text: // RUN: %clang_cc1 -triple i686-linux -Wno-string-plus-int -fsyntax-only -fcxx-exceptions -verify -std=c++11 -pedantic %s -Wno-comment
  
  namespace StaticAssertFoldTest {
  
  int x;
  static_assert(++x, "test"); // expected-error {{not an integral constant expression}}
  static_assert(false, "test"); // expected-error {{test}}
  
  }
  
  typedef decltype(sizeof(char)) size_t;
  
  template<typename T> constexpr T id(const T &t) { return t; }
  template<typename T> constexpr T min(const T &a, const T &b) {
    return a < b ? a : b;
  }
  template<typename T> constexpr T max(const T &a, const T &b) {
    return a < b ? b : a;
  }
  template<typename T, size_t N> constexpr T *begin(T (&xs)[N]) { return xs; }
  template<typename T, size_t N> constexpr T *end(T (&xs)[N]) { return xs + N; }
  
  struct MemberZero {
    constexpr int zero() { return 0; }
  };
  
  namespace DerivedToVBaseCast {
  
    struct U { int n; };
    struct V : U { int n; };
    struct A : virtual V { int n; };
    struct Aa { int n; };
    struct B : virtual A, Aa {};
    struct C : virtual A, Aa {};
    struct D : B, C {};
  
    D d;
    constexpr B *p = &d;
    constexpr C *q = &d;
  
    static_assert((void*)p != (void*)q, "");
    static_assert((A*)p == (A*)q, "");
    static_assert((Aa*)p != (Aa*)q, "");
  
    constexpr B &pp = d;
    constexpr C &qq = d;
    static_assert((void*)&pp != (void*)&qq, "");
    static_assert(&(A&)pp == &(A&)qq, "");
    static_assert(&(Aa&)pp != &(Aa&)qq, "");
  
    constexpr V *v = p;
    constexpr V *w = q;
    constexpr V *x = (A*)p;
    static_assert(v == w, "");
    static_assert(v == x, "");
  
    static_assert((U*)&d == p, "");
    static_assert((U*)&d == q, "");
    static_assert((U*)&d == v, "");
    static_assert((U*)&d == w, "");
    static_assert((U*)&d == x, "");
  
    struct X {};
    struct Y1 : virtual X {};
    struct Y2 : X {};
    struct Z : Y1, Y2 {};
    Z z;
    static_assert((X*)(Y1*)&z != (X*)(Y2*)&z, "");
  }
  
  namespace ConstCast {
  
  constexpr int n1 = 0;
  constexpr int n2 = const_cast<int&>(n1);
  constexpr int *n3 = const_cast<int*>(&n1);
  constexpr int n4 = *const_cast<int*>(&n1);
  constexpr const int * const *n5 = const_cast<const int* const*>(&n3);
  constexpr int **n6 = const_cast<int**>(&n3);
  constexpr int n7 = **n5;
  constexpr int n8 = **n6;
  
  }
  
  namespace TemplateArgumentConversion {
    template<int n> struct IntParam {};
  
    using IntParam0 = IntParam<0>;
    using IntParam0 = IntParam<id(0)>;
    using IntParam0 = IntParam<MemberZero().zero>; // expected-error {{did you mean to call it with no arguments?}}
  }
  
  namespace CaseStatements {
    void f(int n) {
      switch (n) {
      case MemberZero().zero: // expected-error {{did you mean to call it with no arguments?}} expected-note {{previous}}
      case id(0): // expected-error {{duplicate case value '0'}}
        return;
      }
    }
  }
  
  extern int &Recurse1;
  int &Recurse2 = Recurse1; // expected-note {{declared here}}
  int &Recurse1 = Recurse2;
  constexpr int &Recurse3 = Recurse2; // expected-error {{must be initialized by a constant expression}} expected-note {{initializer of 'Recurse2' is not a constant expression}}
  
  extern const int RecurseA;
  const int RecurseB = RecurseA; // expected-note {{declared here}}
  const int RecurseA = 10;
  constexpr int RecurseC = RecurseB; // expected-error {{must be initialized by a constant expression}} expected-note {{initializer of 'RecurseB' is not a constant expression}}
  
  namespace MemberEnum {
    struct WithMemberEnum {
      enum E { A = 42 };
    } wme;
  
    static_assert(wme.A == 42, "");
  }
  
  namespace DefaultArguments {
  
  const int z = int();
  constexpr int Sum(int a = 0, const int &b = 0, const int *c = &z, char d = 0) {
    return a + b + *c + d;
  }
  const int four = 4;
  constexpr int eight = 8;
  constexpr const int twentyseven = 27;
  static_assert(Sum() == 0, "");
  static_assert(Sum(1) == 1, "");
  static_assert(Sum(1, four) == 5, "");
  static_assert(Sum(1, eight, &twentyseven) == 36, "");
  static_assert(Sum(1, 2, &four, eight) == 15, "");
  
  }
  
  namespace Ellipsis {
  
  // Note, values passed through an ellipsis can't actually be used.
  constexpr int F(int a, ...) { return a; }
  static_assert(F(0) == 0, "");
  static_assert(F(1, 0) == 1, "");
  static_assert(F(2, "test") == 2, "");
  static_assert(F(3, &F) == 3, "");
  int k = 0; // expected-note {{here}}
  static_assert(F(4, k) == 3, ""); // expected-error {{constant expression}} expected-note {{read of non-const variable 'k'}}
  
  }
  
  namespace Recursion {
    constexpr int fib(int n) { return n > 1 ? fib(n-1) + fib(n-2) : n; }
    static_assert(fib(11) == 89, "");
  
    constexpr int gcd_inner(int a, int b) {
      return b == 0 ? a : gcd_inner(b, a % b);
    }
    constexpr int gcd(int a, int b) {
      return gcd_inner(max(a, b), min(a, b));
    }
  
    static_assert(gcd(1749237, 5628959) == 7, "");
  }
  
  namespace FunctionCast {
    // When folding, we allow functions to be cast to different types. Such
    // cast functions cannot be called, even if they're constexpr.
    constexpr int f() { return 1; }
    typedef double (*DoubleFn)();
    typedef int (*IntFn)();
    int a[(int)DoubleFn(f)()]; // expected-error {{variable length array}} expected-warning{{C99 feature}}
    int b[(int)IntFn(f)()];    // ok
  }
  
  namespace StaticMemberFunction {
    struct S {
      static constexpr int k = 42;
      static constexpr int f(int n) { return n * k + 2; }
    } s;
  
    constexpr int n = s.f(19);
    static_assert(S::f(19) == 800, "");
    static_assert(s.f(19) == 800, "");
    static_assert(n == 800, "");
  
    constexpr int (*sf1)(int) = &S::f;
    constexpr int (*sf2)(int) = &s.f;
    constexpr const int *sk = &s.k;
  }
  
  namespace ParameterScopes {
  
    const int k = 42;
    constexpr const int &ObscureTheTruth(const int &a) { return a; }
    constexpr const int &MaybeReturnJunk(bool b, const int a) { // expected-note 2{{declared here}}
      return ObscureTheTruth(b ? a : k);
    }
    static_assert(MaybeReturnJunk(false, 0) == 42, ""); // ok
    constexpr int a = MaybeReturnJunk(true, 0); // expected-error {{constant expression}} expected-note {{read of variable whose lifetime has ended}}
  
    constexpr const int MaybeReturnNonstaticRef(bool b, const int a) {
      return ObscureTheTruth(b ? a : k);
    }
    static_assert(MaybeReturnNonstaticRef(false, 0) == 42, ""); // ok
    constexpr int b = MaybeReturnNonstaticRef(true, 0); // ok
  
    constexpr int InternalReturnJunk(int n) {
      return MaybeReturnJunk(true, n); // expected-note {{read of variable whose lifetime has ended}}
    }
    constexpr int n3 = InternalReturnJunk(0); // expected-error {{must be initialized by a constant expression}} expected-note {{in call to 'InternalReturnJunk(0)'}}
  
    constexpr int LToR(int &n) { return n; }
    constexpr int GrabCallersArgument(bool which, int a, int b) {
      return LToR(which ? b : a);
    }
    static_assert(GrabCallersArgument(false, 1, 2) == 1, "");
    static_assert(GrabCallersArgument(true, 4, 8) == 8, "");
  
  }
  
  namespace Pointers {
  
    constexpr int f(int n, const int *a, const int *b, const int *c) {
      return n == 0 ? 0 : *a + f(n-1, b, c, a);
    }
  
    const int x = 1, y = 10, z = 100;
    static_assert(f(23, &x, &y, &z) == 788, "");
  
    constexpr int g(int n, int a, int b, int c) {
      return f(n, &a, &b, &c);
    }
    static_assert(g(23, x, y, z) == 788, "");
  
  }
  
  namespace FunctionPointers {
  
    constexpr int Double(int n) { return 2 * n; }
    constexpr int Triple(int n) { return 3 * n; }
    constexpr int Twice(int (*F)(int), int n) { return F(F(n)); }
    constexpr int Quadruple(int n) { return Twice(Double, n); }
    constexpr auto Select(int n) -> int (*)(int) {
      return n == 2 ? &Double : n == 3 ? &Triple : n == 4 ? &Quadruple : 0;
    }
    constexpr int Apply(int (*F)(int), int n) { return F(n); } // expected-note {{subexpression}}
  
    static_assert(1 + Apply(Select(4), 5) + Apply(Select(3), 7) == 42, "");
  
    constexpr int Invalid = Apply(Select(0), 0); // expected-error {{must be initialized by a constant expression}} expected-note {{in call to 'Apply(0, 0)'}}
  
  }
  
  namespace PointerComparison {
  
  int x, y;
  static_assert(&x == &y, "false"); // expected-error {{false}}
  static_assert(&x != &y, "");
  constexpr bool g1 = &x == &y;
  constexpr bool g2 = &x != &y;
  constexpr bool g3 = &x <= &y; // expected-error {{must be initialized by a constant expression}}
  constexpr bool g4 = &x >= &y; // expected-error {{must be initialized by a constant expression}}
  constexpr bool g5 = &x < &y; // expected-error {{must be initialized by a constant expression}}
  constexpr bool g6 = &x > &y; // expected-error {{must be initialized by a constant expression}}
  
  struct S { int x, y; } s;
  static_assert(&s.x == &s.y, "false"); // expected-error {{false}}
  static_assert(&s.x != &s.y, "");
  static_assert(&s.x <= &s.y, "");
  static_assert(&s.x >= &s.y, "false"); // expected-error {{false}}
  static_assert(&s.x < &s.y, "");
  static_assert(&s.x > &s.y, "false"); // expected-error {{false}}
  
  static_assert(0 == &y, "false"); // expected-error {{false}}
  static_assert(0 != &y, "");
  constexpr bool n3 = 0 <= &y; // expected-error {{must be initialized by a constant expression}}
  constexpr bool n4 = 0 >= &y; // expected-error {{must be initialized by a constant expression}}
  constexpr bool n5 = 0 < &y; // expected-error {{must be initialized by a constant expression}}
  constexpr bool n6 = 0 > &y; // expected-error {{must be initialized by a constant expression}}
  
  static_assert(&x == 0, "false"); // expected-error {{false}}
  static_assert(&x != 0, "");
  constexpr bool n9 = &x <= 0; // expected-error {{must be initialized by a constant expression}}
  constexpr bool n10 = &x >= 0; // expected-error {{must be initialized by a constant expression}}
  constexpr bool n11 = &x < 0; // expected-error {{must be initialized by a constant expression}}
  constexpr bool n12 = &x > 0; // expected-error {{must be initialized by a constant expression}}
  
  static_assert(&x == &x, "");
  static_assert(&x != &x, "false"); // expected-error {{false}}
  static_assert(&x <= &x, "");
  static_assert(&x >= &x, "");
  static_assert(&x < &x, "false"); // expected-error {{false}}
  static_assert(&x > &x, "false"); // expected-error {{false}}
  
  constexpr S* sptr = &s;
  constexpr bool dyncast = sptr == dynamic_cast<S*>(sptr); // expected-error {{constant expression}} expected-note {{dynamic_cast}}
  
  struct U {};
  struct Str {
    int a : dynamic_cast<S*>(sptr) == dynamic_cast<S*>(sptr); // \
      expected-warning {{not an integral constant expression}} \
      expected-note {{dynamic_cast is not allowed in a constant expression}}
    int b : reinterpret_cast<S*>(sptr) == reinterpret_cast<S*>(sptr); // \
      expected-warning {{not an integral constant expression}} \
      expected-note {{reinterpret_cast is not allowed in a constant expression}}
    int c : (S*)(long)(sptr) == (S*)(long)(sptr); // \
      expected-warning {{not an integral constant expression}} \
      expected-note {{cast which performs the conversions of a reinterpret_cast is not allowed in a constant expression}}
    int d : (S*)(42) == (S*)(42); // \
      expected-warning {{not an integral constant expression}} \
      expected-note {{cast which performs the conversions of a reinterpret_cast is not allowed in a constant expression}}
    int e : (Str*)(sptr) == (Str*)(sptr); // \
      expected-warning {{not an integral constant expression}} \
      expected-note {{cast which performs the conversions of a reinterpret_cast is not allowed in a constant expression}}
    int f : &(U&)(*sptr) == &(U&)(*sptr); // \
      expected-warning {{not an integral constant expression}} \
      expected-note {{cast which performs the conversions of a reinterpret_cast is not allowed in a constant expression}}
    int g : (S*)(void*)(sptr) == sptr; // \
      expected-warning {{not an integral constant expression}} \
      expected-note {{cast from 'void *' is not allowed in a constant expression}}
  };
  
  extern char externalvar[];
  constexpr bool constaddress = (void *)externalvar == (void *)0x4000UL; // expected-error {{must be initialized by a constant expression}}
  constexpr bool litaddress = "foo" == "foo"; // expected-error {{must be initialized by a constant expression}} expected-warning {{unspecified}}
  static_assert(0 != "foo", "");
  
  }
  
  namespace MaterializeTemporary {
  
  constexpr int f(const int &r) { return r; }
  constexpr int n = f(1);
  
  constexpr bool same(const int &a, const int &b) { return &a == &b; }
  constexpr bool sameTemporary(const int &n) { return same(n, n); }
  
  static_assert(n, "");
  static_assert(!same(4, 4), "");
  static_assert(same(n, n), "");
  static_assert(sameTemporary(9), "");
  
  }
  
  constexpr int strcmp_ce(const char *p, const char *q) {
    return (!*p || *p != *q) ? *p - *q : strcmp_ce(p+1, q+1);
  }
  
  namespace StringLiteral {
  
  template<typename Char>
  constexpr int MangleChars(const Char *p) {
    return *p + 3 * (*p ? MangleChars(p+1) : 0);
  }
  
  static_assert(MangleChars("constexpr!") == 1768383, "");
  static_assert(MangleChars(u8"constexpr!") == 1768383, "");
  static_assert(MangleChars(L"constexpr!") == 1768383, "");
  static_assert(MangleChars(u"constexpr!") == 1768383, "");
  static_assert(MangleChars(U"constexpr!") == 1768383, "");
  
  constexpr char c0 = "nought index"[0];
  constexpr char c1 = "nice index"[10];
  constexpr char c2 = "nasty index"[12]; // expected-error {{must be initialized by a constant expression}} expected-warning {{is past the end}} expected-note {{read of dereferenced one-past-the-end pointer}}
  constexpr char c3 = "negative index"[-1]; // expected-error {{must be initialized by a constant expression}} expected-warning {{is before the beginning}} expected-note {{cannot refer to element -1 of array of 15 elements}}
  constexpr char c4 = ((char*)(int*)"no reinterpret_casts allowed")[14]; // expected-error {{must be initialized by a constant expression}} expected-note {{cast which performs the conversions of a reinterpret_cast}}
  
  constexpr const char *p = "test" + 2;
  static_assert(*p == 's', "");
  
  constexpr const char *max_iter(const char *a, const char *b) {
    return *a < *b ? b : a;
  }
  constexpr const char *max_element(const char *a, const char *b) {
    return (a+1 >= b) ? a : max_iter(a, max_element(a+1, b));
  }
  
  constexpr char str[] = "the quick brown fox jumped over the lazy dog";
  constexpr const char *max = max_element(begin(str), end(str));
  static_assert(*max == 'z', "");
  static_assert(max == str + 38, "");
  
  static_assert(strcmp_ce("hello world", "hello world") == 0, "");
  static_assert(strcmp_ce("hello world", "hello clang") > 0, "");
  static_assert(strcmp_ce("constexpr", "test") < 0, "");
  static_assert(strcmp_ce("", " ") < 0, "");
  
  struct S {
    int n : "foo"[4]; // expected-error {{constant expression}} expected-note {{read of dereferenced one-past-the-end pointer is not allowed in a constant expression}}
  };
  
  struct T {
    char c[6];
    constexpr T() : c{"foo"} {}
  };
  constexpr T t;
  
  static_assert(t.c[0] == 'f', "");
  static_assert(t.c[1] == 'o', "");
  static_assert(t.c[2] == 'o', "");
  static_assert(t.c[3] == 0, "");
  static_assert(t.c[4] == 0, "");
  static_assert(t.c[5] == 0, "");
  static_assert(t.c[6] == 0, ""); // expected-error {{constant expression}} expected-note {{one-past-the-end}}
  
  struct U {
    wchar_t chars[6];
    int n;
  } constexpr u = { { L"test" }, 0 };
  static_assert(u.chars[2] == L's', "");
  
  struct V {
    char c[4];
    constexpr V() : c("hi!") {}
  };
  static_assert(V().c[1] == "i"[0], "");
  
  }
  
  namespace Array {
  
  template<typename Iter>
  constexpr auto Sum(Iter begin, Iter end) -> decltype(+*begin) {
    return begin == end ? 0 : *begin + Sum(begin+1, end);
  }
  
  constexpr int xs[] = { 1, 2, 3, 4, 5 };
  constexpr int ys[] = { 5, 4, 3, 2, 1 };
  constexpr int sum_xs = Sum(begin(xs), end(xs));
  static_assert(sum_xs == 15, "");
  
  constexpr int ZipFoldR(int (*F)(int x, int y, int c), int n,
                         const int *xs, const int *ys, int c) {
    return n ? F(
                 *xs, // expected-note {{read of dereferenced one-past-the-end pointer}}
                 *ys,
                 ZipFoldR(F, n-1, xs+1, ys+1, c)) // \
        expected-note {{in call to 'ZipFoldR(&SubMul, 2, &xs[4], &ys[4], 1)'}} \
        expected-note {{in call to 'ZipFoldR(&SubMul, 1, &xs[5], &ys[5], 1)'}}
             : c;
  }
  constexpr int MulAdd(int x, int y, int c) { return x * y + c; }
  constexpr int InnerProduct = ZipFoldR(MulAdd, 5, xs, ys, 0);
  static_assert(InnerProduct == 35, "");
  
  constexpr int SubMul(int x, int y, int c) { return (x - y) * c; }
  constexpr int DiffProd = ZipFoldR(SubMul, 2, xs+3, ys+3, 1);
  static_assert(DiffProd == 8, "");
  static_assert(ZipFoldR(SubMul, 3, xs+3, ys+3, 1), ""); // \
        expected-error {{constant expression}} \
        expected-note {{in call to 'ZipFoldR(&SubMul, 3, &xs[3], &ys[3], 1)'}}
  
  constexpr const int *p = xs + 3;
  constexpr int xs4 = p[1]; // ok
  constexpr int xs5 = p[2]; // expected-error {{constant expression}} expected-note {{read of dereferenced one-past-the-end pointer}}
  constexpr int xs6 = p[3]; // expected-error {{constant expression}} expected-note {{cannot refer to element 6}}
  constexpr int xs0 = p[-3]; // ok
  constexpr int xs_1 = p[-4]; // expected-error {{constant expression}} expected-note {{cannot refer to element -1}}
  
  constexpr int zs[2][2][2][2] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 };
  static_assert(zs[0][0][0][0] == 1, "");
  static_assert(zs[1][1][1][1] == 16, "");
  static_assert(zs[0][0][0][2] == 3, ""); // expected-error {{constant expression}} expected-note {{read of dereferenced one-past-the-end pointer}}
  static_assert((&zs[0][0][0][2])[-1] == 2, "");
  static_assert(**(**(zs + 1) + 1) == 11, "");
  static_assert(*(&(&(*(*&(&zs[2] - 1)[0] + 2 - 2))[2])[-1][-1] + 1) == 11, ""); // expected-error {{constant expression}} expected-note {{cannot refer to element -1 of array of 2 elements in a constant expression}}
  static_assert(*(&(&(*(*&(&zs[2] - 1)[0] + 2 - 2))[2])[-1][2] - 2) == 11, "");
  constexpr int err_zs_1_2_0_0 = zs[1][2][0][0]; // expected-error {{constant expression}} expected-note {{cannot access array element of pointer past the end}}
  
  constexpr int fail(const int &p) {
    return (&p)[64]; // expected-note {{cannot refer to element 64 of array of 2 elements}}
  }
  static_assert(fail(*(&(&(*(*&(&zs[2] - 1)[0] + 2 - 2))[2])[-1][2] - 2)) == 11, ""); // \
  expected-error {{static_assert expression is not an integral constant expression}} \
  expected-note {{in call to 'fail(zs[1][0][1][0])'}}
  
  constexpr int arr[40] = { 1, 2, 3, [8] = 4 }; // expected-warning {{C99 feature}}
  constexpr int SumNonzero(const int *p) {
    return *p + (*p ? SumNonzero(p+1) : 0);
  }
  constexpr int CountZero(const int *p, const int *q) {
    return p == q ? 0 : (*p == 0) + CountZero(p+1, q);
  }
  static_assert(SumNonzero(arr) == 6, "");
  static_assert(CountZero(arr, arr + 40) == 36, "");
  
  struct ArrayElem {
    constexpr ArrayElem() : n(0) {}
    int n;
    constexpr int f() { return n; }
  };
  struct ArrayRVal {
    constexpr ArrayRVal() {}
    ArrayElem elems[10];
  };
  static_assert(ArrayRVal().elems[3].f() == 0, "");
  
  constexpr int selfref[2][2][2] = {
    selfref[1][1][1] + 1, selfref[0][0][0] + 1,
    selfref[1][0][1] + 1, selfref[0][1][0] + 1,
    selfref[1][0][0] + 1, selfref[0][1][1] + 1 };
  static_assert(selfref[0][0][0] == 1, "");
  static_assert(selfref[0][0][1] == 2, "");
  static_assert(selfref[0][1][0] == 1, "");
  static_assert(selfref[0][1][1] == 2, "");
  static_assert(selfref[1][0][0] == 1, "");
  static_assert(selfref[1][0][1] == 3, "");
  static_assert(selfref[1][1][0] == 0, "");
  static_assert(selfref[1][1][1] == 0, "");
  
  struct TrivialDefCtor { int n; };
  typedef TrivialDefCtor TDCArray[2][2];
  static_assert(TDCArray{}[1][1].n == 0, "");
  
  struct NonAggregateTDC : TrivialDefCtor {};
  typedef NonAggregateTDC NATDCArray[2][2];
  static_assert(NATDCArray{}[1][1].n == 0, "");
  
  }
  
  namespace DependentValues {
  
  struct I { int n; typedef I V[10]; };
  I::V x, y;
  template<bool B> struct S {
    int k;
    void f() {
      I::V &cells = B ? x : y;
      I &i = cells[k];
      switch (i.n) {}
    }
  };
  
  }
  
  namespace Class {
  
  struct A { constexpr A(int a, int b) : k(a + b) {} int k; };
  constexpr int fn(const A &a) { return a.k; }
  static_assert(fn(A(4,5)) == 9, "");
  
  struct B { int n; int m; } constexpr b = { 0, b.n }; // expected-warning {{uninitialized}}
  struct C {
    constexpr C(C *this_) : m(42), n(this_->m) {} // ok
    int m, n;
  };
  struct D {
    C c;
    constexpr D() : c(&c) {}
  };
  static_assert(D().c.n == 42, "");
  
  struct E {
    constexpr E() : p(&p) {}
    void *p;
  };
  constexpr const E &e1 = E(); // expected-error {{constant expression}} expected-note {{reference to temporary is not a constant expression}} expected-note {{temporary created here}}
  // This is a constant expression if we elide the copy constructor call, and
  // is not a constant expression if we don't! But we do, so it is.
  constexpr E e2 = E();
  static_assert(e2.p == &e2.p, "");
  constexpr E e3;
  static_assert(e3.p == &e3.p, "");
  
  extern const class F f;
  struct F {
    constexpr F() : p(&f.p) {}
    const void *p;
  };
  constexpr F f;
  
  struct G {
    struct T {
      constexpr T(T *p) : u1(), u2(p) {}
      union U1 {
        constexpr U1() {}
        int a, b = 42;
      } u1;
      union U2 {
        constexpr U2(T *p) : c(p->u1.b) {}
        int c, d;
      } u2;
    } t;
    constexpr G() : t(&t) {}
  } constexpr g;
  
  static_assert(g.t.u1.a == 42, ""); // expected-error {{constant expression}} expected-note {{read of member 'a' of union with active member 'b'}}
  static_assert(g.t.u1.b == 42, "");
  static_assert(g.t.u2.c == 42, "");
  static_assert(g.t.u2.d == 42, ""); // expected-error {{constant expression}} expected-note {{read of member 'd' of union with active member 'c'}}
  
  struct S {
    int a, b;
    const S *p;
    double d;
    const char *q;
  
    constexpr S(int n, const S *p) : a(5), b(n), p(p), d(n), q("hello") {}
  };
  
  S global(43, &global);
  
  static_assert(S(15, &global).b == 15, "");
  
  constexpr bool CheckS(const S &s) {
    return s.a == 5 && s.b == 27 && s.p == &global && s.d == 27. && s.q[3] == 'l';
  }
  static_assert(CheckS(S(27, &global)), "");
  
  struct Arr {
    char arr[3];
    constexpr Arr() : arr{'x', 'y', 'z'} {}
  };
  constexpr int hash(Arr &&a) {
    return a.arr[0] + a.arr[1] * 0x100 + a.arr[2] * 0x10000;
  }
  constexpr int k = hash(Arr());
  static_assert(k == 0x007a7978, "");
  
  
  struct AggregateInit {
    const char &c;
    int n;
    double d;
    int arr[5];
    void *p;
  };
  
  constexpr AggregateInit agg1 = { "hello"[0] };
  
  static_assert(strcmp_ce(&agg1.c, "hello") == 0, "");
  static_assert(agg1.n == 0, "");
  static_assert(agg1.d == 0.0, "");
  static_assert(agg1.arr[-1] == 0, ""); // expected-error {{constant expression}} expected-note {{cannot refer to element -1}}
  static_assert(agg1.arr[0] == 0, "");
  static_assert(agg1.arr[4] == 0, "");
  static_assert(agg1.arr[5] == 0, ""); // expected-error {{constant expression}} expected-note {{read of dereferenced one-past-the-end}}
  static_assert(agg1.p == nullptr, "");
  
  static constexpr const unsigned char uc[] = { "foo" };
  static_assert(uc[0] == 'f', "");
  static_assert(uc[3] == 0, "");
  
  namespace SimpleDerivedClass {
  
  struct B {
    constexpr B(int n) : a(n) {}
    int a;
  };
  struct D : B {
    constexpr D(int n) : B(n) {}
  };
  constexpr D d(3);
  static_assert(d.a == 3, "");
  
  }
  
  struct Bottom { constexpr Bottom() {} };
  struct Base : Bottom {
    constexpr Base(int a = 42, const char *b = "test") : a(a), b(b) {}
    int a;
    const char *b;
  };
  struct Base2 : Bottom {
    constexpr Base2(const int &r) : r(r) {}
    int q = 123;
    const int &r;
  };
  struct Derived : Base, Base2 {
    constexpr Derived() : Base(76), Base2(a) {}
    int c = r + b[1];
  };
  
  constexpr bool operator==(const Base &a, const Base &b) {
    return a.a == b.a && strcmp_ce(a.b, b.b) == 0;
  }
  
  constexpr Base base;
  constexpr Base base2(76);
  constexpr Derived derived;
  static_assert(derived.a == 76, "");
  static_assert(derived.b[2] == 's', "");
  static_assert(derived.c == 76 + 'e', "");
  static_assert(derived.q == 123, "");
  static_assert(derived.r == 76, "");
  static_assert(&derived.r == &derived.a, "");
  
  static_assert(!(derived == base), "");
  static_assert(derived == base2, "");
  
  constexpr Bottom &bot1 = (Base&)derived;
  constexpr Bottom &bot2 = (Base2&)derived;
  static_assert(&bot1 != &bot2, "");
  
  constexpr Bottom *pb1 = (Base*)&derived;
  constexpr Bottom *pb2 = (Base2*)&derived;
  static_assert(&pb1 != &pb2, "");
  static_assert(pb1 == &bot1, "");
  static_assert(pb2 == &bot2, "");
  
  constexpr Base2 &fail = (Base2&)bot1; // expected-error {{constant expression}} expected-note {{cannot cast object of dynamic type 'const Class::Derived' to type 'Class::Base2'}}
  constexpr Base &fail2 = (Base&)*pb2; // expected-error {{constant expression}} expected-note {{cannot cast object of dynamic type 'const Class::Derived' to type 'Class::Base'}}
  constexpr Base2 &ok2 = (Base2&)bot2;
  static_assert(&ok2 == &derived, "");
  
  constexpr Base2 *pfail = (Base2*)pb1; // expected-error {{constant expression}} expected-note {{cannot cast object of dynamic type 'const Class::Derived' to type 'Class::Base2'}}
  constexpr Base *pfail2 = (Base*)&bot2; // expected-error {{constant expression}} expected-note {{cannot cast object of dynamic type 'const Class::Derived' to type 'Class::Base'}}
  constexpr Base2 *pok2 = (Base2*)pb2;
  static_assert(pok2 == &derived, "");
  static_assert(&ok2 == pok2, "");
  static_assert((Base2*)(Derived*)(Base*)pb1 == pok2, "");
  static_assert((Derived*)(Base*)pb1 == (Derived*)pok2, "");
  
  constexpr Base *nullB = 42 - 6 * 7; // expected-warning {{expression which evaluates to zero treated as a null pointer constant of type 'Class::Base *const'}}
  static_assert((Bottom*)nullB == 0, "");
  static_assert((Derived*)nullB == 0, "");
  static_assert((void*)(Bottom*)nullB == (void*)(Derived*)nullB, "");
  Base * nullB2 = '\0'; // expected-warning {{expression which evaluates to zero treated as a null pointer constant of type 'Class::Base *'}}
  Base * nullB3 = (0);
  // We suppress the warning in unevaluated contexts to workaround some gtest
  // behavior. Once this becomes an error this isn't a problem anymore.
  static_assert(nullB == (1 - 1), "");
  
  
  namespace ConversionOperators {
  
  struct T {
    constexpr T(int n) : k(5*n - 3) {}
    constexpr operator int() { return k; }
    int k;
  };
  
  struct S {
    constexpr S(int n) : k(2*n + 1) {}
    constexpr operator int() { return k; }
    constexpr operator T() { return T(k); }
    int k;
  };
  
  constexpr bool check(T a, T b) { return a == b.k; }
  
  static_assert(S(5) == 11, "");
  static_assert(check(S(5), 11), "");
  
  }
  
  }
  
  namespace Temporaries {
  
  struct S {
    constexpr S() {}
    constexpr int f();
  };
  struct T : S {
    constexpr T(int n) : S(), n(n) {}
    int n;
  };
  constexpr int S::f() {
    // 'this' must be the postfix-expression in a class member access expression,
    // so we can't just use
    //   return static_cast<T*>(this)->n;
    return this->*(int(S::*))&T::n;
  }
  // The T temporary is implicitly cast to an S subobject, but we can recover the
  // T full-object via a base-to-derived cast, or a derived-to-base-casted member
  // pointer.
  static_assert(T(3).f() == 3, "");
  
  constexpr int f(const S &s) {
    return static_cast<const T&>(s).n;
  }
  constexpr int n = f(T(5));
  static_assert(f(T(5)) == 5, "");
  
  constexpr bool b(int n) { return &n; }
  static_assert(b(0), "");
  
  }
  
  namespace Union {
  
  union U {
    int a;
    int b;
  };
  
  constexpr U u[4] = { { .a = 0 }, { .b = 1 }, { .a = 2 }, { .b = 3 } }; // expected-warning 4{{C99 feature}}
  static_assert(u[0].a == 0, "");
  static_assert(u[0].b, ""); // expected-error {{constant expression}} expected-note {{read of member 'b' of union with active member 'a'}}
  static_assert(u[1].b == 1, "");
  static_assert((&u[1].b)[1] == 2, ""); // expected-error {{constant expression}} expected-note {{read of dereferenced one-past-the-end pointer}}
  static_assert(*(&(u[1].b) + 1 + 1) == 3, ""); // expected-error {{constant expression}} expected-note {{cannot refer to element 2 of non-array object}}
  static_assert((&(u[1]) + 1 + 1)->b == 3, "");
  
  constexpr U v = {};
  static_assert(v.a == 0, "");
  
  union Empty {};
  constexpr Empty e = {};
  
  // Make sure we handle trivial copy constructors for unions.
  constexpr U x = {42};
  constexpr U y = x;
  static_assert(y.a == 42, "");
  static_assert(y.b == 42, ""); // expected-error {{constant expression}} expected-note {{'b' of union with active member 'a'}}
  
  }
  
  namespace MemberPointer {
    struct A {
      constexpr A(int n) : n(n) {}
      int n;
      constexpr int f() { return n + 3; }
    };
    constexpr A a(7);
    static_assert(A(5).*&A::n == 5, "");
    static_assert((&a)->*&A::n == 7, "");
    static_assert((A(8).*&A::f)() == 11, "");
    static_assert(((&a)->*&A::f)() == 10, "");
  
    struct B : A {
      constexpr B(int n, int m) : A(n), m(m) {}
      int m;
      constexpr int g() { return n + m + 1; }
    };
    constexpr B b(9, 13);
    static_assert(B(4, 11).*&A::n == 4, "");
    static_assert(B(4, 11).*&B::m == 11, "");
    static_assert(B(4, 11).*(int(A::*))&B::m == 11, "");
    static_assert((&b)->*&A::n == 9, "");
    static_assert((&b)->*&B::m == 13, "");
    static_assert((&b)->*(int(A::*))&B::m == 13, "");
    static_assert((B(4, 11).*&A::f)() == 7, "");
    static_assert((B(4, 11).*&B::g)() == 16, "");
    static_assert((B(4, 11).*(int(A::*)()const)&B::g)() == 16, "");
    static_assert(((&b)->*&A::f)() == 12, "");
    static_assert(((&b)->*&B::g)() == 23, "");
    static_assert(((&b)->*(int(A::*)()const)&B::g)() == 23, "");
  
    struct S {
      constexpr S(int m, int n, int (S::*pf)() const, int S::*pn) :
        m(m), n(n), pf(pf), pn(pn) {}
      constexpr S() : m(), n(), pf(&S::f), pn(&S::n) {}
  
      constexpr int f() { return this->*pn; }
      virtual int g() const;
  
      int m, n;
      int (S::*pf)() const;
      int S::*pn;
    };
  
    constexpr int S::*pm = &S::m;
    constexpr int S::*pn = &S::n;
    constexpr int (S::*pf)() const = &S::f;
    constexpr int (S::*pg)() const = &S::g;
  
    constexpr S s(2, 5, &S::f, &S::m);
  
    static_assert((s.*&S::f)() == 2, "");
    static_assert((s.*s.pf)() == 2, "");
  
    static_assert(pf == &S::f, "");
    static_assert(pf == s.*&S::pf, "");
    static_assert(pm == &S::m, "");
    static_assert(pm != pn, "");
    static_assert(s.pn != pn, "");
    static_assert(s.pn == pm, "");
    static_assert(pg != nullptr, "");
    static_assert(pf != nullptr, "");
    static_assert((int S::*)nullptr == nullptr, "");
    static_assert(pg == pg, ""); // expected-error {{constant expression}} expected-note {{comparison of pointer to virtual member function 'g' has unspecified value}}
    static_assert(pf != pg, ""); // expected-error {{constant expression}} expected-note {{comparison of pointer to virtual member function 'g' has unspecified value}}
  
    template<int n> struct T : T<n-1> {};
    template<> struct T<0> { int n; };
    template<> struct T<30> : T<29> { int m; };
  
    T<17> t17;
    T<30> t30;
  
    constexpr int (T<10>::*deepn) = &T<0>::n;
    static_assert(&(t17.*deepn) == &t17.n, "");
    static_assert(deepn == &T<2>::n, "");
  
    constexpr int (T<15>::*deepm) = (int(T<10>::*))&T<30>::m;
    constexpr int *pbad = &(t17.*deepm); // expected-error {{constant expression}}
    static_assert(&(t30.*deepm) == &t30.m, "");
    static_assert(deepm == &T<50>::m, "");
    static_assert(deepm != deepn, "");
  
    constexpr T<5> *p17_5 = &t17;
    constexpr T<13> *p17_13 = (T<13>*)p17_5;
    constexpr T<23> *p17_23 = (T<23>*)p17_13; // expected-error {{constant expression}} expected-note {{cannot cast object of dynamic type 'T<17>' to type 'T<23>'}}
    static_assert(&(p17_5->*(int(T<3>::*))deepn) == &t17.n, "");
    static_assert(&(p17_13->*deepn) == &t17.n, "");
    constexpr int *pbad2 = &(p17_13->*(int(T<9>::*))deepm); // expected-error {{constant expression}}
  
    constexpr T<5> *p30_5 = &t30;
    constexpr T<23> *p30_23 = (T<23>*)p30_5;
    constexpr T<13> *p30_13 = p30_23;
    static_assert(&(p30_5->*(int(T<3>::*))deepn) == &t30.n, "");
    static_assert(&(p30_13->*deepn) == &t30.n, "");
    static_assert(&(p30_23->*deepn) == &t30.n, "");
    static_assert(&(p30_5->*(int(T<2>::*))deepm) == &t30.m, "");
    static_assert(&(((T<17>*)p30_13)->*deepm) == &t30.m, "");
    static_assert(&(p30_23->*deepm) == &t30.m, "");
  
    struct Base { int n; };
    template<int N> struct Mid : Base {};
    struct Derived : Mid<0>, Mid<1> {};
    static_assert(&Mid<0>::n == &Mid<1>::n, "");
    static_assert((int Derived::*)(int Mid<0>::*)&Mid<0>::n !=
                  (int Derived::*)(int Mid<1>::*)&Mid<1>::n, "");
    static_assert(&Mid<0>::n == (int Mid<0>::*)&Base::n, "");
  }
  
  namespace ArrayBaseDerived {
  
    struct Base {
      constexpr Base() {}
      int n = 0;
    };
    struct Derived : Base {
      constexpr Derived() {}
      constexpr const int *f() { return &n; }
    };
  
    constexpr Derived a[10];
    constexpr Derived *pd3 = const_cast<Derived*>(&a[3]);
    constexpr Base *pb3 = const_cast<Derived*>(&a[3]);
    static_assert(pb3 == pd3, "");
  
    // pb3 does not point to an array element.
    constexpr Base *pb4 = pb3 + 1; // ok, one-past-the-end pointer.
    constexpr int pb4n = pb4->n; // expected-error {{constant expression}} expected-note {{cannot access field of pointer past the end}}
    constexpr Base *err_pb5 = pb3 + 2; // expected-error {{constant expression}} expected-note {{cannot refer to element 2}} expected-note {{here}}
    constexpr int err_pb5n = err_pb5->n; // expected-error {{constant expression}} expected-note {{initializer of 'err_pb5' is not a constant expression}}
    constexpr Base *err_pb2 = pb3 - 1; // expected-error {{constant expression}} expected-note {{cannot refer to element -1}} expected-note {{here}}
    constexpr int err_pb2n = err_pb2->n; // expected-error {{constant expression}} expected-note {{initializer of 'err_pb2'}}
    constexpr Base *pb3a = pb4 - 1;
  
    // pb4 does not point to a Derived.
    constexpr Derived *err_pd4 = (Derived*)pb4; // expected-error {{constant expression}} expected-note {{cannot access derived class of pointer past the end}}
    constexpr Derived *pd3a = (Derived*)pb3a;
    constexpr int pd3n = pd3a->n;
  
    // pd3a still points to the Derived array.
    constexpr Derived *pd6 = pd3a + 3;
    static_assert(pd6 == &a[6], "");
    constexpr Derived *pd9 = pd6 + 3;
    constexpr Derived *pd10 = pd6 + 4;
    constexpr int pd9n = pd9->n; // ok
    constexpr int err_pd10n = pd10->n; // expected-error {{constant expression}} expected-note {{cannot access base class of pointer past the end}}
    constexpr int pd0n = pd10[-10].n;
    constexpr int err_pdminus1n = pd10[-11].n; // expected-error {{constant expression}} expected-note {{cannot refer to element -1 of}}
  
    constexpr Base *pb9 = pd9;
    constexpr const int *(Base::*pfb)() const =
        static_cast<const int *(Base::*)() const>(&Derived::f);
    static_assert((pb9->*pfb)() == &a[9].n, "");
  }
  
  namespace Complex {
  
  class complex {
    int re, im;
  public:
    constexpr complex(int re = 0, int im = 0) : re(re), im(im) {}
    constexpr complex(const complex &o) : re(o.re), im(o.im) {}
    constexpr complex operator-() const { return complex(-re, -im); }
    friend constexpr complex operator+(const complex &l, const complex &r) {
      return complex(l.re + r.re, l.im + r.im);
    }
    friend constexpr complex operator-(const complex &l, const complex &r) {
      return l + -r;
    }
    friend constexpr complex operator*(const complex &l, const complex &r) {
      return complex(l.re * r.re - l.im * r.im, l.re * r.im + l.im * r.re);
    }
    friend constexpr bool operator==(const complex &l, const complex &r) {
      return l.re == r.re && l.im == r.im;
    }
    constexpr bool operator!=(const complex &r) const {
      return re != r.re || im != r.im;
    }
    constexpr int real() const { return re; }
    constexpr int imag() const { return im; }
  };
  
  constexpr complex i = complex(0, 1);
  constexpr complex k = (3 + 4*i) * (6 - 4*i);
  static_assert(complex(1,0).real() == 1, "");
  static_assert(complex(1,0).imag() == 0, "");
  static_assert(((complex)1).imag() == 0, "");
  static_assert(k.real() == 34, "");
  static_assert(k.imag() == 12, "");
  static_assert(k - 34 == 12*i, "");
  static_assert((complex)1 == complex(1), "");
  static_assert((complex)1 != complex(0, 1), "");
  static_assert(complex(1) == complex(1), "");
  static_assert(complex(1) != complex(0, 1), "");
  constexpr complex makeComplex(int re, int im) { return complex(re, im); }
  static_assert(makeComplex(1,0) == complex(1), "");
  static_assert(makeComplex(1,0) != complex(0, 1), "");
  
  class complex_wrap : public complex {
  public:
    constexpr complex_wrap(int re, int im = 0) : complex(re, im) {}
    constexpr complex_wrap(const complex_wrap &o) : complex(o) {}
  };
  
  static_assert((complex_wrap)1 == complex(1), "");
  static_assert((complex)1 != complex_wrap(0, 1), "");
  static_assert(complex(1) == complex_wrap(1), "");
  static_assert(complex_wrap(1) != complex(0, 1), "");
  constexpr complex_wrap makeComplexWrap(int re, int im) {
    return complex_wrap(re, im);
  }
  static_assert(makeComplexWrap(1,0) == complex(1), "");
  static_assert(makeComplexWrap(1,0) != complex(0, 1), "");
  
  }
  
  namespace PR11595 {
    struct A { constexpr bool operator==(int x) { return true; } };
    struct B { B(); A& x; };
    static_assert(B().x == 3, "");  // expected-error {{constant expression}} expected-note {{non-literal type 'PR11595::B' cannot be used in a constant expression}}
  
    constexpr bool f(int k) { // expected-error {{constexpr function never produces a constant expression}}
      return B().x == k; // expected-note {{non-literal type 'PR11595::B' cannot be used in a constant expression}}
    }
  }
  
  namespace ExprWithCleanups {
    struct A { A(); ~A(); int get(); };
    constexpr int get(bool FromA) { return FromA ? A().get() : 1; }
    constexpr int n = get(false);
  }
  
  namespace Volatile {
  
  volatile constexpr int n1 = 0; // expected-note {{here}}
  volatile const int n2 = 0; // expected-note {{here}}
  int n3 = 37; // expected-note {{declared here}}
  
  constexpr int m1 = n1; // expected-error {{constant expression}} expected-note {{read of volatile-qualified type 'const volatile int'}}
  constexpr int m2 = n2; // expected-error {{constant expression}} expected-note {{read of volatile-qualified type 'const volatile int'}}
  constexpr int m1b = const_cast<const int&>(n1); // expected-error {{constant expression}} expected-note {{read of volatile object 'n1'}}
  constexpr int m2b = const_cast<const int&>(n2); // expected-error {{constant expression}} expected-note {{read of volatile object 'n2'}}
  
  struct T { int n; };
  const T t = { 42 }; // expected-note {{declared here}}
  
  constexpr int f(volatile int &&r) {
    return r; // expected-note {{read of volatile-qualified type 'volatile int'}}
  }
  constexpr int g(volatile int &&r) {
    return const_cast<int&>(r); // expected-note {{read of volatile temporary is not allowed in a constant expression}}
  }
  struct S {
    int j : f(0); // expected-error {{constant expression}} expected-note {{in call to 'f(0)'}}
    int k : g(0); // expected-error {{constant expression}} expected-note {{temporary created here}} expected-note {{in call to 'g(0)'}}
    int l : n3; // expected-error {{constant expression}} expected-note {{read of non-const variable}}
    int m : t.n; // expected-error {{constant expression}} expected-note {{read of non-constexpr variable}}
  };
  
  }
  
  namespace ExternConstexpr {
    extern constexpr int n = 0;
    extern constexpr int m; // expected-error {{constexpr variable declaration must be a definition}}
    void f() {
      extern constexpr int i; // expected-error {{constexpr variable declaration must be a definition}}
      constexpr int j = 0;
      constexpr int k; // expected-error {{default initialization of an object of const type}}
    }
  }
  
  namespace ComplexConstexpr {
    constexpr _Complex float test1 = {};
    constexpr _Complex float test2 = {1};
    constexpr _Complex double test3 = {1,2};
    constexpr _Complex int test4 = {4};
    constexpr _Complex int test5 = 4;
    constexpr _Complex int test6 = {5,6};
    typedef _Complex float fcomplex;
    constexpr fcomplex test7 = fcomplex();
  
    constexpr const double &t2r = __real test3;
    constexpr const double &t2i = __imag test3;
    static_assert(&t2r + 1 == &t2i, "");
    static_assert(t2r == 1.0, "");
    static_assert(t2i == 2.0, "");
    constexpr const double *t2p = &t2r;
    static_assert(t2p[-1] == 0.0, ""); // expected-error {{constant expr}} expected-note {{cannot refer to element -1 of array of 2 elements}}
    static_assert(t2p[0] == 1.0, "");
    static_assert(t2p[1] == 2.0, "");
    static_assert(t2p[2] == 0.0, ""); // expected-error {{constant expr}} expected-note {{one-past-the-end pointer}}
    static_assert(t2p[3] == 0.0, ""); // expected-error {{constant expr}} expected-note {{cannot refer to element 3 of array of 2 elements}}
    constexpr _Complex float *p = 0;
    constexpr float pr = __real *p; // expected-error {{constant expr}} expected-note {{cannot access real component of null}}
    constexpr float pi = __imag *p; // expected-error {{constant expr}} expected-note {{cannot access imaginary component of null}}
    constexpr const _Complex double *q = &test3 + 1;
    constexpr double qr = __real *q; // expected-error {{constant expr}} expected-note {{cannot access real component of pointer past the end}}
    constexpr double qi = __imag *q; // expected-error {{constant expr}} expected-note {{cannot access imaginary component of pointer past the end}}
  
    static_assert(__real test6 == 5, "");
    static_assert(__imag test6 == 6, "");
    static_assert(&__imag test6 == &__real test6 + 1, "");
  }
  
  namespace InstantiateCaseStmt {
    template<int x> constexpr int f() { return x; }
    template<int x> int g(int c) { switch(c) { case f<x>(): return 1; } return 0; }
    int gg(int c) { return g<4>(c); }
  }
  
  namespace ConvertedConstantExpr {
    extern int &m;
    extern int &n;
  
    constexpr int k = 4;
    int &m = const_cast<int&>(k);
  
    // If we have nothing more interesting to say, ensure we don't produce a
    // useless note and instead just point to the non-constant subexpression.
    enum class E {
      em = m,
      en = n, // expected-error {{not a constant expression}}
      eo = (m +
            n // expected-error {{not a constant expression}}
            ),
      eq = reinterpret_cast<int>((int*)0) // expected-error {{not a constant expression}} expected-note {{reinterpret_cast}}
    };
  }
  
  namespace IndirectField {
    struct S {
      struct { // expected-warning {{GNU extension}}
        union {
          struct { // expected-warning {{GNU extension}}
            int a;
            int b;
          };
          int c;
        };
        int d;
      };
      union {
        int e;
        int f;
      };
      constexpr S(int a, int b, int d, int e) : a(a), b(b), d(d), e(e) {}
      constexpr S(int c, int d, int f) : c(c), d(d), f(f) {}
    };
  
    constexpr S s1(1, 2, 3, 4);
    constexpr S s2(5, 6, 7);
  
    // FIXME: The diagnostics here do a very poor job of explaining which unnamed
    // member is active and which is requested.
    static_assert(s1.a == 1, "");
    static_assert(s1.b == 2, "");
    static_assert(s1.c == 0, ""); // expected-error {{constant expression}} expected-note {{union with active member}}
    static_assert(s1.d == 3, "");
    static_assert(s1.e == 4, "");
    static_assert(s1.f == 0, ""); // expected-error {{constant expression}} expected-note {{union with active member}}
  
    static_assert(s2.a == 0, ""); // expected-error {{constant expression}} expected-note {{union with active member}}
    static_assert(s2.b == 0, ""); // expected-error {{constant expression}} expected-note {{union with active member}}
    static_assert(s2.c == 5, "");
    static_assert(s2.d == 6, "");
    static_assert(s2.e == 0, ""); // expected-error {{constant expression}} expected-note {{union with active member}}
    static_assert(s2.f == 7, "");
  }
  
  // DR1405: don't allow reading mutable members in constant expressions.
  namespace MutableMembers {
    struct MM {
      mutable int n; // expected-note 3{{declared here}}
    } constexpr mm = { 4 };
    constexpr int mmn = mm.n; // expected-error {{constant expression}} expected-note {{read of mutable member 'n' is not allowed in a constant expression}}
    int x = (mm.n = 1, 3);
    constexpr int mmn2 = mm.n; // expected-error {{constant expression}} expected-note {{read of mutable member 'n' is not allowed in a constant expression}}
  
    // Here's one reason why allowing this would be a disaster...
    template<int n> struct Id { int k = n; };
    int f() {
      constexpr MM m = { 0 };
      ++m.n;
      return Id<m.n>().k; // expected-error {{not a constant expression}} expected-note {{read of mutable member 'n' is not allowed in a constant expression}}
    }
  
    struct A { int n; };
    struct B { mutable A a; }; // expected-note {{here}}
    struct C { B b; };
    constexpr C c[3] = {};
    constexpr int k = c[1].b.a.n; // expected-error {{constant expression}} expected-note {{mutable}}
  }
  
  namespace Fold {
  
    // This macro forces its argument to be constant-folded, even if it's not
    // otherwise a constant expression.
    #define fold(x) (__builtin_constant_p(x) ? (x) : (x))
  
    constexpr int n = (int)(char*)123; // expected-error {{constant expression}} expected-note {{reinterpret_cast}}
    constexpr int m = fold((int)(char*)123); // ok
    static_assert(m == 123, "");
  
    #undef fold
  
  }
  
  namespace DR1454 {
  
  constexpr const int &f(const int &n) { return n; }
  constexpr int k1 = f(0); // ok
  
  struct Wrap {
    const int &value;
  };
  constexpr const Wrap &g(const Wrap &w) { return w; }
  constexpr int k2 = g({0}).value; // ok
  
  constexpr const int &i = 0; // expected-error {{constant expression}} expected-note {{temporary}} expected-note 2{{here}}
  constexpr const int j = i; // expected-error {{constant expression}} expected-note {{initializer of 'i' is not a constant expression}}
  
  }
  
  namespace RecursiveOpaqueExpr {
    template<typename Iter>
    constexpr auto LastNonzero(Iter p, Iter q) -> decltype(+*p) {
      return p != q ? (LastNonzero(p+1, q) ?: *p) : 0; // expected-warning {{GNU}}
    }
  
    constexpr int arr1[] = { 1, 0, 0, 3, 0, 2, 0, 4, 0, 0 };
    static_assert(LastNonzero(begin(arr1), end(arr1)) == 4, "");
  
    constexpr int arr2[] = { 1, 0, 0, 3, 0, 2, 0, 4, 0, 5 };
    static_assert(LastNonzero(begin(arr2), end(arr2)) == 5, "");
  
    constexpr int arr3[] = {
      1, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0,
      1, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0,
      1, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0,
      1, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0,
      1, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0,
      1, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0,
      1, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0,
      2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
    static_assert(LastNonzero(begin(arr3), end(arr3)) == 2, "");
  }
  
  namespace VLASizeof {
  
    void f(int k) {
      int arr[k]; // expected-warning {{C99}}
      constexpr int n = 1 +
          sizeof(arr) // expected-error {{constant expression}}
          * 3;
    }
  }
  
  namespace CompoundLiteral {
    // FIXME:
    // We don't model the semantics of this correctly: the compound literal is
    // represented as a prvalue in the AST, but actually behaves like an lvalue.
    // We treat the compound literal as a temporary and refuse to produce a
    // pointer to it. This is OK: we're not required to treat this as a constant
    // in C++, and in C we model compound literals as lvalues.
    constexpr int *p = (int*)(int[1]){0}; // expected-warning {{C99}} expected-error {{constant expression}} expected-note 2{{temporary}}
  }
  
  namespace Vector {
    typedef int __attribute__((vector_size(16))) VI4;
    constexpr VI4 f(int n) {
      return VI4 { n * 3, n + 4, n - 5, n / 6 };
    }
    constexpr auto v1 = f(10);
  
    typedef double __attribute__((vector_size(32))) VD4;
    constexpr VD4 g(int n) {
      return (VD4) { n / 2.0, n + 1.5, n - 5.4, n * 0.9 }; // expected-warning {{C99}}
    }
    constexpr auto v2 = g(4);
  }
  
  // PR12626, redux
  namespace InvalidClasses {
    void test0() {
      struct X; // expected-note {{forward declaration}}
      struct Y { bool b; X x; }; // expected-error {{field has incomplete type}}
      Y y;
      auto& b = y.b;
    }
  }
  
  // Constructors can be implicitly constexpr, even for a non-literal type.
  namespace ImplicitConstexpr {
    struct Q { Q() = default; Q(const Q&) = default; Q(Q&&) = default; ~Q(); }; // expected-note 3{{here}}
    struct R { constexpr R() noexcept; constexpr R(const R&) noexcept; constexpr R(R&&) noexcept; ~R() noexcept; };
    struct S { R r; }; // expected-note 3{{here}}
    struct T { T(const T&) noexcept; T(T &&) noexcept; ~T() noexcept; };
    struct U { T t; }; // expected-note 3{{here}}
    static_assert(!__is_literal_type(Q), "");
    static_assert(!__is_literal_type(R), "");
    static_assert(!__is_literal_type(S), "");
    static_assert(!__is_literal_type(T), "");
    static_assert(!__is_literal_type(U), "");
    struct Test {
      friend Q::Q() noexcept; // expected-error {{follows constexpr}}
      friend Q::Q(Q&&) noexcept; // expected-error {{follows constexpr}}
      friend Q::Q(const Q&) noexcept; // expected-error {{follows constexpr}}
      friend S::S() noexcept; // expected-error {{follows constexpr}}
      friend S::S(S&&) noexcept; // expected-error {{follows constexpr}}
      friend S::S(const S&) noexcept; // expected-error {{follows constexpr}}
      friend constexpr U::U() noexcept; // expected-error {{follows non-constexpr}}
      friend constexpr U::U(U&&) noexcept; // expected-error {{follows non-constexpr}}
      friend constexpr U::U(const U&) noexcept; // expected-error {{follows non-constexpr}}
    };
  }
  
  // Indirectly test that an implicit lvalue to xvalue conversion performed for
  // an NRVO move operation isn't implemented as CK_LValueToRValue.
  namespace PR12826 {
    struct Foo {};
    constexpr Foo id(Foo x) { return x; }
    constexpr Foo res(id(Foo()));
  }
  
  namespace PR13273 {
    struct U {
      int t;
      U() = default;
    };
  
    struct S : U {
      S() = default;
    };
  
    // S's default constructor isn't constexpr, because U's default constructor
    // doesn't initialize 't', but it's trivial, so value-initialization doesn't
    // actually call it.
    static_assert(S{}.t == 0, "");
  }
  
  namespace PR12670 {
    struct S {
      constexpr S(int a0) : m(a0) {}
      constexpr S() : m(6) {}
      int m;
    };
    constexpr S x[3] = { {4}, 5 };
    static_assert(x[0].m == 4, "");
    static_assert(x[1].m == 5, "");
    static_assert(x[2].m == 6, "");
  }
  
  // Indirectly test that an implicit lvalue-to-rvalue conversion is performed
  // when a conditional operator has one argument of type void and where the other
  // is a glvalue of class type.
  namespace ConditionalLValToRVal {
    struct A {
      constexpr A(int a) : v(a) {}
      int v;
    };
  
    constexpr A f(const A &a) {
      return a.v == 0 ? throw a : a;
    }
  
    constexpr A a(4);
    static_assert(f(a).v == 4, "");
  }
  
  namespace TLS {
    __thread int n;
    int m;
  
    constexpr bool b = &n == &n;
  
    constexpr int *p = &n; // expected-error{{constexpr variable 'p' must be initialized by a constant expression}}
  
    constexpr int *f() { return &n; }
    constexpr int *q = f(); // expected-error{{constexpr variable 'q' must be initialized by a constant expression}}
    constexpr bool c = f() == f();
  
    constexpr int *g() { return &m; }
    constexpr int *r = g();
  }
  