Compilation error when using c++ compiler: invalid conversion from `void*` to `__u8* {aka unsigned char*}`

[Peter-Krebs]

I have noticed the library lets me compile the C code using a C++ compiler (hence the #ifdef __cplusplus extern "C" { #endif blocks).

However I am getting errors when I compile the library, using g++ 7.5.0:

vendor/libi2c/src/i2c.c: In function ‘ssize_t i2c_ioctl_read(const I2CDevice*, unsigned int, void*, size_t)’:
vendor/libi2c/src/i2c.c:122:28: error: invalid conversion from ‘void*’ to ‘__u8* {aka unsigned char*}’ [-fpermissive]
         ioctl_msg[1].buf = buf;
                            ^~~
vendor/libi2c/src/i2c.c:135:28: error: invalid conversion from ‘void*’ to ‘__u8* {aka unsigned char*}’ [-fpermissive]
         ioctl_msg[0].buf = buf;
                            ^~~
vendor/libi2c/src/i2c.c: In function ‘ssize_t i2c_ioctl_write(const I2CDevice*, unsigned int, const void*, size_t)’:
vendor/libi2c/src/i2c.c:158:35: error: invalid conversion from ‘const void*’ to ‘const unsigned char*’ [-fpermissive]
     const unsigned char *buffer = buf;
                                   ^~~
vendor/libi2c/src/i2c.c: In function ‘ssize_t i2c_write(const I2CDevice*, unsigned int, const void*, size_t)’:
vendor/libi2c/src/i2c.c:265:35: error: invalid conversion from ‘const void*’ to ‘const unsigned char*’ [-fpermissive]
     const unsigned char *buffer = buf;
                                   ^~~
Makefile:28: recipe for target 'build/./vendor/libi2c/src/i2c.c.o' failed

The C++ compiler will not let you implicitly convert pointers.
This should be fixed by casting explicitly to (unsigned char*) (source).

Is there a compiler setting I am missing? -fpermissive is suggested but wouldn't that allow all implicit pointer conversions? All I changed is replacing $(CC) in the Makefile with $(CXX) for *.c, which should work, because of your extern C blocks.

Thank you in advance.

PS: Thanks for making this library