Intellij IDEA:“unmappable字符编码UTF-8”编译ISO-8859-1文件

I have a mixed-encoding source tree and I'm getting the warning above for some of my source files. I managed to sucessfully set the encoding for those files to ISO 8859-1 and, after invalidating IDEA's caches, they now display correctly in the editor. However, when I compile, I still get the error message.I have a mixed-encoding source tree and I'm get