Problem:
msgpack#strptime() finds a timestamp by bisecting strftime() output, and
brackets the search with the extreme UTC offsets. The lower bound
subtracts 12 hours, but -12:00 is the westernmost offset, which produces
the *largest* timestamp for a given local time. The easternmost offset
is +14:00, so in any zone east of UTC+12 the search can start above the
target and the function throws:
internal-start-string:Internal error: start > string
With TZ=GMT-14, four of the five timestamps in msgpack_spec.lua fail,
as do three tests in shada_spec.lua, which reaches the same function
through shada#strings_to_sd().
Solution:
Subtract 14 hours instead. The upper bound is already generous enough at
+14, and widening a bisection bracket downwards cannot change the result
in zones that worked before.
The test disables the python3 provider, because msgpack#strptime() only
uses the Vimscript implementation changed here when no provider answers,
and otherwise hands the work to datetime.strptime().
AI-assisted
This is a breaking change which will make refactor of typval and shada
code a lot easier. In particular, code that would use or check for
v:msgpack_types.binary in the wild would be broken. This appears to be
rarely used in existing plugins.
Also some cases where v:msgpack_type.string would be used to represent a
binary string of "string" type, we use a BLOB instead, which is
vimscripts native type for binary blobs, and already was used for BIN
formats when necessary.
msgpackdump(msgpackparse(data)) no longer preserves the distinction
of BIN and STR strings. This is very common behavior for
language-specific msgpack bindings. Nvim uses msgpack as a tool to
serialize its data. Nvim is not a tool to bit-perfectly manipulate
arbitrary msgpack data out in the wild.
The changed tests should indicate how behavior changes in various edge
cases.
datetime.datetime.timestamp does not exist on Windows and
datetime.datetiem.strftime('%s') is not supported, since '%s' is a POSIX
format. Instead, use the recommended `calendar.timegm(obj.utctimetuple())`.
