[ObjC] Fail for tags with field numbers outside of range.

There is a new conformance test that confirm parse fails if a tag
is outside the valid range for a tag/field number.

PiperOrigin-RevId: 843674783

Author: thomasvl

conformance/failure_list_objc.txt

@@ -1,6 +1,4 @@
 # JSON input or output tests are skipped (in conformance_objc.m) as mobile
 # platforms don't support JSON wire format to avoid code bloat.
 
-Required.*.ProtobufInput.BadTag_FieldNumberTooHigh                                                                 # Should have failed to parse, but didn't.
-Required.*.ProtobufInput.BadTag_FieldNumberSlightlyTooHigh                                                         # Should have failed to parse, but didn't.
 Required.*.ProtobufInput.BadTag_OverlongVarint                                                                     # Should have failed to parse, but didn't.

objectivec/GPBCodedInputStream.m

@@ -206,7 +206,13 @@ int32_t GPBCodedInputStreamReadTag(GPBCodedInputStreamState *state) {
     return 0;
   }
 
-  state->lastTag = ReadRawVarint32(state);
+  uint64_t rawTag = (uint64_t)ReadRawVarint64(state);
+  state->lastTag = (int32_t)rawTag;
+  // Following _upb_Decoder_DecodeLongTag logic, fail if this is >32bit value.
+  if (rawTag > (uint64_t)UINT32_MAX) {
+    GPBRaiseStreamError(GPBCodedInputStreamErrorInvalidTag, @"Invalid tag");
+  }
+
   // Tags have to include a valid wireformat.
   if (!GPBWireFormatIsValidTag(state->lastTag)) {
     GPBRaiseStreamError(GPBCodedInputStreamErrorInvalidTag, @"Invalid wireformat in tag.");