Question

The Arm “#pragma anon_unions” allows:

typedef struct {
    uint32_t sensorID;
    uint8_t  messageHeader;
    uint8_t  messageID;
    uint16_t payloadLength;
} Header;

typedef struct {
    uint8_t startOfPacket[SERIAL_SOP_SIZE]; 
    Header; // Anonymous.
    uint8_t payload[SIZE];
} Packet;

Packet packet;
packet.messageID = 1; // Referencing member of Header through a Packet.

Any ideas on getting this code to compile in VisualStudio?

Answer 1

It compiles in Visual C++ but only in C mode:

A Microsoft C extension allows you to declare a structure variable
within another structure without giving it a name. These nested
structures are called anonymous structures. C++ does not allow
anonymous structures.