Minor fix for autocreated object repeated fields and maps.

- If setting/clearing a repeated field/map that was objects, check the class
  before checking the autocreator.
- Just to be paranoid, don’t mutate within copy/mutableCopy for the autocreated
  classes to ensure there is less chance of issues if someone does something
  really crazy threading wise.
- Some more tests for the internal AutocreatedArray/AutocreatedDictionary
  classes to ensure things are working as expected.
- Add Xcode 8.2 to the full_mac_build.sh supported list.

1 files changed, 10 insertions, 6 deletions

diff --git a/objectivec/GPBUtilities.m b/objectivec/GPBUtilities.m
index d4538598..68aadb77 100644
--- a/objectivec/GPBUtilities.m
+++ b/objectivec/GPBUtilities.m
@@ -408,9 +408,11 @@ void GPBSetRetainedObjectIvarWithFieldInternal(GPBMessage *self,
       if (field.fieldType == GPBFieldTypeRepeated) {
         // If the old array was autocreated by us, then clear it.
         if (GPBDataTypeIsObject(fieldType)) {
-          GPBAutocreatedArray *autoArray = oldValue;
-          if (autoArray->_autocreator == self) {
-            autoArray->_autocreator = nil;
+          if ([oldValue isKindOfClass:[GPBAutocreatedArray class]]) {
+            GPBAutocreatedArray *autoArray = oldValue;
+            if (autoArray->_autocreator == self) {
+              autoArray->_autocreator = nil;
+            }
           }
         } else {
           // Type doesn't matter, it is a GPB*Array.
@@ -423,9 +425,11 @@ void GPBSetRetainedObjectIvarWithFieldInternal(GPBMessage *self,
         // If the old map was autocreated by us, then clear it.
         if ((field.mapKeyDataType == GPBDataTypeString) &&
             GPBDataTypeIsObject(fieldType)) {
-          GPBAutocreatedDictionary *autoDict = oldValue;
-          if (autoDict->_autocreator == self) {
-            autoDict->_autocreator = nil;
+          if ([oldValue isKindOfClass:[GPBAutocreatedDictionary class]]) {
+            GPBAutocreatedDictionary *autoDict = oldValue;
+            if (autoDict->_autocreator == self) {
+              autoDict->_autocreator = nil;
+            }
           }
         } else {
           // Type doesn't matter, it is a GPB*Dictionary.