>> Also the old standard seems to require that ios_base::fixed | >> ios_base::scientific (or any other combination) falls through to the >> uppercase test; I was trying to use abi_tag for a solution as not only >> would two versions of _S_format_float be necessary, but also num_get >> due to the pre-instantiated templates for <char> and <wchar>, which >> led me to http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60642. It might >> just be more trouble than it's worth. > > I don't think we need to worry about that, if I understand correctly > the combination of fixed|scientific has unspecified behaviour in > C++03, so we can make our implementation do exactly what it does in > C++11.
It seems to me that it is well defined, going from [lib.facet.num.put.virtuals] > 6 All tables used in describing stage 1 are ordered. That is, the first line > whose condition is true applies. > A line without a condition is the default behavior when none of the earlier > lines apply. So fixed|scientific would be equivalent to specifying neither according to table 58, and the resulting specifier would be %g or %G depending on whether uppercase is set or not.