tui/input: defer nvim_paste properly.

Otherwise cursor and redraw code for normal and insert mode will not run. The
"tickle" workaround was used for this instead, and can now be removed.

The builtin vim.lua got the name
[string "-- Nvim-Lua stdlib: thevimmodule (:help l..."]
in error messages. Fix it to something reasonable.

src/nvim/api/vim.c

@@ -1283,8 +1283,6 @@ theend:
   api_free_array(args);
   if (cancel || phase == -1 || phase == 3) {  // End of paste-stream.
     draining = false;
-    // XXX: Tickle main loop to ensure cursor is updated.
-    loop_schedule_deferred(&main_loop, event_create(loop_dummy_event, 0));
   }
 
   return !cancel;

src/nvim/lua/executor.c

@@ -269,7 +269,9 @@ static int nlua_state_init(lua_State *const lstate) FUNC_ATTR_NONNULL_ALL
 #endif
 
   // vim
-  if (luaL_dostring(lstate, (char *)&vim_module[0])) {
+  const char *code = (char *)&vim_module[0];
+  if (luaL_loadbuffer(lstate, code, strlen(code), "@vim.lua")
+      || lua_pcall(lstate, 0, LUA_MULTRET, 0)) {
     nlua_error(lstate, _("E5106: Error while creating vim module: %.*s"));
     return 1;
   }

src/nvim/tui/input.c

@@ -106,17 +106,15 @@ static void tinput_wait_enqueue(void **argv)
   RBUFFER_UNTIL_EMPTY(input->key_buffer, buf, len) {
     const String keys = { .data = buf, .size = len };
     if (input->paste) {
-      Error err = ERROR_INIT;
-      // Paste phase: "continue" (unless handler canceled).
-      input->paste = !nvim_paste(keys, true, input->paste, &err)
-        ? 0 : (1 == input->paste ? 2 : input->paste);
+      String copy = copy_string(keys);
+      multiqueue_put(main_loop.events, tinput_paste_event, 3,
+                     copy.data, copy.size, (intptr_t)input->paste);
+      if (input->paste == 1) {
+        // Paste phase: "continue"
+        input->paste = 2;
+      }
       rbuffer_consumed(input->key_buffer, len);
       rbuffer_reset(input->key_buffer);
-      if (ERROR_SET(&err)) {
-        // TODO(justinmk): emsgf() does not display, why?
-        msg_printf_attr(HL_ATTR(HLF_E)|MSG_HIST, "paste: %s", err.msg);
-        api_clear_error(&err);
-      }
     } else {
       const size_t consumed = input_enqueue(keys);
       if (consumed) {
@@ -134,6 +132,33 @@ static void tinput_wait_enqueue(void **argv)
   uv_mutex_unlock(&input->key_buffer_mutex);
 }
 
+static void tinput_paste_event(void **argv)
+{
+  static bool canceled = false;
+
+  String keys = { .data = argv[0], .size = (size_t)argv[1] };
+  intptr_t phase = (intptr_t)argv[2];
+
+  if (phase == -1 || phase == 1) {
+    canceled = false;
+  }
+
+  Error err = ERROR_INIT;
+  if (!canceled) {
+    if (!nvim_paste(keys, true, phase, &err)) {
+      // paste failed, ingore further segments of the same paste
+      canceled = true;
+    }
+  }
+
+  if (ERROR_SET(&err)) {
+    emsgf("paste: %s", err.msg);
+    api_clear_error(&err);
+  }
+
+  api_free_string(keys);
+}
+
 static void tinput_flush(TermInput *input, bool wait_until_empty)
 {
   size_t drain_boundary = wait_until_empty ? 0 : 0xff;

test/functional/terminal/tui_spec.lua

@@ -352,15 +352,23 @@ describe('TUI', function()
     ]]}
     -- Start pasting...
     feed_data('\027[200~line 1\nline 2\n')
-    expect_child_buf_lines({'foo',''})
-    screen:expect{any='paste: Error executing lua'}
+    screen:expect{grid=[[
+      foo                                               |
+                                                        |
+      {5:                                                  }|
+      {8:paste: Error executing lua: [string "<nvim>"]:2: f}|
+      {8:ake fail}                                          |
+      {10:Press ENTER or type command to continue}{1: }          |
+      {3:-- TERMINAL --}                                    |
+    ]]}
     -- Remaining chunks are discarded after vim.paste() failure.
     feed_data('line 3\nline 4\n')
     feed_data('line 5\nline 6\n')
     feed_data('line 7\nline 8\n')
     -- Stop paste.
     feed_data('\027[201~')
-    feed_data('\n')  -- <Enter>
+    feed_data('\n')  -- <CR>
+    expect_child_buf_lines({'foo',''})
     --Dot-repeat/redo is not modified by failed paste.
     feed_data('.')
     screen:expect{grid=[[
@@ -388,7 +396,7 @@ describe('TUI', function()
       vim.paste = _G.save_paste_fn
     ]], {})
     feed_data('\027[200~line A\nline B\n\027[201~')
-    feed_data('\n')  -- <Enter>
+    feed_data('\n')  -- <CR>
     screen:expect{grid=[[
       foo                                               |
       typed input...line A                              |
@@ -414,7 +422,15 @@ describe('TUI', function()
   it("paste: 'nomodifiable' buffer", function()
     child_session:request('nvim_command', 'set nomodifiable')
     feed_data('\027[200~fail 1\nfail 2\n\027[201~')
-    screen:expect{any='Vim:E21'}
+    screen:expect{grid=[[
+                                                        |
+      {4:~                                                 }|
+      {5:                                                  }|
+      {8:paste: Error executing lua: vim.lua:194: Vim:E21: }|
+      {8:Cannot make changes, 'modifiable' is off}          |
+      {10:Press ENTER or type command to continue}{1: }          |
+      {3:-- TERMINAL --}                                    |
+    ]]}
     feed_data('\n')  -- <Enter>
     child_session:request('nvim_command', 'set modifiable')
     feed_data('\027[200~success 1\nsuccess 2\n\027[201~')