https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99439
Bug ID: 99439
Summary: use_facet<time_get<wchar_t>> (l); get() API with
kMonthDayYearFormat = L"%m/%d/%Y" should allow missing
leading zero
Product: gcc
Version: 10.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: libstdc++
Assignee: unassigned at gcc dot gnu.org
Reporter: lewis at sophists dot com
Target Milestone: ---
This code fails to compile (viewable on onlinegcc compiler link
https://onlinegdb.com/rkloG0-7O)
---
#include <cstdio>
#include <locale>
#include <cassert>
#include <sstream>
using namespace std;
auto getPCTMRequiresLeadingZeroBug = [] () {
static constexpr wstring_view kMonthDayYearFormat = L"%m/%d/%Y"sv;
std::locale l = locale::classic ();
const time_get<wchar_t>& tmget = use_facet<time_get<wchar_t>> (l);
ios::iostate state = ios::goodbit;
wistringstream iss (L"11/1/2002");
istreambuf_iterator<wchar_t> itbegin (iss); // beginning of iss
istreambuf_iterator<wchar_t> itend; // end-of-stream
tm resultTM{};
auto i = tmget.get (itbegin, itend, iss, state,
&resultTM, kMonthDayYearFormat.data (), kMonthDayYearFormat.data () +
kMonthDayYearFormat.length ());
#if qCompilerAndStdLib_locale_time_get_PCTM_RequiresLeadingZero_Buggy
assert ((state & ios::badbit) or (state & ios::failbit));
#else
assert (not((state & ios::badbit) or (state & ios::failbit)));
#endif
};
int main()
{
getPCTMRequiresLeadingZeroBug();
printf("Hello World");
return 0;
}
---
The reason this APPEARS to be a bug is the docs:
https://en.cppreference.com/w/cpp/locale/time_get/get
say
parses the month as a decimal number (range [01,12]), leading zeroes permitted
but not required
meaning leading zero CAN be there in month, but not it says NOT REQUIRED.
11/1/2004 fails to parse, but 11/01/2004 works (but the leading zero should be
optional).
