"Invalid value for -O" build failure(s) — clang 3.8.1

clang refuses the command:
$ clang -O6 main.c
(gcc accepts it even if it is meaning less)
PackageVersionSupposed error messageFull log Bug report
basemap 1.0.7+dfsg-4error: invalid integral value 'g' in '-Og' Log
cython 0.24.1-2error: invalid integral value 'g' in '-Og' Log
gamera 1:3.4.2+git20160808.1725654-1error: invalid integral value 'g' in '-Og' Log
matplotlib 1.5.2~rc2-1error: invalid integral value 'g' in '-Og' Log
pillow 3.3.0-1error: invalid integral value 'g' in '-Og' Log
pillow-sane 2.8.2-1error: invalid integral value 'g' in '-Og' Log
psycopg2 2.6.2-1error: invalid integral value 'g' in '-Og' Log
pycurl 7.43.0-1error: invalid integral value 'g' in '-Og' Log
pyicu 1.9.2-2error: invalid integral value 'g' in '-Og' Log
pyodbc 3.0.10-2error: invalid integral value 'g' in '-Og' Log
python-bsddb3 6.1.0-1error: invalid integral value 'g' in '-Og' Log
python-djvulibre 0.8-1error: invalid integral value 'g' in '-Og' Log
python-levenshtein 0.12.0-2error: invalid integral value 'g' in '-Og' Log
python-regex 0.1.20160721-1error: invalid integral value 'g' in '-Og' Log
python-reportlab 3.3.0-1error: invalid integral value 'g' in '-Og' Log
python3-stdlib-extensions 3.5.1-1error: invalid integral value 'g' in '-Og' Log

16 errors