bug#46797: mac_font_shape EXC_BAD_ACCESS

[Jimmy Yuen Ho Wong]

Emacs crash on the NSPort of emacs27 HEAD, here's the LLDB info:

Process 94921 stopped
* thread #1, queue = 'com.apple.main-thread', stop reason =
EXC_BAD_ACCESS (code=1, address=0x7ffeefc00000)
    frame #0: 0x00000001003abd3a
Emacs`mac_font_shape(font=0x000000011fb480c0, string=@"𝆺𝅥𝅯𝉂\0\0\0\0",
glyph_layouts=0x00007ffeefbe9a50, glyph_len=8, dir=DIR_UNKNOWN) at
macfont.m:3754:34
   3751               struct mac_glyph_layout *gl =
   3752                 glbuf + range.location + range.length;
   3753
-> 3754               if (gl->comp_range.length
   3755                   > comp_range.location + comp_range.length)
   3756                 comp_range.length = gl->comp_range.length -
comp_range.location;
   3757               min_location = gl->comp_range.location;
Target 0: (Emacs) stopped.
(lldb) bt --all
error: bt [<digit> | all]
(lldb) bt all
* thread #1, queue = 'com.apple.main-thread', stop reason =
EXC_BAD_ACCESS (code=1, address=0x7ffeefc00000)
  * frame #0: 0x00000001003abd3a
Emacs`mac_font_shape(font=0x000000011fb480c0, string=@"𝆺𝅥𝅯𝉂\0\0\0\0",
glyph_layouts=0x00007ffeefbe9a50, glyph_len=8, dir=DIR_UNKNOWN) at
macfont.m:3754:34
    frame #1: 0x00000001003a529e
Emacs`macfont_shape(lgstring=0x0000000106e2f005,
direction=0x0000000000000000) at macfont.m:3000:16
  thread #4, name = 'gmain'
    frame #0: 0x00007fff203211fe libsystem_kernel.dylib`__select + 10
    frame #1: 0x0000000101f4cbef libglib-2.0.0.dylib`g_poll + 505
    frame #2: 0x0000000101f40a3e
libglib-2.0.0.dylib`g_main_context_iterate + 340
    frame #3: 0x0000000101f40aec
libglib-2.0.0.dylib`g_main_context_iteration + 55
    frame #4: 0x0000000101f41b99 libglib-2.0.0.dylib`glib_worker_main + 30
    frame #5: 0x0000000101f620bd libglib-2.0.0.dylib`g_thread_proxy + 90
    frame #6: 0x00007fff2034d950 libsystem_pthread.dylib`_pthread_start + 224
    frame #7: 0x00007fff2034947b libsystem_pthread.dylib`thread_start + 15
  thread #7
    frame #0: 0x00007fff203211fe libsystem_kernel.dylib`__select + 10
    frame #1: 0x000000010036dd4d Emacs`-[EmacsApp
fd_handler:](self=0x000000010532b7f0, _cmd="fd_handler:",
unused=0x0000000000000000) at nsterm.m:6066:20
    frame #2: 0x00007fff211c9e1d Foundation`__NSThread__start__ + 1042
    frame #3: 0x00007fff2034d950 libsystem_pthread.dylib`_pthread_start + 224
    frame #4: 0x00007fff2034947b libsystem_pthread.dylib`thread_start + 15
  thread #9, name = 'com.apple.NSEventThread'
    frame #0: 0x00007fff20318e7e libsystem_kernel.dylib`mach_msg_trap + 10
    frame #1: 0x00007fff203191f0 libsystem_kernel.dylib`mach_msg + 60
    frame #2: 0x00007fff20445bf7 CoreFoundation`__CFRunLoopServiceMachPort + 316
    frame #3: 0x00007fff204442ca CoreFoundation`__CFRunLoopRun + 1315
    frame #4: 0x00007fff204436ce CoreFoundation`CFRunLoopRunSpecific + 563
    frame #5: 0x00007fff22de97c6 AppKit`_NSEventThread + 124
    frame #6: 0x00007fff2034d950 libsystem_pthread.dylib`_pthread_start + 224
    frame #7: 0x00007fff2034947b libsystem_pthread.dylib`thread_start + 15
  thread #293
    frame #0: 0x00007fff2031a53e libsystem_kernel.dylib`__workq_kernreturn + 10
    frame #1: 0x0019a19a00004000
    frame #2: 0x00007fff20349467 libsystem_pthread.dylib`start_wqthread + 15
(lldb) vars
error: 'vars' is not a valid command.
(lldb) var
(CTFontRef) font = 0x000000011fb480c0
(CFStringRef) string = 0x0000000110d6b1c0 @"𝆺𝅥𝅯𝉂\0\0\0\0"
(mac_glyph_layout *) glyph_layouts = 0x00007ffeefbe9a50
(CFIndex) glyph_len = 8
(lgstring_direction) dir = DIR_UNKNOWN
(CFIndex) used = 4
(CFIndex) result = 0
(CTLineRef) ctline = 0x00000001242fa0a0
(CFArrayRef) ctruns = 0x0000000110da2e10 @"2 elements"
(CFIndex) k = 0
(CFIndex) ctrun_count = 2
(CGFloat) total_advance = 0
(CFIndex) total_glyph_count = 0
(CTRunRef) ctrun = 0x00000001242f9d00
(CFIndex) i = 14
(CFIndex) min_location = 8458716092896928869
(CFIndex) glyph_count = 1
(mac_glyph_layout *) glbuf = 0x00007ffeefbe9a50
(CFRange) string_range = location=0 length=2
(CFRange) comp_range = location=9223372036854775807 length=0
(CFRange) range = location=1142 length=493
(CFIndex *) permutation = 0x0000000000000000
(mac_glyph_layout *) gl = 0x00007ffeefbffff8


Jimmy Yuen Ho Wong