bug#20525: 25.0.50; edebug doesn't cooperate with when-let

[Aaron Ecay]

Edebug does not play well with the single-binding form of the when-let
macro.  This is with git rev 08431a20c55 (and seems to have been the
case on master for several months, possibly since the introduction of
the when-let macro).

Steps to reproduce in emacs -Q:

Evaluate in scratch buffer:

(require 'subr-x)
(setq debug-on-error t)

Then write:

(defun awe-test ()
  (when-let ((foo t))
    foo))

Put point inside the defun and C-u C-M-x.  All works fine.

Remove the outer set of parentheses on the binding, as the when-let
docstring says is possible (“In the special case you only want to bind a
single value, BINDINGS can just be a plain tuple.”):

(defun awe-test ()
  (when-let (foo t)
    foo))

C-u C-M-x leads to the backtrace reproduced below.

Thanks,
Aaron

Debugger entered--Lisp error: (invalid-read-syntax "Failed matching" (&rest 
(symbolp form)))
  signal(invalid-read-syntax ("Failed matching" (&rest (symbolp form))))
  edebug-syntax-error("Failed matching" (&rest (symbolp form)))
  apply(edebug-syntax-error ("Failed matching" (&rest (symbolp form))))
  edebug-no-match(((foo t) (243 . 246) (247 . 248) . 249) "Failed matching" 
(&rest (symbolp form)))
  edebug-match-sublist(((foo t) (243 . 246) (247 . 248) . 249) (&rest (symbolp 
form)))
  edebug-match-list((((foo t) foo) (242 (243 . 246) (247 . 248) . 249) (254 . 
257) . 258) (&rest (symbolp form)))
  edebug-match-one-spec((((foo t) foo) (242 (243 . 246) (247 . 248) . 249) (254 
. 257) . 258) (&rest (symbolp form)))
  edebug-match-specs((((foo t) foo) (242 (243 . 246) (247 . 248) . 249) (254 . 
257) . 258) ((&rest (symbolp form)) form body) edebug-match-specs)
  edebug-match-sublist((((foo t) foo) (242 (243 . 246) (247 . 248) . 249) (254 
. 257) . 258) ((&rest (symbolp form)) form body))
  edebug-list-form((((foo t) foo) (242 (243 . 246) (247 . 248) . 249) (254 . 
257) . 258))
  edebug-form((((when-let (foo t) foo)) (232 (233 . 241) (242 (243 . 246) (247 
. 248) . 249) (254 . 257) . 258) . 259))
  edebug-match-form((((when-let (foo t) foo)) (232 (233 . 241) (242 (243 . 246) 
(247 . 248) . 249) (254 . 257) . 258) . 259))
  edebug-match-symbol((((when-let (foo t) foo)) (232 (233 . 241) (242 (243 . 
246) (247 . 248) . 249) (254 . 257) . 258) . 259) form)
  edebug-match-one-spec((((when-let (foo t) foo)) (232 (233 . 241) (242 (243 . 
246) (247 . 248) . 249) (254 . 257) . 258) . 259) form)
  edebug-match-specs((((when-let (foo t) foo)) (232 (233 . 241) (242 (243 . 
246) (247 . 248) . 249) (254 . 257) . 258) . 259) (form) edebug-&rest-wrapper)
  edebug-&optional-wrapper((((when-let (foo t) foo)) (232 (233 . 241) (242 (243 
. 246) (247 . 248) . 249) (254 . 257) . 258) . 259) (form) edebug-&rest-wrapper)
  edebug-&rest-wrapper((((when-let (foo t) foo)) (232 (233 . 241) (242 (243 . 
246) (247 . 248) . 249) (254 . 257) . 258) . 259) (form) edebug-&rest-wrapper)
  edebug-match-&rest((((when-let (foo t) foo)) (232 (233 . 241) (242 (243 . 
246) (247 . 248) . 249) (254 . 257) . 258) . 259) (form))
  edebug-match-specs((((when-let (foo t) foo)) (232 (233 . 241) (242 (243 . 
246) (247 . 248) . 249) (254 . 257) . 258) . 259) (&rest form) 
edebug-match-specs)
  edebug-match((((when-let (foo t) foo)) (232 (233 . 241) (242 (243 . 246) (247 
. 248) . 249) (254 . 257) . 258) . 259) (&rest form))
  edebug-match-def-body((((when-let (foo t) foo)) (232 (233 . 241) (242 (243 . 
246) (247 . 248) . 249) (254 . 257) . 258) . 259))
  edebug-match-symbol((((when-let (foo t) foo)) (232 (233 . 241) (242 (243 . 
246) (247 . 248) . 249) (254 . 257) . 258) . 259) def-body)
  edebug-match-one-spec((((when-let (foo t) foo)) (232 (233 . 241) (242 (243 . 
246) (247 . 248) . 249) (254 . 257) . 258) . 259) def-body)
  edebug-match-specs((((when-let (foo t) foo)) (232 (233 . 241) (242 (243 . 
246) (247 . 248) . 249) (254 . 257) . 258) . 259) (def-body) edebug-match-specs)
  edebug-match-specs((((when-let (foo t) foo)) (232 (233 . 241) (242 (243 . 
246) (247 . 248) . 249) (254 . 257) . 258) . 259) ([&optional ("interactive" 
interactive)] def-body) edebug-match-specs)
  edebug-match-specs((((when-let (foo t) foo)) (232 (233 . 241) (242 (243 . 
246) (247 . 248) . 249) (254 . 257) . 258) . 259) ([&optional stringp] 
[&optional ("interactive" interactive)] def-body) edebug-match-specs)
  edebug-match-specs((((when-let (foo t) foo)) (232 (233 . 241) (242 (243 . 
246) (247 . 248) . 249) (254 . 257) . 258) . 259) (lambda-list [&optional 
stringp] [&optional ("interactive" interactive)] def-body) edebug-match-specs)
  edebug-match-specs((((when-let (foo t) foo)) (232 (233 . 241) (242 (243 . 
246) (247 . 248) . 249) (254 . 257) . 258) . 259) (name lambda-list [&optional 
stringp] [&optional ("interactive" interactive)] def-body) edebug-match-specs)
  edebug-match-specs((((when-let (foo t) foo)) (232 (233 . 241) (242 (243 . 
246) (247 . 248) . 249) (254 . 257) . 258) . 259) ("defun" name lambda-list 
[&optional stringp] [&optional ("interactive" interactive)] def-body) 
edebug-match-specs)
  edebug-match-sublist((((when-let (foo t) foo)) (232 (233 . 241) (242 (243 . 
246) (247 . 248) . 249) (254 . 257) . 258) . 259) ("defun" name lambda-list 
[&optional stringp] [&optional ("interactive" interactive)] def-body))
  edebug-match-list((((defun awe-test nil (when-let (foo t) foo))) (211 (212 . 
217) (218 . 226) (227 . 229) (232 (233 . 241) (242 (243 . 246) (247 . 248) . 
249) (254 . 257) . 258) . 259)) ("defun" name lambda-list [&optional stringp] 
[&optional ("interactive" interactive)] def-body))
  edebug-match-one-spec((((defun awe-test nil (when-let (foo t) foo))) (211 
(212 . 217) (218 . 226) (227 . 229) (232 (233 . 241) (242 (243 . 246) (247 . 
248) . 249) (254 . 257) . 258) . 259)) ("defun" name lambda-list [&optional 
stringp] [&optional ("interactive" interactive)] def-body))
  edebug-match-specs((((defun awe-test nil (when-let (foo t) foo))) (211 (212 . 
217) (218 . 226) (227 . 229) (232 (233 . 241) (242 (243 . 246) (247 . 248) . 
249) (254 . 257) . 258) . 259)) (("defun" name lambda-list [&optional stringp] 
[&optional ("interactive" interactive)] def-body)) edebug-match-specs)
  edebug-match((((defun awe-test nil (when-let (foo t) foo))) (211 (212 . 217) 
(218 . 226) (227 . 229) (232 (233 . 241) (242 (243 . 246) (247 . 248) . 249) 
(254 . 257) . 258) . 259)) (("defun" name lambda-list [&optional stringp] 
[&optional ("interactive" interactive)] def-body)))
  edebug-make-form-wrapper((((defun awe-test nil (when-let (foo t) foo))) (211 
(212 . 217) (218 . 226) (227 . 229) (232 (233 . 241) (242 (243 . 246) (247 . 
248) . 249) (254 . 257) . 258) . 259)) 211 258 (("defun" name lambda-list 
[&optional stringp] [&optional ("interactive" interactive)] def-body)))
  edebug-read-and-maybe-wrap-form1()
  edebug-read-and-maybe-wrap-form()
  edebug-read-top-level-form()
  edebug-eval-defun((4))
  apply(edebug-eval-defun (4))
  eval-defun((4))
  funcall-interactively(eval-defun (4))
  call-interactively(eval-defun nil nil)
  command-execute(eval-defun)

In GNU Emacs 25.0.50.2 (x86_64-unknown-linux-gnu, GTK+ Version 3.16.2)
 of 2015-05-03 on haize
Windowing system distributor `The X.Org Foundation', version 11.0.11701000
Configured using:
 `configure --prefix=/usr --sysconfdir=/etc --libexecdir=/usr/lib
 --localstatedir=/var --mandir=/usr/share/man
 --pdfdir=/usr/share/doc/emacs/pdf --with-sound=alsa --without-gconf
 --with-x-toolkit=gtk3 --with-xft 'CFLAGS=-march=x86-64 -mtune=generic
 -O2 -pipe -fstack-protector --param=ssp-buffer-size=4'
 CPPFLAGS=-D_FORTIFY_SOURCE=2
 LDFLAGS=-Wl,-O1,--sort-common,--as-needed,-z,relro'

Configured features:
XPM JPEG TIFF GIF PNG RSVG IMAGEMAGICK SOUND GPM DBUS GSETTINGS NOTIFY
ACL GNUTLS LIBXML2 FREETYPE M17N_FLT LIBOTF XFT ZLIB

Important settings:
  value of $LC_COLLATE: C
  value of $LANG: en_US.UTF-8
  locale-coding-system: utf-8-unix



-- 
Aaron Ecay