The variable "result" in Java_sun_nio_ch_FileDispatcherImpl_setDirect0 might be uninitialized, if neither O_DIRECT, F_NOCACHE, or DIRECTIO_ON is defined, because the final #else block is not an assignment, but a comparison.

https://github.com/openjdk/jdk/blob/7e42642939c0c3b8b872d72890fbb5aab4c3e507/src/java.base/unix/native/libnio/ch/FileDispatcherImpl.c