When attempting to compile a program using the Crystal compiler on macOS Sierra 10.12.1, I ran into the following error:
[warn] kq_init: detected broken kqueue; not using.: Undefined error: 0 [warn] kq_init: detected broken kqueue; not using.: Undefined error: 0 [warn] kq_init: detected broken kqueue; not using.: Undefined error: 0 [warn] kq_init: detected broken kqueue; not using.: Undefined error: 0 ld: library not found for -lssl clang: error: linker command failed with exit code 1 (use -v to see invocation)
I solved the problem by reinstalling libevent:
brew update && brew reinstall libevent
…and then reinstalling the Xcode command-line tools:
xcode-select --install
Afterwards, I was able to run crystal -v and compile my program without any errors. 