fix(tui): don't call tinput_init() twice (#36386)

src/nvim/tui/input.c

@@ -125,6 +125,7 @@ static PMap(int) kitty_key_map = MAP_INIT;
 
 void tinput_init(TermInput *input, Loop *loop, TerminfoEntry *ti)
 {
+  assert(input->loop == NULL);
   input->loop = loop;
   input->paste = 0;
   input->in_fd = STDIN_FILENO;
@@ -163,6 +164,7 @@ void tinput_destroy(TermInput *input)
   uv_close((uv_handle_t *)&input->bg_query_timer, NULL);
   rstream_may_close(&input->read_stream);
   termkey_destroy(input->tk);
+  input->loop = NULL;
 }
 
 void tinput_start(TermInput *input)

src/nvim/tui/tui.c

@@ -596,7 +596,9 @@ static void tui_terminal_start(TUIData *tui)
 {
   tui->print_attr_id = -1;
   terminfo_start(tui);
-  tinput_init(&tui->input, &main_loop, &tui->ti);
+  if (tui->input.loop == NULL) {
+    tinput_init(&tui->input, &main_loop, &tui->ti);
+  }
   tui_guess_size(tui);
   tinput_start(&tui->input);
 }

test/functional/terminal/tui_spec.lua

@@ -53,6 +53,48 @@ describe('TUI', function()
     end
     screen:expect({ any = vim.pesc('[Process exited 1]'), unchanged = true })
   end)
+
+  it('suspending does not crash or hang', function()
+    clear()
+    local screen = tt.setup_child_nvim({ '--clean', '--cmd', 'set notermguicolors' })
+    local s0 = [[
+      ^                                                  |
+      ~                                                 |*3
+      {2:[No Name]                       0,0-1          All}|
+                                                        |
+      {5:-- TERMINAL --}                                    |
+    ]]
+    screen:expect(s0)
+    feed_data(':')
+    local s1 = [[
+                                                        |
+      ~                                                 |*3
+      {2:[No Name]                       0,0-1          All}|
+      :^                                                 |
+      {5:-- TERMINAL --}                                    |
+    ]]
+    screen:expect(s1)
+    feed_data('suspend\r')
+    if is_os('win') then -- no-op on Windows
+      screen:expect([[
+        ^                                                  |
+        ~                                                 |*3
+        {2:[No Name]                       0,0-1          All}|
+        :suspend                                          |
+        {5:-- TERMINAL --}                                    |
+      ]])
+    else -- resuming works on other platforms
+      screen:expect([[
+        ^                                                  |
+                                                          |*5
+        {5:-- TERMINAL --}                                    |
+      ]])
+      exec_lua([[vim.uv.kill(vim.fn.jobpid(vim.bo.channel), 'sigcont')]])
+      screen:expect(s0)
+    end
+    feed_data(':')
+    screen:expect(s1)
+  end)
 end)
 
 describe('TUI :detach', function()