Thousands separator "," for the C locale??

[Benjamin Kosnik]

> this is inspired by libstdc++/5499: the testcase submitted as part of it reports
> the comma (",") as the thousands separator for the C locale. On the other hand
> from glibc2.2.5 documentation I understand that the thousands separator is
> *empty* in that case, right?

You are correct that the actual "C" semantics differ from what 14882 deems 
"C" semantics. If you look at the parts of the C++ standard, you'll see:

22.2.3.1.2 - numpunct virtual functions [lib.facet.numpunct.virtuals]

string_type do_thousands_sep() const;

-2- Returns: A character for use as the digit group separator. The 
required instantiations return ',' or L','.