[committed] libstdc++: Fix std::chrono::hh_mm_ss with unsigned rep [PR108265]

[Jonathan Wakely via Gcc-patches]

Tested x86_64-linux. Pushed to trunk, backports to gcc-11 and gcc-12
will follow.

-- >8 --

libstdc++-v3/ChangeLog:

        PR libstdc++/108265
        * include/std/chrono (hh_mm_ss): Do not use chrono::abs if
        duration rep is unsigned.
        * testsuite/std/time/hh_mm_ss/1.cc: Check unsigned rep.
---
 libstdc++-v3/include/std/chrono               | 15 ++++++++++++---
 libstdc++-v3/testsuite/std/time/hh_mm_ss/1.cc | 16 ++++++++++++++++
 2 files changed, 28 insertions(+), 3 deletions(-)

diff --git a/libstdc++-v3/include/std/chrono b/libstdc++-v3/include/std/chrono
index 27f391a1455..e7fd6ed57ab 100644
--- a/libstdc++-v3/include/std/chrono
+++ b/libstdc++-v3/include/std/chrono
@@ -2294,7 +2294,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
        }
 
        constexpr
-       hh_mm_ss(_Duration __d, bool __is_neg) noexcept
+       hh_mm_ss(_Duration __d, bool __is_neg)
        : _M_h (duration_cast<chrono::hours>(__d)),
          _M_m (duration_cast<chrono::minutes>(__d - hours())),
          _M_s (duration_cast<chrono::seconds>(__d - hours() - minutes())),
@@ -2307,6 +2307,15 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
            _M_ss._M_r = duration_cast<precision>(__ss).count();
        }
 
+       static constexpr _Duration
+       _S_abs(_Duration __d)
+       {
+         if constexpr (numeric_limits<typename _Duration::rep>::is_signed)
+           return chrono::abs(__d);
+         else
+           return __d;
+       }
+
       public:
        static constexpr unsigned fractional_width = {_S_fractional_width()};
 
@@ -2318,8 +2327,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
        constexpr hh_mm_ss() noexcept = default;
 
        constexpr explicit
-       hh_mm_ss(_Duration __d) noexcept
-       : hh_mm_ss(chrono::abs(__d), __d < _Duration::zero())
+       hh_mm_ss(_Duration __d)
+       : hh_mm_ss(_S_abs(__d), __d < _Duration::zero())
        { }
 
        constexpr bool
diff --git a/libstdc++-v3/testsuite/std/time/hh_mm_ss/1.cc 
b/libstdc++-v3/testsuite/std/time/hh_mm_ss/1.cc
index 3f8a838c477..3c61145317c 100644
--- a/libstdc++-v3/testsuite/std/time/hh_mm_ss/1.cc
+++ b/libstdc++-v3/testsuite/std/time/hh_mm_ss/1.cc
@@ -115,3 +115,19 @@ size()
   struct S4 { long long h; char m, s; bool neg; double ss; };
   static_assert(sizeof(hh_mm_ss<duration<double, std::micro>>) == sizeof(S4));
 }
+
+constexpr void
+unsigned_rep()
+{
+  using namespace std::chrono;
+
+  constexpr duration<unsigned, std::milli> ms(3690001);
+
+  constexpr hh_mm_ss hms(ms); // PR libstdc++/108265
+  static_assert( ! hms.is_negative() );
+  static_assert( hms.to_duration() == milliseconds(ms.count()) );
+  static_assert( hms.hours() == 1h );
+  static_assert( hms.minutes() == 1min );
+  static_assert( hms.seconds() == 30s );
+  static_assert( hms.subseconds() == 1ms );
+}
-- 
2.39.0