Fix crash when trying to use meta enums on some platforms

Keeping references to static meta objects and meta enums around seems to avoid the crash (cherry picked from commit 278ccb8)
qgis · Nov 20, 2020 · d72e36d · d72e36d
1 parent f5bc8c9
commit d72e36d
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Showing 2 changed files with 16 additions and 5 deletions.
diff --git a/python/core/additions/metaenum.py b/python/core/additions/metaenum.py
@@ -17,6 +17,9 @@
 ***************************************************************************
 """
 
+META_OBJECT_BY_ENUM_CLASS = {}
+META_ENUM_BY_ENUM_CLASS = {}
+
 
 def metaEnumFromValue(enumValue, baseClass=None, raiseException=True):
     """
@@ -39,6 +42,11 @@ def metaEnumFromType(enumClass, baseClass=None, raiseException=True):
     :param raiseException: if False, no exception will be raised and None will be return in case of failure
     :return: the QMetaEnum if it succeeds, None otherwise
     """
+    global META_OBJECT_BY_ENUM_CLASS
+    global META_ENUM_BY_ENUM_CLASS
+    if enumClass in META_ENUM_BY_ENUM_CLASS:
+        return META_ENUM_BY_ENUM_CLASS[enumClass]
+
     if enumClass == int:
         if raiseException:
             raise TypeError("enumClass is an int, while it should be an enum")
@@ -54,8 +62,11 @@ def metaEnumFromType(enumClass, baseClass=None, raiseException=True):
                 raise ValueError("Enum type does not implement baseClass method. Provide the base class as argument.")
 
     try:
-        idx = baseClass.staticMetaObject.indexOfEnumerator(enumClass.__name__)
-        meta_enum = baseClass.staticMetaObject.enumerator(idx)
+        meta_object = baseClass.staticMetaObject
+        META_OBJECT_BY_ENUM_CLASS[enumClass] = meta_object
+        idx = meta_object.indexOfEnumerator(enumClass.__name__)
+        meta_enum = meta_object.enumerator(idx)
+        META_ENUM_BY_ENUM_CLASS[enumClass] = meta_enum
     except AttributeError:
         if raiseException:
             raise TypeError("could not get the metaEnum for {}".format(enumClass.__name__))

diff --git a/tests/src/python/test_core_additions.py b/tests/src/python/test_core_additions.py
@@ -27,10 +27,10 @@ def testMetaEnum(self):
         self.assertIsNotNone(me)
         self.assertEqual(me.valueToKey(QgsTolerance.Pixels), 'Pixels')
 
-        # if using same variable twice (e.g. me = me2), this seg faults
-        me2 = metaEnumFromValue(QgsTolerance.Pixels, QgsTolerance)
+        # check that using same variable twice doesn't segfault
+        me = metaEnumFromValue(QgsTolerance.Pixels, QgsTolerance)
         self.assertIsNotNone(me)
-        self.assertEqual(me2.valueToKey(QgsTolerance.Pixels), 'Pixels')
+        self.assertEqual(me.valueToKey(QgsTolerance.Pixels), 'Pixels')
 
         # do not raise error
         self.assertIsNone(metaEnumFromValue(1, QgsTolerance, False))