libstdc++: Adjust enable_nonlocking_formatter_optimization specializations [PR121790]

This patch addresses several issues related to the additional specializations
for enable_nonlocking_formatter_optimization fomr P3235R3 proposal:

* LWG4399 [1]: Apply remove_cvref_t to tuple and pair elements when checking if
	the direct printing optimization is enabled.
* LWG4398 [2]: Disable the direct printing optimization for the standard library
	 container adaptors: queue, priority_queue, and stack.
* LWG4400 [3]: Enable the direct printing optimization only for durations that
	 use standard arithmetic types. Conditionally enable it for hh_mm_ss
	 and time_points based on their underlying Duration template argument.

[1] https://cplusplus.github.io/LWG/issue4399
[2] https://cplusplus.github.io/LWG/issue4398
[3] https://cplusplus.github.io/LWG/issue4400

	PR libstdc++/121790

libstdc++-v3/ChangeLog:

	* include/bits/chrono_io.h (enable_nonlocking_formatter_optimization):
	Adjust specializations for duration, hh_mm_ss and time_points.
	* include/std/format (enable_nonlocking_formatter_optimization):
	Apply remove_cvref_t on pair and tuple elements.
	* include/std/queue (enable_nonlocking_formatter_optimization):
	Change specialization value to false.
	* include/std/stack (enable_nonlocking_formatter_optimization):
	Change specialization value to false.
	* testsuite/std/format/ranges/adaptors.cc: Adjusted tests.
	* testsuite/std/format/tuple.cc: Adjusted tests.
	* testsuite/std/time/format/nonlocking.cc: Adjusted tests.

Reviewed-by: Jonathan Wakely <jwakely@redhat.com>

libstdc++-v3/include/bits/chrono_io.h

@@ -561,7 +561,7 @@ namespace __format
       __formatter_chrono(_ChronoSpec<_CharT> __spec) noexcept
       : _M_spec(__spec)
       { }
-	
+
       constexpr typename basic_format_parse_context<_CharT>::iterator
       _M_parse(basic_format_parse_context<_CharT>& __pc, _ChronoParts __parts,
 	       const _ChronoSpec<_CharT>& __def)
@@ -2235,10 +2235,12 @@ namespace __format
     };
 
 #if __glibcxx_print >= 202406L
+  // _GLIBCXX_RESOLVE_LIB_DEFECTS
+  // 4400. enable_nonlocking_formatter_optimization for durations with custom rep
   template<typename _Rep, typename _Period>
     constexpr bool
     enable_nonlocking_formatter_optimization<chrono::duration<_Rep, _Period>>
-      = enable_nonlocking_formatter_optimization<_Rep>;
+      = is_arithmetic_v<_Rep>;
 #endif
 
   template<__format::__char _CharT>
@@ -2988,10 +2990,12 @@ namespace __format
     };
 
 #if __glibcxx_print >= 202406L
-   template<typename _Duration>
-     constexpr bool
-     enable_nonlocking_formatter_optimization<chrono::hh_mm_ss<_Duration>>
-        = true;
+  // _GLIBCXX_RESOLVE_LIB_DEFECTS
+  // 4400. enable_nonlocking_formatter_optimization for durations with custom rep
+  template<typename _Duration>
+    constexpr bool
+    enable_nonlocking_formatter_optimization<chrono::hh_mm_ss<_Duration>>
+      = enable_nonlocking_formatter_optimization<_Duration>;
 #endif
 
 #if _GLIBCXX_USE_CXX11_ABI || ! _GLIBCXX_USE_DUAL_ABI
@@ -3079,10 +3083,12 @@ namespace __format
     };
 
 #if __glibcxx_print >= 202406L
-   template<typename _Duration>
-     constexpr bool
-     enable_nonlocking_formatter_optimization<chrono::sys_time<_Duration>>
-       = true;
+  // _GLIBCXX_RESOLVE_LIB_DEFECTS
+  // 4400. enable_nonlocking_formatter_optimization for durations with custom rep
+  template<typename _Duration>
+    constexpr bool
+    enable_nonlocking_formatter_optimization<chrono::sys_time<_Duration>>
+      = enable_nonlocking_formatter_optimization<_Duration>;
 #endif
 
   template<typename _Duration, __format::__char _CharT>
@@ -3130,10 +3136,12 @@ namespace __format
     };
 
 #if __glibcxx_print >= 202406L
-   template<typename _Duration>
-     constexpr bool
-     enable_nonlocking_formatter_optimization<chrono::utc_time<_Duration>>
-       = true;
+  // _GLIBCXX_RESOLVE_LIB_DEFECTS
+  // 4400. enable_nonlocking_formatter_optimization for durations with custom rep
+  template<typename _Duration>
+    constexpr bool
+    enable_nonlocking_formatter_optimization<chrono::utc_time<_Duration>>
+      = enable_nonlocking_formatter_optimization<_Duration>;
 #endif
 
   template<typename _Duration, __format::__char _CharT>
@@ -3172,10 +3180,12 @@ namespace __format
     };
 
 #if __glibcxx_print >= 202406L
-   template<typename _Duration>
-     constexpr bool
-     enable_nonlocking_formatter_optimization<chrono::tai_time<_Duration>>
-       = true;
+  // _GLIBCXX_RESOLVE_LIB_DEFECTS
+  // 4400. enable_nonlocking_formatter_optimization for durations with custom rep
+  template<typename _Duration>
+    constexpr bool
+    enable_nonlocking_formatter_optimization<chrono::tai_time<_Duration>>
+      = enable_nonlocking_formatter_optimization<_Duration>;
 #endif
 
   template<typename _Duration, __format::__char _CharT>
@@ -3214,10 +3224,12 @@ namespace __format
     };
 
 #if __glibcxx_print >= 202406L
-   template<typename _Duration>
-     constexpr bool
-     enable_nonlocking_formatter_optimization<chrono::gps_time<_Duration>>
-       = true;
+  // _GLIBCXX_RESOLVE_LIB_DEFECTS
+  // 4400. enable_nonlocking_formatter_optimization for durations with custom rep
+  template<typename _Duration>
+    constexpr bool
+    enable_nonlocking_formatter_optimization<chrono::gps_time<_Duration>>
+      = enable_nonlocking_formatter_optimization<_Duration>;
 #endif
 
   template<typename _Duration, __format::__char _CharT>
@@ -3256,10 +3268,12 @@ namespace __format
      };
 
 #if __glibcxx_print >= 202406L
-   template<typename _Duration>
-     constexpr bool
-     enable_nonlocking_formatter_optimization<chrono::file_time<_Duration>>
-        = true;
+  // _GLIBCXX_RESOLVE_LIB_DEFECTS
+  // 4400. enable_nonlocking_formatter_optimization for durations with custom rep
+  template<typename _Duration>
+    constexpr bool
+    enable_nonlocking_formatter_optimization<chrono::file_time<_Duration>>
+      = enable_nonlocking_formatter_optimization<_Duration>;
 #endif
 
   template<typename _Duration, __format::__char _CharT>
@@ -3297,10 +3311,12 @@ namespace __format
     };
 
 #if __glibcxx_print >= 202406L
-   template<typename _Duration>
-     constexpr bool
-     enable_nonlocking_formatter_optimization<chrono::local_time<_Duration>>
-        = true;
+  // _GLIBCXX_RESOLVE_LIB_DEFECTS
+  // 4400. enable_nonlocking_formatter_optimization for durations with custom rep
+  template<typename _Duration>
+    constexpr bool
+    enable_nonlocking_formatter_optimization<chrono::local_time<_Duration>>
+      = enable_nonlocking_formatter_optimization<_Duration>;
 #endif
 
   template<typename _Duration, __format::__char _CharT>
@@ -3364,10 +3380,13 @@ namespace __format
     };
 
 #if __glibcxx_print >= 202406L
-   template<typename _Duration>
-     constexpr bool
-     enable_nonlocking_formatter_optimization<
-       chrono::__detail::__local_time_fmt<_Duration>> = true;
+  // _GLIBCXX_RESOLVE_LIB_DEFECTS
+  // 4400. enable_nonlocking_formatter_optimization for durations with custom rep
+  template<typename _Duration>
+    constexpr bool
+    enable_nonlocking_formatter_optimization<
+      chrono::__detail::__local_time_fmt<_Duration>>
+      = enable_nonlocking_formatter_optimization<_Duration>;
 #endif
 
 #if _GLIBCXX_USE_CXX11_ABI || ! _GLIBCXX_USE_DUAL_ABI
@@ -3391,10 +3410,13 @@ namespace __format
     };
 
 #if __glibcxx_print >= 202406L
-   template<typename _Duration>
-     constexpr bool
-     enable_nonlocking_formatter_optimization<
-        chrono::zoned_time<_Duration, const chrono::time_zone*>> = true;
+  // _GLIBCXX_RESOLVE_LIB_DEFECTS
+  // 4400. enable_nonlocking_formatter_optimization for durations with custom rep
+  template<typename _Duration>
+    constexpr bool
+    enable_nonlocking_formatter_optimization<
+      chrono::zoned_time<_Duration, const chrono::time_zone*>>
+      = enable_nonlocking_formatter_optimization<_Duration>;
 #endif
 #endif
 

libstdc++-v3/include/std/format

@@ -5873,11 +5873,12 @@ namespace __format
     };
 
 #if __glibcxx_print >= 202406L
+  // _GLIBCXX_RESOLVE_LIB_DEFECTS
+  // 4399. enable_nonlocking_formatter_optimization for pair and tuple needs remove_cvref_t
   template<typename _Fp, typename _Sp>
     constexpr bool enable_nonlocking_formatter_optimization<pair<_Fp, _Sp>>
-    // TODO this should have remove_cvref_t.
-      = enable_nonlocking_formatter_optimization<_Fp>
-        && enable_nonlocking_formatter_optimization<_Sp>;
+      = enable_nonlocking_formatter_optimization<remove_cvref_t<_Fp>>
+        && enable_nonlocking_formatter_optimization<remove_cvref_t<_Sp>>;
 #endif
 
   template<__format::__char _CharT, formattable<_CharT>... _Tps>
@@ -5899,10 +5900,11 @@ namespace __format
     };
 
 #if __glibcxx_print >= 202406L
+  // _GLIBCXX_RESOLVE_LIB_DEFECTS
+  // 4399. enable_nonlocking_formatter_optimization for pair and tuple needs remove_cvref_t
   template<typename... _Tps>
-    // TODO this should have remove_cvref_t.
     constexpr bool enable_nonlocking_formatter_optimization<tuple<_Tps...>>
-      = (enable_nonlocking_formatter_optimization<_Tps> && ...);
+      = (enable_nonlocking_formatter_optimization<remove_cvref_t<_Tps>> && ...);
 #endif
 
   // [format.range.formatter], class template range_formatter

libstdc++-v3/include/std/queue

@@ -113,10 +113,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     };
 
 #if __glibcxx_print >= 202406L
+  // _GLIBCXX_RESOLVE_LIB_DEFECTS
+  // 4398. enable_nonlocking_formatter_optimization should be disabled for container adaptors
   template<typename _Tp, typename _Container>
     constexpr bool
-    // TODO should be false
-    enable_nonlocking_formatter_optimization<queue<_Tp, _Container>> = true;
+    enable_nonlocking_formatter_optimization<queue<_Tp, _Container>> = false;
 #endif
 
   template<__format::__char _CharT, typename _Tp,
@@ -154,11 +155,12 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     };
 
 #if __glibcxx_print >= 202406L
+  // _GLIBCXX_RESOLVE_LIB_DEFECTS
+  // 4398. enable_nonlocking_formatter_optimization should be disabled for container adaptors
   template<typename _Tp, typename _Container, typename _Comparator>
     constexpr bool
-    // TODO should be false
     enable_nonlocking_formatter_optimization<
-      priority_queue<_Tp, _Container, _Comparator>> = true;
+      priority_queue<_Tp, _Container, _Comparator>> = false;
 #endif
 
 _GLIBCXX_END_NAMESPACE_VERSION

libstdc++-v3/include/std/stack

@@ -107,10 +107,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     };
 
 #if __glibcxx_print >= 202406L
+  // _GLIBCXX_RESOLVE_LIB_DEFECTS
+  // 4398. enable_nonlocking_formatter_optimization should be disabled for container adaptors
   template<typename _Tp, typename _Container>
     constexpr bool
-    // TODO should be false
-    enable_nonlocking_formatter_optimization<stack<_Tp, _Container>> = true;
+    enable_nonlocking_formatter_optimization<stack<_Tp, _Container>> = false;
 #endif
 _GLIBCXX_END_NAMESPACE_VERSION
 } // namespace std

libstdc++-v3/testsuite/std/format/ranges/adaptors.cc

@@ -122,14 +122,13 @@ test_output()
   // Formatter check if container is formattable, not container elements.
   static_assert(!std::formattable<Adaptor<int, NotFormattableCont<int>>, CharT>);
 
-  // TODO should be false
-  static_assert(std::enable_nonlocking_formatter_optimization<
+  static_assert(!std::enable_nonlocking_formatter_optimization<
 		  Adaptor<int>>);
-  static_assert(std::enable_nonlocking_formatter_optimization<
+  static_assert(!std::enable_nonlocking_formatter_optimization<
 		  Adaptor<MutFormat>>);
-  static_assert(std::enable_nonlocking_formatter_optimization<
+  static_assert(!std::enable_nonlocking_formatter_optimization<
 		  Adaptor<int, std::deque<int>>>);
-  static_assert(std::enable_nonlocking_formatter_optimization<
+  static_assert(!std::enable_nonlocking_formatter_optimization<
 		  Adaptor<int, NotFormattableCont<int>>>);
 }
 

libstdc++-v3/testsuite/std/format/tuple.cc

@@ -361,10 +361,9 @@ void test_nonblocking()
 {
   static_assert(std::enable_nonlocking_formatter_optimization<
 		  Tuple<int, float>>);
-  // TODO missing remove_cv_ref
-  static_assert(!std::enable_nonlocking_formatter_optimization<
+  static_assert(std::enable_nonlocking_formatter_optimization<
 		  Tuple<const int, const float>>);
-  static_assert(!std::enable_nonlocking_formatter_optimization<
+  static_assert(std::enable_nonlocking_formatter_optimization<
 		  Tuple<int&, float&>>);
 
   static_assert(!std::enable_nonlocking_formatter_optimization<

libstdc++-v3/testsuite/std/time/format/nonlocking.cc

@@ -43,9 +43,9 @@ static_assert(std::enable_nonlocking_formatter_optimization<
 #endif
 
 template<typename Duration>
-using local_time_fmt 
+using local_time_fmt
   = decltype(std::chrono::local_time_format(std::chrono::local_time<Duration>{}));
- 
+
 static_assert(std::enable_nonlocking_formatter_optimization<
 		std::chrono::seconds>);
 static_assert(std::enable_nonlocking_formatter_optimization<
@@ -71,19 +71,19 @@ using BufferedDuration = std::chrono::duration<Rep<void, int>>;
 
 static_assert(!std::enable_nonlocking_formatter_optimization<
 		BufferedDuration>);
-static_assert(std::enable_nonlocking_formatter_optimization<
+static_assert(!std::enable_nonlocking_formatter_optimization<
 		std::chrono::local_time<BufferedDuration>>);
-static_assert(std::enable_nonlocking_formatter_optimization<
+static_assert(!std::enable_nonlocking_formatter_optimization<
 		std::chrono::sys_time<BufferedDuration>>);
-static_assert(std::enable_nonlocking_formatter_optimization<
+static_assert(!std::enable_nonlocking_formatter_optimization<
 		std::chrono::utc_time<BufferedDuration>>);
-static_assert(std::enable_nonlocking_formatter_optimization<
+static_assert(!std::enable_nonlocking_formatter_optimization<
 		std::chrono::gps_time<BufferedDuration>>);
-static_assert(std::enable_nonlocking_formatter_optimization<
+static_assert(!std::enable_nonlocking_formatter_optimization<
 		std::chrono::tai_time<BufferedDuration>>);
-static_assert(std::enable_nonlocking_formatter_optimization<
+static_assert(!std::enable_nonlocking_formatter_optimization<
 		std::chrono::file_time<BufferedDuration>>);
-static_assert(std::enable_nonlocking_formatter_optimization<
+static_assert(!std::enable_nonlocking_formatter_optimization<
 		local_time_fmt<BufferedDuration>>);
 
 template<>
@@ -92,21 +92,21 @@ inline constexpr bool
 
 using NonBufferedRep = std::chrono::duration<Rep<void, long>>;
 
-static_assert(std::enable_nonlocking_formatter_optimization<
+static_assert(!std::enable_nonlocking_formatter_optimization<
 		NonBufferedRep>);
-static_assert(std::enable_nonlocking_formatter_optimization<
+static_assert(!std::enable_nonlocking_formatter_optimization<
 		std::chrono::local_time<NonBufferedRep>>);
-static_assert(std::enable_nonlocking_formatter_optimization<
+static_assert(!std::enable_nonlocking_formatter_optimization<
 		std::chrono::sys_time<NonBufferedRep>>);
-static_assert(std::enable_nonlocking_formatter_optimization<
+static_assert(!std::enable_nonlocking_formatter_optimization<
 		std::chrono::utc_time<NonBufferedRep>>);
-static_assert(std::enable_nonlocking_formatter_optimization<
+static_assert(!std::enable_nonlocking_formatter_optimization<
 		std::chrono::gps_time<NonBufferedRep>>);
-static_assert(std::enable_nonlocking_formatter_optimization<
+static_assert(!std::enable_nonlocking_formatter_optimization<
 		std::chrono::tai_time<NonBufferedRep>>);
-static_assert(std::enable_nonlocking_formatter_optimization<
+static_assert(!std::enable_nonlocking_formatter_optimization<
 		std::chrono::file_time<NonBufferedRep>>);
-static_assert(std::enable_nonlocking_formatter_optimization<
+static_assert(!std::enable_nonlocking_formatter_optimization<
 		local_time_fmt<NonBufferedRep>>);
 
 using NonBufferedDuration = std::chrono::duration<Rep<void, short>>;
@@ -135,9 +135,9 @@ static_assert(std::enable_nonlocking_formatter_optimization<
 #if _GLIBCXX_USE_CXX11_ABI || !_GLIBCXX_USE_DUAL_ABI
 static_assert(std::enable_nonlocking_formatter_optimization<
 		std::chrono::zoned_time<std::chrono::seconds>>);
-static_assert(std::enable_nonlocking_formatter_optimization<
+static_assert(!std::enable_nonlocking_formatter_optimization<
 		std::chrono::zoned_time<BufferedDuration>>);
-static_assert(std::enable_nonlocking_formatter_optimization<
+static_assert(!std::enable_nonlocking_formatter_optimization<
 		std::chrono::zoned_time<NonBufferedRep>>);
 static_assert(std::enable_nonlocking_formatter_optimization<
 		std::chrono::zoned_time<NonBufferedDuration>>);
@@ -150,7 +150,7 @@ struct std::chrono::zoned_traits<MyTimeZone>
 {
   static const MyTimeZone* default_zone();
   static const MyTimeZone* locate_zone(std::string_view name);
-};	
+};
 
 static_assert(!std::enable_nonlocking_formatter_optimization<
 		std::chrono::zoned_time<std::chrono::seconds, MyTimeZone>>);