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
