Give more precise warning when passing header=-1 in pandas.read_csv, or don't throw error

[MarcoGorelli]

Code Sample, a copy-pastable example if possible

from io import StringIO
import pandas as pd

print(f"Using pandas version {pd.__version__}")
pd.read_csv(StringIO('spam'), header=-1)

Using pandas version 0.25.0

---

OverflowError

Problem description

In previous versions of pandas (e.g. 0.24.2), this would have worked fine. Instead, now, one has to pass header=None. However, when working with old code after having updated pandas, it may be unclear where the problem lies.

Expected Output

      0
0  spam

Output of pd.show_versions()

[paste the output of pd.show_versions() here below this line]
INSTALLED VERSIONS

commit : None
python : 3.7.3.final.0
python-bits : 64
OS : Linux
OS-release : 4.15.0-55-generic
machine : x86_64
processor : x86_64
byteorder : little
LC_ALL : None
LANG : en_GB.UTF-8
LOCALE : en_GB.UTF-8

pandas : 0.25.0
numpy : 1.16.4
pytz : 2019.1
dateutil : 2.8.0
pip : 19.1.1
setuptools : 41.0.1
Cython : 0.29.12
pytest : 4.5.0
hypothesis : None
sphinx : None
blosc : None
feather : None
xlsxwriter : None
lxml.etree : None
html5lib : None
pymysql : None
psycopg2 : None
jinja2 : 2.10.1
IPython : 7.7.0
pandas_datareader: None
bs4 : None
bottleneck : None
fastparquet : None
gcsfs : None
lxml.etree : None
matplotlib : 3.1.0
numexpr : None
odfpy : None
openpyxl : None
pandas_gbq : None
pyarrow : 0.13.0
pytables : None
s3fs : 0.2.1
scipy : 1.3.0
sqlalchemy : 1.3.5
tables : None
xarray : None
xlrd : None
xlwt : None
xlsxwriter : None

[TomAugspurger]

@MarcoGorelli are you interested in submitting a pull request?

[MarcoGorelli]

If this would be of interest to you, then yes, sure! I'll get to work

…

On Fri, 9 Aug 2019, 19:18 Tom Augspurger, ***@***.***> wrote: @MarcoGorelli <https://github.com/MarcoGorelli> are you interested in submitting a pull request? — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#27779?email_source=notifications&email_token=AH7QVMG4FEQS62QA4FLRZF3QDWYIFA5CNFSM4IJWWNK2YY3PNVWWK3TUL52HS4DFVREXG43VMVBW63LNMVXHJKTDN5WW2ZLOORPWSZGOD37NBBI#issuecomment-520016005>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AH7QVMCECIDPIO55Z5N6TVLQDWYIFANCNFSM4IJWWNKQ> .

[MarcoGorelli]

I've attempted to fix this by modifying validate_header from pandas/io/common.py to check that header=-1 wasn't passed and to raise an error advising user to pass header=None instead if their data has no header, along with an accompanying test.