* src/floatfns.c (double_integer_scale): Distinguish Inf from NaN.
(rounding_driver): Handle (ceil 0 0.0) and (ceil 0 1.0e+INF).
* test/src/floatfns-tests.el (special-round): Add tests for
weird cases like this.

Avoid crash with (floor 0 0.0)
* src/floatfns.c (rounding_driver): Signal an arithmetic
error if divisor is 0.0 or -0.0, instead of crashing.

Problem reported by Paul Pogonyshev (Bug#38191).
* src/editfns.c (styled_format): When checking for adjacent
%-sequences, use byte position rather than character position.
* test/src/editfns-tests.el (format-properties): Test for fix.

This is doable now that we have bignums.
* src/floatfns.c (integer_value): Remove; no longer used.
(rescale_for_division): New function.
(rounding_driver): Use it to divide properly (by using bignums)
even when arguments are float, fixing a double-rounding FIXME.
* src/lisp.h (LOG2_FLT_RADIX): Move here ...
* src/timefns.c (frac_to_double): ... from here.
* test/src/floatfns-tests.el (big-round):
Add a test to catch the double-rounding bug.

* test/src/doc-tests.el (doc-test-substitute-command-keys):
Disable component that fails twice in the past 5 weeks
due to changes in the minibuffer map.

* test/src/minibuf-tests.el (test-try-completion-ignore-case):
New test, suggested by Stefan Monnier <monnier@iro.umontreal.ca>.

* src/minibuf.c (Ftry_completion): Don't treat strings that
are identical but for the case as if they were identical for
the purposes of not counting the same string twice.  This
fixes case-insensitive completion when all the candidates are
identical but for the letter-case.  (Bug#11339)

* src/process.c (Fmake_network_process) [AF_INET6]: Only build ::1
localhost when IPv6 is supported.
(Fnetwork_lookup_address_info) [AF_INET6]: Move check for Qipv6 inside
ifdef, since its definition depends on AF_INET6.  Don't return IPv6
addresses when they're not supported.

* test/src/process-tests.el (lookup-family-specification,
lookup-google): Only do IPv6 lookup if IPv6 is supported.

Similarly for (expt 0 bignum) and (expt -1 bignum).
The result is always a -1, 0 or 1, so do not signal overflow.
* src/data.c (expt_integer): Do not signal an overflow if
-1 <= X <= 1.  Be clearer about when overflow is signaled.
* test/src/floatfns-tests.el (bignum-expt): Test this.

Fix infinite loops in print.c when a circular list is passed
to command-error-default-function or to error-message-string.
* src/print.c (print_error_message):
Use FOR_EACH_TAIL to avoid infloop on circular lists.
(print_object): Use FOR_EACH_TAIL_SAFE, as it uses
Brent’s teleporting tortoise-hare algorithm which is
asymptotically better than the classic tortoise-hare
algorithm that the code wsas using.
* test/src/print-tests.el (print-circle-2): When print-circle
is nil, do not insist on a particular cycle-detection heuristic.
(error-message-string-circular): New test.

Fix infinite loops in fileio.c when a circular list is the
value of after_insert_file_functions,
buffer-auto-save-file-format, buffer-file-format, or
write-region-annotate-functions.
* src/fileio.c (Finsert_file_contents, build_annotations):
Use FOR_EACH_TAIL to avoid infloop on circular lists.
(build_annotations): Use an EMACS_INT, not an int, to count
nesting level.
* test/src/fileio-tests.el:
(fileio-tests--circular-after-insert-file-functions): New test.