constant-expression-cxx11.cpp revision 6c95787b25c72a1c2421e349ef3459912362714a 
1// RUN: %clang_cc1 -triple i686-linux -fsyntax-only -verify -std=c++11 %s
2
3// This version of static_assert just requires a foldable value as the
4// expression, not an ICE.
5// FIXME: Once we implement the C++11 ICE rules, most uses of this here should
6// be converted to static_assert.
7#define static_assert_fold(expr, str) \
8    static_assert(__builtin_constant_p(expr), "not an integral constant expression"); \
9    static_assert(__builtin_constant_p(expr) ? expr : true, str)
10
11namespace StaticAssertFoldTest {
12
13int x;
14static_assert_fold(++x, "test"); // expected-error {{not an integral constant expression}}
15static_assert_fold(false, "test"); // expected-error {{test}}
16
17}
18
19// FIXME: support const T& parameters here.
20//template<typename T> constexpr T id(const T &t) { return t; }
21template<typename T> constexpr T id(T t) { return t; }
22// FIXME: support templates here.
23//template<typename T> constexpr T min(const T &a, const T &b) {
24//  return a < b ? a : b;
25//}
26//template<typename T> constexpr T max(const T &a, const T &b) {
27//  return a < b ? b : a;
28//}
29constexpr int min(const int &a, const int &b) { return a < b ? a : b; }
30constexpr int max(const int &a, const int &b) { return a < b ? b : a; }
31
32struct MemberZero {
33  constexpr int zero() { return 0; }
34};
35
36namespace DerivedToVBaseCast {
37
38  struct U { int n; };
39  struct V : U { int n; };
40  struct A : virtual V { int n; };
41  struct Aa { int n; };
42  struct B : virtual A, Aa {};
43  struct C : virtual A, Aa {};
44  struct D : B, C {};
45
46  D d;
47  constexpr B *p = &d;
48  constexpr C *q = &d;
49  static_assert_fold((void*)p != (void*)q, "");
50  static_assert_fold((A*)p == (A*)q, "");
51  static_assert_fold((Aa*)p != (Aa*)q, "");
52
53  constexpr B &pp = d;
54  constexpr C &qq = d;
55  static_assert_fold((void*)&pp != (void*)&qq, "");
56  static_assert_fold(&(A&)pp == &(A&)qq, "");
57  static_assert_fold(&(Aa&)pp != &(Aa&)qq, "");
58
59  constexpr V *v = p;
60  constexpr V *w = q;
61  constexpr V *x = (A*)p;
62  static_assert_fold(v == w, "");
63  static_assert_fold(v == x, "");
64
65  static_assert_fold((U*)&d == p, "");
66  static_assert_fold((U*)&d == q, "");
67  static_assert_fold((U*)&d == v, "");
68  static_assert_fold((U*)&d == w, "");
69  static_assert_fold((U*)&d == x, "");
70
71  struct X {};
72  struct Y1 : virtual X {};
73  struct Y2 : X {};
74  struct Z : Y1, Y2 {};
75  Z z;
76  static_assert_fold((X*)(Y1*)&z != (X*)(Y2*)&z, "");
77
78}
79
80namespace TemplateArgumentConversion {
81  template<int n> struct IntParam {};
82
83  using IntParam0 = IntParam<0>;
84  // FIXME: This should be accepted once we do constexpr function invocation.
85  using IntParam0 = IntParam<id(0)>; // expected-error {{not an integral constant expression}}
86  using IntParam0 = IntParam<MemberZero().zero>; // expected-error {{did you mean to call it with no arguments?}} expected-error {{not an integral constant expression}}
87}
88
89namespace CaseStatements {
90  void f(int n) {
91    switch (n) {
92    // FIXME: Produce the 'add ()' fixit for this.
93    case MemberZero().zero: // desired-error {{did you mean to call it with no arguments?}} expected-error {{not an integer constant expression}}
94    // FIXME: This should be accepted once we do constexpr function invocation.
95    case id(1): // expected-error {{not an integer constant expression}}
96      return;
97    }
98  }
99}
100
101extern int &Recurse1;
102int &Recurse2 = Recurse1, &Recurse1 = Recurse2;
103constexpr int &Recurse3 = Recurse2; // expected-error {{must be initialized by a constant expression}}
104
105namespace MemberEnum {
106  struct WithMemberEnum {
107    enum E { A = 42 };
108  } wme;
109
110  static_assert_fold(wme.A == 42, "");
111}
112
113namespace DefaultArguments {
114
115const int z = int();
116constexpr int Sum(int a = 0, const int &b = 0, const int *c = &z, char d = 0) {
117  return a + b + *c + d;
118}
119const int four = 4;
120constexpr int eight = 8;
121constexpr const int twentyseven = 27;
122static_assert_fold(Sum() == 0, "");
123static_assert_fold(Sum(1) == 1, "");
124static_assert_fold(Sum(1, four) == 5, "");
125static_assert_fold(Sum(1, eight, &twentyseven) == 36, "");
126static_assert_fold(Sum(1, 2, &four, eight) == 15, "");
127
128}
129
130namespace Ellipsis {
131
132// Note, values passed through an ellipsis can't actually be used.
133constexpr int F(int a, ...) { return a; }
134static_assert_fold(F(0) == 0, "");
135static_assert_fold(F(1, 0) == 1, "");
136static_assert_fold(F(2, "test") == 2, "");
137static_assert_fold(F(3, &F) == 3, "");
138int k = 0;
139static_assert_fold(F(4, k) == 3, ""); // expected-error {{constant expression}}
140
141}
142
143namespace Recursion {
144  constexpr int fib(int n) { return n > 1 ? fib(n-1) + fib(n-2) : n; }
145  static_assert_fold(fib(11) == 89, "");
146
147  constexpr int gcd_inner(int a, int b) {
148    return b == 0 ? a : gcd_inner(b, a % b);
149  }
150  constexpr int gcd(int a, int b) {
151    return gcd_inner(max(a, b), min(a, b));
152  }
153
154  static_assert_fold(gcd(1749237, 5628959) == 7, "");
155}
156
157namespace FunctionCast {
158  // When folding, we allow functions to be cast to different types. Such
159  // cast functions cannot be called, even if they're constexpr.
160  constexpr int f() { return 1; }
161  typedef double (*DoubleFn)();
162  typedef int (*IntFn)();
163  int a[(int)DoubleFn(f)()]; // expected-error {{variable length array}}
164  int b[(int)IntFn(f)()];    // ok
165}
166
167namespace StaticMemberFunction {
168  struct S {
169    static constexpr int k = 42;
170    static constexpr int f(int n) { return n * k + 2; }
171  } s;
172
173  constexpr int n = s.f(19);
174  static_assert_fold(S::f(19) == 800, "");
175  static_assert_fold(s.f(19) == 800, "");
176  static_assert_fold(n == 800, "");
177}
178
179namespace ParameterScopes {
180
181  const int k = 42;
182  constexpr const int &ObscureTheTruth(const int &a) { return a; }
183  constexpr const int &MaybeReturnJunk(bool b, const int a) {
184    return ObscureTheTruth(b ? a : k);
185  }
186  static_assert_fold(MaybeReturnJunk(false, 0) == 42, ""); // ok
187  constexpr int a = MaybeReturnJunk(true, 0); // expected-error {{constant expression}}
188
189  constexpr const int MaybeReturnNonstaticRef(bool b, const int a) {
190    // If ObscureTheTruth returns a reference to 'a', the result is not a
191    // constant expression even though 'a' is still in scope.
192    return ObscureTheTruth(b ? a : k);
193  }
194  static_assert_fold(MaybeReturnNonstaticRef(false, 0) == 42, ""); // ok
195  constexpr int b = MaybeReturnNonstaticRef(true, 0); // expected-error {{constant expression}}
196
197  constexpr int InternalReturnJunk(int n) {
198    // FIXME: We should reject this: it never produces a constant expression.
199    return MaybeReturnJunk(true, n);
200  }
201  constexpr int n3 = InternalReturnJunk(0); // expected-error {{must be initialized by a constant expression}}
202
203  constexpr int LToR(int &n) { return n; }
204  constexpr int GrabCallersArgument(bool which, int a, int b) {
205    return LToR(which ? b : a);
206  }
207  static_assert_fold(GrabCallersArgument(false, 1, 2) == 1, "");
208  static_assert_fold(GrabCallersArgument(true, 4, 8) == 8, "");
209
210}
211
212namespace Pointers {
213
214  constexpr int f(int n, const int *a, const int *b, const int *c) {
215    return n == 0 ? 0 : *a + f(n-1, b, c, a);
216  }
217
218  const int x = 1, y = 10, z = 100;
219  static_assert_fold(f(23, &x, &y, &z) == 788, "");
220
221  constexpr int g(int n, int a, int b, int c) {
222    return f(n, &a, &b, &c);
223  }
224  static_assert_fold(g(23, x, y, z) == 788, "");
225
226}
227
228namespace FunctionPointers {
229
230  constexpr int Double(int n) { return 2 * n; }
231  constexpr int Triple(int n) { return 3 * n; }
232  constexpr int Twice(int (*F)(int), int n) { return F(F(n)); }
233  constexpr int Quadruple(int n) { return Twice(Double, n); }
234  constexpr auto Select(int n) -> int (*)(int) {
235    return n == 2 ? &Double : n == 3 ? &Triple : n == 4 ? &Quadruple : 0;
236  }
237  constexpr int Apply(int (*F)(int), int n) { return F(n); }
238
239  static_assert_fold(1 + Apply(Select(4), 5) + Apply(Select(3), 7) == 42, "");
240
241  constexpr int Invalid = Apply(Select(0), 0); // expected-error {{must be initialized by a constant expression}}
242
243}
244
245namespace PointerComparison {
246
247int x, y;
248static_assert_fold(&x == &y, "false"); // expected-error {{false}}
249static_assert_fold(&x != &y, "");
250constexpr bool g1 = &x == &y;
251constexpr bool g2 = &x != &y;
252constexpr bool g3 = &x <= &y; // expected-error {{must be initialized by a constant expression}}
253constexpr bool g4 = &x >= &y; // expected-error {{must be initialized by a constant expression}}
254constexpr bool g5 = &x < &y; // expected-error {{must be initialized by a constant expression}}
255constexpr bool g6 = &x > &y; // expected-error {{must be initialized by a constant expression}}
256
257struct S { int x, y; } s;
258static_assert_fold(&s.x == &s.y, "false"); // expected-error {{false}}
259static_assert_fold(&s.x != &s.y, "");
260static_assert_fold(&s.x <= &s.y, "");
261static_assert_fold(&s.x >= &s.y, "false"); // expected-error {{false}}
262static_assert_fold(&s.x < &s.y, "");
263static_assert_fold(&s.x > &s.y, "false"); // expected-error {{false}}
264
265static_assert_fold(0 == &y, "false"); // expected-error {{false}}
266static_assert_fold(0 != &y, "");
267constexpr bool n3 = 0 <= &y; // expected-error {{must be initialized by a constant expression}}
268constexpr bool n4 = 0 >= &y; // expected-error {{must be initialized by a constant expression}}
269constexpr bool n5 = 0 < &y; // expected-error {{must be initialized by a constant expression}}
270constexpr bool n6 = 0 > &y; // expected-error {{must be initialized by a constant expression}}
271
272static_assert_fold(&x == 0, "false"); // expected-error {{false}}
273static_assert_fold(&x != 0, "");
274constexpr bool n9 = &x <= 0; // expected-error {{must be initialized by a constant expression}}
275constexpr bool n10 = &x >= 0; // expected-error {{must be initialized by a constant expression}}
276constexpr bool n11 = &x < 0; // expected-error {{must be initialized by a constant expression}}
277constexpr bool n12 = &x > 0; // expected-error {{must be initialized by a constant expression}}
278
279static_assert_fold(&x == &x, "");
280static_assert_fold(&x != &x, "false"); // expected-error {{false}}
281static_assert_fold(&x <= &x, "");
282static_assert_fold(&x >= &x, "");
283static_assert_fold(&x < &x, "false"); // expected-error {{false}}
284static_assert_fold(&x > &x, "false"); // expected-error {{false}}
285
286constexpr S* sptr = &s;
287// FIXME: This is not a constant expression; check we reject this and move this
288// test elsewhere.
289constexpr bool dyncast = sptr == dynamic_cast<S*>(sptr);
290
291extern char externalvar[];
292// FIXME: This is not a constant expression; check we reject this and move this
293// test elsewhere.
294constexpr bool constaddress = (void *)externalvar == (void *)0x4000UL;  // expected-error {{must be initialized by a constant expression}}
295constexpr bool litaddress = "foo" == "foo"; // expected-error {{must be initialized by a constant expression}} expected-warning {{unspecified}}
296static_assert_fold(0 != "foo", "");
297
298}
299
300namespace MaterializeTemporary {
301
302constexpr int f(const int &r) { return r; }
303constexpr int n = f(1);
304
305constexpr bool same(const int &a, const int &b) { return &a == &b; }
306constexpr bool sameTemporary(const int &n) { return same(n, n); }
307
308static_assert_fold(n, "");
309static_assert_fold(!same(4, 4), "");
310static_assert_fold(same(n, n), "");
311static_assert_fold(sameTemporary(9), "");
312
313}
314
315constexpr int strcmp_ce(const char *p, const char *q) {
316  return (!*p || *p != *q) ? *p - *q : strcmp_ce(p+1, q+1);
317}
318
319namespace StringLiteral {
320
321// FIXME: Refactor this once we support constexpr templates.
322constexpr int MangleChars(const char *p) {
323  return *p + 3 * (*p ? MangleChars(p+1) : 0);
324}
325constexpr int MangleChars(const char16_t *p) {
326  return *p + 3 * (*p ? MangleChars(p+1) : 0);
327}
328constexpr int MangleChars(const char32_t *p) {
329  return *p + 3 * (*p ? MangleChars(p+1) : 0);
330}
331
332static_assert_fold(MangleChars("constexpr!") == 1768383, "");
333static_assert_fold(MangleChars(u"constexpr!") == 1768383, "");
334static_assert_fold(MangleChars(U"constexpr!") == 1768383, "");
335
336constexpr char c0 = "nought index"[0];
337constexpr char c1 = "nice index"[10];
338constexpr char c2 = "nasty index"[12]; // expected-error {{must be initialized by a constant expression}} expected-warning {{indexes past the end}}
339constexpr char c3 = "negative index"[-1]; // expected-error {{must be initialized by a constant expression}} expected-warning {{indexes before the beginning}}
340constexpr char c4 = ((char*)(int*)"no reinterpret_casts allowed")[14]; // expected-error {{must be initialized by a constant expression}}
341
342constexpr const char *p = "test" + 2;
343static_assert_fold(*p == 's', "");
344
345constexpr const char *max_iter(const char *a, const char *b) {
346  return *a < *b ? b : a;
347}
348constexpr const char *max_element(const char *a, const char *b) {
349  return (a+1 >= b) ? a : max_iter(a, max_element(a+1, b));
350}
351
352constexpr const char *begin(const char (&arr)[45]) { return arr; }
353constexpr const char *end(const char (&arr)[45]) { return arr + 45; }
354
355constexpr char str[] = "the quick brown fox jumped over the lazy dog";
356constexpr const char *max = max_element(begin(str), end(str));
357static_assert_fold(*max == 'z', "");
358static_assert_fold(max == str + 38, "");
359
360static_assert_fold(strcmp_ce("hello world", "hello world") == 0, "");
361static_assert_fold(strcmp_ce("hello world", "hello clang") > 0, "");
362static_assert_fold(strcmp_ce("constexpr", "test") < 0, "");
363static_assert_fold(strcmp_ce("", " ") < 0, "");
364
365}
366
367namespace Array {
368
369// FIXME: Use templates for these once we support constexpr templates.
370constexpr int Sum(const int *begin, const int *end) {
371  return begin == end ? 0 : *begin + Sum(begin+1, end);
372}
373constexpr const int *begin(const int (&xs)[5]) { return xs; }
374constexpr const int *end(const int (&xs)[5]) { return xs + 5; }
375
376constexpr int xs[] = { 1, 2, 3, 4, 5 };
377constexpr int ys[] = { 5, 4, 3, 2, 1 };
378constexpr int sum_xs = Sum(begin(xs), end(xs));
379static_assert_fold(sum_xs == 15, "");
380
381constexpr int ZipFoldR(int (*F)(int x, int y, int c), int n,
382                       const int *xs, const int *ys, int c) {
383  return n ? F(*xs, *ys, ZipFoldR(F, n-1, xs+1, ys+1, c)) : c;
384}
385constexpr int MulAdd(int x, int y, int c) { return x * y + c; }
386constexpr int InnerProduct = ZipFoldR(MulAdd, 5, xs, ys, 0);
387static_assert_fold(InnerProduct == 35, "");
388
389constexpr int SubMul(int x, int y, int c) { return (x - y) * c; }
390constexpr int DiffProd = ZipFoldR(SubMul, 2, xs+3, ys+3, 1);
391static_assert_fold(DiffProd == 8, "");
392static_assert_fold(ZipFoldR(SubMul, 3, xs+3, ys+3, 1), ""); // expected-error {{constant expression}}
393
394constexpr const int *p = xs + 3;
395constexpr int xs4 = p[1]; // ok
396constexpr int xs5 = p[2]; // expected-error {{constant expression}}
397constexpr int xs0 = p[-3]; // ok
398constexpr int xs_1 = p[-4]; // expected-error {{constant expression}}
399
400constexpr int zs[2][2][2][2] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 };
401static_assert_fold(zs[0][0][0][0] == 1, "");
402static_assert_fold(zs[1][1][1][1] == 16, "");
403static_assert_fold(zs[0][0][0][2] == 3, ""); // expected-error {{constant expression}}
404static_assert_fold((&zs[0][0][0][2])[-1] == 2, "");
405static_assert_fold(**(**(zs + 1) + 1) == 11, "");
406static_assert_fold(*(&(&(*(*&(&zs[2] - 1)[0] + 2 - 2))[2])[-1][-1] + 1) == 11, "");
407
408constexpr int arr[40] = { 1, 2, 3, [8] = 4 };
409constexpr int SumNonzero(const int *p) {
410  return *p + (*p ? SumNonzero(p+1) : 0);
411}
412constexpr int CountZero(const int *p, const int *q) {
413  return p == q ? 0 : (*p == 0) + CountZero(p+1, q);
414}
415static_assert_fold(SumNonzero(arr) == 6, "");
416static_assert_fold(CountZero(arr, arr + 40) == 36, "");
417
418}
419
420namespace DependentValues {
421
422struct I { int n; typedef I V[10]; };
423I::V x, y;
424template<bool B> struct S {
425  int k;
426  void f() {
427    I::V &cells = B ? x : y;
428    I &i = cells[k];
429    switch (i.n) {}
430  }
431};
432
433}
434
435namespace Class {
436
437struct A { constexpr A(int a, int b) : k(a + b) {} int k; };
438constexpr int fn(const A &a) { return a.k; }
439static_assert_fold(fn(A(4,5)) == 9, "");
440
441struct B { int n; int m; } constexpr b = { 0, b.n }; // expected-warning {{uninitialized}}
442struct C {
443  constexpr C(C *this_) : m(42), n(this_->m) {} // ok
444  int m, n;
445};
446struct D {
447  C c;
448  constexpr D() : c(&c) {}
449};
450static_assert_fold(D().c.n == 42, "");
451
452struct E {
453  constexpr E() : p(&p) {}
454  void *p;
455};
456constexpr const E &e1 = E(); // expected-error {{constant expression}}
457// This is a constant expression if we elide the copy constructor call, and
458// is not a constant expression if we don't! But we do, so it is.
459// FIXME: The move constructor is not currently implicitly defined as constexpr.
460// We notice this when evaluating an expression which uses it, but not when
461// checking its initializer.
462constexpr E e2 = E(); // unexpected-error {{constant expression}}
463static_assert_fold(e2.p == &e2.p, ""); // unexpected-error {{constant expression}}
464// FIXME: We don't pass through the fact that 'this' is ::e3 when checking the
465// initializer of this declaration.
466constexpr E e3; // unexpected-error {{constant expression}}
467static_assert_fold(e3.p == &e3.p, "");
468
469extern const class F f;
470struct F {
471  constexpr F() : p(&f.p) {}
472  const void *p;
473};
474constexpr F f = F();
475
476struct G {
477  struct T {
478    constexpr T(T *p) : u1(), u2(p) {}
479    union U1 {
480      constexpr U1() {}
481      int a, b = 42;
482    } u1;
483    union U2 {
484      constexpr U2(T *p) : c(p->u1.b) {}
485      int c, d;
486    } u2;
487  } t;
488  constexpr G() : t(&t) {}
489} constexpr g;
490
491static_assert_fold(g.t.u1.a == 42, ""); // expected-error {{constant expression}}
492static_assert_fold(g.t.u1.b == 42, "");
493static_assert_fold(g.t.u2.c == 42, "");
494static_assert_fold(g.t.u2.d == 42, ""); // expected-error {{constant expression}}
495
496struct S {
497  int a, b;
498  const S *p;
499  double d;
500  const char *q;
501
502  constexpr S(int n, const S *p) : a(5), b(n), p(p), d(n), q("hello") {}
503};
504
505S global(43, &global);
506
507static_assert_fold(S(15, &global).b == 15, "");
508
509constexpr bool CheckS(const S &s) {
510  return s.a == 5 && s.b == 27 && s.p == &global && s.d == 27. && s.q[3] == 'l';
511}
512static_assert_fold(CheckS(S(27, &global)), "");
513
514struct Arr {
515  char arr[3];
516  constexpr Arr() : arr{'x', 'y', 'z'} {}
517};
518constexpr int hash(Arr &&a) {
519  return a.arr[0] + a.arr[1] * 0x100 + a.arr[2] * 0x10000;
520}
521constexpr int k = hash(Arr());
522static_assert_fold(k == 0x007a7978, "");
523
524
525struct AggregateInit {
526  const char &c;
527  int n;
528  double d;
529  int arr[5];
530  void *p;
531};
532
533constexpr AggregateInit agg1 = { "hello"[0] };
534
535static_assert_fold(strcmp_ce(&agg1.c, "hello") == 0, "");
536static_assert_fold(agg1.n == 0, "");
537static_assert_fold(agg1.d == 0.0, "");
538static_assert_fold(agg1.arr[-1] == 0, ""); // expected-error {{constant expression}}
539static_assert_fold(agg1.arr[0] == 0, "");
540static_assert_fold(agg1.arr[4] == 0, "");
541static_assert_fold(agg1.arr[5] == 0, ""); // expected-error {{constant expression}}
542static_assert_fold(agg1.p == nullptr, "");
543
544namespace SimpleDerivedClass {
545
546struct B {
547  constexpr B(int n) : a(n) {}
548  int a;
549};
550struct D : B {
551  constexpr D(int n) : B(n) {}
552};
553constexpr D d(3);
554static_assert_fold(d.a == 3, "");
555
556}
557
558struct Base {
559  constexpr Base(int a = 42, const char *b = "test") : a(a), b(b) {}
560  int a;
561  const char *b;
562};
563struct Base2 {
564  constexpr Base2(const int &r) : r(r) {}
565  int q = 123;
566  // FIXME: When we track the global for which we are computing the initializer,
567  // use a reference here.
568  //const int &r;
569  int r;
570};
571struct Derived : Base, Base2 {
572  constexpr Derived() : Base(76), Base2(a) {}
573  int c = r + b[1];
574};
575
576constexpr bool operator==(const Base &a, const Base &b) {
577  return a.a == b.a && strcmp_ce(a.b, b.b) == 0;
578}
579
580constexpr Base base;
581constexpr Base base2(76);
582constexpr Derived derived;
583static_assert_fold(derived.a == 76, "");
584static_assert_fold(derived.b[2] == 's', "");
585static_assert_fold(derived.c == 76 + 'e', "");
586static_assert_fold(derived.q == 123, "");
587static_assert_fold(derived.r == 76, "");
588static_assert_fold(&derived.r == &derived.a, ""); // expected-error {{}}
589
590static_assert_fold(!(derived == base), "");
591static_assert_fold(derived == base2, "");
592
593}
594
595namespace Union {
596
597union U {
598  int a;
599  int b;
600};
601
602constexpr U u[4] = { { .a = 0 }, { .b = 1 }, { .a = 2 }, { .b = 3 } };
603static_assert_fold(u[0].a == 0, "");
604static_assert_fold(u[0].b, ""); // expected-error {{constant expression}}
605static_assert_fold(u[1].b == 1, "");
606static_assert_fold((&u[1].b)[1] == 2, ""); // expected-error {{constant expression}}
607static_assert_fold(*(&(u[1].b) + 1 + 1) == 3, ""); // expected-error {{constant expression}}
608static_assert_fold((&(u[1]) + 1 + 1)->b == 3, "");
609
610}
611
612namespace Complex {
613
614class complex {
615  int re, im;
616public:
617  constexpr complex(int re = 0, int im = 0) : re(re), im(im) {}
618  constexpr complex(const complex &o) : re(o.re), im(o.im) {}
619  constexpr complex operator-() const { return complex(-re, -im); }
620  friend constexpr complex operator+(const complex &l, const complex &r) {
621    return complex(l.re + r.re, l.im + r.im);
622  }
623  friend constexpr complex operator-(const complex &l, const complex &r) {
624    return l + -r;
625  }
626  friend constexpr complex operator*(const complex &l, const complex &r) {
627    return complex(l.re * r.re - l.im * r.im, l.re * r.im + l.im * r.re);
628  }
629  friend constexpr bool operator==(const complex &l, const complex &r) {
630    return l.re == r.re && l.im == r.im;
631  }
632  constexpr int real() const { return re; }
633  constexpr int imag() const { return im; }
634};
635
636constexpr complex i = complex(0, 1);
637constexpr complex k = (3 + 4*i) * (6 - 4*i);
638static_assert_fold(k.real() == 34, "");
639static_assert_fold(k.imag() == 12, "");
640static_assert_fold(k - 34 == 12*i, "");
641
642}
643