vim-patch:9.0.0837: append() reports failure when not appending anything

Problem:    append() reports failure when not appending anything.
Solution:   Only report failure when appending something. (closes vim/vim#11498)

https://github.com/vim/vim/commit/cd9c8d400c1eb9cbb4ff6a33be02f91a30ab13b2

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

1 files changed, 10 insertions, 6 deletions

diff --git a/src/nvim/eval.lua b/src/nvim/eval.lua
index f6ccc803c0..886887dedb 100644
--- a/src/nvim/eval.lua
+++ b/src/nvim/eval.lua
@@ -141,7 +141,8 @@ M.funcs = {
       {lnum} can be zero to insert a line before the first one.
       {lnum} is used like with |getline()|.
       Returns 1 for failure ({lnum} out of range or out of memory),
-      0 for success.  Example: >vim
+      0 for success.  When {text} is an empty list zero is returned,
+      no matter the value of {lnum}.  Example: >vim
       	let failed = append(line('$'), "# THE END")
       	let failed = append(0, ["Chapter 1", "the beginning"])
       <
@@ -173,7 +174,8 @@ M.funcs = {
       If {buf} is not a valid buffer or {lnum} is not valid, an
       error message is given. Example: >vim
       	let failed = appendbufline(13, 0, "# THE START")
-      <
+      <However, when {text} is an empty list then no error is given
+      for an invalid {lnum}, since {lnum} isn't actually used.
 
     ]=],
     name = 'appendbufline',
@@ -8871,9 +8873,10 @@ M.funcs = {
 
       To insert lines use |appendbufline()|.
 
-      {text} can be a string to set one line, or a list of strings
-      to set multiple lines.  If the list extends below the last
-      line then those lines are added.
+      {text} can be a string to set one line, or a List of strings
+      to set multiple lines.  If the List extends below the last
+      line then those lines are added.  If the List is empty then
+      nothing is changed and zero is returned.
 
       For the use of {buf}, see |bufname()| above.
 
@@ -9117,7 +9120,8 @@ M.funcs = {
       When {lnum} is just below the last line the {text} will be
       added below the last line.
       {text} can be any type or a List of any type, each item is
-      converted to a String.
+      converted to a String.  When {text} is an empty List then
+      nothing is changed and FALSE is returned.
 
       If this succeeds, FALSE is returned.  If this fails (most likely
       because {lnum} is invalid) TRUE is returned.