Add more warnings to for the ObjC runtime build

Working on protocolbuffers#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.

objectivec/GPBArray.m

@@ -32,6 +32,12 @@
 
 #import "GPBMessage_PackagePrivate.h"
 
+// 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"
+
 // Mutable arrays use an internal buffer that can always hold a multiple of this elements.
 #define kChunkSize 16
 #define CapacityFromCount(x) (((x / kChunkSize) + 1) * kChunkSize)
@@ -2532,3 +2538,5 @@ - (void)enumerateObjectsWithOptions:(NSEnumerationOptions)opts
 }
 
 @end
+
+#pragma clang diagnostic pop

objectivec/GPBBootstrap.h

@@ -48,7 +48,7 @@
 // doesn't allow us to forward declare. We work around this one case by
 // providing a local definition. The default case has to use NS_ENUM for the
 // magic that is Swift bridging of enums.
-#if (__cplusplus && __cplusplus < 201103L)
+#if (defined(__cplusplus) && __cplusplus && __cplusplus < 201103L)
  #define GPB_ENUM(X) enum X : int32_t X; enum X : int32_t
 #else
  #define GPB_ENUM(X) NS_ENUM(int32_t, X)

objectivec/GPBCodedInputStream.h

@@ -93,7 +93,7 @@ NS_ASSUME_NONNULL_BEGIN
 ///
 /// @param message           The message to set fields on as they are read.
 /// @param extensionRegistry An optional extension registry to use to lookup
-///                          extensions for @message.
+///                          extensions for @c message.
 - (void)readMessage:(GPBMessage *)message
   extensionRegistry:(nullable GPBExtensionRegistry *)extensionRegistry;
 

objectivec/GPBCodedInputStream.m

@@ -316,6 +316,12 @@ - (void)dealloc {
   [super dealloc];
 }
 
+// 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"
+
 - (int32_t)readTag {
   return GPBCodedInputStreamReadTag(&state_);
 }
@@ -496,4 +502,6 @@ - (int64_t)readSInt64 {
   return GPBCodedInputStreamReadSInt64(&state_);
 }
 
+#pragma clang diagnostic pop
+
 @end

objectivec/GPBCodedOutputStream.m

@@ -144,7 +144,7 @@ static void GPBWriteRawLittleEndian64(GPBOutputBufferState *state,
   GPBWriteRawByte(state, (int32_t)(value >> 56) & 0xFF);
 }
 
-#if DEBUG && !defined(NS_BLOCK_ASSERTIONS)
+#if defined(DEBUG) && DEBUG && !defined(NS_BLOCK_ASSERTIONS)
 + (void)load {
   // This test exists to verify that CFStrings with embedded NULLs will work
   // for us. If this Assert fails, all code below that depends on
@@ -203,6 +203,12 @@ + (instancetype)streamWithData:(NSMutableData *)data {
   return [[[self alloc] initWithData:data] autorelease];
 }
 
+// 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)writeDoubleNoTag:(double)value {
   GPBWriteRawLittleEndian64(&state_, GPBConvertDoubleToInt64(value));
 }
@@ -981,6 +987,8 @@ - (void)writeRawLittleEndian64:(int64_t)value {
   GPBWriteRawLittleEndian64(&state_, value);
 }
 
+#pragma clang diagnostic pop
+
 @end
 
 size_t GPBComputeDoubleSizeNoTag(Float64 value) {

objectivec/GPBDescriptor.h

@@ -135,7 +135,7 @@ typedef NS_ENUM(uint8_t, GPBFieldType) {
 @property(nonatomic, readonly, assign) Class msgClass;
 @property(nonatomic, readonly) NSString *singletonName;
 @property(nonatomic, readonly, strong, nullable) GPBEnumDescriptor *enumDescriptor;
-@property(nonatomic, readonly) id defaultValue;
+@property(nonatomic, readonly, nullable) id defaultValue;
 @end
 
 NS_ASSUME_NONNULL_END

objectivec/GPBDescriptor.m

@@ -36,6 +36,12 @@
 #import "GPBWireFormat.h"
 #import "GPBMessage_PackagePrivate.h"
 
+// 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"
+
 // The address of this variable is used as a key for obj_getAssociatedObject.
 static const char kTextFormatExtraValueKey = 0;
 
@@ -803,7 +809,7 @@ - (instancetype)initWithExtensionDescription:
   if ((self = [super init])) {
     description_ = description;
 
-#if DEBUG
+#if defined(DEBUG) && DEBUG
     const char *className = description->messageOrGroupClassName;
     if (className) {
       NSAssert(objc_lookUpClass(className) != Nil,
@@ -961,3 +967,5 @@ - (NSComparisonResult)compareByFieldNumber:(GPBExtensionDescriptor *)other {
 }
 
 @end
+
+#pragma clang diagnostic pop

objectivec/GPBDescriptor_PackagePrivate.h

@@ -245,6 +245,12 @@ typedef NS_OPTIONS(uint32_t, GPBDescriptorInitializationFlags) {
 
 CF_EXTERN_C_BEGIN
 
+// 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"
+
 GPB_INLINE BOOL GPBFieldIsMapOrArray(GPBFieldDescriptor *field) {
   return (field->description_->flags &
           (GPBFieldRepeated | GPBFieldMapKeyMask)) != 0;
@@ -262,6 +268,8 @@ GPB_INLINE uint32_t GPBFieldNumber(GPBFieldDescriptor *field) {
   return field->description_->number;
 }
 
+#pragma clang diagnostic pop
+
 uint32_t GPBFieldTag(GPBFieldDescriptor *self);
 
 // For repeated fields, alternateWireType is the wireType with the opposite
@@ -291,23 +299,23 @@ GPB_INLINE BOOL GPBExtensionIsWireFormat(GPBExtensionDescription *description) {
 }
 
 // Helper for compile time assets.
-#ifndef _GPBCompileAssert
+#ifndef GPBInternalCompileAssert
   #if __has_feature(c_static_assert) || __has_extension(c_static_assert)
-    #define _GPBCompileAssert(test, msg) _Static_assert((test), #msg)
+    #define GPBInternalCompileAssert(test, msg) _Static_assert((test), #msg)
   #else
     // Pre-Xcode 7 support.
-    #define _GPBCompileAssertSymbolInner(line, msg) _GPBCompileAssert ## line ## __ ## msg
-    #define _GPBCompileAssertSymbol(line, msg) _GPBCompileAssertSymbolInner(line, msg)
-    #define _GPBCompileAssert(test, msg) \
-        typedef char _GPBCompileAssertSymbol(__LINE__, msg) [ ((test) ? 1 : -1) ]
+    #define GPBInternalCompileAssertSymbolInner(line, msg) GPBInternalCompileAssert ## line ## __ ## msg
+    #define GPBInternalCompileAssertSymbol(line, msg) GPBInternalCompileAssertSymbolInner(line, msg)
+    #define GPBInternalCompileAssert(test, msg) \
+        typedef char GPBInternalCompileAssertSymbol(__LINE__, msg) [ ((test) ? 1 : -1) ]
   #endif  // __has_feature(c_static_assert) || __has_extension(c_static_assert)
-#endif // _GPBCompileAssert
+#endif // GPBInternalCompileAssert
 
 // Sanity check that there isn't padding between the field description
 // structures with and without a default.
-_GPBCompileAssert(sizeof(GPBMessageFieldDescriptionWithDefault) ==
-                  (sizeof(GPBGenericValue) +
-                   sizeof(GPBMessageFieldDescription)),
-                  DescriptionsWithDefault_different_size_than_expected);
+GPBInternalCompileAssert(sizeof(GPBMessageFieldDescriptionWithDefault) ==
+                         (sizeof(GPBGenericValue) +
+                          sizeof(GPBMessageFieldDescription)),
+                         DescriptionsWithDefault_different_size_than_expected);
 
 CF_EXTERN_C_END

objectivec/GPBDictionary.m

@@ -45,6 +45,12 @@
 // directly.
 // ------------------------------------------------------------------
 
+// 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"
+
 // Used to include code only visible to specific versions of the static
 // analyzer. Useful for wrapping code that only exists to silence the analyzer.
 // Determine the values you want to use for BEGIN_APPLE_BUILD_VERSION,
@@ -484,6 +490,8 @@ void GPBDictionaryReadEntry(id mapDictionary,
       key.valueString = [@"" retain];
     }
     if (GPBDataTypeIsObject(valueDataType) && value.valueString == nil) {
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wswitch-enum"
       switch (valueDataType) {
         case GPBDataTypeString:
           value.valueString = [@"" retain];
@@ -505,6 +513,7 @@ void GPBDictionaryReadEntry(id mapDictionary,
           // Nothing
           break;
       }
+#pragma clang diagnostic pop
     }
 
     if ((keyDataType == GPBDataTypeString) && GPBDataTypeIsObject(valueDataType)) {
@@ -13553,3 +13562,5 @@ - (void)enumerateKeysAndObjectsWithOptions:(NSEnumerationOptions)opts
 }
 
 @end
+
+#pragma clang diagnostic pop

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

objectivec/GPBExtensionRegistry.m

@@ -51,6 +51,12 @@ - (void)dealloc {
   [super dealloc];
 }
 
+// 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"
+
 - (instancetype)copyWithZone:(NSZone *)zone {
   GPBExtensionRegistry *result = [[[self class] allocWithZone:zone] init];
   if (result && mutableClassMap_.count) {
@@ -105,4 +111,6 @@ - (void)addExtensions:(GPBExtensionRegistry *)registry {
   }
 }
 
+#pragma clang diagnostic pop
+
 @end

objectivec/GPBMessage.m

@@ -44,6 +44,12 @@
 #import "GPBUnknownFieldSet_PackagePrivate.h"
 #import "GPBUtilities_PackagePrivate.h"
 
+// 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"
+
 NSString *const GPBMessageErrorDomain =
     GPBNSStringifySymbol(GPBMessageErrorDomain);
 
@@ -694,7 +700,7 @@ void GPBClearMessageAutocreator(GPBMessage *self) {
     return;
   }
 
-#if DEBUG && !defined(NS_BLOCK_ASSERTIONS)
+#if defined(DEBUG) && DEBUG && !defined(NS_BLOCK_ASSERTIONS)
   // Either the autocreator must have its "has" flag set to YES, or it must be
   // NO and not equal to ourselves.
   BOOL autocreatorHas =
@@ -1736,7 +1742,7 @@ - (id)getExistingExtension:(GPBExtensionDescriptor *)extension {
 }
 
 - (BOOL)hasExtension:(GPBExtensionDescriptor *)extension {
-#if DEBUG
+#if defined(DEBUG) && DEBUG
   CheckExtension(self, extension);
 #endif  // DEBUG
   return nil != [extensionMap_ objectForKey:extension];
@@ -2621,7 +2627,7 @@ - (BOOL)isEqual:(GPBMessage *)other {
         case GPBDataTypeFixed32:
         case GPBDataTypeUInt32:
         case GPBDataTypeFloat: {
-          _GPBCompileAssert(sizeof(float) == sizeof(uint32_t), float_not_32_bits);
+          GPBInternalCompileAssert(sizeof(float) == sizeof(uint32_t), float_not_32_bits);
           // These are all 32bit, signed/unsigned doesn't matter for equality.
           uint32_t *selfValPtr = (uint32_t *)&selfStorage[fieldOffset];
           uint32_t *otherValPtr = (uint32_t *)&otherStorage[fieldOffset];
@@ -2636,7 +2642,7 @@ - (BOOL)isEqual:(GPBMessage *)other {
         case GPBDataTypeFixed64:
         case GPBDataTypeUInt64:
         case GPBDataTypeDouble: {
-          _GPBCompileAssert(sizeof(double) == sizeof(uint64_t), double_not_64_bits);
+          GPBInternalCompileAssert(sizeof(double) == sizeof(uint64_t), double_not_64_bits);
           // These are all 64bit, signed/unsigned doesn't matter for equality.
           uint64_t *selfValPtr = (uint64_t *)&selfStorage[fieldOffset];
           uint64_t *otherValPtr = (uint64_t *)&otherStorage[fieldOffset];
@@ -2733,7 +2739,7 @@ - (NSUInteger)hash {
         case GPBDataTypeFixed32:
         case GPBDataTypeUInt32:
         case GPBDataTypeFloat: {
-          _GPBCompileAssert(sizeof(float) == sizeof(uint32_t), float_not_32_bits);
+          GPBInternalCompileAssert(sizeof(float) == sizeof(uint32_t), float_not_32_bits);
           // These are all 32bit, just mix it in.
           uint32_t *valPtr = (uint32_t *)&storage[fieldOffset];
           result = prime * result + *valPtr;
@@ -2745,7 +2751,7 @@ - (NSUInteger)hash {
         case GPBDataTypeFixed64:
         case GPBDataTypeUInt64:
         case GPBDataTypeDouble: {
-          _GPBCompileAssert(sizeof(double) == sizeof(uint64_t), double_not_64_bits);
+          GPBInternalCompileAssert(sizeof(double) == sizeof(uint64_t), double_not_64_bits);
           // These are all 64bit, just mix what fits into an NSUInteger in.
           uint64_t *valPtr = (uint64_t *)&storage[fieldOffset];
           result = prime * result + (NSUInteger)(*valPtr);
@@ -2792,7 +2798,7 @@ - (NSString *)description {
   return description;
 }
 
-#if DEBUG
+#if defined(DEBUG) && DEBUG
 
 // Xcode 5.1 added support for custom quick look info.
 // https://developer.apple.com/library/ios/documentation/IDEs/Conceptual/CustomClassDisplay_in_QuickLook/CH01-quick_look_for_custom_objects/CH01-quick_look_for_custom_objects.html#//apple_ref/doc/uid/TP40014001-CH2-SW1
@@ -3182,3 +3188,5 @@ + (BOOL)accessInstanceVariablesDirectly {
 }
 
 @end
+
+#pragma clang diagnostic pop

objectivec/GPBMessage_PackagePrivate.h

@@ -110,9 +110,12 @@ CF_EXTERN_C_BEGIN
 
 // Call this before using the readOnlySemaphore_. This ensures it is created only once.
 NS_INLINE void GPBPrepareReadOnlySemaphore(GPBMessage *self) {
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wdirect-ivar-access"
   dispatch_once(&self->readOnlySemaphoreCreationOnce_, ^{
     self->readOnlySemaphore_ = dispatch_semaphore_create(1);
   });
+#pragma clang diagnostic pop
 }
 
 // Returns a new instance that was automatically created by |autocreator| for

objectivec/GPBUnknownField.m

@@ -67,6 +67,12 @@ - (void)dealloc {
   [super dealloc];
 }
 
+// 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"
+
 - (id)copyWithZone:(NSZone *)zone {
   GPBUnknownField *result =
       [[GPBUnknownField allocWithZone:zone] initWithNumber:number_];
@@ -323,4 +329,6 @@ - (void)addGroup:(GPBUnknownFieldSet *)value {
   }
 }
 
+#pragma clang diagnostic pop
+
 @end