C程序编译器只在Windows中发出警告(MinGW-w64)

I built a multi-language software image processing program and made it generally available with binaries for Mac OS X and Ubuntu. The binaries have been tested on their respective operating systems and every thing works perfectly. I recently also tried to release binaries for Windows (64 bit) but the GCC (through MinGW-w64) compiler gave me warnings for one of the C programs when I create the shared library (dll) file. This did not happen in Mac OS X or Ubuntu. Here are the warnings and the corresponding line of code in the C file:I built a multi-language software image process