab_T *ht = find_var_ht_dict(name, name_len, &varname, &dict);
+
+  if (ht != NULL && *varname != NUL) {
+    dict_T *d = get_current_funccal_dict(ht);
+    if (d == NULL) {
+      if (ht == &globvarht) {
+        d = &globvardict;
+      } else if (is_compatht(ht)) {
+        d = &vimvardict;
+      } else {
+        dictitem_T *const di = find_var_in_ht(ht, *name, "", 0, false);
+        d = di->di_tv.vval.v_dict;
+      }
+      if (d == NULL) {
+        internal_error("do_unlet()");
+        return FAIL;
+      }
+    }
+
+    hashitem_T *hi = hash_find(ht, varname);
+    if (HASHITEM_EMPTY(hi)) {
+      hi = find_hi_in_scoped_ht(name, &ht);
+    }
+    if (hi != NULL && !HASHITEM_EMPTY(hi)) {
+      dictitem_T *const di = TV_DICT_HI2DI(hi);
+      if (var_check_fixed(di->di_flags, name, TV_CSTRING)
+          || var_check_ro(di->di_flags, name, TV_CSTRING)
+          || var_check_lock(d->dv_lock, name, TV_CSTRING)) {
+        return FAIL;
+      }
+
+      if (var_check_lock(d->dv_lock, name, TV_CSTRING)) {
+        return FAIL;
+      }
+
+      typval_T oldtv;
+      bool watched = tv_dict_is_watched(dict);
+
+      if (watched) {
+        tv_copy(&di->di_tv, &oldtv);
+      }
+
+      delete_var(ht, hi);
+
+      if (watched) {
+        tv_dict_watcher_notify(dict, varname, NULL, &oldtv);
+        tv_clear(&oldtv);
+      }
+      return OK;
+    }
+  }
+  if (forceit) {
+    return OK;
+  }
+  semsg(_("E108: No such variable: \"%s\""), name);
+  return FAIL;
+}
+
+// TODO(ZyX-I): move to eval/ex_cmds
+
+/// Lock or unlock variable indicated by `lp`.
+///
+/// Locks if `eap->cmdidx == CMD_lockvar`, unlocks otherwise.
+///
+/// @param[in]  lp  The lvalue.
+/// @param[in]  name_end  Unused.
+/// @param[in]  eap  Ex command arguments for :(un)lockvar.
+/// @param[in]  deep  Levels to (un)lock, -1 to (un)lock everything.
+///
+/// @return OK on success, or FAIL on failure.
+static int do_lock_var(lval_T *lp, char *name_end FUNC_ATTR_UNUSED, exarg_T *eap, int deep)
+  FUNC_ATTR_NONNULL_ARG(1, 3)
+{
+  bool lock = eap->cmdidx == CMD_lockvar;
+  int ret = OK;
+
+  if (deep == 0) {  // Nothing to do.
+    return OK;
+  }
+
+  if (lp->ll_tv == NULL) {
+    if (*lp->ll_name == '$') {
+      semsg(_(e_lock_unlock), lp->ll_name);
+      ret = FAIL;
+    } else {
+      // Normal name or expanded name.
+      dictitem_T *const di = find_var(lp->ll_name, lp->ll_name_len, NULL,
+                                      true);
+      if (di == NULL) {
+        ret = FAIL;
+      } else if ((di->di_flags & DI_FLAGS_FIX)
+                 && di->di_tv.v_type != VAR_DICT
+                 && di->di_tv.v_type != VAR_LIST) {
+        // For historical reasons this error is not given for Lists and
+        // Dictionaries. E.g. b: dictionary may be locked/unlocked.
+        semsg(_(e_lock_unlock), lp->ll_name);
+        ret = FAIL;
+      } else {
+        if (lock) {
+          di->di_flags |= DI_FLAGS_LOCK;
+        } else {
+          di->di_flags &= (uint8_t)(~DI_FLAGS_LOCK);
+        }
+        tv_item_lock(&di->di_tv, deep, lock, false);
+      }
+    }
+  } else if (lp->ll_range) {
+    listitem_T *li = lp->ll_li;
+
+    // (un)lock a range of List items.
+    while (li != NULL && (lp->ll_empty2 || lp->ll_n2 >= lp->ll_n1)) {
+      tv_item_lock(TV_LIST_ITEM_TV(li), deep, lock, false);
+      li = TV_LIST_ITEM_NEXT(lp->ll_list, li);
+      lp->ll_n1++;
+    }
+  } else if (lp->ll_list != NULL) {
+    // (un)lock a List item.
+    tv_item_lock(TV_LIST_ITEM_TV(lp->ll_li), deep, lock, false);
+  } else {
+    // (un)lock a Dictionary item.
+    tv_item_lock(&lp->ll_di->di_tv, deep, lock, false);
+  }
+
+  return ret;
+}
+
+/// Get the value of internal variable "name".
+/// Return OK or FAIL.  If OK is returned "rettv" must be cleared.
+///
+/// @param len  length of "name"
+/// @param rettv  NULL when only checking existence
+/// @param dip  non-NULL when typval's dict item is needed
+/// @param verbose  may give error message
+/// @param no_autoload  do not use script autoloading
+int get_var_tv(const char *name, int len, typval_T *rettv, dictitem_T **dip, bool verbose,
+               bool no_autoload)
+{
+  int ret = OK;
+  typval_T *tv = NULL;
+  dictitem_T *v;
+
+  v = find_var(name, (size_t)len, NULL, no_autoload);
+  if (v != NULL) {
+    tv = &v->di_tv;
+    if (dip != NULL) {
+      *dip = v;
+    }
+  }
+
+  if (tv == NULL) {
+    if (rettv != NULL && verbose) {
+      semsg(_("E121: Undefined variable: %.*s"), len, name);
+    }
+    ret = FAIL;
+  } else if (rettv != NULL) {
+    tv_copy(tv, rettv);
+  }
+
+  return ret;
+}
+
+/// @return  the string value of a (global/local) variable or
+///          NULL when it doesn't exist.
+///
+/// @see  tv_get_string() for how long the pointer remains valid.
+char_u *get_var_value(const char *const name)
+{
+  dictitem_T *v;
+
+  v = find_var(name, strlen(name), NULL, false);
+  if (v == NULL) {
+    return NULL;
+  }
+  return (char_u *)tv_get_string(&v->di_tv);
+}
+
+/// Clean up a list of internal variables.
+/// Frees all allocated variables and the value they contain.
+/// Clears hashtab "ht", does not free it.
+void vars_clear(hashtab_T *ht)
+{
+  vars_clear_ext(ht, true);
+}
+
+/// Like vars_clear(), but only free the value if "free_val" is TRUE.
+void vars_clear_ext(hashtab_T *ht, int free_val)
+{
+  int todo;
+  hashitem_T *hi;
+  dictitem_T *v;
+
+  hash_lock(ht);
+  todo = (int)ht->ht_used;
+  for (hi = ht->ht_array; todo > 0; hi++) {
+    if (!HASHITEM_EMPTY(hi)) {
+      todo--;
+
+      // Free the variable.  Don't remove it from the hashtab,
+      // ht_array might change then.  hash_clear() takes care of it
+      // later.
+      v = TV_DICT_HI2DI(hi);
+      if (free_val) {
+        tv_clear(&v->di_tv);
+      }
+      if (v->di_flags & DI_FLAGS_ALLOC) {
+        xfree(v);
+      }
+    }
+  }
+  hash_clear(ht);
+  ht->ht_used = 0;
+}
+
+/// Delete a variable from hashtab "ht" at item "hi".
+/// Clear the variable value and free the dictitem.
+void delete_var(hashtab_T *ht, hashitem_T *hi)
+{
+  dictitem_T *di = TV_DICT_HI2DI(hi);
+
+  hash_remove(ht, hi);
+  tv_clear(&di->di_tv);
+  xfree(di);
+}
+
+/// List the value of one internal variable.
+static void list_one_var(dictitem_T *v, const char *prefix, int *first)
+{
+  char *const s = encode_tv2echo(&v->di_tv, NULL);
+  list_one_var_a(prefix, (const char *)v->di_key, (ptrdiff_t)STRLEN(v->di_key),
+                 v->di_tv.v_type, (s == NULL ? "" : s), first);
+  xfree(s);
+}
+
+/// @param[in]  name_len  Length of the name. May be -1, in this case strlen()
+///                       will be used.
+/// @param[in,out]  first  When true clear rest of screen and set to false.
+static void list_one_var_a(const char *prefix, const char *name, const ptrdiff_t name_len,
+                           const VarType type, const char *string, int *first)
+{
+  // don't use msg() or msg_attr() to avoid overwriting "v:statusmsg"
+  msg_start();
+  msg_puts(prefix);
+  if (name != NULL) {  // "a:" vars don't have a name stored
+    msg_puts_attr_len(name, name_len, 0);
+  }
+  msg_putchar(' ');
+  msg_advance(22);
+  if (type == VAR_NUMBER) {
+    msg_putchar('#');
+  } else if (type == VAR_FUNC || type == VAR_PARTIAL) {
+    msg_putchar('*');
+  } else if (type == VAR_LIST) {
+    msg_putchar('[');
+    if (*string == '[') {
+      string++;
+    }
+  } else if (type == VAR_DICT) {
+    msg_putchar('{');
+    if (*string == '{') {
+      string++;
+    }
+  } else {
+    msg_putchar(' ');
+  }
+
+  msg_outtrans((char *)string);
+
+  if (type == VAR_FUNC || type == VAR_PARTIAL) {
+    msg_puts("()");
+  }
+  if (*first) {
+    msg_clr_eos();
+    *first = false;
+  }
+}
+
+/// Set variable to the given value
+///
+/// If the variable already exists, the value is updated. Otherwise the variable
+/// is created.
+///
+/// @param[in]  name  Variable name to set.
+/// @param[in]  name_len  Length of the variable name.
+/// @param  tv  Variable value.
+/// @param[in]  copy  True if value in tv is to be copied.
+void set_var(const char *name, const size_t name_len, typval_T *const tv, const bool copy)
+  FUNC_ATTR_NONNULL_ALL
+{
+  set_var_const(name, name_len, tv, copy, false);
+}
+
+/// Set variable to the given value
+///
+/// If the variable already exists, the value is updated. Otherwise the variable
+/// is created.
+///
+/// @param[in]  name  Variable name to set.
+/// @param[in]  name_len  Length of the variable name.
+/// @param  tv  Variable value.
+/// @param[in]  copy  True if value in tv is to be copied.
+/// @param[in]  is_const  True if value in tv is to be locked.
+void set_var_const(const char *name, const size_t name_len, typval_T *const tv, const bool copy,
+                   const bool is_const)
+  FUNC_ATTR_NONNULL_ALL
+{
+  dictitem_T *v;
+  hashtab_T *ht;
+  dict_T *dict;
+
+  const char *varname;
+  ht = find_var_ht_dict(name, name_len, &varname, &dict);
+  const bool watched = tv_dict_is_watched(dict);
+
+  if (ht == NULL || *varname == NUL) {
+    semsg(_(e_illvar), name);
+    return;
+  }
+  v = find_var_in_ht(ht, 0, varname, name_len - (size_t)(varname - name), true);
+
+  // Search in parent scope which is possible to reference from lambda
+  if (v == NULL) {
+    v = find_var_in_scoped_ht(name, name_len, true);
+  }
+
+  if (tv_is_func(*tv) && !var_check_func_name(name, v == NULL)) {
+    return;
+  }
+
+  typval_T oldtv = TV_INITIAL_VALUE;
+  if (v != NULL) {
+    if (is_const) {
+      emsg(_(e_cannot_mod));
+      return;
+    }
+
+    // existing variable, need to clear the value
+    if (var_check_ro(v->di_flags, name, name_len)
+        || var_check_lock(v->di_tv.v_lock, name, name_len)) {
+      return;
+    }
+
+    // Handle setting internal v: variables separately where needed to
+    // prevent changing the type.
+    if (is_vimvarht(ht)) {
+      if (v->di_tv.v_type == VAR_STRING) {
+        XFREE_CLEAR(v->di_tv.vval.v_string);
+        if (copy || tv->v_type != VAR_STRING) {
+          const char *const val = tv_get_string(tv);
+
+          // Careful: when assigning to v:errmsg and tv_get_string()
+          // causes an error message the variable will already be set.
+          if (v->di_tv.vval.v_string == NULL) {
+            v->di_tv.vval.v_string = xstrdup(val);
+          }
+        } else {
+          // Take over the string to avoid an extra alloc/free.
+          v->di_tv.vval.v_string = tv->vval.v_string;
+          tv->vval.v_string = NULL;
+        }
+        return;
+      } else if (v->di_tv.v_type == VAR_NUMBER) {
+        v->di_tv.vval.v_number = tv_get_number(tv);
+        if (strcmp(varname, "searchforward") == 0) {
+          set_search_direction(v->di_tv.vval.v_number ? '/' : '?');
+        } else if (strcmp(varname, "hlsearch") == 0) {
+          no_hlsearch = !v->di_tv.vval.v_number;
+          redraw_all_later(SOME_VALID);
+        }
+        return;
+      } else if (v->di_tv.v_type != tv->v_type) {
+        semsg(_("E963: setting %s to value with wrong type"), name);
+        return;
+      }
+    }
+
+    if (watched) {
+      tv_copy(&v->di_tv, &oldtv);
+    }
+    tv_clear(&v->di_tv);
+  } else {  // Add a new variable.
+    // Can't add "v:" or "a:" variable.
+    if (is_vimvarht(ht) || ht == get_funccal_args_ht()) {
+      semsg(_(e_illvar), name);
+      return;
+    }
+
+    // Make sure the variable name is valid.
+    if (!valid_varname(varname)) {
+      return;
+    }
+
+    // Make sure dict is valid
+    assert(dict != NULL);
+
+    v = xmalloc(sizeof(dictitem_T) + strlen(varname));
+    STRCPY(v->di_key, varname);
+    if (tv_dict_add(dict, v) == FAIL) {
+      xfree(v);
+      return;
+    }
+    v->di_flags = DI_FLAGS_ALLOC;
+    if (is_const) {
+      v->di_flags |= DI_FLAGS_LOCK;
+    }
+  }
+
+  if (copy || tv->v_type == VAR_NUMBER || tv->v_type == VAR_FLOAT) {
+    tv_copy(tv, &v->di_tv);
+  } else {
+    v->di_tv = *tv;
+    v->di_tv.v_lock = VAR_UNLOCKED;
+    tv_init(tv);
+  }
+
+  if (watched) {
+    if (oldtv.v_type == VAR_UNKNOWN) {
+      tv_dict_watcher_notify(dict, (char *)v->di_key, &v->di_tv, NULL);
+    } else {
+      tv_dict_watcher_notify(dict, (char *)v->di_key, &v->di_tv, &oldtv);
+      tv_clear(&oldtv);
+    }
+  }
+
+  if (is_const) {
+    // Like :lockvar! name: lock the value and what it contains, but only
+    // if the reference count is up to one.  That locks only literal
+    // values.
+    tv_item_lock(&v->di_tv, DICT_MAXNEST, true, true);
+  }
+}
+
+/// Check whether variable is read-only (DI_FLAGS_RO, DI_FLAGS_RO_SBX)
+///
+/// Also gives an error message.
+///
+/// @param[in]  flags  di_flags attribute value.
+/// @param[in]  name  Variable name, for use in error message.
+/// @param[in]  name_len  Variable name length. Use #TV_TRANSLATE to translate
+///                       variable name and compute the length. Use #TV_CSTRING
+///                       to compute the length with strlen() without
+///                       translating.
+///
+///                       Both #TV_… values are used for optimization purposes:
+///                       variable name with its length is needed only in case
+///                       of error, when no error occurs computing them is
+///                       a waste of CPU resources. This especially applies to
+///                       gettext.
+///
+/// @return True if variable is read-only: either always or in sandbox when
+///         sandbox is enabled, false otherwise.
+bool var_check_ro(const int flags, const char *name, size_t name_len)
+  FUNC_ATTR_WARN_UNUSED_RESULT FUNC_ATTR_NONNULL_ALL
+{
+  const char *error_message = NULL;
+  if (flags & DI_FLAGS_RO) {
+    error_message = _(e_readonlyvar);
+  } else if ((flags & DI_FLAGS_RO_SBX) && sandbox) {
+    error_message = N_("E794: Cannot set variable in the sandbox: \"%.*s\"");
+  }
+
+  if (error_message == NULL) {
+    return false;
+  }
+  if (name_len == TV_TRANSLATE) {
+    name = _(name);
+    name_len = strlen(name);
+  } else if (name_len == TV_CSTRING) {
+    name_len = strlen(name);
+  }
+
+  semsg(_(error_message), (int)name_len, name);
+
+  return true;
+}
+
+/// Check whether variable is fixed (DI_FLAGS_FIX)
+///
+/// Also gives an error message.
+///
+/// @param[in]  flags  di_flags attribute value.
+/// @param[in]  name  Variable name, for use in error message.
+/// @param[in]  name_len  Variable name length. Use #TV_TRANSLATE to translate
+///                       variable name and compute the length. Use #TV_CSTRING
+///                       to compute the length with strlen() without
+///                       translating.
+///
+///                       Both #TV_… values are used for optimization purposes:
+///                       variable name with its length is needed only in case
+///                       of error, when no error occurs computing them is
+///                       a waste of CPU resources. This especially applies to
+///                       gettext.
+///
+/// @return True if variable is fixed, false otherwise.
+bool var_check_fixed(const int flags, const char *name, size_t name_len)
+  FUNC_ATTR_WARN_UNUSED_RESULT FUNC_ATTR_NONNULL_ALL
+{
+  if (flags & DI_FLAGS_FIX) {
+    if (name_len == TV_TRANSLATE) {
+      name = _(name);
+      name_len = strlen(name);
+    } else if (name_len == TV_CSTRING) {
+      name_len = strlen(name);
+    }
+    semsg(_("E795: Cannot delete variable %.*s"), (int)name_len, name);
+    return true;
+  }
+  return false;
+}
+
+// TODO(ZyX-I): move to eval/expressions
+
+/// Check if name is a valid name to assign funcref to
+///
+/// @param[in]  name  Possible function/funcref name.
+/// @param[in]  new_var  True if it is a name for a variable.
+///
+/// @return false in case of error, true in case of success. Also gives an
+///         error message if appropriate.
+bool var_check_func_name(const char *const name, const bool new_var)
+  FUNC_ATTR_NONNULL_ALL FUNC_ATTR_WARN_UNUSED_RESULT
+{
+  // Allow for w: b: s: and t:.
+  if (!(vim_strchr("wbst", name[0]) != NULL && name[1] == ':')
+      && !ASCII_ISUPPER((name[0] != NUL && name[1] == ':')
+                        ? name[2] : name[0])) {
+    semsg(_("E704: Funcref variable name must start with a capital: %s"), name);
+    return false;
+  }
+  // Don't allow hiding a function.  When "v" is not NULL we might be
+  // assigning another function to the same var, the type is checked
+  // below.
+  if (new_var && function_exists(name, false)) {
+    semsg(_("E705: Variable name conflicts with existing function: %s"), name);
+    return false;
+  }
+  return true;
+}
+
+// TODO(ZyX-I): move to eval/expressions
+
+/// Check if a variable name is valid
+///
+/// @param[in]  varname  Variable name to check.
+///
+/// @return false when variable name is not valid, true when it is. Also gives
+///         an error message if appropriate.
+bool valid_varname(const char *varname)
+  FUNC_ATTR_NONNULL_ALL FUNC_ATTR_WARN_UNUSED_RESULT
+{
+  for (const char *p = varname; *p != NUL; p++) {
+    if (!eval_isnamec1((int)(uint8_t)(*p))
+        && (p == varname || !ascii_isdigit(*p))
+        && *p != AUTOLOAD_CHAR) {
+      semsg(_(e_illvar), varname);
+      return false;
+    }
+  }
+  return true;
+}
+
+/// getwinvar() and gettabwinvar()
+///
+/// @param off  1 for gettabwinvar()
+void getwinvar(typval_T *argvars, typval_T *rettv, int off)
+{
+  win_T *win;
+  dictitem_T *v;
+  tabpage_T *tp = NULL;
+  bool done = false;
+
+  if (off == 1) {
+    tp = find_tabpage((int)tv_get_number_chk(&argvars[0], NULL));
+  } else {
+    tp = curtab;
+  }
+  win = find_win_by_nr(&argvars[off], tp);
+  const char *varname = tv_get_string_chk(&argvars[off + 1]);
+
+  rettv->v_type = VAR_STRING;
+  rettv->vval.v_string = NULL;
+
+  emsg_off++;
+  if (win != NULL && varname != NULL) {
+    // Set curwin to be our win, temporarily.  Also set the tabpage,
+    // otherwise the window is not valid. Only do this when needed,
+    // autocommands get blocked.
+    bool need_switch_win = tp != curtab || win != curwin;
+    switchwin_T switchwin;
+    if (!need_switch_win || switch_win(&switchwin, win, tp, true) == OK) {
+      if (*varname == '&') {
+        if (varname[1] == NUL) {
+          // get all window-local options in a dict
+          dict_T *opts = get_winbuf_options(false);
+
+          if (opts != NULL) {
+            tv_dict_set_ret(rettv, opts);
+            done = true;
+          }
+        } else if (get_option_tv(&varname, rettv, 1) == OK) {
+          // window-local-option
+          done = true;
+        }
+      } else {
+        // Look up the variable.
+        // Let getwinvar({nr}, "") return the "w:" dictionary.
+        v = find_var_in_ht(&win->w_vars->dv_hashtab, 'w', varname,
+                           strlen(varname), false);
+        if (v != NULL) {
+          tv_copy(&v->di_tv, rettv);
+          done = true;
+        }
+      }
+    }
+
+    if (need_switch_win) {
+      // restore previous notion of curwin
+      restore_win(&switchwin, true);
+    }
+  }
+  emsg_off--;
+
+  if (!done && argvars[off + 2].v_type != VAR_UNKNOWN) {
+    // use the default return value
+    tv_copy(&argvars[off + 2], rettv);
+  }
+}
+
+/// "setwinvar()" and "settabwinvar()" functions
+void setwinvar(typval_T *argvars, typval_T *rettv, int off)
+{
+  if (check_secure()) {
+    return;
+  }
+
+  tabpage_T *tp = NULL;
+  if (off == 1) {
+    tp = find_tabpage((int)tv_get_number_chk(&argvars[0], NULL));
+  } else {
+    tp = curtab;
+  }
+  win_T *const win = find_win_by_nr(&argvars[off], tp);
+  const char *varname = tv_get_string_chk(&argvars[off + 1]);
+  typval_T *varp = &argvars[off + 2];
+
+  if (win != NULL && varname != NULL && varp != NULL) {
+    bool need_switch_win = tp != curtab || win != curwin;
+    switchwin_T switchwin;
+    if (!need_switch_win || switch_win(&switchwin, win, tp, true) == OK) {
+      if (*varname == '&') {
+        long numval;
+        bool error = false;
+
+        varname++;
+        numval = tv_get_number_chk(varp, &error);
+        char nbuf[NUMBUFLEN];
+        const char *const strval = tv_get_string_buf_chk(varp, nbuf);
+        if (!error && strval != NULL) {
+          set_option_value(varname, numval, strval, OPT_LOCAL);
+        }
+      } else {
+        const size_t varname_len = strlen(varname);
+        char *const winvarname = xmalloc(varname_len + 3);
+        memcpy(winvarname, "w:", 2);
+        memcpy(winvarname + 2, varname, varname_len + 1);
+        set_var(winvarname, varname_len + 2, varp, true);
+        xfree(winvarname);
+      }
+    }
+    if (need_switch_win) {
+      restore_win(&switchwin, true);
+    }
+  }
+}
+
+bool var_exists(const char *var)
+  FUNC_ATTR_NONNULL_ALL
+{
+  char *tofree;
+  bool n = false;
+
+  // get_name_len() takes care of expanding curly braces
+  const char *name = var;
+  const int len = get_name_len(&var, &tofree, true, false);
+  if (len > 0) {
+    typval_T tv;
+
+    if (tofree != NULL) {
+      name = tofree;
+    }
+    n = get_var_tv(name, len, &tv, NULL, false, true) == OK;
+    if (n) {
+      // Handle d.key, l[idx], f(expr).
+      n = handle_subscript(&var, &tv, true, false, name, &name) == OK;
+      if (n) {
+        tv_clear(&tv);
+      }
+    }
+  }
+  if (*var != NUL) {
+    n = false;
+  }
+
+  xfree(tofree);
+  return n;
+}
+
+/// "gettabvar()" function
+void f_gettabvar(typval_T *argvars, typval_T *rettv, FunPtr fptr)
+{
+  bool done = false;
+
+  rettv->v_type = VAR_STRING;
+  rettv->vval.v_string = NULL;
+
+  const char *const varname = tv_get_string_chk(&argvars[1]);
+  tabpage_T *const tp = find_tabpage((int)tv_get_number_chk(&argvars[0], NULL));
+  if (tp != NULL && varname != NULL) {
+    // Set tp to be our tabpage, temporarily.  Also set the window to the
+    // first window in the tabpage, otherwise the window is not valid.
+    win_T *const window = tp == curtab || tp->tp_firstwin == NULL
+        ? firstwin
+        : tp->tp_firstwin;
+    switchwin_T switchwin;
+    if (switch_win(&switchwin, window, tp, true) == OK) {
+      // look up the variable
+      // Let gettabvar({nr}, "") return the "t:" dictionary.
+      const dictitem_T *const v = find_var_in_ht(&tp->tp_vars->dv_hashtab, 't',
+                                                 varname, strlen(varname),
+                                                 false);
+      if (v != NULL) {
+        tv_copy(&v->di_tv, rettv);
+        done = true;
+      }
+    }
+
+    // restore previous notion of curwin
+    restore_win(&switchwin, true);
+  }
+
+  if (!done && argvars[2].v_type != VAR_UNKNOWN) {
+    tv_copy(&argvars[2], rettv);
+  }
+}
+
+/// "gettabwinvar()" function
+void f_gettabwinvar(typval_T *argvars, typval_T *rettv, FunPtr fptr)
+{
+  getwinvar(argvars, rettv, 1);
+}
+
+/// "getwinvar()" function
+void f_getwinvar(typval_T *argvars, typval_T *rettv, FunPtr fptr)
+{
+  getwinvar(argvars, rettv, 0);
+}
+
+/// "settabvar()" function
+void f_settabvar(typval_T *argvars, typval_T *rettv, FunPtr fptr)
+{
+  rettv->vval.v_number = 0;
+
+  if (check_secure()) {
+    return;
+  }
+
+  tabpage_T *const tp = find_tabpage((int)tv_get_number_chk(&argvars[0], NULL));
+  const char *const varname = tv_get_string_chk(&argvars[1]);
+  typval_T *const varp = &argvars[2];
+
+  if (varname != NULL && tp != NULL) {
+    tabpage_T *const save_curtab = curtab;
+    goto_tabpage_tp(tp, false, false);
+
+    const size_t varname_len = strlen(varname);
+    char *const tabvarname = xmalloc(varname_len + 3);
+    memcpy(tabvarname, "t:", 2);
+    memcpy(tabvarname + 2, varname, varname_len + 1);
+    set_var(tabvarname, varname_len + 2, varp, true);
+    xfree(tabvarname);
+
+    // Restore current tabpage.
+    if (valid_tabpage(save_curtab)) {
+      goto_tabpage_tp(save_curtab, false, false);
+    }
+  }
+}
+
+/// "settabwinvar()" function
+void f_settabwinvar(typval_T *argvars, typval_T *rettv, FunPtr fptr)
+{
+  setwinvar(argvars, rettv, 1);
+}
+
+/// "setwinvar()" function
+void f_setwinvar(typval_T *argvars, typval_T *rettv, FunPtr fptr)
+{
+  setwinvar(argvars, rettv, 0);
+}
diff --git a/src/nvim/eval/vars.h b/src/nvim/eval/vars.h
new file mode 100644
index 0000000000..4eea37d404
--- /dev/null
+++ b/src/nvim/eval/vars.h
@@ -0,0 +1,10 @@
+#ifndef NVIM_EVAL_VARS_H
+#define NVIM_EVAL_VARS_H
+
+#include "nvim/eval/funcs.h"  // For FunPtr
+#include "nvim/ex_cmds_defs.h"  // For exarg_T
+
+#ifdef INCLUDE_GENERATED_DECLARATIONS
+# include "eval/vars.h.generated.h"
+#endif
+#endif  // NVIM_EVAL_VARS_H
diff --git a/src/nvim/ex_cmds2.c b/src/nvim/ex_cmds2.c
index e57dc5d13f..540e7224c1 100644
--- a/src/nvim/ex_cmds2.c
+++ b/src/nvim/ex_cmds2.c
@@ -24,6 +24,7 @@
 #include "nvim/charset.h"
 #include "nvim/debugger.h"
 #include "nvim/eval/userfunc.h"
+#include "nvim/eval/vars.h"
 #include "nvim/ex_cmds.h"
 #include "nvim/ex_cmds2.h"
 #include "nvim/ex_eval.h"
diff --git a/src/nvim/ex_docmd.c b/src/nvim/ex_docmd.c
index f52115ef0f..0a9285b7fe 100644
--- a/src/nvim/ex_docmd.c
+++ b/src/nvim/ex_docmd.c
@@ -21,6 +21,7 @@
 #include "nvim/edit.h"
 #include "nvim/eval.h"
 #include "nvim/eval/userfunc.h"
+#include "nvim/eval/vars.h"
 #include "nvim/event/rstream.h"
 #include "nvim/event/wstream.h"
 #include "nvim/ex_cmds.h"
diff --git a/src/nvim/globals.h b/src/nvim/globals.h
index e2667257b8..b585467bd0 100644
--- a/src/nvim/globals.h
+++ b/src/nvim/globals.h
@@ -941,6 +941,9 @@ EXTERN char e_loclist[] INIT(= N_("E776: No location list"));
 EXTERN char e_re_damg[] INIT(= N_("E43: Damaged match string"));
 EXTERN char e_re_corr[] INIT(= N_("E44: Corrupted regexp program"));
 EXTERN char e_readonly[] INIT(= N_("E45: 'readonly' option is set (add ! to override)"));
+EXTERN char e_letwrong[] INIT(= N_("E734: Wrong variable type for %s="));
+EXTERN char e_illvar[] INIT(= N_("E461: Illegal variable name: %s"));
+EXTERN char e_cannot_mod[] INIT(= N_("E995: Cannot modify existing variable"));
 EXTERN char e_readonlyvar[] INIT(= N_("E46: Cannot change read-only variable \"%.*s\""));
 EXTERN char e_stringreq[] INIT(= N_("E928: String required"));
 EXTERN char e_dictreq[] INIT(= N_("E715: Dictionary required"));
diff --git a/src/nvim/highlight_group.c b/src/nvim/highlight_group.c
index 5027454222..ae8a6877b0 100644
--- a/src/nvim/highlight_group.c
+++ b/src/nvim/highlight_group.c
@@ -9,6 +9,7 @@
 #include "nvim/autocmd.h"
 #include "nvim/charset.h"
 #include "nvim/cursor_shape.h"
+#include "nvim/eval/vars.h"
 #include "nvim/fold.h"
 #include "nvim/highlight.h"
 #include "nvim/highlight_group.h"
diff --git a/src/nvim/keycodes.c b/src/nvim/keycodes.c
index dd78ebe722..063e6f45f8 100644
--- a/src/nvim/keycodes.c
+++ b/src/nvim/keycodes.c
@@ -8,7 +8,7 @@
 #include "nvim/ascii.h"
 #include "nvim/charset.h"
 #include "nvim/edit.h"
-#include "nvim/eval.h"
+#include "nvim/eval/vars.h"
 #include "nvim/keycodes.h"
 #include "nvim/memory.h"
 #include "nvim/message.h"
diff --git a/src/nvim/option.c b/src/nvim/option.c
index 6bbea8e2ae..bb3881b809 100644
--- a/src/nvim/option.c
+++ b/src/nvim/option.c
@@ -37,6 +37,7 @@
 #include "nvim/edit.h"
 #include "nvim/eval.h"
 #include "nvim/eval/typval.h"
+#include "nvim/eval/vars.h"
 #include "nvim/ex_cmds2.h"
 #include "nvim/ex_docmd.h"
 #include "nvim/ex_getln.h"
diff --git a/src/nvim/syntax.c b/src/nvim/syntax.c
index 43dbeccf01..aedb4b4862 100644
--- a/src/nvim/syntax.c
+++ b/src/nvim/syntax.c
@@ -18,6 +18,7 @@
 #include "nvim/charset.h"
 #include "nvim/cursor_shape.h"
 #include "nvim/eval.h"
+#include "nvim/eval/vars.h"
 #include "nvim/ex_cmds2.h"
 #include "nvim/ex_docmd.h"
 #include "nvim/fileio.h"
diff --git a/src/nvim/window.c b/src/nvim/window.c
index 909b02083e..8f52f40ef2 100644
--- a/src/nvim/window.c
+++ b/src/nvim/window.c
@@ -13,6 +13,7 @@
 #include "nvim/diff.h"
 #include "nvim/edit.h"
 #include "nvim/eval.h"
+#include "nvim/eval/vars.h"
 #include "nvim/ex_cmds.h"
 #include "nvim/ex_cmds2.h"
 #include "nvim/ex_docmd.h"