Fixes static analyzer issues from xcode.

src/google/protobuf/compiler/parser.cc

@@ -570,6 +570,7 @@ bool Parser::Parse(io::Tokenizer* input, FileDescriptorProto* file) {
 
   input_ = NULL;
   source_code_info_ = NULL;
+  assert(file != NULL);
   source_code_info.Swap(file->mutable_source_code_info());
   return !had_errors_;
 }

src/google/protobuf/stubs/substitute.cc

@@ -113,7 +113,9 @@ void SubstituteAndAppend(
   for (int i = 0; format[i] != '\0'; i++) {
     if (format[i] == '$') {
       if (ascii_isdigit(format[i+1])) {
-        const SubstituteArg* src = args_array[format[i+1] - '0'];
+        unsigned int index = format[i+1] - '0';
+        assert(index < 10);
+        const SubstituteArg* src = args_array[index];
         memcpy(target, src->data(), src->size());
         target += src->size();
         ++i;  // Skip next char.

src/google/protobuf/util/internal/default_value_objectwriter.cc

@@ -586,7 +586,6 @@ void DefaultValueObjectWriter::RenderDataPiece(StringPiece name,
         new Node(name.ToString(), NULL, PRIMITIVE, data, false,
                  child == NULL ? current_->path() : child->path(),
                  suppress_empty_list_, field_scrub_callback_.get()));
-    child = node.get();
     current_->AddChild(node.release());
   } else {
     child->set_data(data);

src/google/protobuf/util/internal/json_stream_parser.cc

@@ -315,7 +315,6 @@ util::Status JsonStreamParser::ParseStringHelper() {
       // We're about to handle an escape, copy all bytes from last to data.
       if (last < data) {
         parsed_storage_.append(last, data - last);
-        last = data;
       }
       // If we ran out of string after the \, cancel or report an error
       // depending on if we expect more data later.
@@ -371,7 +370,6 @@ util::Status JsonStreamParser::ParseStringHelper() {
       } else {
         if (last < data) {
           parsed_storage_.append(last, data - last);
-          last = data;
         }
         parsed_ = StringPiece(parsed_storage_);
       }

src/google/protobuf/util/message_differencer.cc

@@ -626,6 +626,7 @@ bool MessageDifferencer::CompareWithFieldsInternal(
       }
 
       if (reporter_ != NULL) {
+        assert(field1 != NULL);
         int count = field1->is_repeated() ?
             reflection1->FieldSize(message1, field1) : 1;
 
@@ -706,6 +707,7 @@ bool MessageDifferencer::CompareWithFieldsInternal(
     }
 
     bool fieldDifferent = false;
+    assert(field1 != NULL);
     if (field1->is_repeated()) {
       fieldDifferent = !CompareRepeatedField(message1, message2, field1,
                                              parent_fields);
@@ -875,6 +877,7 @@ bool MessageDifferencer::CompareRepeatedField(
 
   for (int i = 0; i < count1; ++i) {
     if (match_list1[i] != -1) continue;
+    assert(reporter_ != NULL);
     specific_field.index = i;
     parent_fields->push_back(specific_field);
     reporter_->ReportDeleted(message1, message2, *parent_fields);