error: invalid conversion from 'void*' to 'const uint8_t* {aka const unsigned char*}' [-fpermissive]

Question

I am trying to import a C library into my C++ project but I'm stuck with this error

invalid conversion from 'void*' to 'const uint8_t* {aka const unsigned char*}' [-fpermissive] uint8_t const* raw = static_cast(getPointerToData(id, message->data, message->length)); ^ compilation terminated due to -Wfatal-errors.

This code compile well using C compiler but get this error using C++ one

bool XbusMessage_getDataItem(void* item, enum XsDataIdentifier id, struct XbusMessage const* message)
{
uint8_t const* raw = (getPointerToData(id, message->data, message->length));

Can you help me?

Thanks

Answer 1

You need to explicitly cast the return value from getPointerToData to const uint8_t* . Implicit conversions between pointer types are not allowed in C++ but are in C.

Try:

uint8_t const* raw = static_cast<uint8_t const*>(getPointerToData(id, message->data, message->length));

Edit: You can also use a C-style cast if you want to keep the C code C and not C++.

 uint8_t const* raw = (uint8_t const*)(getPointerToData(id, message->data, message->length));

Answer 2

This code posted by Jean-François Fabre works

uint8_t const* raw = (getPointerToData(id, static_cast<const uint8_t*>(message->data), message->length));

Thanks!