Hey bug-gnu-emacs, Is the following a bug? # No backtrace?! $ emacs -Q --batch --eval '(setq debug-on-error t)' --eval '(string-match-p nil "A")' Wrong type argument: stringp, nil # Yes backtrace?!? $ emacs -Q --batch --eval '(setq debug-on-error t)' --eval '(string-match nil "A")' Debugger entered--Lisp error: (wrong-type-argument stringp nil) string-match(nil "A") eval((string-match nil "A")) ... This isn't new, but it behaved differently in Emacs 24.5: $ emacs-24.5 -Q --batch --eval '(setq debug-on-error t)' --eval '(string-match nil "A")' Debugger entered--Lisp error: (wrong-type-argument stringp nil) string-match(nil "A") eval((string-match nil "A")) ... $ emacs-24.5 -Q --batch --eval '(setq debug-on-error t)' --eval '(string-match-p nil "A")' Args out of range: 0 Clément. In GNU Emacs 25.1.50.7 (x86_64-pc-linux-gnu, GTK+ Version 3.18.9) of 2016-07-20 built on clem-w50-mint Repository revision: a1a0c208e3e895a6ea0942e8e5c4077faf12c7ad Windowing system distributor 'The X.Org Foundation', version 11.0.11803000 System Description: Linux Mint 18 Sarah