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// RUN: %clang_cc1 -std=c++2a -verify %s -fcxx-exceptions -Wno-constant-evaluated -triple=x86_64-linux-gnu
#define fold(x) (__builtin_constant_p(x) ? (x) : (x))
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 assertion 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
namespace fold_initializer {
// Global 'f' has a constant initializer.
const float f = __builtin_is_constant_evaluated();
static_assert(fold(f == 1.0f));
void g() {
// Local static 'sf' has a constant initializer.
static const float sf = __builtin_is_constant_evaluated();
static_assert(fold(sf == 1.0f));
// Local non-static 'f' has a non-constant initializer.
const float f = __builtin_is_constant_evaluated();
static_assert(fold(f == 0.0f));
}
struct A {
static const float f;
};
const float A::f = __builtin_is_constant_evaluated();
static_assert(fold(A::f == 1.0f));
}
namespace narrowing {
struct X { unsigned u; };
constexpr int f(X x) {return x.u;}
void g() {
static_assert(f({0xFFFFFFFFLL + __builtin_is_constant_evaluated()}) == 0);
f({0x100000000LL - __builtin_is_constant_evaluated()}); // expected-error {{constant expression evaluates to 4294967296}} \
// expected-warning {{implicit conversion}} \
// expected-note {{insert an explicit cast to silence this issue}}
}
}
struct GH99680 {
static const int x1 = 1/(1-__builtin_is_constant_evaluated()); // expected-error {{in-class initializer for static data member is not a constant expression}} \
// expected-note {{division by zero}}
static const int x2 = __builtin_is_constant_evaluated();
static_assert(x2 == 1);
static const float x3 = 1/(1-__builtin_is_constant_evaluated()); // expected-error {{in-class initializer for static data member of type 'const float' requires 'constexpr' specifier}} \
// expected-note {{add 'constexpr'}} \
// expected-error {{in-class initializer for static data member is not a constant expression}} \
// expected-note {{division by zero}}
static const float x4 = __builtin_is_constant_evaluated(); // expected-error {{in-class initializer for static data member of type 'const float' requires 'constexpr' specifier}} \
// expected-note {{add 'constexpr'}}
static_assert(fold(x4 == 1));
};
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