1 files changed, 121 insertions, 0 deletions
diff --git a/test/SemaCXX/builtin-is-constant-evaluated.cpp b/test/SemaCXX/builtin-is-constant-evaluated.cpp
new file mode 100644
index 0000000000..47b54d6ac3
--- /dev/null
+++ b/test/SemaCXX/builtin-is-constant-evaluated.cpp
@@ -0,0 +1,121 @@
+// RUN: %clang_cc1 -std=c++2a -verify %s -fcxx-exceptions -triple=x86_64-linux-gnu
+
+using size_t = decltype(sizeof(int));
+
+namespace std {
+inline constexpr bool is_constant_evaluated() noexcept {
+  return __builtin_is_constant_evaluated();
+}
+} // namespace std
+
+extern int dummy; // expected-note 1+ {{declared here}}
+
+static_assert(__builtin_is_constant_evaluated());
+static_assert(noexcept(__builtin_is_constant_evaluated()));
+
+constexpr bool b = __builtin_is_constant_evaluated();
+static_assert(b);
+
+const int n = __builtin_is_constant_evaluated() ? 4 : dummy;
+static_assert(n == 4);
+constexpr int cn = __builtin_is_constant_evaluated() ? 11 : dummy;
+static_assert(cn == 11);
+// expected-error@+1 {{'bn' must be initialized by a constant expression}}
+constexpr int bn = __builtin_is_constant_evaluated() ? dummy : 42; // expected-note {{non-const variable 'dummy' is not allowed}}
+
+const int n2 = __builtin_is_constant_evaluated() ? dummy : 42; // expected-note {{declared here}}
+static_assert(n2 == 42);                                       // expected-error {{static_assert expression is not an integral constant}}
+// expected-note@-1 {{initializer of 'n2' is not a constant expression}}
+
+template <bool V, bool Default = std::is_constant_evaluated()>
+struct Templ { static_assert(V); static_assert(Default); };
+Templ<__builtin_is_constant_evaluated()> x; // type X<true>
+
+template <class T>
+void test_if_constexpr() {
+  if constexpr (__builtin_is_constant_evaluated()) {
+    static_assert(__is_same(T, int));
+  } else {
+    using Test = typename T::DOES_NOT_EXIST;
+  }
+}
+template void test_if_constexpr<int>();
+
+void test_array_decl() {
+  char x[__builtin_is_constant_evaluated() + std::is_constant_evaluated()];
+  static_assert(sizeof(x) == 2, "");
+}
+
+void test_case_stmt(int x) {
+  switch (x) {
+  case 0:                                                                // OK
+  case __builtin_is_constant_evaluated():                                // expected-note {{previous case}}
+  case std::is_constant_evaluated() + __builtin_is_constant_evaluated(): // expected-note {{previous case}}
+  case 1:                                                                // expected-error {{duplicate case value '1'}}
+  case 2:                                                                // expected-error {{duplicate case value '2'}}
+    break;
+  }
+}
+
+constexpr size_t good_array_size() {
+  return std::is_constant_evaluated() ? 42 : static_cast<size_t>(-1);
+}
+
+constexpr size_t bad_array_size() {
+  return std::is_constant_evaluated() ? static_cast<size_t>(-1) : 13;
+}
+
+template <class T>
+constexpr T require_constexpr(T v) {
+  if (!std::is_constant_evaluated())
+    throw "BOOM";
+  return v;
+}
+
+void test_new_expr() {
+  constexpr size_t TooLarge = -1;
+  auto *x = new int[std::is_constant_evaluated() ? 1 : TooLarge];      // expected-error {{array is too large}}
+  auto *x2 = new int[std::is_constant_evaluated() ? TooLarge : 1];     // OK
+  auto *y = new int[1][std::is_constant_evaluated() ? TooLarge : 1]{}; // expected-error {{array is too large}}
+  auto *y2 = new int[1][require_constexpr(42)];
+}
+
+void test_alignas_operand() {
+  alignas(std::is_constant_evaluated() ? 8 : 2) char dummy;
+  static_assert(__alignof(dummy) == 8);
+}
+
+void test_static_assert_operand() {
+  static_assert(std::is_constant_evaluated(), "");
+}
+
+void test_enumerator() {
+  enum MyEnum {
+    ZERO = 0,
+    ONE = std::is_constant_evaluated()
+  };
+  static_assert(ONE == 1, "");
+}
+
+struct TestBitfieldWidth {
+  unsigned Bits : std::is_constant_evaluated();
+};
+
+void test_operand_of_noexcept_fn() noexcept(std::is_constant_evaluated());
+static_assert(noexcept(test_operand_of_noexcept_fn()), "");
+
+
+namespace test_ref_initialization {
+int x;
+int y;
+int &r = __builtin_is_constant_evaluated() ? x : y;
+static_assert(&r == &x);
+
+} // namespace test_ref_initialization
+
+#if defined(__cpp_conditional_explicit)
+struct TestConditionalExplicit {
+  explicit(__builtin_is_constant_evaluated()) TestConditionalExplicit(int) {}
+};
+TestConditionalExplicit e = 42;
+#endif