[PATCH] libstdc++: Add test for std::con/disjunction's short circuiting

[Patrick Palka <ppalka@redhat.com>]

Tested on x86_64-pc-linux-gnu, does this look OK for trunk?

libstdc++-v3/ChangeLog:

	* testsuite/20_util/logical_traits/requirements/short_circuit.cc: New test.
---
 .../requirements/short_circuit.cc             | 32 +++++++++++++++++++
 1 file changed, 32 insertions(+)
 create mode 100644 libstdc++-v3/testsuite/20_util/logical_traits/requirements/short_circuit.cc

diff --git a/libstdc++-v3/testsuite/20_util/logical_traits/requirements/short_circuit.cc b/libstdc++-v3/testsuite/20_util/logical_traits/requirements/short_circuit.cc
new file mode 100644
index 00000000000..b6a8091cdb0
--- /dev/null
+++ b/libstdc++-v3/testsuite/20_util/logical_traits/requirements/short_circuit.cc
@@ -0,0 +1,32 @@
+// { dg-do compile { target c++17 } }
+
+#include <type_traits>
+
+template<class T> struct A { using type = typename T::type; };
+using invalid = A<void>;
+
+// [meta.logical]/3: For a specialization conjunction<B_1, ..., B_n>, if
+// there is a template type argument B_i for which bool(B_i::value) is false,
+// then instantiating conjunction<B_1, ..., B_n>::value does not require the
+// instantiation of B_j::value for j > i.
+
+static_assert(!std::conjunction_v<std::false_type, invalid>);
+static_assert(!std::conjunction_v<std::false_type, invalid, invalid>);
+static_assert(!std::conjunction_v<std::false_type>);
+
+static_assert(!std::conjunction_v<std::true_type, std::false_type, invalid>);
+static_assert(!std::conjunction_v<std::true_type, std::false_type, invalid, invalid>);
+static_assert(!std::conjunction_v<std::true_type, std::false_type>);
+
+// [meta.logical]/8: For a specialization disjunction<B_1, ..., B_n>, if
+// there is a template type argument B_i for which bool(B_i::value) is true,
+// then instantiating disjunction<B_1, ..., B_n>::value does not require the
+// instantiation of B_j::value for j > i.
+
+static_assert(std::disjunction_v<std::true_type, invalid>);
+static_assert(std::disjunction_v<std::true_type, invalid, invalid>);
+static_assert(std::disjunction_v<std::true_type>);
+
+static_assert(std::disjunction_v<std::false_type, std::true_type, invalid>);
+static_assert(std::disjunction_v<std::false_type, std::true_type, invalid, invalid>);
+static_assert(std::disjunction_v<std::false_type, std::true_type>);
-- 
2.37.2.490.g6c8e4ee870