Bug report #1248

QgsGeometry.Union causes Segfault when unioning multi-polyon features

Added by cfarmer - over 14 years ago. Updated over 13 years ago.

Assignee:Jürgen Fischer
Affected QGIS version: Regression?:No
Operating System:Linux Easy fix?:No
Pull Request or Patch supplied: Resolution:duplicate
Crashes QGIS or corrupts data: Copied to github as #:11308


When unioning two features using QgsGeometry.Union, if one of the features is a multi-polygon, QGIS crashes without warning.

Example (should combine all geometries of a single layer together through unioning):

geom = QgsGeometry()
geom2 = QgsGeometry()
geom = feat.geometry()
while provider.getNextFeature(feat):
geom2 = feat.geometry()
geom = geom.Union(geom2)


#1 Updated by Jürgen Fischer over 14 years ago

  • Resolution set to duplicate
  • Status changed from Open to Closed

Looks like this is the same problem as #777. Union is simply called with a geometry that has already been destructed.

getNextFeature deletes the geometry of the first feature and therefore the geometry you retrieved earlier becomes invalid.

If you copy the geometry the crash disappears:

geom = [[QgsGeometry]]()

p = iface.getMapCanvas().currentLayer().dataProvider()

f = [[QgsFeature]]()
geom = [[QgsGeometry]](f.geometry())

while p.getNextFeature(f):
  geom = geom.Union( f.geometry() )

f = [[QgsFeature]]()
f.setGeometry( geom )

#2 Updated by Anonymous over 13 years ago

Milestone Version 1.0.0 deleted

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