When writing to stderr fails, ECL wants to write an error message to stderr to say that this write failed. This is obviously an infinite loop. This can occur in real-life situations when stderr is a log file on a full (ENOSPC) file system. Example shell session:
$ echo syntax error | ./ecl 2>/dev/full ECL (Embeddable Common-Lisp) 13.4.1 (git:6a39823a1eb313e9c316b64ece15911e8b2bf472) Copyright (C) 1984 Taiichi Yuasa and Masami Hagiya Copyright (C) 1993 Giuseppe Attardi Copyright (C) 2000 Juan J. Garcia-Ripoll ECL is free software, and you are welcome to redistribute it under certain conditions; see file 'Copyright' for details. Type :h for Help. Top level in: #<process TOP-LEVEL>. > Segmentation fault
The simplest solution (see patch) is ignoring errors when writing to stderr.