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, 11 insertions, 0 deletions

diff --git a/objectivec/GPBExtensionInternals.m b/objectivec/GPBExtensionInternals.m
index 7d0dcb2e..290c82a1 100644
--- a/objectivec/GPBExtensionInternals.m
+++ b/objectivec/GPBExtensionInternals.m
@@ -45,6 +45,8 @@ static id NewSingleValueFromInputStream(GPBExtensionDescriptor *extension,
     __attribute__((ns_returns_retained));
 
 GPB_INLINE size_t DataTypeSize(GPBDataType dataType) {
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wswitch-enum"
   switch (dataType) {
     case GPBDataTypeBool:
       return 1;
@@ -59,6 +61,7 @@ GPB_INLINE size_t DataTypeSize(GPBDataType dataType) {
     default:
       return 0;
   }
+#pragma clang diagnostic pop
 }
 
 static size_t ComputePBSerializedSizeNoTagOfObject(GPBDataType dataType, id object) {
@@ -261,6 +264,12 @@ static void WriteArrayIncludingTagsToCodedOutputStream(
   }
 }
 
+// Direct access is use for speed, to avoid even internally declaring things
+// read/write, etc. The warning is enabled in the project to ensure code calling
+// protos can turn on -Wdirect-ivar-access without issues.
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wdirect-ivar-access"
+
 void GPBExtensionMergeFromInputStream(GPBExtensionDescriptor *extension,
                                       BOOL isPackedOnStream,
                                       GPBCodedInputStream *input,
@@ -378,3 +387,5 @@ static id NewSingleValueFromInputStream(GPBExtensionDescriptor *extension,
 
   return nil;
 }
+
+#pragma clang diagnostic pop