[libcxx-commits] [PATCH] D136318: [libc++] type_traits: fix short-circuiting in std::conjunction.

[Aaron Jacobs via Phabricator via libcxx-commits]

jacobsa updated this revision to Diff 469347.
jacobsa marked an inline comment as done.
jacobsa edited the summary of this revision.
jacobsa added a comment.

Simpler test case, better commit description, test std::disjunction too.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D136318/new/

https://reviews.llvm.org/D136318

Files:
  libcxx/include/__type_traits/conjunction.h
  libcxx/test/std/utilities/meta/meta.logical/conjunction.compile.pass.cpp
  libcxx/test/std/utilities/meta/meta.logical/disjunction.compile.pass.cpp


Index: libcxx/test/std/utilities/meta/meta.logical/disjunction.compile.pass.cpp
===================================================================
--- libcxx/test/std/utilities/meta/meta.logical/disjunction.compile.pass.cpp
+++ libcxx/test/std/utilities/meta/meta.logical/disjunction.compile.pass.cpp
@@ -80,6 +80,12 @@
 static_assert(std::disjunction<std::true_type, HasNoValue>::value);
 static_assert(std::disjunction_v<std::true_type, HasNoValue>);
 
+static_assert(std::disjunction<std::true_type, HasNoValue, std::true_type>::value);
+static_assert(std::disjunction_v<std::true_type, HasNoValue, std::true_type>);
+
+static_assert(std::disjunction<std::true_type, HasNoValue, std::false_type>::value);
+static_assert(std::disjunction_v<std::true_type, HasNoValue, std::false_type>);
+
 static_assert(std::disjunction<MySpecialTrueType>::value == -1);
 static_assert(std::disjunction_v<MySpecialTrueType>);
 
Index: libcxx/test/std/utilities/meta/meta.logical/conjunction.compile.pass.cpp
===================================================================
--- libcxx/test/std/utilities/meta/meta.logical/conjunction.compile.pass.cpp
+++ libcxx/test/std/utilities/meta/meta.logical/conjunction.compile.pass.cpp
@@ -80,6 +80,12 @@
 static_assert(!std::conjunction<std::false_type, HasNoValue>::value);
 static_assert(!std::conjunction_v<std::false_type, HasNoValue>);
 
+static_assert(!std::conjunction<std::false_type, HasNoValue, std::true_type>::value);
+static_assert(!std::conjunction_v<std::false_type, HasNoValue, std::true_type>);
+
+static_assert(!std::conjunction<std::false_type, HasNoValue, std::false_type>::value);
+static_assert(!std::conjunction_v<std::false_type, HasNoValue, std::false_type>);
+
 static_assert(std::conjunction<MyOtherSpecialTrueType>::value == -1);
 static_assert(std::conjunction_v<MyOtherSpecialTrueType>);
 
Index: libcxx/include/__type_traits/conjunction.h
===================================================================
--- libcxx/include/__type_traits/conjunction.h
+++ libcxx/include/__type_traits/conjunction.h
@@ -20,26 +20,6 @@
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
-#if _LIBCPP_STD_VER > 14
-
-template <class _Arg, class... _Args>
-struct __conjunction_impl {
-  using type = conditional_t<!bool(_Arg::value), _Arg, typename __conjunction_impl<_Args...>::type>;
-};
-
-template <class _Arg>
-struct __conjunction_impl<_Arg> {
-  using type = _Arg;
-};
-
-template <class... _Args>
-struct conjunction : __conjunction_impl<true_type, _Args...>::type {};
-
-template<class... _Args>
-inline constexpr bool conjunction_v = conjunction<_Args...>::value;
-
-#endif // _LIBCPP_STD_VER > 14
-
 template <class...>
 using __expand_to_true = true_type;
 
@@ -52,6 +32,22 @@
 template <class... _Pred>
 using _And _LIBCPP_NODEBUG = decltype(__and_helper<_Pred...>(0));
 
+#if _LIBCPP_STD_VER > 14
+
+template <class...>
+struct conjunction : true_type {};
+
+template <class _Arg>
+struct conjunction<_Arg> : _Arg {};
+
+template <class _Arg, class... _Args>
+struct conjunction<_Arg, _Args...> : conditional_t<!bool(_Arg::value), _Arg, conjunction<_Args...>> {};
+
+template <class... _Args>
+inline constexpr bool conjunction_v = conjunction<_Args...>::value;
+
+#endif // _LIBCPP_STD_VER > 14
+
 _LIBCPP_END_NAMESPACE_STD
 
 #endif // _LIBCPP___TYPE_TRAITS_CONJUNCTION_H


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