Removing map layer crashes wxGUI

[cmbarton]

If you try to remove a raster or vector map from the layer manager, using the "remove" option in the popup list launched by the button on the right side of the layer, it will crash the entire GUI with the following error:

/Applications/GRASS-7.5.app/Contents/Resources/bin/pythonw: line 3: 25590 Segmentation fault: 11 /Applications/GRASS-7.5.app/Contents/Resources/python.app/Contents/MacOS/python "$@"

This error and behavior is similar to those reported in #3472 and #3487. This was reported to me for v. 7.4.0 but also occurs in the most recent trunk (r73007)

[annakrat]

I can't test myself now, but this seems weird. Does this happen every time? Do you have at the same time vector digitizer or 3D view on?

[cmbarton]

Every time, but only if removed in this way. All other remove methods work fine.

[neteler]

Ticket retargeted after milestone closed

[martinl]

Bump milestone to 7.4.4

[neteler]

Ticket retargeted after milestone closed

[nila]

This is still an issue with 7.8 branch and master (7.9.dev), with Python 3.8.2 and wxPython 4.0.7.post2.

[annakrat]

Just to make it clear, do you have to press the button to crash, or also right click (or whatever you use on mac) would do it as well?

[nila]

Yes, this only crashes when removing layer from button-menu.

But not from contextual menu (right click), where it works as expected.

[nila]

backtrace log up to crash

[nila]

I managed to find the cause of this bug (see attachment above). In short:

1. clicking the button triggers an event with the GenBitmapButton embedded
2. the layer (TreeItem) is deleted (GMFrame::OnDeleteLayer()) and with it the included button (the same as in the event)
3. further event handling (in wx.lib.buttons.GenButton::OnLeftUp()) deals with a still living python object with a

"wrapped C/C++ object of type GenBitmapButton has been deleted"

I couldn't find a quick fix for this, but I'll try to come up with a solution. Still, if someone more experienced is up to the challenge to address this I'd be more than happy.

[annakrat]

Thanks for the detailed analysis. I can't test but this might work:

diff --git a/gui/wxpython/lmgr/layertree.py b/gui/wxpython/lmgr/layertree.py
index 52c20dcc0..b2b39c613 100644
--- a/gui/wxpython/lmgr/layertree.py
+++ b/gui/wxpython/lmgr/layertree.py
@@ -421,7 +421,7 @@ class LayerTree(treemixin.DragAndDrop, CT.CustomTreeCtrl):
             # select the layer in the same way as right click
             if not self.IsSelected(layer):
                 self.DoSelectItem(layer, True, False)
-            self.OnLayerContextMenu(event)
+            wx.CallAfter(self.OnLayerContextMenu, event)

[nila]

Replying to annakrat:

Thanks for the detailed analysis. I can't test but this might work:

diff --git a/gui/wxpython/lmgr/layertree.py b/gui/wxpython/lmgr/layertree.py
index 52c20dcc0..b2b39c613 100644
--- a/gui/wxpython/lmgr/layertree.py
+++ b/gui/wxpython/lmgr/layertree.py
@@ -421,7 +421,7 @@ class LayerTree(treemixin.DragAndDrop, CT.CustomTreeCtrl):
             # select the layer in the same way as right click
             if not self.IsSelected(layer):
                 self.DoSelectItem(layer, True, False)
-            self.OnLayerContextMenu(event)
+            wx.CallAfter(self.OnLayerContextMenu, event)

Brilliant, it works fine, thanks!

Will you put up a PR?

[annakrat]

Sure: ​https://github.com/OSGeo/grass/pull/462

[annakrat]

Merged to master and 78.