bug#27779: #27779; C stack overflow from `read' on deeply nested lisp object.

[Keith David Bershatsky <esq@lawlist.com>]

TWO (2) TESTS:

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;;; TEST # 1.

SOURCE:  git clone -b emacs-26 git://git.sv.gnu.org/emacs.git

CONFIGURE:

CFLAGS='-Wall -O2 -g3' ./configure \
--with-ns \
--enable-checking='yes,glyphs' \
--enable-check-lisp-object-type \
--without-compress-install \
--without-makeinfo \
--with-gnutls=no \
--with-mailutils \
--without-makeinfo

LISP:

(require 'cl-lib)

(defun make-deep-object (depth)
    (let ((obj 1))
      (while (> (cl-decf depth) 0)
        (setq obj (vector (list obj))))
      obj))

;;; STACK OVERFLOW:  problem with `read'
;;; The bug was introduced on December 8, 2016 with
;;; commit:  f0a1e9ec3fba3d5bea5bd62f525dba3fb005d1b1
(let* ((print-circle t)
       (max-lisp-eval-depth most-positive-fixnum)
       (max-specpdl-size most-positive-fixnum)
       (deep-object (make-deep-object 6000))
       (string (prin1-to-string deep-object))
       (result (read string)))
  (when result
    (message "Bug #27779:  Success! (%d)" (length string))))

TEST:  Lanched without the terminal by opening Emacs.app.

RESULT:  Bug #27779:  Success! (23997)

No need to set the terminal with "ulimit -S -s unlimited" before launching Emacs from the terminal.

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;;; TEST # 2.

SOURCE:  git clone -b emacs-26 git://git.sv.gnu.org/emacs.git

CONFIGURE:

CFLAGS='-Wall -O0 -g3' ./configure \
--with-ns \
--enable-check-lisp-object-type \
--without-compress-install \
--without-makeinfo \
--with-gnutls=no \
--with-mailutils \
--without-makeinfo

LISP:

(require 'cl-lib)

(defun make-deep-object (depth)
    (let ((obj 1))
      (while (> (cl-decf depth) 0)
        (setq obj (vector (list obj))))
      obj))

;;; STACK OVERFLOW:  problem with `read'
;;; The bug was introduced on December 8, 2016 with
;;; commit:  f0a1e9ec3fba3d5bea5bd62f525dba3fb005d1b1
(let* ((print-circle t)
       (max-lisp-eval-depth most-positive-fixnum)
       (max-specpdl-size most-positive-fixnum)
       (deep-object (make-deep-object 6000))
       (string (prin1-to-string deep-object))
       (result (read string)))
  (when result
    (message "Bug #27779:  Success! (%d)" (length string))))

TEST:  Lanched without the terminal by opening Emacs.app.

RESULT:  Re-entering top level after C stack overflow

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> Date: [05-02-2019 00:26:45] <2 May 2019 00:26:45 -0700>
> From: Paul Eggert <eggert@cs.ucla.edu>
> To: Keith David Bershatsky <esq@lawlist.com>, Noam Postavsky <npostavs@gmail.com>
> Cc: 27779@debbugs.gnu.org, mail@vasilij.de
> Subject: Re: bug#27779: #27779; C stack overflow from `read' on deeply nested lisp object.
> 
> Keith David Bershatsky wrote:
> > CONFIGURE:  CFLAGS='-Wall -O0 -g3' ./configure \
> >              --with-ns \
> >              --enable-checking='yes,glyphs' \
> >              --enable-check-lisp-object-type \
> >              --without-compress-install \
> >              --without-makeinfo \
> >              --with-gnutls=no \
> >              --with-mailutils \
> >              --without-makeinfo
> 
> What happens if you try it with -O2 rather than -O0?
> 
> Also, what happens if you try it without --enable-checking='yes,glyphs'?
> 
> I have a suspicion that the debugging options are blowing the stack.