Hello,

the following piece of elisp crashes Emacs 26.1 (core dump):

> ;;; -*- lexical-binding: t -*-
> (defvar ;dead-beef* (symbol-function #'dead-beef)
>     "Some random description")

Note a couple of things:

- lexical binding seems to be important (otherwise no crash)

- ; seems to be the major cause

- the variable definition must be split across two lines

Please find attached a minimal proof of concept. You should be able to
reproduce the crash with 'emacs -Q --script test_min.el'.

Best regards,

Thomas

-- 
Thomas Barabosch

Fraunhofer FKIE                        Tel.:   +49 228 50212-601
Cyber Analysis & Defense               Fax:    +49 228 73-4571
Zanderstraße 5                         D-53113 Bonn, Germany
http://www.fkie.fraunhofer.de/