patch 9.0.0914: deletebufline() may move marks in the wrong window

Problem:    deletebufline() may move marks in the wrong window.
Solution:   Find a window for the buffer being changed. (closes #11583)

src/evalbuffer.c

@@ -119,6 +119,59 @@ find_win_for_curbuf(void)
     }
 }
 
+typedef struct {
+    win_T	*cob_curwin_save;
+    aco_save_T	cob_aco;
+    int		cob_using_aco;
+    int		cob_save_VIsual_active;
+} cob_T;
+
+/*
+ * Used before making a change in "buf", which is not the current one: Make
+ * "buf" the current buffer and find a window for this buffer, so that side
+ * effects are done correctly (e.g., adjusting marks).
+ *
+ * Information is saved in "cob" and MUST be restored by calling
+ * change_other_buffer_restore().
+ */
+    static void
+change_other_buffer_prepare(cob_T *cob, buf_T *buf)
+{
+    CLEAR_POINTER(cob);
+
+    // Set "curbuf" to the buffer being changed.  Then make sure there is a
+    // window for it to handle any side effects.
+    cob->cob_save_VIsual_active = VIsual_active;
+    VIsual_active = FALSE;
+    cob->cob_curwin_save = curwin;
+    curbuf = buf;
+    find_win_for_curbuf();  // simplest: find existing window for "buf"
+
+    if (curwin->w_buffer != buf)
+    {
+	// No existing window for this buffer.  It is dangerous to have
+	// curwin->w_buffer differ from "curbuf", use the autocmd window.
+	curbuf = curwin->w_buffer;
+	aucmd_prepbuf(&cob->cob_aco, buf);
+	cob->cob_using_aco = TRUE;
+    }
+}
+
+    static void
+change_other_buffer_restore(cob_T *cob)
+{
+    if (cob->cob_using_aco)
+    {
+	aucmd_restbuf(&cob->cob_aco);
+    }
+    else
+    {
+	curwin = cob->cob_curwin_save;
+	curbuf = curwin->w_buffer;
+    }
+    VIsual_active = cob->cob_save_VIsual_active;
+}
+
 /*
  * Set line or list of lines in buffer "buf" to "lines".
  * Any type is allowed and converted to a string.
@@ -137,10 +190,6 @@ set_buffer_lines(
     listitem_T	*li = NULL;
     long	added = 0;
     linenr_T	append_lnum;
-    win_T	*curwin_save = NULL;
-    aco_save_T	aco;
-    int		using_aco = FALSE;
-    int		save_VIsual_active = VIsual_active;
 
     // When using the current buffer ml_mfp will be set if needed.  Useful when
     // setline() is used on startup.  For other buffers the buffer must be
@@ -154,24 +203,11 @@ set_buffer_lines(
 	return;
     }
 
+    // After this don't use "return", goto "cleanup"!
+    cob_T cob;
     if (!is_curbuf)
-    {
+	// set "curbuf" to "buf" and find a window for this buffer
-	// Set "curbuf" to the buffer being changed.  Then make sure there is a
+	change_other_buffer_prepare(&cob, buf);
-	// window for it to handle any side effects.
-	VIsual_active = FALSE;
-	curwin_save = curwin;
-	curbuf = buf;
-	find_win_for_curbuf();  // simplest: find existing window for "buf"
-
-	if (curwin->w_buffer != buf)
-	{
-	    // No existing window for this buffer.  It is dangerous to have
-	    // curwin->w_buffer differ from "curbuf", use the autocmd window.
-	    curbuf = curwin->w_buffer;
-	    aucmd_prepbuf(&aco, buf);
-	    using_aco = TRUE;
-	}
-    }
 
     if (append)
 	// appendbufline() uses the line number below which we insert
@@ -272,18 +308,7 @@ set_buffer_lines(
 
 done:
     if (!is_curbuf)
-    {
+	change_other_buffer_restore(&cob);
-	if (using_aco)
-	{
-	    aucmd_restbuf(&aco);
-	}
-	else
-	{
-	    curwin = curwin_save;
-	    curbuf = curwin->w_buffer;
-	}
-	VIsual_active = save_VIsual_active;
-    }
 }
 
 /*
@@ -521,12 +546,9 @@ f_deletebufline(typval_T *argvars, typval_T *rettv)
     linenr_T	lnum;
     long	count;
     int		is_curbuf;
-    buf_T	*curbuf_save = NULL;
-    win_T	*curwin_save = NULL;
     tabpage_T	*tp;
     win_T	*wp;
     int		did_emsg_before = did_emsg;
-    int		save_VIsual_active = VIsual_active;
 
     rettv->vval.v_number = 1;	// FAIL by default
 
@@ -539,7 +561,6 @@ f_deletebufline(typval_T *argvars, typval_T *rettv)
     buf = tv_get_buf(&argvars[0], FALSE);
     if (buf == NULL)
 	return;
-    is_curbuf = buf == curbuf;
 
     first = tv_get_lnum_buf(&argvars[1], buf);
     if (did_emsg > did_emsg_before)
@@ -554,14 +575,12 @@ f_deletebufline(typval_T *argvars, typval_T *rettv)
 	return;
 
     // After this don't use "return", goto "cleanup"!
+    is_curbuf = buf == curbuf;
+    cob_T cob;
     if (!is_curbuf)
-    {
+	// set "curbuf" to "buf" and find a window for this buffer
-	VIsual_active = FALSE;
+	change_other_buffer_prepare(&cob, buf);
-	curbuf_save = curbuf;
+
-	curwin_save = curwin;
-	curbuf = buf;
-	find_win_for_curbuf();
-    }
     if (last > curbuf->b_ml.ml_line_count)
 	last = curbuf->b_ml.ml_line_count;
     count = last - first + 1;
@@ -599,11 +618,7 @@ f_deletebufline(typval_T *argvars, typval_T *rettv)
 
 cleanup:
     if (!is_curbuf)
-    {
+	change_other_buffer_restore(&cob);
-	curbuf = curbuf_save;
-	curwin = curwin_save;
-	VIsual_active = save_VIsual_active;
-    }
 }
 
 /*

src/testdir/test_bufline.vim

@@ -98,12 +98,25 @@ func Test_appendbufline()
   new
   let b = bufnr('%')
   hide
+
+  new
+  call setline(1, ['line1', 'line2', 'line3'])
+  normal! 2gggg
+  call assert_equal(2, line("''"))
+
   call assert_equal(0, appendbufline(b, 0, ['foo', 'bar']))
   call assert_equal(['foo'], getbufline(b, 1))
   call assert_equal(['bar'], getbufline(b, 2))
   call assert_equal(['foo', 'bar'], getbufline(b, 1, 2))
+  call assert_equal(0, appendbufline(b, 0, 'baz'))
+  call assert_equal(['baz', 'foo', 'bar'], getbufline(b, 1, 3))
+
+  " appendbufline() in a hidden buffer shouldn't move marks in current window.
+  call assert_equal(2, line("''"))
+  bwipe!
+
   exe "bd!" b
-  call assert_equal([], getbufline(b, 1, 2))
+  call assert_equal([], getbufline(b, 1, 3))
 
   split Xtest
   call setline(1, ['a', 'b', 'c'])
@@ -173,10 +186,21 @@ func Test_deletebufline()
   let b = bufnr('%')
   call setline(1, ['aaa', 'bbb', 'ccc'])
   hide
+
+  new
+  call setline(1, ['line1', 'line2', 'line3'])
+  normal! 2gggg
+  call assert_equal(2, line("''"))
+
   call assert_equal(0, deletebufline(b, 2))
   call assert_equal(['aaa', 'ccc'], getbufline(b, 1, 2))
   call assert_equal(0, deletebufline(b, 2, 8))
   call assert_equal(['aaa'], getbufline(b, 1, 2))
+
+  " deletebufline() in a hidden buffer shouldn't move marks in current window.
+  call assert_equal(2, line("''"))
+  bwipe!
+
   exe "bd!" b
   call assert_equal(1, b->deletebufline(1))
 

src/version.c

@@ -695,6 +695,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    914,
 /**/
     913,
 /**/