patch 8.1.0062: popup menu broken if a callback changes the window layout

Problem:    Popup menu broken if a callback changes the window layout. (Qiming
            Zhao)
Solution:   Recompute the popup menu position if needed.  Redraw the ruler
            even when the popup menu is displayed.

src/popupmnu.c

@@ -29,6 +29,12 @@ static int pum_scrollbar;		/* TRUE when scrollbar present */
 static int pum_row;			/* top row of pum */
 static int pum_col;			/* left column of pum */
 
+static int pum_win_row;
+static int pum_win_height;
+static int pum_win_col;
+static int pum_win_wcol;
+static int pum_win_width;
+
 static int pum_do_redraw = FALSE;	/* do redraw anyway */
 
 static int pum_set_selected(int n, int repeat);
@@ -81,7 +87,6 @@ pum_display(
 {
     int		def_width;
     int		max_width;
-    int		row;
     int		context_lines;
     int		cursor_col;
     int		above_row;
@@ -103,7 +108,13 @@ pum_display(
 	validate_cursor_col();
 	pum_array = NULL;
 
-	row = curwin->w_wrow + W_WINROW(curwin);
+	// Remember the essential parts of the window position and size, so we
+	// can decide when to reposition the popup menu.
+	pum_win_row = curwin->w_wrow + W_WINROW(curwin);
+	pum_win_height = curwin->w_height;
+	pum_win_col = curwin->w_wincol;
+	pum_win_wcol = curwin->w_wcol;
+	pum_win_width = curwin->w_width;
 
 #if defined(FEAT_QUICKFIX)
 	FOR_ALL_WINDOWS(pvwin)
@@ -128,12 +139,12 @@ pum_display(
 	if (p_ph > 0 && pum_height > p_ph)
 	    pum_height = p_ph;
 
-	/* Put the pum below "row" if possible.  If there are few lines decide
+	/* Put the pum below "pum_win_row" if possible.  If there are few lines decide
 	 * on where there is more room. */
-	if (row + 2 >= below_row - pum_height
+	if (pum_win_row + 2 >= below_row - pum_height
-			      && row - above_row > (below_row - above_row) / 2)
+		      && pum_win_row - above_row > (below_row - above_row) / 2)
 	{
-	    /* pum above "row" */
+	    /* pum above "pum_win_row" */
 
 	    /* Leave two lines of context if possible */
 	    if (curwin->w_wrow - curwin->w_cline_row >= 2)
@@ -141,15 +152,15 @@ pum_display(
 	    else
 		context_lines = curwin->w_wrow - curwin->w_cline_row;
 
-	    if (row >= size + context_lines)
+	    if (pum_win_row >= size + context_lines)
 	    {
-		pum_row = row - size - context_lines;
+		pum_row = pum_win_row - size - context_lines;
 		pum_height = size;
 	    }
 	    else
 	    {
 		pum_row = 0;
-		pum_height = row - context_lines;
+		pum_height = pum_win_row - context_lines;
 	    }
 	    if (p_ph > 0 && pum_height > p_ph)
 	    {
@@ -159,7 +170,7 @@ pum_display(
 	}
 	else
 	{
-	    /* pum below "row" */
+	    /* pum below "pum_win_row" */
 
 	    /* Leave two lines of context if possible */
 	    if (curwin->w_cline_row
@@ -169,7 +180,7 @@ pum_display(
 		context_lines = curwin->w_cline_row
 				    + curwin->w_cline_height - curwin->w_wrow;
 
-	    pum_row = row + context_lines;
+	    pum_row = pum_win_row + context_lines;
 	    if (size > below_row - pum_row)
 		pum_height = below_row - pum_row;
 	    else
@@ -822,6 +833,42 @@ pum_visible(void)
     return !pum_do_redraw && pum_array != NULL;
 }
 
+/*
+ * Reposition the popup menu to adjust for window layout changes.
+ */
+    void
+pum_may_redraw(void)
+{
+    pumitem_T	*array = pum_array;
+    int		len = pum_size;
+    int		selected = pum_selected;
+
+    if (!pum_visible())
+	return;  // nothing to do
+
+    if (pum_win_row == curwin->w_wrow + W_WINROW(curwin)
+	    && pum_win_height == curwin->w_height
+	    && pum_win_col == curwin->w_wincol
+	    && pum_win_width == curwin->w_width)
+    {
+	// window position didn't change, redraw in the same position
+	pum_redraw();
+    }
+    else
+    {
+	int wcol = curwin->w_wcol;
+
+	// Window layout changed, recompute the position.
+	// Use the remembered w_wcol value, the cursor may have moved when a
+	// completion was inserted, but we want the menu in the same position.
+	pum_undisplay();
+	curwin->w_wcol = pum_win_wcol;
+	curwin->w_valid |= VALID_WCOL;
+	pum_display(array, len, selected);
+	curwin->w_wcol = wcol;
+    }
+}
+
 /*
  * Return the height of the popup menu, the number of entries visible.
  * Only valid when pum_visible() returns TRUE!

src/proto/popupmnu.pro

@@ -4,6 +4,7 @@ void pum_redraw(void);
 void pum_undisplay(void);
 void pum_clear(void);
 int pum_visible(void);
+void pum_may_redraw(void);
 int pum_get_height(void);
 int split_message(char_u *mesg, pumitem_T **array);
 void ui_remove_balloon(void);

src/screen.c

@@ -171,7 +171,7 @@ static void redraw_win_toolbar(win_T *wp);
 static void win_redr_custom(win_T *wp, int draw_ruler);
 #endif
 #ifdef FEAT_CMDL_INFO
-static void win_redr_ruler(win_T *wp, int always);
+static void win_redr_ruler(win_T *wp, int always, int ignore_pum);
 #endif
 
 /* Ugly global: overrule attribute used by screen_char() */
@@ -783,8 +783,7 @@ update_screen(int type_arg)
 #endif
 #ifdef FEAT_INS_EXPAND
     /* May need to redraw the popup menu. */
-    if (pum_visible())
+    pum_may_redraw();
-	pum_redraw();
 #endif
 
     /* Reset b_mod_set flags.  Going through all windows is probably faster
@@ -7002,7 +7001,7 @@ win_redr_status(win_T *wp, int ignore_pum)
 						   - 1 + wp->w_wincol), attr);
 
 #ifdef FEAT_CMDL_INFO
-	win_redr_ruler(wp, TRUE);
+	win_redr_ruler(wp, TRUE, ignore_pum);
 #endif
     }
 
@@ -10455,7 +10454,7 @@ showmode(void)
     /* If the last window has no status line, the ruler is after the mode
      * message and must be redrawn */
     if (redrawing() && lastwin->w_status_height == 0)
-	win_redr_ruler(lastwin, TRUE);
+	win_redr_ruler(lastwin, TRUE, FALSE);
 #endif
     redraw_cmdline = FALSE;
     clear_cmdline = FALSE;
@@ -10874,6 +10873,7 @@ redraw_win_toolbar(win_T *wp)
 						     (int)wp->w_width, FALSE);
 }
 #endif
+
 /*
  * Show current status info in ruler and various other places
  * If always is FALSE, only show ruler if position has changed.
@@ -10899,7 +10899,7 @@ showruler(int always)
     else
 #endif
 #ifdef FEAT_CMDL_INFO
-	win_redr_ruler(curwin, always);
+	win_redr_ruler(curwin, always, FALSE);
 #endif
 
 #ifdef FEAT_TITLE
@@ -10918,7 +10918,7 @@ showruler(int always)
 
 #ifdef FEAT_CMDL_INFO
     static void
-win_redr_ruler(win_T *wp, int always)
+win_redr_ruler(win_T *wp, int always, int ignore_pum)
 {
 #define RULER_BUF_LEN 70
     char_u	buffer[RULER_BUF_LEN];
@@ -10951,8 +10951,9 @@ win_redr_ruler(win_T *wp, int always)
     if (wp == lastwin && lastwin->w_status_height == 0)
 	if (edit_submode != NULL)
 	    return;
-    /* Don't draw the ruler when the popup menu is visible, it may overlap. */
+    // Don't draw the ruler when the popup menu is visible, it may overlap.
-    if (pum_visible())
+    // Except when the popup menu will be redrawn anyway.
+    if (!ignore_pum && pum_visible())
 	return;
 #endif
 

src/version.c

@@ -761,6 +761,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    62,
 /**/
     61,
 /**/