ENH: Support dateutil.tz.tzrange objects

[Tux1]

Code Sample, a copy-pastable example if possible

mytz = dateutil.tz.tzrange("EST", -18000, "EDT", -14400,
                  dateutil.relativedelta.relativedelta(hours=+2, month=4,
                                weekday=dateutil.relativedelta.SU(+1)),
                  dateutil.relativedelta.relativedelta(hours=+1, month=10,
                                weekday=dateutil.relativedelta.SU(-1)))
pd.to_datetime('20190204', utc=True).tz_convert(mytz)

---

AttributeError Traceback (most recent call last)
pandas_libs\tslibs\timezones.pyx in pandas._libs.tslibs.timezones.get_dst_info()

AttributeError: 'NoneType' object has no attribute 'total_seconds'
Exception ignored in: 'pandas._libs.tslibs.conversion.localize_tso'
Traceback (most recent call last):
File "pandas_libs\tslibs\timezones.pyx", line 220, in pandas._libs.tslibs.timezones.get_dst_info
AttributeError: 'NoneType' object has no attribute 'total_seconds'
Out[243]: Timestamp('2019-02-04 00:00:00')

Problem description

tz_convert fails on custom timezone with DST provided. Here is the example with dateutil but it would fail with any custom timezone with DST offset

Expected Output

Timestamp('2019-02-03 19:00:00-0500', tz='mytz')

Output of pd.show_versions()

INSTALLED VERSIONS

commit : None
python : 3.7.4.final.0
python-bits : 64
OS : Windows
OS-release : 10
machine : AMD64
processor : Intel64 Family 6 Model 85 Stepping 4, GenuineIntel
byteorder : little
LC_ALL : None
LANG : None
LOCALE : None.None

pandas : 0.25.1
numpy : 1.16.5
pytz : 2019.3
dateutil : 2.8.0
pip : 19.2.3
setuptools : 41.4.0
Cython : 0.29.13
pytest : 5.2.1
hypothesis : None
sphinx : 2.2.0
blosc : None
feather : None
xlsxwriter : 1.2.1
lxml.etree : 4.4.1
html5lib : 1.0.1
pymysql : None
psycopg2 : None
jinja2 : 2.10.3
IPython : 7.8.0
pandas_datareader: None
bs4 : 4.8.0
bottleneck : 1.2.1
fastparquet : None
gcsfs : None
lxml.etree : 4.4.1
matplotlib : 3.1.1
numexpr : 2.7.0
odfpy : None
openpyxl : 3.0.0
pandas_gbq : None
pyarrow : 0.13.0
pytables : None
s3fs : None
scipy : 1.3.1
sqlalchemy : 1.3.9
tables : 3.5.2
xarray : 0.14.0
xlrd : 1.2.0
xlwt : 1.3.0
xlsxwriter : 1.2.1

[Tux1]

Actually it is more a new feature to implement. But since tzrange does not have transition list, I don't know how to do that...

[jbrockmendel]

In Localizer.__cinit__ we call get_dst_info(tz), which is wrong with this kind of tz. A few lines above that call is a check for elif is_tzlocal(tz) or is_zoneinfo(tz): and we need to amend that check so that this branch (and in general and un-recognized tzinfo) goes down that path.

[mroeschke]

Thanks for the issue, but it appears this hasn't gotten traction in a while so closing