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* Re: buffer.c/buffer.h: How to add new buffer-local variables?
@ 2019-04-08  8:03 Keith David Bershatsky
  2019-04-08  9:37 ` Eli Zaretskii
  0 siblings, 1 reply; 34+ messages in thread
From: Keith David Bershatsky @ 2019-04-08  8:03 UTC (permalink / raw)
  To: Paul Eggert; +Cc: emacs-devel, schwab, monnier, acm, eliz, dancol

[-- Attachment #1: Type: text/plain, Size: 2724 bytes --]

Thank you, Paul, for taking the time to try and reproduce the behavior that I am experiencing on my end.

I am assuming that this round of tests is with a current version of the master branch (0b8117ed1abfc17bb0bc1690a8997736f1e8f98c) and _after_ applying the x.diff patch.  I built the Emacs master branch (current version) without any modifications so that the build could complete without errors, and then I applied the x.diff patch and built again and then performed the gdb test.  The build with the patch will crash on my end when garbage collection occurs; however, the ptype test is able to complete and I have attached a gdb printout 0b8117ed1abfc17bb0bc1690a8997736f1e8f98c.txt.  The current issue is beyond my current level of programming abilities to resolve, so other than performing a standard M-x diff between your ptype test (relabeled as ptype_by_paul.txt) and my own test (0b8117ed1abfc17
 bb0bc1690a8997736f1e8f98c.txt), I would need further guidance regarding how best to be of assistance.

My setup on Windows XP SP-3 didn't recognize a build option of -m32, so I just used the same old build options that I have used previously; i.e.,:

CFLAGS='-O0 -g3' ./configure \
--enable-checking='yes,glyphs' \
--enable-check-lisp-object-type \
--without-compress-install \
--without-makeinfo \
--with-gnutls=no \
--with-mailutils \
--without-makeinfo

Keith

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

> Date: [04-07-2019 22:23:07] <7 Apr 2019 22:23:07 -0700>
> From: Paul Eggert <eggert@cs.ucla.edu>
> To: Keith David Bershatsky <esq@lawlist.com>
> Cc: emacs-devel@gnu.org, Stefan Monnier <monnier@iro.umontreal.ca>,
> Andreas Schwab <schwab@linux-m68k.org>, Alan Mackenzie <acm@muc.de>,
> Daniel Colascione <dancol@dancol.org>
> Subject: Re: buffer.c/buffer.h: How to add new buffer-local variables?
> 
> Keith David Bershatsky wrote:
> > Perhaps there is something that may stand out (to a trained programmer) in the 01/31/2019 commit ....
> 
> It did change the buffer struct layout, so it's a good candidate for a culprit.
> 
> For what it's worth, I cannot reproduce the problem in a 32-bit build under Fedora 29 x86-64 (GCC 8.3.1). I configured this way:
> 
> ./configure CC=gcc -m32 -march=native --enable-gcc-warnings --without-imagemagick --without-gif --with-modules --enable-checking=yes,glyphs --enable-check-lisp-object-type --with-gnutls=no
> 
> and built Emacs master with the attached patch x.diff.
> 
> My guess is that the problem has something to do with the unportable assumptions we've long made about struct buffer layout. I am attaching ptype.txt, the output of the GDB command "ptype /o current_buffer" that Eli suggested; please compare it to your ptype output.


[-- Attachment #2: 0b8117ed1abfc17bb0bc1690a8997736f1e8f98c.txt --]
[-- Type: application/txt, Size: 8361 bytes --]

[-- Attachment #3: ptype_by_paul.txt --]
[-- Type: application/txt, Size: 8076 bytes --]

[-- Attachment #4: x.diff --]
[-- Type: application/diff, Size: 11218 bytes --]

^ permalink raw reply	[flat|nested] 34+ messages in thread
* Re: buffer.c/buffer.h: How to add new buffer-local variables?
@ 2019-04-09  3:49 Keith David Bershatsky
  0 siblings, 0 replies; 34+ messages in thread
From: Keith David Bershatsky @ 2019-04-09  3:49 UTC (permalink / raw)
  To: Paul Eggert; +Cc: mwd, emacs-devel, schwab, monnier, acm, eliz, dancol

I have successfully built Emacs (a038df77de7b1aa2d73a6478493b8838b59e4982) on the following platforms:

1.  w32:  Windows XP SP-3 (MinGW with ezwinports from a couple of years ago).

2.  X11:  Running on a machine with OSX 10.6.8.

3.  NS:  OSX 10.6.8.

All issues that I previously raised by virtue of this particular thread are now resolved.

Thank you very much to everyone for participating in this thread and working on these issues.

Greatly appreciated!!!

Keith



^ permalink raw reply	[flat|nested] 34+ messages in thread
* Re: buffer.c/buffer.h: How to add new buffer-local variables?
@ 2019-04-09  0:48 Keith David Bershatsky
  0 siblings, 0 replies; 34+ messages in thread
From: Keith David Bershatsky @ 2019-04-09  0:48 UTC (permalink / raw)
  To: Paul Eggert; +Cc: emacs-devel, schwab, monnier, acm, eliz, dancol

My bad ... I missed reading the new comment that "mode_line_help_echo must be the last Lisp member":

  /* No Lisp data may follow this point; mode_line_help_echo must be
     the last Lisp member.  */

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

> Date: [04-08-2019 17:40:33] <08 Apr 2019 17:40:33 -0700>
> From: Keith David Bershatsky <esq@lawlist.com>
> 
> Is it possible that a038df77de7b1aa2d73a6478493b8838b59e4982 broke the ability for Emacs to maintain the value of certain WINDOW Lisp_Object defined in window.h?
> 
> * * *



^ permalink raw reply	[flat|nested] 34+ messages in thread
* Re: buffer.c/buffer.h: How to add new buffer-local variables?
@ 2019-04-09  0:40 Keith David Bershatsky
  0 siblings, 0 replies; 34+ messages in thread
From: Keith David Bershatsky @ 2019-04-09  0:40 UTC (permalink / raw)
  To: Paul Eggert; +Cc: emacs-devel, schwab, monnier, acm, eliz, dancol

Is it possible that a038df77de7b1aa2d73a6478493b8838b59e4982 broke the ability for Emacs to maintain the value of certain WINDOW Lisp_Object defined in window.h?

Here is a snippet from a modified window.h.  All of the WINDOW caches for the fake cursors are coming back as INVALID_LISP_OBJECT.  A test for NILP on those invalid lisp objects comes back TRUE, and subsequent functions fail when trying to process the object that reports as being "DEAD" in gdb printouts.  This happens on the NS and w32 ports of Emacs.  I have not tested X11, but I assume the result will be the same.

If it is highly unlikely that a038df77de7b1aa2d73a6478493b8838b59e4982 is the culprit, then I would imagine that the culprit is somewhere between March 28, 2019 and today.  If anyone would like me to start going back in time to test other comments between March 28, 2019 and today, please let me know ....

    /* An alist with parameters.  */
    Lisp_Object window_parameters;

    /* The help echo text for this window.  Qnil if there's none.  */
    Lisp_Object mode_line_help_echo;


/* *************************************************************************** */
/* MULTIPLE-CURSORS */

    Lisp_Object mc_temp_cache;

    /* The cache for multiple fake cursors. */
    Lisp_Object mc_cache;

    /* The cache for crosshairs. */
    Lisp_Object ch_cache;

    /* The cache for visible fill column. */
    Lisp_Object fc_cache;

    /* L.S.L. color vector used by crosshairs. */
    Lisp_Object ch_foreground;

    /* L.S.L. color vector used by visible fill column. */
    Lisp_Object fc_foreground;

/* *************************************************************************** */


    /* No Lisp data may follow this point; mode_line_help_echo must be
       the last Lisp member.  */

    /* Glyph matrices.  */
    struct glyph_matrix *current_matrix;
    struct glyph_matrix *desired_matrix;



^ permalink raw reply	[flat|nested] 34+ messages in thread
* Re: buffer.c/buffer.h:  How to add new buffer-local variables?
@ 2019-04-08  4:34 Keith David Bershatsky
  0 siblings, 0 replies; 34+ messages in thread
From: Keith David Bershatsky @ 2019-04-08  4:34 UTC (permalink / raw)
  To: Eli Zaretskii; +Cc: eggert, emacs-devel, schwab, monnier, acm, dancol

[-- Attachment #1: Type: text/plain, Size: 17848 bytes --]

Thank you, Eli, for providing the steps to facilitate troubleshooting this issue.  The attached files may make it easier to do a diff between the gdb output for both commits.  I performed the gdb tests on the stock Emacs versions on the w32 platform without making any edits by me to the underlying source code; i.e., I did not add any buffer-local variables in these tests.

a68eee50eb515b28b448894299334afced26ef78

and

05d2fc7170fb66a87601b1c76ddae2c1b7b4b934

I am also posing the results in text form below just in case you prefer that instead of text files:

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

a68eee50eb515b28b448894299334afced26ef78

$ gdb ./emacs.exe

...

(gdb) start -Q

...

(gdb) ptype /o current_buffer

type = struct buffer {
/*    0      |     4 */    union vectorlike_header {
/*                 4 */        ptrdiff_t size;

                               /* total size (bytes):    4 */
                           } header;
/*    4      |     4 */    Lisp_Object name_;
/*    8      |     4 */    Lisp_Object filename_;
/*   12      |     4 */    Lisp_Object directory_;
/*   16      |     4 */    Lisp_Object backed_up_;
/*   20      |     4 */    Lisp_Object save_length_;
/*   24      |     4 */    Lisp_Object auto_save_file_name_;
/*   28      |     4 */    Lisp_Object read_only_;
/*   32      |     4 */    Lisp_Object mark_;
/*   36      |     4 */    Lisp_Object local_var_alist_;
/*   40      |     4 */    Lisp_Object major_mode_;
/*   44      |     4 */    Lisp_Object mode_name_;
/*   48      |     4 */    Lisp_Object mode_line_format_;
/*   52      |     4 */    Lisp_Object header_line_format_;
/*   56      |     4 */    Lisp_Object keymap_;
/*   60      |     4 */    Lisp_Object abbrev_table_;
/*   64      |     4 */    Lisp_Object syntax_table_;
/*   68      |     4 */    Lisp_Object category_table_;
/*   72      |     4 */    Lisp_Object case_fold_search_;
/*   76      |     4 */    Lisp_Object tab_width_;
/*   80      |     4 */    Lisp_Object fill_column_;
/*   84      |     4 */    Lisp_Object left_margin_;
/*   88      |     4 */    Lisp_Object auto_fill_function_;
/*   92      |     4 */    Lisp_Object downcase_table_;
/*   96      |     4 */    Lisp_Object upcase_table_;
/*  100      |     4 */    Lisp_Object case_canon_table_;
/*  104      |     4 */    Lisp_Object case_eqv_table_;
/*  108      |     4 */    Lisp_Object truncate_lines_;
/*  112      |     4 */    Lisp_Object word_wrap_;
/*  116      |     4 */    Lisp_Object ctl_arrow_;
/*  120      |     4 */    Lisp_Object bidi_display_reordering_;
/*  124      |     4 */    Lisp_Object bidi_paragraph_direction_;
/*  128      |     4 */    Lisp_Object bidi_paragraph_separate_re_;
/*  132      |     4 */    Lisp_Object bidi_paragraph_start_re_;
/*  136      |     4 */    Lisp_Object selective_display_;
/*  140      |     4 */    Lisp_Object selective_display_ellipses_;
/*  144      |     4 */    Lisp_Object minor_modes_;
/*  148      |     4 */    Lisp_Object overwrite_mode_;
/*  152      |     4 */    Lisp_Object abbrev_mode_;
/*  156      |     4 */    Lisp_Object display_table_;
/*  160      |     4 */    Lisp_Object mark_active_;
/*  164      |     4 */    Lisp_Object enable_multibyte_characters_;
/*  168      |     4 */    Lisp_Object buffer_file_coding_system_;
/*  172      |     4 */    Lisp_Object file_format_;
/*  176      |     4 */    Lisp_Object auto_save_file_format_;
/*  180      |     4 */    Lisp_Object cache_long_scans_;
/*  184      |     4 */    Lisp_Object width_table_;
/*  188      |     4 */    Lisp_Object pt_marker_;
/*  192      |     4 */    Lisp_Object begv_marker_;
/*  196      |     4 */    Lisp_Object zv_marker_;
/*  200      |     4 */    Lisp_Object point_before_scroll_;
/*  204      |     4 */    Lisp_Object file_truename_;
/*  208      |     4 */    Lisp_Object invisibility_spec_;
/*  212      |     4 */    Lisp_Object last_selected_window_;
/*  216      |     4 */    Lisp_Object display_count_;
/*  220      |     4 */    Lisp_Object left_margin_cols_;
/*  224      |     4 */    Lisp_Object right_margin_cols_;
/*  228      |     4 */    Lisp_Object left_fringe_width_;
/*  232      |     4 */    Lisp_Object right_fringe_width_;
/*  236      |     4 */    Lisp_Object fringes_outside_margins_;
/*  240      |     4 */    Lisp_Object scroll_bar_width_;
/*  244      |     4 */    Lisp_Object scroll_bar_height_;
/*  248      |     4 */    Lisp_Object vertical_scroll_bar_type_;
/*  252      |     4 */    Lisp_Object horizontal_scroll_bar_type_;
/*  256      |     4 */    Lisp_Object indicate_empty_lines_;
/*  260      |     4 */    Lisp_Object indicate_buffer_boundaries_;
/*  264      |     4 */    Lisp_Object fringe_indicator_alist_;
---Type <return> to continue, or q <return> to quit---
/*  268      |     4 */    Lisp_Object fringe_cursor_alist_;
/*  272      |     4 */    Lisp_Object display_time_;
/*  276      |     4 */    Lisp_Object scroll_up_aggressively_;
/*  280      |     4 */    Lisp_Object scroll_down_aggressively_;
/*  284      |     4 */    Lisp_Object cursor_type_;
/*  288      |     4 */    Lisp_Object extra_line_spacing_;
/*  292      |     4 */    Lisp_Object cursor_in_non_selected_windows_;
/*  296      |    72 */    struct buffer_text {
/*  296      |     4 */        unsigned char *beg;
/*  300      |     4 */        ptrdiff_t gpt;
/*  304      |     4 */        ptrdiff_t z;
/*  308      |     4 */        ptrdiff_t gpt_byte;
/*  312      |     4 */        ptrdiff_t z_byte;
/*  316      |     4 */        ptrdiff_t gap_size;
/*  320      |     4 */        EMACS_INT modiff;
/*  324      |     4 */        EMACS_INT chars_modiff;
/*  328      |     4 */        EMACS_INT save_modiff;
/*  332      |     4 */        EMACS_INT overlay_modiff;
/*  336      |     4 */        EMACS_INT compact;
/*  340      |     4 */        ptrdiff_t beg_unchanged;
/*  344      |     4 */        ptrdiff_t end_unchanged;
/*  348      |     4 */        EMACS_INT unchanged_modified;
/*  352      |     4 */        EMACS_INT overlay_unchanged_modified;
/*  356      |     4 */        INTERVAL intervals;
/*  360      |     4 */        struct Lisp_Marker *markers;
/*  364:31   |     4 */        bool_bf inhibit_shrinking : 1;
/*  364:30   |     4 */        bool_bf redisplay : 1;

                               /* total size (bytes):   72 */
                           } own_text;
/*  368      |     4 */    struct buffer_text *text;
/*  372      |     4 */    struct buffer *next;
/*  376      |     4 */    ptrdiff_t pt;
/*  380      |     4 */    ptrdiff_t pt_byte;
/*  384      |     4 */    ptrdiff_t begv;
/*  388      |     4 */    ptrdiff_t begv_byte;
/*  392      |     4 */    ptrdiff_t zv;
/*  396      |     4 */    ptrdiff_t zv_byte;
/*  400      |     4 */    struct buffer *base_buffer;
/*  404      |     4 */    int indirections;
/*  408      |     4 */    int window_count;
/*  412      |    50 */    char local_flags[50];
/* XXX  2-byte hole  */
/*  464      |    16 */    struct timespec {
/*  464      |     8 */        union {
/*                 4 */            time_t tv_sec;
/*                 4 */            __time32_t __tv32_sec;
/*                 8 */            __time64_t __tv64_sec;

                                   /* total size (bytes):    8 */
                               };
/*  472      |     4 */        long tv_nsec;

                               /* total size (bytes):   16 */
                           } modtime;
/*  480      |     4 */    off_t modtime_size;
/*  484      |     4 */    EMACS_INT auto_save_modified;
/*  488      |     4 */    EMACS_INT display_error_modiff;
/*  492      |     4 */    time_t auto_save_failure_time;
/*  496      |     4 */    ptrdiff_t last_window_start;
/*  500      |     4 */    struct region_cache *newline_cache;
/*  504      |     4 */    struct region_cache *width_run_cache;
/*  508      |     4 */    struct region_cache *bidi_paragraph_cache;
/*  512:31   |     4 */    bool_bf prevent_redisplay_optimizations_p : 1;
/*  512:30   |     4 */    bool_bf clip_changed : 1;
/* XXX  6-bit hole   */
/* XXX  3-byte hole  */
/*  516      |     4 */    struct Lisp_Overlay *overlays_before;
/*  520      |     4 */    struct Lisp_Overlay *overlays_after;
/*  524      |     4 */    ptrdiff_t overlay_center;
/*  528      |     4 */    Lisp_Object undo_list_;

---Type <return> to continue, or q <return> to quit---
                           /* total size (bytes):  536 */
                         } *
(gdb)

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

05d2fc7170fb66a87601b1c76ddae2c1b7b4b934

$ gdb ./emacs.exe

...

(gdb) start -Q

...

(gdb) ptype /o current_buffer

type = struct buffer {
/*    0      |     4 */    union vectorlike_header {
/*                 4 */        ptrdiff_t size;

                               /* total size (bytes):    4 */
                           } header;
/*    4      |     4 */    Lisp_Object name_;
/*    8      |     4 */    Lisp_Object filename_;
/*   12      |     4 */    Lisp_Object directory_;
/*   16      |     4 */    Lisp_Object backed_up_;
/*   20      |     4 */    Lisp_Object save_length_;
/*   24      |     4 */    Lisp_Object auto_save_file_name_;
/*   28      |     4 */    Lisp_Object read_only_;
/*   32      |     4 */    Lisp_Object mark_;
/*   36      |     4 */    Lisp_Object local_var_alist_;
/*   40      |     4 */    Lisp_Object major_mode_;
/*   44      |     4 */    Lisp_Object mode_name_;
/*   48      |     4 */    Lisp_Object mode_line_format_;
/*   52      |     4 */    Lisp_Object header_line_format_;
/*   56      |     4 */    Lisp_Object keymap_;
/*   60      |     4 */    Lisp_Object abbrev_table_;
/*   64      |     4 */    Lisp_Object syntax_table_;
/*   68      |     4 */    Lisp_Object category_table_;
/*   72      |     4 */    Lisp_Object case_fold_search_;
/*   76      |     4 */    Lisp_Object tab_width_;
/*   80      |     4 */    Lisp_Object fill_column_;
/*   84      |     4 */    Lisp_Object left_margin_;
/*   88      |     4 */    Lisp_Object auto_fill_function_;
/*   92      |     4 */    Lisp_Object downcase_table_;
/*   96      |     4 */    Lisp_Object upcase_table_;
/*  100      |     4 */    Lisp_Object case_canon_table_;
/*  104      |     4 */    Lisp_Object case_eqv_table_;
/*  108      |     4 */    Lisp_Object truncate_lines_;
/*  112      |     4 */    Lisp_Object word_wrap_;
/*  116      |     4 */    Lisp_Object ctl_arrow_;
/*  120      |     4 */    Lisp_Object bidi_display_reordering_;
/*  124      |     4 */    Lisp_Object bidi_paragraph_direction_;
/*  128      |     4 */    Lisp_Object bidi_paragraph_separate_re_;
/*  132      |     4 */    Lisp_Object bidi_paragraph_start_re_;
/*  136      |     4 */    Lisp_Object selective_display_;
/*  140      |     4 */    Lisp_Object selective_display_ellipses_;
/*  144      |     4 */    Lisp_Object minor_modes_;
/*  148      |     4 */    Lisp_Object overwrite_mode_;
/*  152      |     4 */    Lisp_Object abbrev_mode_;
/*  156      |     4 */    Lisp_Object display_table_;
/*  160      |     4 */    Lisp_Object mark_active_;
/*  164      |     4 */    Lisp_Object enable_multibyte_characters_;
/*  168      |     4 */    Lisp_Object buffer_file_coding_system_;
/*  172      |     4 */    Lisp_Object file_format_;
/*  176      |     4 */    Lisp_Object auto_save_file_format_;
/*  180      |     4 */    Lisp_Object cache_long_scans_;
/*  184      |     4 */    Lisp_Object width_table_;
/*  188      |     4 */    Lisp_Object pt_marker_;
/*  192      |     4 */    Lisp_Object begv_marker_;
/*  196      |     4 */    Lisp_Object zv_marker_;
/*  200      |     4 */    Lisp_Object point_before_scroll_;
/*  204      |     4 */    Lisp_Object file_truename_;
/*  208      |     4 */    Lisp_Object invisibility_spec_;
/*  212      |     4 */    Lisp_Object last_selected_window_;
/*  216      |     4 */    Lisp_Object display_count_;
/*  220      |     4 */    Lisp_Object left_margin_cols_;
/*  224      |     4 */    Lisp_Object right_margin_cols_;
/*  228      |     4 */    Lisp_Object left_fringe_width_;
/*  232      |     4 */    Lisp_Object right_fringe_width_;
/*  236      |     4 */    Lisp_Object fringes_outside_margins_;
/*  240      |     4 */    Lisp_Object scroll_bar_width_;
/*  244      |     4 */    Lisp_Object scroll_bar_height_;
/*  248      |     4 */    Lisp_Object vertical_scroll_bar_type_;
/*  252      |     4 */    Lisp_Object horizontal_scroll_bar_type_;
/*  256      |     4 */    Lisp_Object indicate_empty_lines_;
/*  260      |     4 */    Lisp_Object indicate_buffer_boundaries_;
/*  264      |     4 */    Lisp_Object fringe_indicator_alist_;
---Type <return> to continue, or q <return> to quit---
/*  268      |     4 */    Lisp_Object fringe_cursor_alist_;
/*  272      |     4 */    Lisp_Object display_time_;
/*  276      |     4 */    Lisp_Object scroll_up_aggressively_;
/*  280      |     4 */    Lisp_Object scroll_down_aggressively_;
/*  284      |     4 */    Lisp_Object cursor_type_;
/*  288      |     4 */    Lisp_Object extra_line_spacing_;
/*  292      |     4 */    Lisp_Object cursor_in_non_selected_windows_;
/*  296      |   104 */    struct buffer_text {
/*  296      |     4 */        unsigned char *beg;
/*  300      |     4 */        ptrdiff_t gpt;
/*  304      |     4 */        ptrdiff_t z;
/*  308      |     4 */        ptrdiff_t gpt_byte;
/*  312      |     4 */        ptrdiff_t z_byte;
/*  316      |     4 */        ptrdiff_t gap_size;
/*  320      |     8 */        modiff_count modiff;
/*  328      |     8 */        modiff_count chars_modiff;
/*  336      |     8 */        modiff_count save_modiff;
/*  344      |     8 */        modiff_count overlay_modiff;
/*  352      |     8 */        modiff_count compact;
/*  360      |     4 */        ptrdiff_t beg_unchanged;
/*  364      |     4 */        ptrdiff_t end_unchanged;
/*  368      |     8 */        modiff_count unchanged_modified;
/*  376      |     8 */        modiff_count overlay_unchanged_modified;
/*  384      |     4 */        INTERVAL intervals;
/*  388      |     4 */        struct Lisp_Marker *markers;
/*  392:31   |     4 */        bool_bf inhibit_shrinking : 1;
/*  392:30   |     4 */        bool_bf redisplay : 1;

                               /* total size (bytes):  104 */
                           } own_text;
/*  400      |     4 */    struct buffer_text *text;
/*  404      |     4 */    struct buffer *next;
/*  408      |     4 */    ptrdiff_t pt;
/*  412      |     4 */    ptrdiff_t pt_byte;
/*  416      |     4 */    ptrdiff_t begv;
/*  420      |     4 */    ptrdiff_t begv_byte;
/*  424      |     4 */    ptrdiff_t zv;
/*  428      |     4 */    ptrdiff_t zv_byte;
/*  432      |     4 */    struct buffer *base_buffer;
/*  436      |     4 */    int indirections;
/*  440      |     4 */    int window_count;
/*  444      |    50 */    char local_flags[50];
/* XXX  2-byte hole  */
/*  496      |    16 */    struct timespec {
/*  496      |     8 */        union {
/*                 4 */            time_t tv_sec;
/*                 4 */            __time32_t __tv32_sec;
/*                 8 */            __time64_t __tv64_sec;

                                   /* total size (bytes):    8 */
                               };
/*  504      |     4 */        long tv_nsec;

                               /* total size (bytes):   16 */
                           } modtime;
/*  512      |     4 */    off_t modtime_size;
/* XXX  4-byte hole  */
/*  520      |     8 */    modiff_count auto_save_modified;
/*  528      |     8 */    modiff_count display_error_modiff;
/*  536      |     4 */    time_t auto_save_failure_time;
/*  540      |     4 */    ptrdiff_t last_window_start;
/*  544      |     4 */    struct region_cache *newline_cache;
/*  548      |     4 */    struct region_cache *width_run_cache;
/*  552      |     4 */    struct region_cache *bidi_paragraph_cache;
/*  556:31   |     4 */    bool_bf prevent_redisplay_optimizations_p : 1;
/*  556:30   |     4 */    bool_bf clip_changed : 1;
/* XXX  6-bit hole   */
/* XXX  3-byte hole  */
/*  560      |     4 */    struct Lisp_Overlay *overlays_before;
/*  564      |     4 */    struct Lisp_Overlay *overlays_after;
/*  568      |     4 */    ptrdiff_t overlay_center;
/*  572      |     4 */    Lisp_Object undo_list_;
---Type <return> to continue, or q <return> to quit---

                           /* total size (bytes):  576 */
                         } *
(gdb)

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

> Date: [04-07-2019 08:48:21] <07 Apr 2019 18:48:21 +0300>
> From: Eli Zaretskii <eliz@gnu.org>
> To: Keith David Bershatsky <esq@lawlist.com>
> CC: emacs-devel@gnu.org,monnier@iro.umontreal.ca,schwab@linux-m68k.org,acm@muc.de,dancol@dancol.org,eggert@cs.ucla.edu
> Subject: Re: buffer.c/buffer.h:  How to add new buffer-local variables?
> 
> > Date:  Sat, 06 Apr 2019 19:50:14 -0700
> > From:  Keith David Bershatsky <esq@lawlist.com>
> > Cc:  emacs-devel@gnu.org,Stefan Monnier <monnier@iro.umontreal.ca>,Andreas Schwab <schwab@linux-m68k.org>,Alan Mackenzie <acm@muc.de>,Daniel Colascione <dancol@dancol.org>,Paul Eggert <eggert@cs.ucla.edu>
> >
> > Using an unsophisticated method of going back in time and building various versions of Emacs on the w32 platform, I tracked down the inability to add a few new buffer-local variables in buffer.c/buffer.h to a commit that occurred on 01/31/2019:  05d2fc7170fb66a87601b1c76ddae2c1b7b4b934.
> 
> Is your GDB version 8.1 or later?  If so, please do this:
> 
>   $ cd /path/to/emacs/src
>   $ gdb ./emacs.exe
>   ...
>   (gdb) start -Q
>   ...
>   (gdb) ptype /o current_buffer
> 
> and post here the result.  Please do this both in the build before and
> after the above commit, and let us see both results.


[-- Attachment #2: 05d2fc7170fb66a87601b1c76ddae2c1b7b4b934.txt --]
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^ permalink raw reply	[flat|nested] 34+ messages in thread
* Re: buffer.c/buffer.h:  How to add new buffer-local variables?
@ 2019-04-07  2:50 Keith David Bershatsky
  2019-04-07 15:48 ` Eli Zaretskii
  2019-04-08  5:23 ` Paul Eggert
  0 siblings, 2 replies; 34+ messages in thread
From: Keith David Bershatsky @ 2019-04-07  2:50 UTC (permalink / raw)
  To: Eli Zaretskii
  Cc: Paul Eggert, emacs-devel, Andreas Schwab, Stefan Monnier,
	Alan Mackenzie, Daniel Colascione

[-- Attachment #1: Type: text/plain, Size: 1698 bytes --]

Using an unsophisticated method of going back in time and building various versions of Emacs on the w32 platform, I tracked down the inability to add a few new buffer-local variables in buffer.c/buffer.h to a commit that occurred on 01/31/2019:  05d2fc7170fb66a87601b1c76ddae2c1b7b4b934.

Steps to reproduce the issue:

1.  git reset --hard 05d2fc7170fb66a87601b1c76ddae2c1b7b4b934

2.  Apply the attached patch that adds a few new buffer local variables.

3.  Build a w32 version of Emacs [I use MinGW_32 and ezwinports downloaded a couple of years ago, on a Windows XP SP-3 box]:

CFLAGS='-O0 -g3' ./configure \
--prefix=/c/docume~1/admini~1/desktop/trunk \
--enable-checking='yes,glyphs' \
--enable-check-lisp-object-type \
--without-compress-install \
--without-makeinfo \
--with-gnutls=no \
--with-mailutils \
--without-makeinfo

4.  The build terminates abnormally at the following location:

This application has requested the Runtime to terminate it in an unusual way.
Please contact the application's support team for more information.
make[2]: *** [emacs-lisp/macroexp.elc] Error 3
make[2]: Leaving directory `/c/docume~1/admini~1/desktop/.0.2019_01_31__05d2fc7170fb66a87601b1c76ddae2c1b7b4b934/lisp'
make[1]: *** [bootstrap-emacs.pdmp] Error 2
make[1]: Leaving directory `/c/docume~1/admini~1/desktop/.0.2019_01_31__05d2fc7170fb66a87601b1c76ddae2c1b7b4b934/src'
make: *** [src] Error 2

Beyond pinpointing the exact commit where the Emacs build goes awry, I would be pleased to help further towards resolving this issue -- however, some pointers would be greatly appreciated.  Perhaps there is something that may stand out (to a trained programmer) in the 01/31/2019 commit ....

Keith


[-- Attachment #2: 2019_04_06__19_33_22_280.diff --]
[-- Type: application/diff, Size: 11209 bytes --]

^ permalink raw reply	[flat|nested] 34+ messages in thread
* Re: buffer.c/buffer.h:  How to add new buffer-local variables?
@ 2019-04-04 18:57 Keith David Bershatsky
  2019-04-04 19:29 ` Eli Zaretskii
  0 siblings, 1 reply; 34+ messages in thread
From: Keith David Bershatsky @ 2019-04-04 18:57 UTC (permalink / raw)
  To: Eli Zaretskii
  Cc: Alan Mackenzie, Daniel Colascione, Andreas Schwab, Stefan Monnier,
	emacs-devel

[-- Attachment #1: Type: text/plain, Size: 1143 bytes --]

Increasing the eassert value in field_relpos, and increasing the value of MAX_PER_BUFFER_VARS, are sufficient to build and use Emacs for the NS and X11 ports.

The w32 port of Emacs, however, crashes when adding one too many local-variables in buffer.c/h that breaks the camel's back:

Program received signal SIGSEGV, Segmentation fault.
0x01189584 in vector_marked_p (v=0xbaadf008) at alloc.c:3980
3980      return XVECTOR_MARKED_P (v);
(gdb) bt
#0  0x01189584 in vector_marked_p (v=0xbaadf008) at alloc.c:3980
#1  0x0118dc21 in mark_object (arg=...) at alloc.c:6684
#2  0x0118d2d4 in mark_vectorlike (header=0x5ab4b98) at alloc.c:6361
#3  0x0118d510 in mark_buffer (buffer=0x5ab4b98) at alloc.c:6428
#4  0x0118dd1f in mark_object (arg=...) at alloc.c:6717
#5  0x0118d69d in mark_localized_symbol (ptr=0x4a86c40) at alloc.c:6481

Attached is a gdb backtrace and a minimal diff working example that causes the w32 port to crash during garbage collection.  To reproduce the crash on the w32 port of Emacs, launch the GUI Emacs and at the *GNU Emacs* welcome screen, and hold down the right arrow key until a garbage collection occurs.

Keith


[-- Attachment #2: 001.diff --]
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[-- Attachment #3: gdb_001.txt --]
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^ permalink raw reply	[flat|nested] 34+ messages in thread
* Re: buffer.c/buffer.h:  How to add new buffer-local variables?
@ 2019-04-01  7:43 Keith David Bershatsky
  0 siblings, 0 replies; 34+ messages in thread
From: Keith David Bershatsky @ 2019-04-01  7:43 UTC (permalink / raw)
  To: Stefan Monnier; +Cc: Alan Mackenzie, Eli Zaretskii, Andreas Schwab, emacs-devel

Thank you, Stefan, for the insight regarding how to handle this particular issue.  Greatly appreciated!

Keith

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

> From: 	Stefan Monnier
> Subject: 	Re: buffer.c/buffer.h: How to add new buffer-local variables?
> Date: 	Sun, 31 Mar 2019 16:02:49 -0400
> 
>> if (!NILP (BVAR (XBUFFER (w->contents), crosshairs))) ...
> 
> Buffer-local variables are appropriate in the `struct buffer` when it's
> likely that most buffers will have their own setting for it.
> 
> For variables that are likely to be used only in some particular
> buffers, or only under some particular circumstances, it can make a lot
> more sense to declare them as global variables and then rely on the
> Elisp side using `make-local-variable` or `make-variable-buffer-local`,
> so you don't pay for that slot in every buffer even tho it's almost
> never used.
> 
>         Stefan



^ permalink raw reply	[flat|nested] 34+ messages in thread
* Re: buffer.c/buffer.h:  How to add new buffer-local variables?
@ 2019-03-31 16:32 Keith David Bershatsky
  2019-03-31 20:02 ` Stefan Monnier
  0 siblings, 1 reply; 34+ messages in thread
From: Keith David Bershatsky @ 2019-03-31 16:32 UTC (permalink / raw)
  To: Alan Mackenzie; +Cc: Eli Zaretskii, Andreas Schwab, emacs-devel

Thank you, Alan.  I was unaware that there are other means of declaring buffer-local variables in C.

In a few areas of the code for the features that I am working on, I have statements such as:

if (!NILP (BVAR (XBUFFER (w->contents), crosshairs))) ...

I have been using the existing method in buffer.c/h to define buffer local variables for the past three years (while chiseling away at the multiple fake cursors feature).  The last proof concept patch applied to an Emacs version from 12/13/2018, and I am just about ready to submit a new proof concept patch for a current version of Emacs.

If there is a way to increase the maximum number of buffer local variables to continue using the same method as is done in buffer.c/h, then I would prefer to do that.  If not, then the method you suggested below could be fallback plan.  Other than personal preference and my existing code that has worked well up until recently, there is no pressing reason that it has to be done a certain way.

Keith

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

> Date: [03-31-2019 05:22:38] <31 Mar 2019 12:22:38 +0000>
> From: Alan Mackenzie <acm@muc.de>
> 
> You're surely aware that you can add a new local variable in C source by
> declaring it with DEFVAR, then calling Fmake_variable_buffer_local in
> syms_of_foo?  Or something like that (I've forgotten the exact details).
> 
> Is there some pressing reason why the new variable has to be part of
> struct buffer rather than an "ordinary" buffer local?
> 
> It's worth noting that there's nothing in the elisp manual about how to
> create buffer local variables in the C source.
> 
> It may be that there're BL variables in struct buffer that don't really
> need to be there, and could be converted to "ordinary" variables.  I
> think I might have added one or two of these myself, but don't remember.



^ permalink raw reply	[flat|nested] 34+ messages in thread
* Re: buffer.c/buffer.h:  How to add new buffer-local variables?
@ 2019-03-31  9:03 Keith David Bershatsky
  0 siblings, 0 replies; 34+ messages in thread
From: Keith David Bershatsky @ 2019-03-31  9:03 UTC (permalink / raw)
  To: Eli Zaretskii; +Cc: emacs-devel

Thank you, Eli, for reading and responding to this particular thread.

I have tried increasing MAX_PER_BUFFER_VARS from 50 to 60 and even 75, but that no longer works.  That approach worked back in early/mid-December 2018, but does not work with a current version of Emacs master branch.

I searched pdumper.c for a few popular buffer-local variables such as mode_line_format and cache_long_scans, but did not find them.  As such, I have no idea where else to add the new buffer local variables other than the regular locations in buffer.c and buffer.h as demonstrated in the working/broken patches attached to the initial post of this particular thread.

The build messages gives little clues for us to investigate this issue.  I have learned how to extract the new hash values from dmpstruct.h and insert them at the appropriate location of pdumper.c, but that is not what causes the build to fail in this particular issue.

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

> Date: [03-30-2019 20:49:57] <31 Mar 2019 06:49:57 +0300>
> From: Eli Zaretskii <eliz@gnu.org>
> To: emacs-devel@gnu.org,Keith David Bershatsky <esq@lawlist.com>
> Subject: Re: buffer.c/buffer.h:  How to add new buffer-local variables?
> 
> * * *
> 
> Could it be you are overflowing MAX_PER_BUFFER_VARS?



^ permalink raw reply	[flat|nested] 34+ messages in thread
* buffer.c/buffer.h:  How to add new buffer-local variables?
@ 2019-03-30 23:19 Keith David Bershatsky
  2019-03-31  2:37 ` Eli Zaretskii
                   ` (2 more replies)
  0 siblings, 3 replies; 34+ messages in thread
From: Keith David Bershatsky @ 2019-03-30 23:19 UTC (permalink / raw)
  To: Emacs Devel

[-- Attachment #1: Type: text/plain, Size: 1559 bytes --]

I am working on feature requests #22873 (multiple fake cursors) and #17684 (crosshairs that track the cursor position).

In an earlier version of the Emacs master branch from a few months ago, I was able to increase the number of buffer-local variables in buffer.c/buffer.h by changing the value of MAX_PER_BUFFER_VARS from 50 to 60.  That approach does not permit me to build a current version of the Emacs master branch, which fails with the following error:

    Dumping under the name bootstrap-emacs.pdmp
    dumping fingerprint: 50894efcc2cdb17747a4536c9f53c4d093895712c3604daa88d068c383ea4780

    pdumper.c:1786: Emacs fatal error: assertion failed: relpos < 1024
    Fatal error 6: Abort trapmake[1]: *** [bootstrap-emacs.pdmp] Abort trap
    make[1]: *** Deleting file `bootstrap-emacs.pdmp'
    make: *** [src] Error 2

    Compilation exited abnormally with code 2 at Sat Mar 30 15:53:18

I have narrowed the issue down to adding just one (1) more buffer local variable, which breaks the camel's back.  Attached are git diffs for a working build and a broken build.  I am using Emacs master branch from 03/28/2019:  2da9f8bf4222fda504f43b4757e154999cdbbf2c

My config options are as follows:

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

How can I increase the number of buffer local variables in buffer.c/buffer.h without breaking the ability to build Emacs?

Keith


[-- Attachment #2: patch_working.diff --]
[-- Type: application/diff, Size: 10583 bytes --]

[-- Attachment #3: patch_broken.diff --]
[-- Type: application/diff, Size: 10517 bytes --]

^ permalink raw reply	[flat|nested] 34+ messages in thread
end of thread, other threads:[~2019-04-09  6:13 UTC | newest]

Thread overview: 34+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2019-04-08  8:03 buffer.c/buffer.h: How to add new buffer-local variables? Keith David Bershatsky
2019-04-08  9:37 ` Eli Zaretskii
2019-04-08 15:04   ` Eli Zaretskii
2019-04-08 17:31   ` Andreas Schwab
2019-04-08 17:43     ` Eli Zaretskii
2019-04-08 18:33       ` Stefan Monnier
2019-04-08 20:07         ` Paul Eggert
2019-04-08 22:19           ` Michael Welsh Duggan
2019-04-08 23:06             ` Paul Eggert
2019-04-09  6:13               ` Eli Zaretskii
  -- strict thread matches above, loose matches on Subject: below --
2019-04-09  3:49 Keith David Bershatsky
2019-04-09  0:48 Keith David Bershatsky
2019-04-09  0:40 Keith David Bershatsky
2019-04-08  4:34 Keith David Bershatsky
2019-04-07  2:50 Keith David Bershatsky
2019-04-07 15:48 ` Eli Zaretskii
2019-04-08  5:23 ` Paul Eggert
2019-04-04 18:57 Keith David Bershatsky
2019-04-04 19:29 ` Eli Zaretskii
2019-04-01  7:43 Keith David Bershatsky
2019-03-31 16:32 Keith David Bershatsky
2019-03-31 20:02 ` Stefan Monnier
2019-03-31  9:03 Keith David Bershatsky
2019-03-30 23:19 Keith David Bershatsky
2019-03-31  2:37 ` Eli Zaretskii
2019-03-31  3:49   ` Eli Zaretskii
2019-03-31  9:42 ` Andreas Schwab
2019-03-31 10:06   ` Eli Zaretskii
2019-03-31 11:41     ` Andreas Schwab
2019-03-31 15:10       ` Eli Zaretskii
2019-04-02 16:18       ` Eli Zaretskii
2019-04-02 18:46         ` Daniel Colascione
2019-04-03 17:43           ` Eli Zaretskii
2019-03-31 12:22 ` Alan Mackenzie

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