Add more warnings to for the ObjC runtime build

Working on https://github.com/google/protobuf/issues/1599, specifically:
- Turn on more warnings that the Xcode UI calls out with individual controls.
- Manually add:
  -Wundef
  -Wswitch-enum
- Manually add and then diable in the unittests because of XCTest's headers:
  -Wreserved-id-macro
  -Wdocumentation-unknown-command
- Manually add -Wdirect-ivar-access, but disable it for the unittests and in
  the library code (via #pragmas to suppress it). This is done so proto users
  can enable the warning.

1 files changed, 7 insertions, 1 deletions

diff --git a/objectivec/GPBUtilities_PackagePrivate.h b/objectivec/GPBUtilities_PackagePrivate.h
index a6b6c84d..c02493b2 100644
--- a/objectivec/GPBUtilities_PackagePrivate.h
+++ b/objectivec/GPBUtilities_PackagePrivate.h
@@ -52,7 +52,7 @@ CF_EXTERN_C_BEGIN
 // generated sources to make sure they are linked with a supporting runtime.
 void GPBCheckRuntimeVersionInternal(int32_t version);
 GPB_INLINE void GPBDebugCheckRuntimeVersion() {
-#if DEBUG
+#if defined(DEBUG) && DEBUG
   GPBCheckRuntimeVersionInternal(GOOGLE_PROTOBUF_OBJC_GEN_VERSION);
 #endif
 }
@@ -125,6 +125,10 @@ GPB_INLINE uint64_t GPBEncodeZigZag64(int64_t n) {
   return (n << 1) ^ (n >> 63);
 }
 
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wswitch-enum"
+#pragma clang diagnostic ignored "-Wdirect-ivar-access"
+
 GPB_INLINE BOOL GPBDataTypeIsObject(GPBDataType type) {
   switch (type) {
     case GPBDataTypeBytes:
@@ -187,6 +191,8 @@ GPB_INLINE void GPBSetHasIvarField(GPBMessage *self, GPBFieldDescriptor *field,
 void GPBMaybeClearOneof(GPBMessage *self, GPBOneofDescriptor *oneof,
                         int32_t oneofHasIndex, uint32_t fieldNumberNotToClear);
 
+#pragma clang diagnostic pop
+
 //%PDDM-DEFINE GPB_IVAR_SET_DECL(NAME, TYPE)
 //%void GPBSet##NAME##IvarWithFieldInternal(GPBMessage *self,
 //%            NAME$S                     GPBFieldDescriptor *field,