写了个交互库，结果提交代码时的这个CE提示又是什么问题？

No valid executable file was produced by the compiler
/nix/store/js66s0xwjnzg0ggi2lq9bcvlk6x2za13-binutils-2.35.2/bin/ld: ./cc7FtMq5.o: in function `main':
src:(.text+0x0): multiple definition of `main'; /tmp/compiler_xk2ltnb0/lib.o:src:(.text.startup+0x0): first defined here
collect2: 错误：ld 返回 1