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)
a84a3dd663

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.
553e5a5c56

vim-patch:8.1.1053: warning for missing return statement

Problem:    Warning for missing return statement. (Dominique Pelle)
Solution:   Add return statement.
d6c3f1fa2b

src/nvim/normal.c

@@ -7465,8 +7465,12 @@ static void nv_esc(cmdarg_T *cap)
         && cmdwin_type == 0
         && !VIsual_active
         && no_reason) {
+      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

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()

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.

test/functional/eval/system_spec.lua

@@ -275,7 +275,7 @@ describe('system()', function()
         ~                                                    |
         ~                                                    |
         ~                                                    |
-        Type  :qa!  and press <E...all changes and exit Nvim |
+        Type  :qa  and press <Enter> to exit Nvim            |
       ]])
     end)
   end)
@@ -481,7 +481,7 @@ describe('systemlist()', function()
         ~                                                    |
         ~                                                    |
         ~                                                    |
-        Type  :qa!  and press <E...all changes and exit Nvim |
+        Type  :qa  and press <Enter> to exit Nvim            |
       ]])
     end)
   end)

test/functional/ui/cmdline_highlight_spec.lua

@@ -494,7 +494,7 @@ describe('Command-line coloring', function()
       {EOB:~                                       }|
       {EOB:~                                       }|
       {EOB:~                                       }|
-      Type  :qa!  and pr...nges and exit Nvim |
+      Type  :qa  and pre...nter> to exit Nvim |
     ]])
   end)
   it('works fine with NUL, NL, CR', function()

test/functional/ui/messages_spec.lua

@@ -631,7 +631,7 @@ describe('ui/ext_messages', function()
       {1:~                        }|
       {1:~                        }|
     ]], messages={{
-      content = {{ "Type  :qa!  and press <Enter> to abandon all changes and exit Nvim" }},
+      content = {{ "Type  :qa  and press <Enter> to exit Nvim" }},
       kind = ""}
     }}
 
@@ -678,7 +678,7 @@ describe('ui/ext_messages', function()
       {1:~                        }|
     ]], messages={
       {kind="echomsg", content={{"howdy"}}},
-      {kind="", content={{"Type  :qa!  and press <Enter> to abandon all changes and exit Nvim"}}},
+      {kind="", content={{"Type  :qa  and press <Enter> to exit Nvim"}}},
       {kind="echoerr", content={{"bork", 2}}},
       {kind="emsg", content={{"E117: Unknown function: nosuchfunction", 2}}}
     }}