4 files changed, 37 insertions, 14 deletions
diff --git a/src/nvim/eval.lua b/src/nvim/eval.lua
index 2b89d34a6d..154023b25f 100644
--- a/src/nvim/eval.lua
+++ b/src/nvim/eval.lua
@@ -8151,11 +8151,13 @@ M.funcs = {
     args = 1,
     base = 1,
     desc = [=[
-      Reverse the order of items in {object} in-place.
-      {object} can be a |List| or a |Blob|.
-      Returns {object}.
-      Returns zero if {object} is not a List or a Blob.
-      If you want an object to remain unmodified make a copy first: >vim
+      Reverse the order of items in {object}.  {object} can be a
+      |List|, a |Blob| or a |String|.  For a List and a Blob the
+      items are reversed in-place and {object} is returned.
+      For a String a new String is returned.
+      Returns zero if {object} is not a List, Blob or a String.
+      If you want a List or Blob to remain unmodified make a copy
+      first: >vim
       	let revlist = reverse(copy(mylist))
       <
     ]=],
diff --git a/src/nvim/eval/funcs.c b/src/nvim/eval/funcs.c
index 9926530d58..250b5c5556 100644
--- a/src/nvim/eval/funcs.c
+++ b/src/nvim/eval/funcs.c
@@ -6199,6 +6199,10 @@ static void f_resolve(typval_T *argvars, typval_T *rettv, EvalFuncData fptr)
 /// "reverse({list})" function
 static void f_reverse(typval_T *argvars, typval_T *rettv, EvalFuncData fptr)
 {
+  if (tv_check_for_string_or_list_or_blob_arg(argvars, 0) == FAIL) {
+    return;
+  }
+
   if (argvars[0].v_type == VAR_BLOB) {
     blob_T *const b = argvars[0].vval.v_blob;
     const int len = tv_blob_len(b);
@@ -6209,9 +6213,14 @@ static void f_reverse(typval_T *argvars, typval_T *rettv, EvalFuncData fptr)
       tv_blob_set(b, len - i - 1, tmp);
     }
     tv_blob_set_ret(rettv, b);
-  } else if (argvars[0].v_type != VAR_LIST) {
-    semsg(_(e_listblobarg), "reverse()");
-  } else {
+  } else if (argvars[0].v_type == VAR_STRING) {
+    rettv->v_type = VAR_STRING;
+    if (argvars[0].vval.v_string != NULL) {
+      rettv->vval.v_string = reverse_text(argvars[0].vval.v_string);
+    } else {
+      rettv->vval.v_string = NULL;
+    }
+  } else if (argvars[0].v_type == VAR_LIST) {
     list_T *const l = argvars[0].vval.v_list;
     if (!value_check_lock(tv_list_locked(l), N_("reverse() argument"),
                           TV_TRANSLATE)) {
diff --git a/src/nvim/eval/typval.c b/src/nvim/eval/typval.c
index 5f7bd98298..ba2c23ffe8 100644
--- a/src/nvim/eval/typval.c
+++ b/src/nvim/eval/typval.c
@@ -81,6 +81,8 @@ 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[]
   = N_("E1239: Invalid value for blob: %d");
+static const char e_string_list_or_blob_required_for_argument_nr[]
+  = N_("E1252: String, List or Blob required for argument %d");
 static const char e_string_or_function_required_for_argument_nr[]
   = N_("E1256: String or function required for argument %d");
 static const char e_non_null_dict_required_for_argument_nr[]
@@ -4350,7 +4352,20 @@ int tv_check_for_string_or_list_arg(const typval_T *const args, const int idx)
   return OK;
 }
 
-/// Check for an optional string or list argument at 'idx'
+/// Give an error and return FAIL unless "args[idx]" is a string, a list or a blob.
+int tv_check_for_string_or_list_or_blob_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_STRING
+      && args[idx].v_type != VAR_LIST
+      && args[idx].v_type != VAR_BLOB) {
+    semsg(_(e_string_list_or_blob_required_for_argument_nr), idx + 1);
+    return FAIL;
+  }
+  return OK;
+}
+
+/// Check for an optional string or list argument at "idx"
 int tv_check_for_opt_string_or_list_arg(const typval_T *const args, const int idx)
   FUNC_ATTR_NONNULL_ALL FUNC_ATTR_WARN_UNUSED_RESULT FUNC_ATTR_PURE
 {
diff --git a/src/nvim/strings.c b/src/nvim/strings.c
index cfc7738ad7..ec770de4a0 100644
--- a/src/nvim/strings.c
+++ b/src/nvim/strings.c
@@ -2168,20 +2168,17 @@ int kv_do_printf(StringBuilder *str, const char *fmt, ...)
 ///
 /// @return  the allocated string.
 char *reverse_text(char *s)
-  FUNC_ATTR_NONNULL_RET
+  FUNC_ATTR_NONNULL_ALL FUNC_ATTR_NONNULL_RET
 {
-  // Reverse the pattern.
   size_t len = strlen(s);
   char *rev = xmalloc(len + 1);
-  size_t rev_i = len;
-  for (size_t s_i = 0; s_i < len; s_i++) {
+  for (size_t s_i = 0, rev_i = len; s_i < len; s_i++) {
     const int mb_len = utfc_ptr2len(s + s_i);
     rev_i -= (size_t)mb_len;
     memmove(rev + rev_i, s + s_i, (size_t)mb_len);
     s_i += (size_t)mb_len - 1;
   }
   rev[len] = NUL;
-
   return rev;
 }