terminal: handle &confirm and :confirm on unloading (#8726)

Show a proper confirmation dialog when trying to unload a terminal buffer while
the confirm option is set or when :confirm is used.

Fixes https://github.com/neovim/neovim/issues/4651

2 files changed, 26 insertions, 3 deletions

diff --git a/src/nvim/buffer.c b/src/nvim/buffer.c
index 95eaf4dcf6..81bbc56eb9 100644
--- a/src/nvim/buffer.c
+++ b/src/nvim/buffer.c
@@ -1172,14 +1172,21 @@ do_buffer (
         }
       } else {
         if (buf->terminal) {
-          EMSG2(_("E89: %s will be killed(add ! to override)"),
-              (char *)buf->b_fname);
+          if (p_confirm || cmdmod.confirm) {
+            if (!dialog_close_terminal(buf)) {
+              return FAIL;
+            }
+          } else {
+            EMSG2(_("E89: %s will be killed(add ! to override)"),
+                  (char *)buf->b_fname);
+            return FAIL;
+          }
         } else {
           EMSGN(_("E89: No write since last change for buffer %" PRId64
                   " (add ! to override)"),
                 buf->b_fnum);
+          return FAIL;
         }
-        return FAIL;
       }
     }
 
diff --git a/src/nvim/ex_cmds2.c b/src/nvim/ex_cmds2.c
index 46a7c869e1..f07bc0e137 100644
--- a/src/nvim/ex_cmds2.c
+++ b/src/nvim/ex_cmds2.c
@@ -1339,6 +1339,22 @@ void dialog_changed(buf_T *buf, int checkall)
   }
 }
 
+/// Ask the user whether to close the terminal buffer or not.
+///
+/// @param buf The terminal buffer.
+/// @return bool Whether to close the buffer or not.
+bool dialog_close_terminal(buf_T *buf)
+{
+  char_u buff[DIALOG_MSG_SIZE];
+
+  dialog_msg(buff, _("Close \"%s\"?"),
+             (buf->b_fname != NULL) ? buf->b_fname : (char_u *)"?");
+
+  int ret = vim_dialog_yesnocancel(VIM_QUESTION, NULL, buff, 1);
+
+  return (ret == VIM_YES) ? true : false;
+}
+
 /// Return true if the buffer "buf" can be abandoned, either by making it
 /// hidden, autowriting it or unloading it.
 bool can_abandon(buf_T *buf, int forceit)