Qunbound is uninterned and can therefore never be EQ to any symbol
with position.

* src/buffer.c (Fbuffer_local_value, buffer_lisp_local_variables)
(buffer_local_variables_1):
* src/bytecode.c (exec_byte_code):
* src/comp.c (compile_function, Fcomp__compile_ctxt_to_file):
* src/composite.c (composition_gstring_cache_clear_font):
* src/data.c (Fboundp, Fsymbol_value, set_internal)
(Fdefault_boundp, Fdefault_value, Fmake_variable_buffer_local):
* src/emacs-module.c (module_global_reference_p):
* src/eval.c (Fdefault_toplevel_value, defvar)
(run_hook_with_args):
* src/fns.c (hash_put, Fmaphash):
* src/font.c (font_put_extra):
* src/frame.c (gui_set_frame_parameters)
(gui_frame_get_and_record_arg, gui_default_parameter)
(gui_figure_window_size):
* src/haikufns.c (get_geometry_from_preferences)
(haiku_create_frame, haiku_create_tip_frame):
* src/haikuterm.c (haiku_draw_text_decoration)
(haiku_default_font_parameter):
* src/json.c (lisp_to_json_nonscalar_1):
* src/keymap.c (access_keymap_1, access_keymap, current_minor_maps):
* src/lread.c (readevalloop, define_symbol):
* src/minibuf.c (read_minibuf, Ftry_completion):
(Fall_completions, Ftest_completion):
* src/pgtkfns.c (pgtk_default_font_parameter, Fx_create_frame)
(x_create_tip_frame):
* src/pgtkselect.c (Fpgtk_own_selection_internal):
* src/print.c (print):
* src/profiler.c (evict_lower_half, record_backtrace):
* src/terminal.c (create_terminal):
* src/textprop.c (set_properties):
* src/w32fns.c (my_create_window, w32_icon)
(w32_default_font_parameter, Fx_create_frame)
(w32_create_tip_frame):
* src/w32term.c (w32_draw_glyph_string):
* src/xdisp.c (handle_single_display_spec)
(cursor_row_fully_visible_p, calc_pixel_width_or_height):
* src/xfns.c (x_default_scroll_bar_color_parameter, x_icon_verify)
(x_icon, x_default_font_parameter, Fx_create_frame)
(x_create_tip_frame):
* src/xselect.c (x_handle_selection_request):
* src/xterm.c (x_draw_glyph_string, x_term_init):
Use BASE_EQ instead of EQ when comparing with Qunbound.

Run "TZ=UTC0 admin/update-copyright".

Run "TZ=UTC0 admin/update-copyright $(git ls-files)".

Now that "key == Qunbound" is used to determine if a hash table entry
is available, we can't stash pre-allocated vectors into the `key` slot
anymore, so use the `value` slot instead.

(make_log): Pre-fill the `value` slots i.s.o `key`.
(evict_lower_half): Stash key back into `value`, i.s.o `key`.
(record_backtrace): Get pre-allocated vector for `value` i.s.o `key`.

With --enable-checking, make_fixnum (N) now checks that N is
in fixnum range.  Suggested by Pip Cet in:
https://lists.gnu.org/r/emacs-devel/2019-07/msg00548.html
A new function make_ufixnum (N) is for the rare cases where N
is intended to be unsigned and is in the range 0..INTMASK.
* configure.ac (AC_C_TYPEOF): Add.
(HAVE_STATEMENT_EXPRESSIONS): Resurrect this macro.
* src/fns.c (Frandom, hashfn_eq, hashfn_equal, hashfn_user_defined):
* src/profiler.c (hashfn_profiler):
Use make_ufixnum rather than make_fixum, since the argument is
an unsigned integer in the range 0..INTMASK rather than a signed
integer in the range MOST_NEGATIVE_FIXNUM..MOST_POSITIVE_FIXNUM.
Typically this is for hashes.
* src/lisp.h (lisp_h_make_fixnum_wrap) [USE_LSB_TAG]:
Rename from lisp_h_make_fixnum.
(lisp_h_make_fixnum): Redefine in terms of lisp_h_make_fixnum_wrap.
Check for fixnum overflow on compilers like GCC that
have statement expressions and typeof.
(FIXNUM_OVERFLOW_P): Move up.
(make_fixnum): Check for fixnum overflow.
(make_ufixnum): New function, which checks that the arg
fits into 0..INTMASK range.

* src/profiler.c (cmpfn_profiler):
Improve performance when VECTORP (bt1) && EQ (bt1, bt2).

* src/fns.c (restore_mutability)
(hash_table_user_defined_call): New functions.
(cmpfn_user_defined, hashfn_user_defined): Use them.
(make_hash_table, copy_hash_table):
Mark new hash table as mutable.
(check_mutable_hash_table): New function.
(Fclrhash, Fputhash, Fremhash): Use it instead of CHECK_IMPURE.
* src/lisp.h (struct hash_table_test): User-defined functions
now take pointers to struct Lisp_Hash_Table, not to struct
hash_table_test.  All uses changed.
(struct Lisp_Hash_Table): New member ‘mutable’.
* src/pdumper.c (dump_hash_table): Copy it.
* test/src/fns-tests.el (test-hash-function-that-mutates-hash-table):
New test, which tests for the bug.

* src/fns.c (cmpfn_eql, cmpfn_equal, cmpfn_user_defined)
(hashfn_eq, hashfn_equal, hashfn_eql, hashfn_user_defined):
* src/profiler.c (cmpfn_profiler, hashfn_profiler):
Use new calling convention where the return value is a fixnum
instead of EMACS_UINT.  While we’re at it, put the hash table
at the end, since that’s a bit simpler and generates better
code (at least on the x86-64).  All callers changed.
* src/fns.c (hash_lookup): Store fixnum rather than EMACS_UINT.
All callers changed.
(hash_put): Take a fixnum rather than an EMACS_UINT.
All callers changed.  Remove unnecessary eassert (XUFIXNUM does it).
* src/lisp.h (struct hash_table_test):
Adjust signatures of cmpfn and hashfn.