Check for self-assignment in wxArrayString

Assigning array to itself destroyed its contents -- check for this now.

Closes #17619.

src/common/arrstr.cpp

@@ -89,7 +89,14 @@ wxArrayString::wxArrayString(const wxArrayString& src)
 wxArrayString& wxArrayString::operator=(const wxArrayString& src)
 {
   if ( m_nSize > 0 )
+  {
+    // Do this test here to avoid unnecessary overhead when assigning to an
+    // empty array, in that case there is no harm in self-assignment.
+    if ( &src == this )
+        return *this;
+
     Clear();
+  }
 
   Copy(src);
 

tests/arrays/arrays.cpp

@@ -350,6 +350,13 @@ void ArraysTestCase::wxStringArrayTest()
     wxArrayString a6;
     a6.Add("Foo");
     a6.Insert(a6[0], 1, 100);
+
+    wxArrayString a7;
+    a7 = a7;
+    CPPUNIT_ASSERT_EQUAL( 0, a7.size() );
+    a7.Add("Bar");
+    a7 = a7;
+    CPPUNIT_ASSERT_EQUAL( 1, a7.size() );
 }
 
 void ArraysTestCase::SortedArray()