1 files changed, 81 insertions, 0 deletions
diff --git a/libcxx/test/std/numerics/rand/rand.eng/rand.eng.mers/ctor_sseq_all_zero.pass.cpp b/libcxx/test/std/numerics/rand/rand.eng/rand.eng.mers/ctor_sseq_all_zero.pass.cpp
new file mode 100644
index 00000000000..4599348f4a0
--- /dev/null
+++ b/libcxx/test/std/numerics/rand/rand.eng/rand.eng.mers/ctor_sseq_all_zero.pass.cpp
@@ -0,0 +1,81 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// <random>
+
+// template <class UIntType, size_t w, size_t n, size_t m, size_t r,
+//           UIntType a, size_t u, UIntType d, size_t s,
+//           UIntType b, size_t t,
+//           UIntType c, size_t l, UIntType f>
+// class mersenne_twister_engine;
+
+// template <class Sseq> explicit mersenne_twister_engine(Sseq &q);
+//
+//     [ ... ] Finally, if the most significant $w-r$ bits of $X_{-n}$ are zero,
+//     and if each of the other resulting $X_i$ is $0$, changes $X_{-n}$ to
+//     $ 2^{w-1} $.
+
+#include <random>
+
+#include <algorithm>
+#include <cassert>
+#include <cstddef>
+#if TEST_STD_VER >= 11
+#include <initializer_list>
+#endif
+
+struct all_zero_seed_seq {
+  typedef unsigned int result_type;
+
+  all_zero_seed_seq() {}
+
+  template <typename InputIterator>
+  all_zero_seed_seq(InputIterator, InputIterator) {}
+#if TEST_STD_VER >= 11
+  all_zero_seed_seq(std::initializer_list<result_type>) {}
+#endif
+
+  template <typename RandomAccessIterator>
+  void generate(RandomAccessIterator rb, RandomAccessIterator re) {
+    std::fill(rb, re, 0u);
+  }
+
+  std::size_t size() const { return 0u; }
+  template <typename OutputIterator> void param(OutputIterator) const {}
+};
+
+template <typename result_type, std::size_t word_size>
+void test(void) {
+  const std::size_t state_size = 1u;
+  const std::size_t shift_size = 1u;
+  const std::size_t tempering_l = word_size;
+
+  all_zero_seed_seq q;
+  std::mersenne_twister_engine<result_type, word_size, state_size,
+                               shift_size,
+                               0u,
+                               0x0,
+                               0u, 0x0, 0u, 0x0, 0u, 0x0,
+                               tempering_l,
+                               0u>
+      e(q);
+
+  const result_type Xneg1 = result_type(1) << (word_size - 1);
+  const result_type Y = Xneg1;
+  const result_type X0 = Xneg1 ^ (Y >> 1);
+  assert(e() == X0);
+}
+
+int main() {
+  // Test for k == 1: word_size <= 32.
+  test<unsigned short, 3u>();
+
+  // Test for k == 2: (32 < word_size <= 64).
+  test<unsigned long long, 33u>();
+}