The description of num_put<>::do_put(bool) function states (22.2.2.2.2):
iter_type do_put(iter_type out, ios_base& str, char_type fill, bool val) const;
Effects: If (str.flags()&ios_base::boolalpha)==0 then do
out = do_put(out, str, fill, (int)val)
Otherwise do
const numpunct& np = use_facet<numpunct<charT> >(loc);
string_type s = val ? np.truename() : np.falsename();
and then insert the characters of s into out.
It is not specified how exactly the insertion the characters of s into out
iterator is performed. It seems that the padding of the string is done the same
way as for the other functions from num_put<>::do_put() family, namely
(22.2.2.2.2 p19 Table 61):
adjustfield == iosbase::left - pad after
adjustfield == iosbase::right - pad before
adjustfield == internal and a sign occurs in the representation - pad after the
sign
adjustfield == internal and representation after stage 1 began with 0x or 0X -
pad after x or X
otherwise pad before
num_put<>::do_put(bool), however, should output a string that in general is not
a string representation of some number. It makes no sense for a string that can
be arbitrary to process the sign symbols, "0x" or "0X" in a different way than
its other substrings. That means, the 'internal' flag should be functionally
equivalent to 'right' ("pad before") in this case.
This is exactly the way the operator for inserting sequences of symbols into a
stream (operator<< for const charT*) is implemented. Although the description
of padding in this case (27.6.2.5.4, p2) refers to the description of
num_put<>::do_put, in practice the 'internal' flag is functionally equivalent
to 'right' in this case, which makes sense.
However, the implementation of num_put<>::do_put(bool) performs 'internal'
padding not like operator<< for sequences of characters but rather the same way
as the other functions from num_put<>::do_put family: it inserts fill symbols
between the 'sign' or "0x"/"0X" and the rest of the string.
--
Summary: num_put<>::do_put(bool) performs 'internal' padding
incorrectly when boolalpha==true
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: libstdc++
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: tsyvarev at ispras dot ru
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38196
