vim-patch:9.0.0331: cannot use items() on a string

Problem:    Cannot use items() on a string.
Solution:   Make items() work on a string. (closes vim/vim#11016)

https://github.com/vim/vim/commit/3e518a8ec74065aedd67d352c93d6ae6be550316

Co-authored-by: Bram Moolenaar <Bram@vim.org>

2 files changed, 47 insertions, 17 deletions

diff --git a/src/nvim/eval/typval.c b/src/nvim/eval/typval.c
index 8fc8dcc479..4458dba27d 100644
--- a/src/nvim/eval/typval.c
+++ b/src/nvim/eval/typval.c
@@ -93,10 +93,10 @@ static const char e_string_or_number_required_for_argument_nr[]
   = N_("E1220: String or Number required for argument %d");
 static const char e_string_or_list_required_for_argument_nr[]
   = N_("E1222: String or List required for argument %d");
+static const char e_string_list_or_dict_required_for_argument_nr[]
+  = N_("E1225: String, List or Dictionary required for argument %d");
 static const char e_list_or_blob_required_for_argument_nr[]
   = N_("E1226: List or Blob required for argument %d");
-static const char e_list_or_dict_required_for_argument_nr[]
-  = N_("E1227: List or Dictionary required for argument %d");
 static const char e_blob_required_for_argument_nr[]
   = N_("E1238: Blob required for argument %d");
 static const char e_invalid_value_for_blob_nr[]
@@ -813,6 +813,30 @@ static void tv_list2items(typval_T *argvars, typval_T *rettv)
   });
 }
 
+/// "items(string)" function
+/// Caller must have already checked that argvars[0] is a String.
+static void tv_string2items(typval_T *argvars, typval_T *rettv)
+{
+  const char *p = argvars[0].vval.v_string;
+
+  tv_list_alloc_ret(rettv, kListLenMayKnow);
+  if (p == NULL) {
+    return;  // null string behaves like an empty string
+  }
+
+  for (varnumber_T idx = 0; *p != NUL; idx++) {
+    int len = utfc_ptr2len(p);
+    if (len == 0) {
+      break;
+    }
+    list_T *l2 = tv_list_alloc(2);
+    tv_list_append_list(rettv->vval.v_list, l2);
+    tv_list_append_number(l2, idx);
+    tv_list_append_string(l2, p, len);
+    p += len;
+  }
+}
+
 /// Extend first list with the second
 ///
 /// @param[out]  l1  List to extend.
@@ -3172,7 +3196,7 @@ void tv_dict_alloc_ret(typval_T *const ret_tv)
 static void tv_dict2list(typval_T *const argvars, typval_T *const rettv, const DictListType what)
 {
   if ((what == kDict2ListItems
-       ? tv_check_for_list_or_dict_arg(argvars, 0)
+       ? tv_check_for_string_or_list_or_dict_arg(argvars, 0)
        : tv_check_for_dict_arg(argvars, 0)) == FAIL) {
     tv_list_alloc_ret(rettv, 0);
     return;
@@ -3202,15 +3226,8 @@ static void tv_dict2list(typval_T *const argvars, typval_T *const rettv, const D
         tv_item.v_type = VAR_LIST;
         tv_item.vval.v_list = sub_l;
         tv_list_ref(sub_l);
-
-        tv_list_append_owned_tv(sub_l, (typval_T) {
-          .v_type = VAR_STRING,
-          .v_lock = VAR_UNLOCKED,
-          .vval.v_string = xstrdup(di->di_key),
-        });
-
+        tv_list_append_string(sub_l, di->di_key, -1);
         tv_list_append_tv(sub_l, &di->di_tv);
-
         break;
       }
     }
@@ -3222,7 +3239,9 @@ static void tv_dict2list(typval_T *const argvars, typval_T *const rettv, const D
 /// "items(dict)" function
 void f_items(typval_T *argvars, typval_T *rettv, EvalFuncData fptr)
 {
-  if (argvars[0].v_type == VAR_LIST) {
+  if (argvars[0].v_type == VAR_STRING) {
+    tv_string2items(argvars, rettv);
+  } else if (argvars[0].v_type == VAR_LIST) {
     tv_list2items(argvars, rettv);
   } else {
     tv_dict2list(argvars, rettv, kDict2ListItems);
@@ -4436,12 +4455,14 @@ int tv_check_for_opt_string_or_list_arg(const typval_T *const args, const int id
           || tv_check_for_string_or_list_arg(args, idx) != FAIL) ? OK : FAIL;
 }
 
-/// Give an error and return FAIL unless "args[idx]" is a list or dict
-int tv_check_for_list_or_dict_arg(const typval_T *const args, const int idx)
+/// Give an error and return FAIL unless "args[idx]" is a string or a list or a dict
+int tv_check_for_string_or_list_or_dict_arg(const typval_T *const args, const int idx)
   FUNC_ATTR_NONNULL_ALL FUNC_ATTR_WARN_UNUSED_RESULT FUNC_ATTR_PURE
 {
-  if (args[idx].v_type != VAR_LIST && args[idx].v_type != VAR_DICT) {
-    semsg(_(e_list_or_dict_required_for_argument_nr), idx + 1);
+  if (args[idx].v_type != VAR_STRING
+      && args[idx].v_type != VAR_LIST
+      && args[idx].v_type != VAR_DICT) {
+    semsg(_(e_string_list_or_dict_required_for_argument_nr), idx + 1);
     return FAIL;
   }
   return OK;
diff --git a/test/old/testdir/test_listdict.vim b/test/old/testdir/test_listdict.vim
index e976dc4c29..5e4a3fd1f8 100644
--- a/test/old/testdir/test_listdict.vim
+++ b/test/old/testdir/test_listdict.vim
@@ -203,7 +203,16 @@ func Test_list_items()
   endfor
   call assert_equal([[0, 'a'], [1, 'b'], [2, 'c']], r)
 
-  call assert_fails('call items(3)', 'E1227:')
+  call assert_fails('call items(3)', 'E1225:')
+endfunc
+
+func Test_string_items()
+  let r = []
+  let s = 'ábツ'
+  for [idx, val] in items(s)
+    call extend(r, [[idx, val]])
+  endfor
+  call assert_equal([[0, 'á'], [1, 'b'], [2, 'ツ']], r)
 endfunc
 
 " Test removing items in list