vim-patch:9.0.0051: using CTRL-C wih :append may hang Vim

Problem:    Using CTRL-C wih :append may hang Vim.
Solution:   Reset got_int. (closes vim/vim#10729, closes vim/vim#10728)
https://github.com/vim/vim/commit/f754fe6a3d5384b5146c38a32db6da9d46e00c40

3 files changed, 76 insertions, 0 deletions

diff --git a/src/nvim/ex_getln.c b/src/nvim/ex_getln.c
index 3038e7bd04..8c8f8cec4b 100644
--- a/src/nvim/ex_getln.c
+++ b/src/nvim/ex_getln.c
@@ -1006,6 +1006,8 @@ static int command_line_check(VimState *state)
                            // that occurs while typing a command should
                            // cause the command not to be executed.
 
+  got_int = false;         // avoid infinite Ctrl-C loop in Ex mode
+
   cursorcmd();             // set the cursor on the right spot
   ui_cursor_shape();
   return 1;
diff --git a/src/nvim/testdir/test_ex_mode.vim b/src/nvim/testdir/test_ex_mode.vim
index c06d143425..c6bd234e65 100644
--- a/src/nvim/testdir/test_ex_mode.vim
+++ b/src/nvim/testdir/test_ex_mode.vim
@@ -135,6 +135,29 @@ func Test_Ex_global()
   bwipe!
 endfunc
 
+" Test for pressing Ctrl-C in :append inside a loop in Ex mode
+" This used to hang Vim
+func Test_Ex_append_in_loop()
+  CheckRunVimInTerminal
+  let buf = RunVimInTerminal('', {'rows': 6})
+
+  call term_sendkeys(buf, "gQ")
+  call term_sendkeys(buf, "for i in range(1)\<CR>")
+  call term_sendkeys(buf, "append\<CR>")
+  call WaitForAssert({-> assert_match(':  append', term_getline(buf, 5))}, 1000)
+  call term_sendkeys(buf, "\<C-C>")
+  call term_wait(buf)
+  call term_sendkeys(buf, "foo\<CR>")
+  call WaitForAssert({-> assert_match('foo', term_getline(buf, 5))}, 1000)
+  call term_sendkeys(buf, ".\<CR>")
+  call WaitForAssert({-> assert_match('.', term_getline(buf, 5))}, 1000)
+  call term_sendkeys(buf, "endfor\<CR>")
+  call term_sendkeys(buf, "vi\<CR>")
+  call WaitForAssert({-> assert_match('foo', term_getline(buf, 1))}, 1000)
+
+  call StopVimInTerminal(buf)
+endfunc
+
 " In Ex-mode, a backslash escapes a newline
 func Test_Ex_escape_enter()
   call feedkeys("gQlet l = \"a\\\<kEnter>b\"\<cr>vi\<cr>", 'xt')
diff --git a/test/functional/legacy/ex_mode_spec.lua b/test/functional/legacy/ex_mode_spec.lua
index 98f113bbd0..59f4a21f5f 100644
--- a/test/functional/legacy/ex_mode_spec.lua
+++ b/test/functional/legacy/ex_mode_spec.lua
@@ -6,6 +6,7 @@ local eq = helpers.eq
 local eval = helpers.eval
 local feed = helpers.feed
 local meths = helpers.meths
+local sleep = helpers.sleep
 
 before_each(clear)
 
@@ -122,4 +123,54 @@ describe('Ex mode', function()
                                                                   |
     ]])
   end)
+
+  it('pressing Ctrl-C in :append inside a loop in Ex mode does not hang', function()
+    local screen = Screen.new(60, 6)
+    screen:set_default_attr_ids({
+      [0] = {bold = true, reverse = true},  -- MsgSeparator
+      [1] = {bold = true, foreground = Screen.colors.Blue},  -- NonText
+    })
+    screen:attach()
+    feed('gQ')
+    feed('for i in range(1)<CR>')
+    feed('append<CR>')
+    screen:expect([[
+      {0:                                                            }|
+      Entering Ex mode.  Type "visual" to go to Normal mode.      |
+      :for i in range(1)                                          |
+                                                                  |
+      :  append                                                   |
+      ^                                                            |
+    ]])
+    feed('<C-C>')
+    sleep(10)  -- Wait for Ctrl-C to flush input
+    feed('foo<CR>')
+    screen:expect([[
+      Entering Ex mode.  Type "visual" to go to Normal mode.      |
+      :for i in range(1)                                          |
+                                                                  |
+      :  append                                                   |
+      foo                                                         |
+      ^                                                            |
+    ]])
+    feed('.<CR>')
+    screen:expect([[
+      :for i in range(1)                                          |
+                                                                  |
+      :  append                                                   |
+      foo                                                         |
+      .                                                           |
+      :  ^                                                         |
+    ]])
+    feed('endfor<CR>')
+    feed('vi<CR>')
+    screen:expect([[
+      ^foo                                                         |
+      {1:~                                                           }|
+      {1:~                                                           }|
+      {1:~                                                           }|
+      {1:~                                                           }|
+                                                                  |
+    ]])
+  end)
 end)