OK, then I’ll prepare appropriate patch with tests and send it when I’m done implementing it.
Thanks, Mateusz Zych On Wed, 2 Jul 2025 at 16:59, Jonathan Wakely <jwak...@redhat.com> wrote: > On Wed, 2 Jul 2025 at 14:45, Mateusz Zych <mte.z...@gmail.com> wrote: > > > > > Oh actually the radix members should be of type int, not bool. I can > fix that. > > > > Yes - thank you very much Jonathan for catching that! > > It was my honest oversight - I am so used to using auto, that I have > accidentally copied the wrong type. > > Also, thank you for adding tests - I should have added them myself in > the first place. > > > > > Thanks, I don't think there was any reason to omit these members, > > > and I agree we should add them. > > > > Regarding adding missing members, > > I am wondering whether template specializations of std::numeric_limits<> > for integer-class types > > should define remaining static data members and static member functions, > that is: > > - max_digits10 > > - traps > > - is_iec559 > > - round_style > > - has_infinity > > - has_quiet_NaN > > - has_signaling_NaN > > - has_denorm > > - has_denorm_loss > > - min_exponent > > - min_exponent10 > > - max_exponent > > - max_exponent10 > > - tinyness_before > > - epsilon() > > - round_error() > > - infinity() > > - quiet_NaN() > > - signaling_NaN() > > - denorm_min() > > > > Here are reading relevant sections of the C++ standard: > > > > 25.3.4.4 Concept weakly_incrementable [iterator.concept.winc] > > > > (5) For every integer-class type I, > > let B(I) be a unique hypothetical extended integer type > > of the same signedness with the same width as I. > > > > [Note 2: The corresponding > > hypothetical specialization numeric_limits<B(I)> > > meets the requirements on > > numeric_limits specializations for integral types.] > > > > (11) For every (possibly cv-qualified) integer-class type I, > > numeric_limits<I> is specialized such that: > > > > - each static data member m > > has the same value as numeric_limits<B(I)>::m, and > > > > - each static member function f > > returns I(numeric_limits<B(I)>::f()). > > > > In short, std::numeric_limits<> specializations for integer-class types > should be defined > > identically to std::numeric_limits<> specializations for extended > integer types, > > and thus define all static data members and static member functions. > > Am I reading this correctly? > > Ah yes, if we're missing those ones too then we need to add them. > > > > > > Thank you, Mateusz Zych > > > > On Wed, Jul 2, 2025 at 1:59 PM Jonathan Wakely <jwak...@redhat.com> > wrote: > >> > >> On 02/07/25 11:52 +0100, Jonathan Wakely wrote: > >> >On Wed, 2 Jul 2025 at 10:50, Jonathan Wakely <jwak...@redhat.com> > wrote: > >> >> > >> >> On 02/07/25 03:36 +0300, Mateusz Zych wrote: > >> >> >Hello libstdc++ Team! > >> >> > > >> >> >I have recently found a bug in libstdc++, that is, > >> >> >the std::numeric_limits<> template specializations for > integer-class types > >> >> >are missing some of static data members, > >> >> >which results in compilation errors of valid C++ code: > >> >> > > >> >> > - Compiler Explorer: https://godbolt.org/z/E7z4WYfj4 > >> >> > > >> >> >Since adding missing member constants, which are the most relevant > to > >> >> >integer-like types, > >> >> >was not a lot of code, I have prepared a Git patch with relevant > changes. > >> >> > > >> >> >I hope this patch is useful, Mateusz Zych > >> >> > >> >> Thanks, I don't think there was any reason to omit these members, > and I > >> >> agree we should add them. > >> >> > >> >> The patch is simple and obvious enough that I don't think we need a > >> >> copyright assignment or DCO sign-off, so I'll push this to the > >> >> relevant branches. Thanks! > >> > > >> >Oh actually the radix members should be of type int, not bool. I can > fix that. > >> > >> Here's what I'm testing: > >> > >> > >> commit ddd5b88db4fe99166835fe1b94beca451bc1ce30 > >> Author: Mateusz Zych <mte.z...@gmail.com> > >> AuthorDate: Tue Jul 1 23:51:40 2025 > >> Commit: Jonathan Wakely <r...@gcc.gnu.org> > >> CommitDate: Wed Jul 2 11:57:45 2025 > >> > >> libstdc++: Add missing members to numeric_limits specializations > for integer-class types > >> > >> [iterator.concept.winc]/11 says that std::numeric_limits should be > >> specialized for integer-class types, with each member defined > >> appropriately. > >> > >> libstdc++-v3/ChangeLog: > >> > >> * include/bits/max_size_type.h > (numeric_limits<__max_size_type>): > >> New static data members. > >> (numeric_limits<__max_diff_type>): Likewise. > >> * testsuite/std/ranges/iota/max_size_type.cc: Check new > members. > >> > >> Co-authored-by: Jonathan Wakely <jwak...@redhat.com> > >> > >> diff --git a/libstdc++-v3/include/bits/max_size_type.h > b/libstdc++-v3/include/bits/max_size_type.h > >> index 73a6d141d5bc..3ac2b8e6b878 100644 > >> --- a/libstdc++-v3/include/bits/max_size_type.h > >> +++ b/libstdc++-v3/include/bits/max_size_type.h > >> @@ -775,6 +775,9 @@ namespace ranges > >> static constexpr bool is_signed = false; > >> static constexpr bool is_integer = true; > >> static constexpr bool is_exact = true; > >> + static constexpr bool is_bounded = true; > >> + static constexpr bool is_modulo = true; > >> + static constexpr int radix = 2; > >> static constexpr int digits > >> = __gnu_cxx::__int_traits<_Sp::__rep>::__digits + 1; > >> static constexpr int digits10 > >> @@ -802,6 +805,9 @@ namespace ranges > >> static constexpr bool is_signed = true; > >> static constexpr bool is_integer = true; > >> static constexpr bool is_exact = true; > >> + static constexpr bool is_bounded = true; > >> + static constexpr bool is_modulo = false; > >> + static constexpr int radix = 2; > >> static constexpr int digits = numeric_limits<_Sp>::digits - 1; > >> static constexpr int digits10 > >> = static_cast<int>(digits * numbers::ln2 / numbers::ln10); > >> diff --git a/libstdc++-v3/testsuite/std/ranges/iota/max_size_type.cc > b/libstdc++-v3/testsuite/std/ranges/iota/max_size_type.cc > >> index 4739d9e2f790..fc5284594c7e 100644 > >> --- a/libstdc++-v3/testsuite/std/ranges/iota/max_size_type.cc > >> +++ b/libstdc++-v3/testsuite/std/ranges/iota/max_size_type.cc > >> @@ -352,6 +352,9 @@ > static_assert(numeric_limits<max_size_t>::is_specialized); > >> static_assert(!numeric_limits<max_size_t>::is_signed); > >> static_assert(numeric_limits<max_size_t>::is_integer); > >> static_assert(numeric_limits<max_size_t>::is_exact); > >> +static_assert(numeric_limits<max_size_t>::is_bounded); > >> +static_assert(numeric_limits<max_size_t>::is_modulo); > >> +static_assert(numeric_limits<max_size_t>::radix == 2); > >> // We can't unconditionally use numeric_limits here because __int128 > is an > >> // integral type only in GNU mode. > >> #if __SIZEOF_INT128__ > >> @@ -379,6 +382,9 @@ > static_assert(numeric_limits<max_diff_t>::is_specialized); > >> static_assert(numeric_limits<max_diff_t>::is_signed); > >> static_assert(numeric_limits<max_diff_t>::is_integer); > >> static_assert(numeric_limits<max_diff_t>::is_exact); > >> +static_assert(numeric_limits<max_diff_t>::is_bounded); > >> +static_assert(!numeric_limits<max_diff_t>::is_modulo); > >> +static_assert(numeric_limits<max_diff_t>::radix == 2); > >> static_assert(numeric_limits<max_diff_t>::digits > >> == numeric_limits<max_size_t>::digits - 1); > >> static_assert(numeric_limits<max_diff_t>::digits10 > >> > >
