[libc++] money_get::do_get() set failbit and eofbit if iterator begin equals end

[jasonliu]

Summary

Currently, if we pass in the same iterator for begin and end, the long double version of do_get would throw a runtime error.
However, according to standard (https://eel.is/c++draft/locale.money.get#virtuals-1):

If a valid sequence is recognized, does not change err; otherwise, sets err to (err|str.failbit), or
(err|str.failbit|str.eofbit) if no more characters are available, and does not change units or
digits.

So we should set the failbit and eofbit when no more characters are available.

[curdeius]

LGTM % suggestion. But please wait for libc++'s group approval.

libcxx/include/locale

3116–3120

Instead of putting this check here and in the other do_get overload, you can just put everything into __do_get (at the beginning):

if (__b == __e) {
    __err |= ios_base::failbit;
    return false;
}

No need to set eofbit there, as it's set in do_get anyway.

[curdeius]

libcxx/test/std/localization/locale.categories/category.monetary/locale.money.get/locale.money.get.members/get_long_double_en_US.pass.cpp

729

Oh, and please change the value from 0 to some other (magic) value to verify it's not changed.

[jasonliu]

Address comments.

[jasonliu]

libcxx/include/locale

3116–3120

Thanks. Make sense.

[jasonliu]

Speculative fix for clang-format error in CI.

[jasonliu]

Run clang-format and hopefully it fix the pre-commit CI.

[curdeius]

The format failure isn't your fault. There was a misconfig that's already fixed in main. Just rebase.

[jasonliu]

rebase.

[jasonliu]

Gentle ping for libc++ group's review.

[jasonliu]

Ping.

[jasonliu]

Ping.
@ldionne Any comments?

libcxx/include/locale

money_get<_CharT, _InputIterator>::__do_get(iter_type& __b, iter_type __e,
                                             bool __intl, const locale& __loc,
                                             ios_base::fmtflags __flags,
                                             ios_base::iostate& __err,
                                             bool& __neg,
                                             const ctype<char_type>& __ct,
                                             unique_ptr<char_type, void(*)(void*)>& __wb,
                                             char_type*& __wn, char_type* __we)
 {
+    if (__b == __e) {
+        __err |= ios_base::failbit;
+        return false;
+    }
     const unsigned __bz = 100;
     unsigned __gbuf[__bz];
     unique_ptr<unsigned, void(*)(void*)> __gb(__gbuf, __do_nothing);
     unsigned* __gn = __gb.get();
     unsigned* __ge = __gn + __bz;
     money_base::pattern __pat;
     char_type __dp;
     char_type __ts;

 
 template <class _CharT, class _InputIterator>
 _InputIterator
 money_get<_CharT, _InputIterator>::do_get(iter_type __b, iter_type __e,
                                           bool __intl, ios_base& __iob,
                                           ios_base::iostate& __err,
                                           long double& __v) const
 {
     const int __bz = 100;
     char_type __wbuf[__bz];
     unique_ptr<char_type, void(*)(void*)> __wb(__wbuf, __do_nothing);
     char_type* __wn;
     char_type* __we = __wbuf + __bz;
     locale __loc = __iob.getloc();
     const ctype<char_type>& __ct = use_facet<ctype<char_type> >(__loc);
     bool __neg = false;
     if (__do_get(__b, __e, __intl, __loc, __iob.flags(), __err, __neg, __ct,
                  __wb, __wn, __we))
     {
         const char __src[] = "0123456789";
         char_type __atoms[sizeof(__src)-1];

libcxx/test/std/localization/locale.categories/category.monetary/locale.money.get/locale.money.get.members/get_long_double_en_US.pass.cpp

ios.imbue(std::locale(ios.getloc(),
             long double ex;
             std::ios_base::iostate err = std::ios_base::goodbit;
             I iter = f.get(I(v.data()), I(v.data() + v.size()),
                                                 true, ios, err, ex);
             assert(iter.base() == v.data() + 1);
             assert(err == std::ios_base::failbit);
         }
     }
+    {
+      // test for err
+      const my_facet f(1);
+      std::string v = "1.23";
+      typedef cpp17_input_iterator<const char*> I;
+      long double ex = -1L;
+      std::ios_base::iostate err = std::ios_base::goodbit;
+      f.get(I(v.data()), I(v.data()), false, ios, err, ex);
+      assert(err == (std::ios_base::failbit | std::ios_base::eofbit));
+      assert(ex == -1L);
+    }
 
   return 0;
 }

libcxx/test/std/localization/locale.categories/category.monetary/locale.money.get/locale.money.get.members/get_string_en_US.pass.cpp

ios.imbue(std::locale(ios.getloc(),
             std::ios_base::iostate err = std::ios_base::goodbit;
             I iter = f.get(I(v.data()), I(v.data() + v.size()),
                                                 true, ios, err, ex);
             assert(iter.base() == v.data() + 1);
             assert(err == std::ios_base::failbit);
             assert(ex == L"");
         }
     }
+    {
+      // test for err
+      const my_facet f(1);
+      std::string v = "1.23";
+      typedef cpp17_input_iterator<const char*> I;
+      std::string ex = "NULL";
+      std::ios_base::iostate err = std::ios_base::goodbit;
+      f.get(I(v.data()), I(v.data()), false, ios, err, ex);
+      assert(err == (std::ios_base::failbit | std::ios_base::eofbit));
+      assert(ex == "NULL");
+    }
 
   return 0;
 }