From: Jonathan Wakely <jwakely@redhat.com>
Date: Mon, 17 Feb 2020 18:15:00 +0000 (+0000)
Subject: libstdc++: P1964R2 Wording for boolean-testable
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=c5e1c1d3aba39e960cc5fb0dcd77e447e5dee7eb;p=gcc.git

libstdc++: P1964R2 Wording for boolean-testable

This removes the complicated std::boolean concept, as agreed in Prague.

	* include/bits/ranges_algo.h (__find_fn, __find_first_of_fn)
	(__adjacent_find_fn): Cast result of predicate to bool.
	* include/std/concepts (__boolean): Remove.
	(__detail::__boolean_testable_impl, __detail::__boolean_testable): Add
	new helper concepts.
	(__detail::__weakly_eq_cmp_with, totally_ordered, totally_ordered_with)
	(predicate): Use __boolean_testable instead of boolean.
	* libsupc++/compare (__detail::__partially_ordered, _Synth3way):
	Likewise.
---

diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index 547337dda90..7e48bee2b18 100644
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -1,5 +1,16 @@
 2020-02-17  Jonathan Wakely  <jwakely@redhat.com>
 
+	P1964R2 Wording for boolean-testable
+	* include/bits/ranges_algo.h (__find_fn, __find_first_of_fn)
+	(__adjacent_find_fn): Cast result of predicate to bool.
+	* include/std/concepts (__boolean): Remove.
+	(__detail::__boolean_testable_impl, __detail::__boolean_testable): Add
+	new helper concepts.
+	(__detail::__weakly_eq_cmp_with, totally_ordered, totally_ordered_with)
+	(predicate): Use __boolean_testable instead of boolean.
+	* libsupc++/compare (__detail::__partially_ordered, _Synth3way):
+	Likewise.
+
 	P1970R2 Consistency for size() functions: Add ranges::ssize
 	* include/bits/range_access.h (_SSize, ssize): Define for C++20.
 	* testsuite/std/ranges/access/ssize.cc: New test.
diff --git a/libstdc++-v3/include/bits/ranges_algo.h b/libstdc++-v3/include/bits/ranges_algo.h
index f3a349ef839..83f295722e9 100644
--- a/libstdc++-v3/include/bits/ranges_algo.h
+++ b/libstdc++-v3/include/bits/ranges_algo.h
@@ -206,7 +206,7 @@ namespace ranges
 		 const _Tp& __value, _Proj __proj = {}) const
       {
 	while (__first != __last
-	    && !(std::__invoke(__proj, *__first) == __value))
+	    && !(bool)(std::__invoke(__proj, *__first) == __value))
 	  ++__first;
 	return __first;
       }
@@ -295,9 +295,9 @@ namespace ranges
       {
 	for (; __first1 != __last1; ++__first1)
 	  for (auto __iter = __first2; __iter != __last2; ++__iter)
-	    if (std::__invoke(__pred,
-			      std::__invoke(__proj1, *__first1),
-			      std::__invoke(__proj2, *__iter)))
+	    if ((bool)std::__invoke(__pred,
+				    std::__invoke(__proj1, *__first1),
+				    std::__invoke(__proj2, *__iter)))
 	      return __first1;
 	return __first1;
       }
@@ -687,9 +687,9 @@ namespace ranges
 	auto __next = __first;
 	for (; ++__next != __last; __first = __next)
 	  {
-	    if (std::__invoke(__pred,
-			      std::__invoke(__proj, *__first),
-			      std::__invoke(__proj, *__next)))
+	    if ((bool)std::__invoke(__pred,
+				    std::__invoke(__proj, *__first),
+				    std::__invoke(__proj, *__next)))
 	      return __first;
 	  }
 	return __next;
diff --git a/libstdc++-v3/include/std/concepts b/libstdc++-v3/include/std/concepts
index acc9dd2599d..f3db40b798f 100644
--- a/libstdc++-v3/include/std/concepts
+++ b/libstdc++-v3/include/std/concepts
@@ -259,27 +259,18 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
   // [concepts.compare], comparison concepts
 
-  /// [concept.boolean], concept boolean
-  template<typename _Bp>
-    concept boolean
-      = movable<remove_cvref_t<_Bp>>
-      && requires(__detail::__cref<_Bp> __b1, __detail::__cref<_Bp> __b2,
-		  const bool __a) {
-	{ __b1 } -> convertible_to<bool>;
-	{ !__b1 } -> convertible_to<bool>;
-	{ __b1 && __b2 } -> same_as<bool>;
-	{ __b1 && __a  } -> same_as<bool>;
-	{ __a  && __b2 } -> same_as<bool>;
-	{ __b1 || __b2 } -> same_as<bool>;
-	{ __b1 || __a  } -> same_as<bool>;
-	{ __a  || __b2 } -> same_as<bool>;
-	{ __b1 == __b2 } -> convertible_to<bool>;
-	{ __b1 == __a  } -> convertible_to<bool>;
-	{ __a  == __b2 } -> convertible_to<bool>;
-	{ __b1 != __b2 } -> convertible_to<bool>;
-	{ __b1 != __a  } -> convertible_to<bool>;
-	{ __a  != __b2 } -> convertible_to<bool>;
-      };
+  // [concept.booleantestable], Boolean testability
+  namespace __detail
+  {
+    template<typename _Tp>
+      concept __boolean_testable_impl = convertible_to<_Tp, bool>;
+
+    template<typename _Tp>
+      concept __boolean_testable
+	= __boolean_testable_impl<_Tp>
+	  && requires(_Tp&& __t)
+	  { { !static_cast<_Tp&&>(__t) } -> __boolean_testable_impl; };
+  } // namespace __detail
 
   // [concept.equalitycomparable], concept equality_comparable
 
@@ -288,10 +279,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     template<typename _Tp, typename _Up>
       concept __weakly_eq_cmp_with
 	= requires(__detail::__cref<_Tp> __t, __detail::__cref<_Up> __u) {
-	  { __t == __u } -> boolean;
-	  { __t != __u } -> boolean;
-	  { __u == __t } -> boolean;
-	  { __u != __t } -> boolean;
+	  { __t == __u } -> __boolean_testable;
+	  { __t != __u } -> __boolean_testable;
+	  { __u == __t } -> __boolean_testable;
+	  { __u != __t } -> __boolean_testable;
 	};
   } // namespace __detail
 
@@ -311,10 +302,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     concept totally_ordered
       = equality_comparable<_Tp>
       && requires(__detail::__cref<_Tp> __a, __detail::__cref<_Tp> __b) {
-	{ __a <  __b } -> boolean;
-	{ __a >  __b } -> boolean;
-	{ __a <= __b } -> boolean;
-	{ __a >= __b } -> boolean;
+	{ __a <  __b } -> __detail::__boolean_testable;
+	{ __a >  __b } -> __detail::__boolean_testable;
+	{ __a <= __b } -> __detail::__boolean_testable;
+	{ __a >= __b } -> __detail::__boolean_testable;
       };
 
   template<typename _Tp, typename _Up>
@@ -325,14 +316,14 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 					    __detail::__cref<_Up>>>
       && equality_comparable_with<_Tp, _Up>
       && requires(__detail::__cref<_Tp> __t, __detail::__cref<_Up> __u) {
-	{ __t <  __u } -> boolean;
-	{ __t >  __u } -> boolean;
-	{ __t <= __u } -> boolean;
-	{ __t >= __u } -> boolean;
-	{ __u <  __t } -> boolean;
-	{ __u >  __t } -> boolean;
-	{ __u <= __t } -> boolean;
-	{ __u >= __t } -> boolean;
+	{ __t <  __u } -> __detail::__boolean_testable;
+	{ __t >  __u } -> __detail::__boolean_testable;
+	{ __t <= __u } -> __detail::__boolean_testable;
+	{ __t >= __u } -> __detail::__boolean_testable;
+	{ __u <  __t } -> __detail::__boolean_testable;
+	{ __u >  __t } -> __detail::__boolean_testable;
+	{ __u <= __t } -> __detail::__boolean_testable;
+	{ __u >= __t } -> __detail::__boolean_testable;
       };
 
   template<typename _Tp>
@@ -351,7 +342,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
   /// [concept.predicate], concept predicate
   template<typename _Fn, typename... _Args>
     concept predicate = regular_invocable<_Fn, _Args...>
-      && boolean<invoke_result_t<_Fn, _Args...>>;
+      && __detail::__boolean_testable<invoke_result_t<_Fn, _Args...>>;
 
   /// [concept.relation], concept relation
   template<typename _Rel, typename _Tp, typename _Up>
diff --git a/libstdc++-v3/libsupc++/compare b/libstdc++-v3/libsupc++/compare
index b2d64ef74a4..ba7db316486 100644
--- a/libstdc++-v3/libsupc++/compare
+++ b/libstdc++-v3/libsupc++/compare
@@ -416,14 +416,14 @@ namespace std
       concept __partially_ordered_with
 	= requires(const remove_reference_t<_Tp>& __t,
 		   const remove_reference_t<_Up>& __u) {
-	  { __t <  __u } -> boolean;
-	  { __t >  __u } -> boolean;
-	  { __t <= __u } -> boolean;
-	  { __t >= __u } -> boolean;
-	  { __u <  __t } -> boolean;
-	  { __u >  __t } -> boolean;
-	  { __u <= __t } -> boolean;
-	  { __u >= __t } -> boolean;
+	  { __t <  __u } -> __boolean_testable;
+	  { __t >  __u } -> __boolean_testable;
+	  { __t <= __u } -> __boolean_testable;
+	  { __t >= __u } -> __boolean_testable;
+	  { __u <  __t } -> __boolean_testable;
+	  { __u >  __t } -> __boolean_testable;
+	  { __u <= __t } -> __boolean_testable;
+	  { __u >= __t } -> __boolean_testable;
 	};
   } // namespace __detail
 
@@ -879,8 +879,8 @@ namespace std
 	operator()(const _Tp& __t, const _Up& __u) const
 	requires requires
 	{
-	  { __t < __u } -> convertible_to<bool>;
-	  { __u < __t } -> convertible_to<bool>;
+	  { __t < __u } -> __boolean_testable;
+	  { __u < __t } -> __boolean_testable;
 	}
 	{
 	  if constexpr (three_way_comparable_with<_Tp, _Up>)