The culprit seems to be the unterminated string (no ending double quote) 
with a parenthesis in front of it.

  emacs -q dummy.c --eval='(global-font-lock-mode 0)

===
// dummy.c

// type anything after this line without global font-lock-mode

// parenthesis + unterminated string seems to be the culprit
("unterminated string
=== EOF


-- 
G. Mounié - Associate Prof., Univ. Grenoble Alpes (Grenoble-INP/Ensimag)
LIG - Datamove Inria team, off. 440, IMAG building,+33(0)457 421 533, FR