When bison is invoked with input from a pipe (e.g. `/dev/stdin`) on a grammar that contains an error, it will hang indefinitely when trying to print the caret diagnostic.
Testing with `strace` indicates that the `read` syscall is being called repeatedly even though it returns 0 (i.e. EOF). Without investigation, I can only assume this is a failure to check `feof` in libc? As a workaround, pass `--feature=none` to disable caret diagnostics. Tested with bison 3.0.2 (as packaged in Debian Jessie, which is probably just removing the nonfree documentation), but I've checked the git log for 3.0.4 and don't see anything that looks like it would change this. -o11c
