bug#63283: Emacs crash within fontset

[Seppo Ronkainen via "Bug reports for GNU Emacs, the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>]

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Honorable GNU developers !

For some reason the new Emacs 29.0.90 did not build at work the other day unless I provided configuration option --without-all (I plan to look into why later but that is not why I am writing this report now).

When I experimented with Emacs (29.0.90 --without-all) I noticed a crash defect that was easy to reproduce. It seemed to have with fonts to do. I have noticed the same problem both at work CentOS 7.9 and at home (currently on a raspberry pi 4) not that it matters but anyhow several machines / architectures. The problem seemed non-present when I built Emacs without configuration option --without-all

I attach details about my findings in an org file, hope it helps

Live long and prosper

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* 20230504172048utc Steps to reproduce

create a test file with some unicode character
#+begin_src emacs-lisp
  (with-temp-file (expand-file-name "~/examplefilewithunicodetext")
    (insert-char (char-from-name "LEFT WHITE CORNER BRACKET")))
#+end_src

~/examplefilewithunicodetext
#+begin_export
『
#+end_export


/home/user/.local/emacs-29.0.90_minimal/cons/src/config.h:131
#+begin_src c
/* Define to the options passed to configure. */
#define EMACS_CONFIG_OPTIONS "--prefix=/home/user/.local/emacs-29.0.90_minimal/inst --without-all"
#+end_src


run Emacs without configuration and after one second increase the font size a few times
#+begin_src sh
  PATH="/home/user/.local/emacs-29.0.90_minimal/inst/bin:${PATH}" gdb --ex run --args emacs -Q ~/examplefilewithunicodetext --eval "(run-at-time 1 '() (lambda() (dotimes (i 10) (text-scale-adjust 1))))"
#+end_src

expected behavior: emacs resizes the font

observed behavior: gdb reports emacs defect in fontset.c on line 555
src/fontset.c:549
#+begin_src c
/* 549 */ static Lisp_Object
/* 550 */ fontset_find_font (Lisp_Object fontset, int c, struct face /* *fa */ce,
/* 551 */                    int charset_id, bool fallback)
/* 552 */ {
/* 553 */   Lisp_Object vec, font_group;
/* 554 */   int i, charset_matched = 0, found_index;
/* 555 */   struct frame *f = (FRAMEP (FONTSET_FRAME (fontset))
/* 556 */                      ? XFRAME (FONTSET_FRAME (fontset))
/* 557 */                      : XFRAME (selected_frame));
#+end_src

#+begin_export
0x00000055557864c8 in fontset_find_font (fontset=fontset@entry=0x20, c=c@entry=12302, face=face@entry=0x5556519100, 
    charset_id=charset_id@entry=-1, fallback=fallback@entry=false) at fontset.c:555
555       struct frame *f = (FRAMEP (FONTSET_FRAME (fontset))
#+end_export





when I run a more recent Emacs 30 withoug specifying --without-all then no defect seem present
#+begin_export
--prefix=/home/user/.local/emacs-head-0d2fdf6e36d35e7ab64d8894e8d4c27b0cc06875/inst --with-gif=no --with-included-regex --with-jpeg=no --with-json=yes --with-mailutils=no --with-makeinfo=no --with-modules --with-rsvg=no --with-threads --with-tiff=no --with-xml2=yes --without-gpm --without-gsettings --without-imagemagick --without-javascript --without-sound
#+end_export

#+begin_src sh
  PATH="/home/user/.local/emacs-head-0d2fdf6e36d35e7ab64d8894e8d4c27b0cc06875/inst/bin:${PATH}" gdb --ex run --args emacs -Q ~/examplefilewithunicodetext --eval "(run-at-time 1 '() (lambda() (dotimes (i 10) (text-scale-adjust 1))))"
#+end_src