vim-patch:8.1.1049: when user tries to exit with CTRL-C message is confusing

Problem:    When user tries to exit with CTRL-C message is confusing.
Solution:   Only mention ":qa!" when there is a changed buffer. (closes vim/vim#4163)
https://github.com/vim/vim/commit/a84a3dd6635fcd2e07f510cba6a999585dcc381a

vim-patch:8.1.1052: test for CTRL-C message sometimes fails

Problem:    test for CTRL-C message sometimes fails
Solution:   Make sure there are no changed buffers.
https://github.com/vim/vim/commit/553e5a5c568e7d175b65b0472cd6d9843b25f4c8

vim-patch:8.1.1053: warning for missing return statement

Problem:    Warning for missing return statement. (Dominique Pelle)
Solution:   Add return statement.
https://github.com/vim/vim/commit/d6c3f1fa2b5e1dd7dc87cf608d72b84ad696b58f

3 files changed, 34 insertions, 2 deletions

diff --git a/src/nvim/normal.c b/src/nvim/normal.c
index 2e4cdc1fe1..4cfd11ab7c 100644
--- a/src/nvim/normal.c
+++ b/src/nvim/normal.c
@@ -7465,8 +7465,12 @@ static void nv_esc(cmdarg_T *cap)
         && cmdwin_type == 0
         && !VIsual_active
         && no_reason) {
-      MSG(_("Type  :qa!  and press <Enter> to abandon all changes"
-            " and exit Nvim"));
+      if (anyBufIsChanged()) {
+        MSG(_("Type  :qa!  and press <Enter> to abandon all changes"
+              " and exit Nvim"));
+      } else {
+        MSG(_("Type  :qa  and press <Enter> to exit Nvim"));
+      }
     }
 
     /* Don't reset "restart_edit" when 'insertmode' is set, it won't be
diff --git a/src/nvim/testdir/test_normal.vim b/src/nvim/testdir/test_normal.vim
index ef17209f74..945cd5a617 100644
--- a/src/nvim/testdir/test_normal.vim
+++ b/src/nvim/testdir/test_normal.vim
@@ -2552,6 +2552,21 @@ func Test_delete_until_paragraph()
   bwipe!
 endfunc
 
+func Test_message_when_using_ctrl_c()
+  " Make sure no buffers are changed.
+  %bwipe!
+
+  exe "normal \<C-C>"
+  call assert_match("Type  :qa  and press <Enter> to exit Nvim", Screenline(&lines))
+
+  new
+  cal setline(1, 'hi!')
+  exe "normal \<C-C>"
+  call assert_match("Type  :qa!  and press <Enter> to abandon all changes and exit Nvim", Screenline(&lines))
+
+  bwipe!
+endfunc
+
 " Test for '[m', ']m', '[M' and ']M'
 " Jumping to beginning and end of methods in Java-like languages
 func Test_java_motion()
diff --git a/src/nvim/undo.c b/src/nvim/undo.c
index c9b0d96866..1305e013ad 100644
--- a/src/nvim/undo.c
+++ b/src/nvim/undo.c
@@ -2961,10 +2961,23 @@ static char_u *u_save_line(linenr_T lnum)
 ///
 /// @return true if the buffer has changed
 bool bufIsChanged(buf_T *buf)
+  FUNC_ATTR_WARN_UNUSED_RESULT
 {
   return !bt_dontwrite(buf) && (buf->b_changed || file_ff_differs(buf, true));
 }
 
+// Return true if any buffer has changes.  Also buffers that are not written.
+bool anyBufIsChanged(void)
+  FUNC_ATTR_WARN_UNUSED_RESULT
+{
+  FOR_ALL_BUFFERS(buf) {
+    if (bufIsChanged(buf)) {
+      return true;
+    }
+  }
+  return false;
+}
+
 /// Check if the 'modified' flag is set, or 'ff' has changed (only need to
 /// check the first character, because it can only be "dos", "unix" or "mac").
 /// "nofile" and "scratch" type buffers are considered to always be unchanged.