Multiple Definition when linking

[aaron-neal]

Describe the bug

I am have included Ethernet_Generic.h in my main file for starting a webserver. I also have Ethernet_Generic included in another header file for a Modbus TCP class.

On compiling I get many multiple definition errors such as
c:/users/??????/.platformio/packages/toolchain-gccarmnoneeabi/bin/../lib/gcc/arm-none-eabi/9.2.1/../../../../arm-none-eabi/bin/ld.exe: .pio/build/stm32-5mi/src/modbus/ModbusTCPSlave.cpp.o:(.bss._ZN10W5100Class4chipE+0x0): multiple definition of `W5100Class::chip'; .pio/build/stm32-5mi/src/main.cpp.o:(.bss._ZN10W5100Class4chipE+0x0): first defined here

Any help would be appreciated.

Expected behavior

When using previous Ethernet library, everything compiled as normal. Previous Library

Information

• Latest development STM32 core

[aaron-neal]

It looks like using inline on functions clears them from the multiple definitions list. e.g.:

inline int DNSClient::inet_aton(const char* address, IPAddress& result)

[khoih-prog]

Did you try and follow the instructions in multiFileProject example to avoid Multiple Definitions

This library was used in many more complex projects / libraries without error by not carelessly and blindly including any h file.

Please spend some time to research which libraries is using and how to have some ideas, if necessary.

I'm sure won't go back to the old cpp style.

Good Luck,

[aaron-neal]

Thank you @khoih-prog, I had not seen that example. Got me on my way. Cheers.