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, 9 insertions, 1 deletions

diff --git a/objectivec/GPBCodedOutputStream.m b/objectivec/GPBCodedOutputStream.m
index fd9ed66c..63ba8068 100644
--- a/objectivec/GPBCodedOutputStream.m
+++ b/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 @@ static void GPBWriteRawLittleEndian64(GPBOutputBufferState *state,
   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 @@ static void GPBWriteRawLittleEndian64(GPBOutputBufferState *state,
   GPBWriteRawLittleEndian64(&state_, value);
 }
 
+#pragma clang diagnostic pop
+
 @end
 
 size_t GPBComputeDoubleSizeNoTag(Float64 value) {