I needed to specify stdlib options in a certain environment, so I changed the flycheck executable to
clang -std=c++11 -stdlib=libc++, which is needed to compile the file.
However, I got the error
Error while checking syntax automatically: (error "Output file descriptor of flycheck-c/c++-clang is closed") after doing so, and searches don't turn anything up.
How do I help flycheck out?