Add casts to removed undefined behaviors around shifts.

Fixes #4246
Fixes #4247

objectivec/GPBCodedInputStream.m

@@ -110,7 +110,7 @@ static int64_t ReadRawVarint64(GPBCodedInputStreamState *state) {
   int64_t result = 0;
   while (shift < 64) {
     int8_t b = ReadRawByte(state);
-    result |= (int64_t)(b & 0x7F) << shift;
+    result |= (int64_t)((uint64_t)(b & 0x7F) << shift);
     if ((b & 0x80) == 0) {
       return result;
     }

objectivec/GPBUtilities.m

@@ -291,7 +291,7 @@ BOOL GPBGetHasIvar(GPBMessage *self, int32_t idx, uint32_t fieldNumber) {
   } else {
     NSCAssert(idx != GPBNoHasBit, @"Invalid has bit.");
     uint32_t byteIndex = idx / 32;
-    uint32_t bitMask = (1 << (idx % 32));
+    uint32_t bitMask = (1U << (idx % 32));
     BOOL hasIvar =
         (self->messageStorage_->_has_storage_[byteIndex] & bitMask) ? YES : NO;
     return hasIvar;
@@ -315,7 +315,7 @@ void GPBSetHasIvar(GPBMessage *self, int32_t idx, uint32_t fieldNumber,
     NSCAssert(idx != GPBNoHasBit, @"Invalid has bit.");
     uint32_t *has_storage = self->messageStorage_->_has_storage_;
     uint32_t byte = idx / 32;
-    uint32_t bitMask = (1 << (idx % 32));
+    uint32_t bitMask = (1U << (idx % 32));
     if (value) {
       has_storage[byte] |= bitMask;
     } else {

objectivec/GPBUtilities_PackagePrivate.h

@@ -124,7 +124,7 @@ GPB_INLINE int64_t GPBDecodeZigZag64(uint64_t n) {
 // thus always taking 10 bytes on the wire.)
 GPB_INLINE uint32_t GPBEncodeZigZag32(int32_t n) {
   // Note:  the right-shift must be arithmetic
-  return (uint32_t)((n << 1) ^ (n >> 31));
+  return ((uint32_t)n << 1) ^ (uint32_t)(n >> 31);
 }
 
 // Encode a ZigZag-encoded 64-bit value.  ZigZag encodes signed integers
@@ -133,7 +133,7 @@ GPB_INLINE uint32_t GPBEncodeZigZag32(int32_t n) {
 // thus always taking 10 bytes on the wire.)
 GPB_INLINE uint64_t GPBEncodeZigZag64(int64_t n) {
   // Note:  the right-shift must be arithmetic
-  return (uint64_t)((n << 1) ^ (n >> 63));
+  return ((uint64_t)n << 1) ^ (uint64_t)(n >> 63);
 }
 
 #pragma clang diagnostic push

objectivec/Tests/GPBCodedInputStreamTests.m

@@ -220,7 +220,7 @@
                              0xa6, 0x01)
                  value:(0x1b << 0) | (0x28 << 7) | (0x79 << 14) | (0x42 << 21) |
                        (0x3bLL << 28) | (0x56LL << 35) | (0x00LL << 42) |
-                       (0x05LL << 49) | (0x26LL << 56) | (0x01LL << 63)];
+                       (0x05LL << 49) | (0x26LL << 56) | (0x01ULL << 63)];
 
   // Failures
   [self assertReadVarintFailure:bytes(0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80,

objectivec/Tests/GPBCodedOuputStreamTests.m

@@ -266,7 +266,7 @@
                     value:(0x1b << 0) | (0x28 << 7) | (0x79 << 14) |
                           (0x42 << 21) | (0x3bLL << 28) | (0x56LL << 35) |
                           (0x00LL << 42) | (0x05LL << 49) | (0x26LL << 56) |
-                          (0x01LL << 63)];
+                          (0x01ULL << 63)];
 }
 
 - (void)testWriteLittleEndian {

objectivec/Tests/GPBUtilitiesTests.m

@@ -52,12 +52,12 @@
 
 - (void)testRightShiftFunctions {
   XCTAssertEqual((1UL << 31) >> 31, 1UL);
-  XCTAssertEqual((1 << 31) >> 31, -1);
+  XCTAssertEqual((int32_t)(1U << 31) >> 31, -1);
   XCTAssertEqual((1ULL << 63) >> 63, 1ULL);
-  XCTAssertEqual((1LL << 63) >> 63, -1LL);
+  XCTAssertEqual((int64_t)(1ULL << 63) >> 63, -1LL);
 
-  XCTAssertEqual(GPBLogicalRightShift32((1 << 31), 31), 1);
-  XCTAssertEqual(GPBLogicalRightShift64((1LL << 63), 63), 1LL);
+  XCTAssertEqual(GPBLogicalRightShift32((1U << 31), 31), 1);
+  XCTAssertEqual(GPBLogicalRightShift64((1ULL << 63), 63), 1LL);
 }
 
 - (void)testGPBDecodeTextFormatName {