Tweak the union used for Extensions to support old generated code.
Support the old field name as well as the union to keep the old generated code
building.
Fixes #7555
diff --git a/objectivec/GPBDescriptor_PackagePrivate.h b/objectivec/GPBDescriptor_PackagePrivate.h
index b3d6730..408f8d4 100644
--- a/objectivec/GPBDescriptor_PackagePrivate.h
+++ b/objectivec/GPBDescriptor_PackagePrivate.h
@@ -131,14 +131,29 @@
typedef struct GPBExtensionDescription {
GPBGenericValue defaultValue;
const char *singletonName;
+ // Before 3.12, `extendedClass` was just a `const char *`. Thanks to nested
+ // initialization (https://en.cppreference.com/w/c/language/struct_initialization#Nested_initialization)
+ // old generated code with `.extendedClass = GPBStringifySymbol(Something)`
+ // still works; and the current generator can use `extendedClass.clazz`, to
+ // pass a Class reference.
union {
const char *name;
Class clazz;
} extendedClass;
+ // Before 3.12, this was `const char *messageOrGroupClassName`. In the
+ // initial 3.12 release, we moved the `union messageOrGroupClass`, and failed
+ // to realize that would break existing source code for extensions. So to
+ // keep existing source code working, we added an unnamed union (C11) to
+ // provide both the old field name and the new union. This keeps both older
+ // and newer code working.
+ // Background: https://github.com/protocolbuffers/protobuf/issues/7555
union {
- const char *name;
- Class clazz;
- } messageOrGroupClass;
+ const char *messageOrGroupClassName;
+ union {
+ const char *name;
+ Class clazz;
+ } messageOrGroupClass;
+ };
GPBEnumDescriptorFunc enumDescriptorFunc;
int32_t fieldNumber;
GPBDataType dataType;
