1 // RUN: %clang_cc1 -std=c++1y -verify %s -fcxx-exceptions -triple=x86_64-linux-gnu
4 // dummy ctor to make this a literal type
11 constexpr int &get(int n) { return arr[n]; }
12 constexpr const int &get(int n) const { return arr[n]; }
17 static_assert(&s.get(4) - &sr.get(2) == 2, "");
19 // Compound-statements can be used in constexpr functions.
20 constexpr int e() {{{{}} return 5; }}
21 static_assert(e() == 5, "");
23 // Types can be defined in constexpr functions.
25 enum E { e1, e2, e3 };
28 constexpr S(E e) : e(e) {}
29 constexpr int get() { return e; }
35 static_assert(f() == 1, "");
37 // Variables can be declared in constexpr functions.
38 constexpr int g(int k) {
42 return 3 * k3 + 5 * k2 + n * k - 20;
44 static_assert(g(2) == 42, "");
45 constexpr int h(int n) {
46 static const int m = n; // expected-error {{static variable not permitted in a constexpr function}}
49 constexpr int i(int n) {
50 thread_local const int m = n; // expected-error {{thread_local variable not permitted in a constexpr function}}
54 // if-statements can be used in constexpr functions.
55 constexpr int j(int k) {
61 if (int n = 2 * k - 4) {
66 } // expected-note 2{{control reached end of constexpr function}}
67 static_assert(j(0) == -3, "");
68 static_assert(j(1) == 5, "");
69 static_assert(j(2), ""); // expected-error {{constant expression}} expected-note {{in call to 'j(2)'}}
70 static_assert(j(3) == 3, "");
71 static_assert(j(4) == 5, "");
72 static_assert(j(5) == 1, "");
74 // There can be 0 return-statements.
78 // If the return type is not 'void', no return statements => never a constant
79 // expression, so still diagnose that case.
80 [[noreturn]] constexpr int fn() { // expected-error {{no return statement in constexpr function}}
84 // We evaluate the body of a constexpr constructor, to check for side-effects.
87 if (j(n)) {} // expected-note {{in call to 'j(2)'}}
91 constexpr U u2{2}; // expected-error {{constant expression}} expected-note {{in call to 'U(2)'}}
93 // We allow expression-statements.
94 constexpr int l(bool b) {
96 throw "invalid value for b!"; // expected-note {{subexpression not valid}}
99 static_assert(l(false) == 5, "");
100 static_assert(l(true), ""); // expected-error {{constant expression}} expected-note {{in call to 'l(true)'}}
102 // Potential constant expression checking is still applied where possible.
103 constexpr int htonl(int x) { // expected-error {{never produces a constant expression}}
104 typedef unsigned char uchar;
105 uchar arr[4] = { uchar(x >> 24), uchar(x >> 16), uchar(x >> 8), uchar(x) };
106 return *reinterpret_cast<int*>(arr); // expected-note {{reinterpret_cast is not allowed in a constant expression}}
109 constexpr int maybe_htonl(bool isBigEndian, int x) {
113 typedef unsigned char uchar;
114 uchar arr[4] = { uchar(x >> 24), uchar(x >> 16), uchar(x >> 8), uchar(x) };
115 return *reinterpret_cast<int*>(arr); // expected-note {{reinterpret_cast is not allowed in a constant expression}}
118 constexpr int swapped = maybe_htonl(false, 123); // expected-error {{constant expression}} expected-note {{in call}}
123 constexpr int namespace_alias() {
131 int c = 0; // expected-note {{here}}
133 constexpr void set(const int &a, int b) {
134 const_cast<int&>(a) = b; // expected-note 3{{constant expression cannot modify an object that is visible outside that expression}}
136 constexpr int wrap(int a, int b) {
141 static_assert((set(a, 1), a) == 1, ""); // expected-error {{constant expression}} expected-note {{in call to 'set(a, 1)'}}
142 static_assert((set(b, 1), b) == 1, ""); // expected-error {{constant expression}} expected-note {{in call to 'set(b, 1)'}}
143 static_assert((set(c, 1), c) == 1, ""); // expected-error {{constant expression}} expected-note {{in call to 'set(c, 1)'}}
145 static_assert(wrap(a, 1) == 1, "");
146 static_assert(wrap(b, 1) == 1, "");
147 static_assert(wrap(c, 1) == 1, ""); // expected-error {{constant expression}} expected-note {{read of non-const variable 'c'}}
150 namespace string_assign {
152 constexpr void swap(T &a, T &b) {
157 template<typename Iterator>
158 constexpr void reverse(Iterator begin, Iterator end) {
159 while (begin != end && begin != --end)
160 swap(*begin++, *end);
162 template<typename Iterator1, typename Iterator2>
163 constexpr bool equal(Iterator1 a, Iterator1 ae, Iterator2 b, Iterator2 be) {
164 while (a != ae && b != be)
167 return a == ae && b == be;
169 constexpr bool test1(int n) {
170 char stuff[100] = "foobarfoo";
171 const char stuff2[100] = "oofraboof";
172 reverse(stuff, stuff + n); // expected-note {{cannot refer to element 101 of array of 100 elements}}
173 return equal(stuff, stuff + n, stuff2, stuff2 + n);
175 static_assert(!test1(1), "");
176 static_assert(test1(3), "");
177 static_assert(!test1(6), "");
178 static_assert(test1(9), "");
179 static_assert(!test1(100), "");
180 static_assert(!test1(101), ""); // expected-error {{constant expression}} expected-note {{in call to 'test1(101)'}}
182 constexpr void f() { // expected-error{{constexpr function never produces a constant expression}} expected-note@+2{{assignment to dereferenced one-past-the-end pointer is not allowed in a constant expression}}
183 char foo[10] = { "z" }; // expected-note {{here}}
184 foo[10] = 'x'; // expected-warning {{past the end}}
188 namespace array_resize {
189 constexpr int do_stuff(int k1, int k2) {
190 int arr[1234] = { 1, 2, 3, 4 };
191 arr[k1] = 5; // expected-note {{past-the-end}} expected-note {{cannot refer to element 1235}} expected-note {{cannot refer to element -1}}
194 static_assert(do_stuff(1, 2) == 3, "");
195 static_assert(do_stuff(0, 0) == 5, "");
196 static_assert(do_stuff(1233, 1233) == 5, "");
197 static_assert(do_stuff(1233, 0) == 1, "");
198 static_assert(do_stuff(1234, 0) == 1, ""); // expected-error {{constant expression}} expected-note {{in call}}
199 static_assert(do_stuff(1235, 0) == 1, ""); // expected-error {{constant expression}} expected-note {{in call}}
200 static_assert(do_stuff(-1, 0) == 1, ""); // expected-error {{constant expression}} expected-note {{in call}}
203 namespace potential_const_expr {
204 constexpr void set(int &n) { n = 1; }
205 constexpr int div_zero_1() { int z = 0; set(z); return 100 / z; } // no error
206 constexpr int div_zero_2() { // expected-error {{never produces a constant expression}}
208 return 100 / (set(z), 0); // expected-note {{division by zero}}
210 int n; // expected-note {{declared here}}
211 constexpr int ref() { // expected-error {{never produces a constant expression}}
213 return r; // expected-note {{read of non-const variable 'n'}}
217 namespace subobject {
218 union A { constexpr A() : y(5) {} int x, y; };
221 union D { constexpr D() : c() {} constexpr D(int n) : n(n) {} C c; int n; };
222 constexpr void f(D &d) {
224 // expected-note@-1 {{cannot modify an object that is visible outside}}
225 // expected-note@-2 {{assignment to member 'c' of union with active member 'n'}}
227 constexpr bool check(D &d) { return d.c.a.y == 3; }
229 constexpr bool g() { D d; f(d); return d.c.a.y == 3; }
230 static_assert(g(), "");
233 constexpr bool h() { f(d); return check(d); } // expected-note {{in call}}
234 static_assert(h(), ""); // expected-error {{constant expression}} expected-note {{in call}}
236 constexpr bool i() { D d(0); f(d); return check(d); } // expected-note {{in call}}
237 static_assert(i(), ""); // expected-error {{constant expression}} expected-note {{in call}}
239 constexpr bool j() { D d; d.c.a.x = 3; return check(d); } // expected-note {{assignment to member 'x' of union with active member 'y'}}
240 static_assert(j(), ""); // expected-error {{constant expression}} expected-note {{in call}}
244 constexpr int &&id(int &&n) { return static_cast<int&&>(n); }
245 constexpr int &&dead() { return id(0); } // expected-note {{temporary created here}}
246 constexpr int bad() { int &&n = dead(); n = 1; return n; } // expected-note {{assignment to temporary whose lifetime has ended}}
247 static_assert(bad(), ""); // expected-error {{constant expression}} expected-note {{in call}}
250 namespace const_modify {
251 constexpr int modify(int &n) { return n = 1; } // expected-note 2 {{modification of object of const-qualified type 'const int'}}
252 constexpr int test1() { int k = 0; return modify(k); }
253 constexpr int test2() { const int k = 0; return modify(const_cast<int&>(k)); } // expected-note 2 {{in call}}
254 static_assert(test1() == 1, "");
255 static_assert(test2() == 1, ""); // expected-error {{constant expression}} expected-note {{in call}}
256 constexpr int i = test2(); // expected-error {{constant expression}} expected-note {{in call}}
260 constexpr int test(int *p) {
261 return *p = 123; // expected-note {{assignment to dereferenced null pointer}}
263 static_assert(test(0), ""); // expected-error {{constant expression}} expected-note {{in call}}
267 template<typename T> constexpr T &ref(T &&r) { return r; }
268 template<typename T> constexpr T postinc(T &&r) { return (r++, r); }
269 template<typename T> constexpr T postdec(T &&r) { return (r--, r); }
271 static_assert(++ref(0) == 1, "");
272 static_assert(ref(0)++ == 0, "");
273 static_assert(postinc(0) == 1, "");
274 static_assert(--ref(0) == -1, "");
275 static_assert(ref(0)-- == 0, "");
276 static_assert(postdec(0) == -1, "");
278 constexpr int overflow_int_inc_1 = ref(0x7fffffff)++; // expected-error {{constant}} expected-note {{2147483648}}
279 constexpr int overflow_int_inc_1_ok = ref(0x7ffffffe)++;
280 constexpr int overflow_int_inc_2 = ++ref(0x7fffffff); // expected-error {{constant}} expected-note {{2147483648}}
281 constexpr int overflow_int_inc_2_ok = ++ref(0x7ffffffe);
283 // inc/dec on short can't overflow because we promote to int first
284 static_assert(++ref<short>(0x7fff) == (int)0xffff8000u, "");
285 static_assert(--ref<short>(0x8000) == 0x7fff, "");
287 // inc on bool sets to true
288 static_assert(++ref(false), ""); // expected-warning {{deprecated}}
289 static_assert(++ref(true), ""); // expected-warning {{deprecated}}
292 static_assert(++ref(&arr[0]) == &arr[1], "");
293 static_assert(++ref(&arr[9]) == &arr[10], "");
294 static_assert(++ref(&arr[10]) == &arr[11], ""); // expected-error {{constant}} expected-note {{cannot refer to element 11}}
295 static_assert(ref(&arr[0])++ == &arr[0], "");
296 static_assert(ref(&arr[10])++ == &arr[10], ""); // expected-error {{constant}} expected-note {{cannot refer to element 11}}
297 static_assert(postinc(&arr[0]) == &arr[1], "");
298 static_assert(--ref(&arr[10]) == &arr[9], "");
299 static_assert(--ref(&arr[1]) == &arr[0], "");
300 static_assert(--ref(&arr[0]) != &arr[0], ""); // expected-error {{constant}} expected-note {{cannot refer to element -1}}
301 static_assert(ref(&arr[1])-- == &arr[1], "");
302 static_assert(ref(&arr[0])-- == &arr[0], ""); // expected-error {{constant}} expected-note {{cannot refer to element -1}}
303 static_assert(postdec(&arr[1]) == &arr[0], "");
306 static_assert(++ref(&x) == &x + 1, "");
308 static_assert(++ref(0.0) == 1.0, "");
309 static_assert(ref(0.0)++ == 0.0, "");
310 static_assert(postinc(0.0) == 1.0, "");
311 static_assert(--ref(0.0) == -1.0, "");
312 static_assert(ref(0.0)-- == 0.0, "");
313 static_assert(postdec(0.0) == -1.0, "");
315 static_assert(++ref(1e100) == 1e100, "");
316 static_assert(--ref(1e100) == 1e100, "");
321 constexpr int f(U u) {
322 return ++u.b; // expected-note {{increment of member 'b' of union with active member 'a'}}
324 constexpr int wrong_member = f({0}); // expected-error {{constant}} expected-note {{in call to 'f({.a = 0})'}}
325 constexpr int vol = --ref<volatile int>(0); // expected-error {{constant}} expected-note {{decrement of volatile-qualified}}
327 constexpr int incr(int k) {
333 static_assert(incr(0) == 101, "");
336 namespace compound_assign {
337 constexpr bool test_int() {
340 if (a != 9) return false;
342 if (a != 7) return false;
344 if (a != 21) return false;
345 if (&(a /= 10) != &a) return false;
346 if (a != 2) return false;
348 if (a != 16) return false;
350 if (a != 4) return false;
352 if (a != 2) return false;
354 if (a != 8) return false;
356 if (a != 13) return false;
358 if (a != 12) return false;
361 static_assert(test_int(), "");
363 constexpr bool test_float() {
366 if (f != 246.) return false;
367 if ((f -= 0.5) != 245.5) return false;
368 if (f != 245.5) return false;
370 if (f != 491.) return false;
372 if (f != 451.) return false;
375 static_assert(test_float(), "");
377 constexpr bool test_ptr() {
380 if ((p += 4) != &arr[4]) return false;
381 if (p != &arr[4]) return false;
383 if (p != &arr[3]) return false;
384 if ((p -= -10) != &arr[13]) return false;
385 if (p != &arr[13]) return false;
387 if (p != &arr[2]) return false;
390 static_assert(test_ptr(), "");
393 constexpr bool test_overflow() {
396 a *= 2; // expected-note {{value 2147483648 is outside the range}} expected-note {{ 9223372036854775808 }} expected-note {{floating point arithmetic produces an infinity}}
400 static_assert(test_overflow<int>(), ""); // expected-error {{constant}} expected-note {{call}}
401 static_assert(test_overflow<unsigned>(), ""); // ok, unsigned overflow is defined
402 static_assert(test_overflow<short>(), ""); // ok, short is promoted to int before multiplication
403 static_assert(test_overflow<unsigned short>(), ""); // ok
404 static_assert(test_overflow<unsigned long long>(), ""); // ok
405 static_assert(test_overflow<long long>(), ""); // expected-error {{constant}} expected-note {{call}}
406 static_assert(test_overflow<float>(), ""); // expected-error {{constant}} expected-note {{call}}
408 constexpr short test_promotion(short k) {
413 static_assert(test_promotion(100) == 10000, "");
414 static_assert(test_promotion(200) == -25536, "");
415 static_assert(test_promotion(256) == 0, "");
417 constexpr const char *test_bounds(const char *p, int o) {
418 return p += o; // expected-note {{element 5 of}} expected-note {{element -1 of}} expected-note {{element 1000 of}}
420 static_assert(test_bounds("foo", 0)[0] == 'f', "");
421 static_assert(test_bounds("foo", 3)[0] == 0, "");
422 static_assert(test_bounds("foo", 4)[-3] == 'o', "");
423 static_assert(test_bounds("foo" + 4, -4)[0] == 'f', "");
424 static_assert(test_bounds("foo", 5) != 0, ""); // expected-error {{constant}} expected-note {{call}}
425 static_assert(test_bounds("foo", -1) != 0, ""); // expected-error {{constant}} expected-note {{call}}
426 static_assert(test_bounds("foo", 1000) != 0, ""); // expected-error {{constant}} expected-note {{call}}
430 constexpr int fib_loop(int a) {
431 int f_k = 0, f_k_plus_one = 1;
432 for (int k = 1; k != a; ++k) {
433 int f_k_plus_two = f_k + f_k_plus_one;
435 f_k_plus_one = f_k_plus_two;
439 static_assert(fib_loop(46) == 1836311903, "");
441 constexpr bool breaks_work() {
443 for (int n = 0; n != 100; ++n) {
445 if (a == 5) continue;
446 if ((a % 5) == 0) break;
452 if (b == 6) continue;
453 if ((b % 6) == 0) break;
459 if (c == 7) continue;
460 if ((c % 7) == 0) break;
463 return a == 10 && b == 12 && c == 14;
465 static_assert(breaks_work(), "");
467 void not_constexpr();
468 constexpr bool no_cont_after_break() {
483 static_assert(no_cont_after_break(), "");
485 constexpr bool cond() {
486 for (int a = 1; bool b = a != 3; ++a) {
490 while (bool b = true) {
496 static_assert(cond(), "");
498 constexpr int range_for() {
499 int arr[] = { 1, 2, 3, 4, 5 };
505 static_assert(range_for() == 15, "");
507 template<int...N> struct ints {};
508 template<typename A, typename B> struct join_ints;
509 template<int...As, int...Bs> struct join_ints<ints<As...>, ints<Bs...>> {
510 using type = ints<As..., sizeof...(As) + Bs...>;
512 template<unsigned N> struct make_ints {
513 using type = typename join_ints<typename make_ints<N/2>::type, typename make_ints<(N+1)/2>::type>::type;
515 template<> struct make_ints<0> { using type = ints<>; };
516 template<> struct make_ints<1> { using type = ints<0>; };
518 struct ignore { template<typename ...Ts> constexpr ignore(Ts &&...) {} };
520 template<typename T, unsigned N> struct array {
521 constexpr array() : arr{} {}
522 template<typename ...X>
523 constexpr array(X ...x) : arr{} {
524 init(typename make_ints<sizeof...(X)>::type{}, x...);
526 template<int ...I, typename ...X> constexpr void init(ints<I...>, X ...x) {
527 ignore{arr[I] = x ...};
532 constexpr explicit iterator(T *p) : p(p) {}
533 constexpr bool operator!=(iterator o) { return p != o.p; }
534 constexpr iterator &operator++() { ++p; return *this; }
535 constexpr T &operator*() { return *p; }
537 constexpr iterator begin() { return iterator(arr); }
538 constexpr iterator end() { return iterator(arr + N); }
541 constexpr int range_for_2() {
542 array<int, 5> arr { 1, 2, 3, 4, 5 };
550 static_assert(range_for_2() == 10, "");
553 namespace assignment_op {
555 constexpr A() : n(5) {}
560 constexpr U() : y(4) {}
566 constexpr bool testA() {
571 return b.n == 7 && b.b.u.y == 5 && b.b.k == 1;
573 static_assert(testA(), "");
576 bool assigned = false;
577 constexpr B &operator=(const B&) {
586 constexpr bool testC() {
591 return d.n == 7 && d.assigned && d.b.assigned;
593 static_assert(testC(), "");
596 namespace switch_stmt {
597 constexpr int f(char k) {
621 } else if (false) case 8: z = 8;
634 static_assert(f(0) == 0, "");
635 static_assert(f(1) == 1, "");
636 static_assert(f(2) == 2, "");
637 static_assert(f(3) == 3, "");
638 static_assert(f(4) == 4, "");
639 static_assert(f(5) == 5, "");
640 static_assert(f(6) == 6, "");
641 static_assert(f(7) == 7, "");
642 static_assert(f(8) == 8, "");
643 static_assert(f(9) == 9, "");
644 static_assert(f(10) == 10, "");
646 // Check that we can continue an outer loop from within a switch.
647 constexpr bool contin() {
648 for (int n = 0; n != 10; ++n) {
661 static_assert(contin(), "");
663 constexpr bool switch_into_for() {
666 for (; n == 1; ++n) {
673 static_assert(switch_into_for(), "");
675 constexpr void duff_copy(char *a, const char *b, int n) {
676 switch ((n - 1) % 8 + 1) {
677 for ( ; n; n = (n - 1) & ~7) {
678 case 8: a[n-8] = b[n-8];
679 case 7: a[n-7] = b[n-7];
680 case 6: a[n-6] = b[n-6];
681 case 5: a[n-5] = b[n-5];
682 case 4: a[n-4] = b[n-4];
683 case 3: a[n-3] = b[n-3];
684 case 2: a[n-2] = b[n-2];
685 case 1: a[n-1] = b[n-1];
691 constexpr bool test_copy(const char *str, int n) {
692 char buffer[16] = {};
693 duff_copy(buffer, str, n);
694 for (int i = 0; i != sizeof(buffer); ++i)
695 if (buffer[i] != (i < n ? str[i] : 0))
699 static_assert(test_copy("foo", 0), "");
700 static_assert(test_copy("foo", 1), "");
701 static_assert(test_copy("foo", 2), "");
702 static_assert(test_copy("hello world", 0), "");
703 static_assert(test_copy("hello world", 7), "");
704 static_assert(test_copy("hello world", 8), "");
705 static_assert(test_copy("hello world", 9), "");
706 static_assert(test_copy("hello world", 10), "");
707 static_assert(test_copy("hello world", 10), "");
710 namespace deduced_return_type {
711 constexpr auto f() { return 0; }
712 template<typename T> constexpr auto g(T t) { return t; }
713 static_assert(f() == 0, "");
714 static_assert(g(true), "");
717 namespace modify_temporary_during_construction {
718 struct A { int &&temporary; int x; int y; };
719 constexpr int f(int &r) { r *= 9; return r - 12; }
720 constexpr A a = { 6, f(a.temporary), a.temporary }; // expected-note {{temporary created here}}
721 static_assert(a.x == 42, "");
722 static_assert(a.y == 54, "");
723 constexpr int k = a.temporary++; // expected-error {{constant expression}} expected-note {{outside the expression that created the temporary}}
727 typedef decltype(sizeof(int)) size_t;
730 class initializer_list
735 constexpr initializer_list(const _E* __b, size_t __s)
741 typedef _E value_type;
742 typedef const _E& reference;
743 typedef const _E& const_reference;
744 typedef size_t size_type;
746 typedef const _E* iterator;
747 typedef const _E* const_iterator;
749 constexpr initializer_list() : __begin_(nullptr), __size_(0) {}
751 constexpr size_t size() const {return __size_;}
752 constexpr const _E* begin() const {return __begin_;}
753 constexpr const _E* end() const {return __begin_ + __size_;}
757 namespace InitializerList {
758 constexpr int sum(std::initializer_list<int> ints) {
760 for (int n : ints) total += n;
763 static_assert(sum({1, 2, 3, 4, 5}) == 15, "");
767 constexpr int f(int k) {
773 case 1: // expected-note {{not supported}}
778 static_assert(f(1) == 1, ""); // expected-error {{constant expression}} expected-note {{in call}}
780 constexpr int g() { // expected-error {{never produces a constant}}
781 return ({ int n; n; }); // expected-note {{object of type 'int' is not initialized}}
784 // FIXME: We should handle the void statement expression case.
785 constexpr int h() { // expected-error {{never produces a constant}}
786 ({ if (true) {} }); // expected-note {{not supported}}
791 namespace VirtualFromBase {
793 virtual int f() const;
798 template <typename T> struct X : T {
801 constexpr int f() { return sizeof(T); }
804 // Non-virtual f(), OK.
805 constexpr X<X<S1>> xxs1;
806 constexpr X<S1> *p = const_cast<X<X<S1>>*>(&xxs1);
807 static_assert(p->f() == sizeof(S1), "");
809 // Virtual f(), not OK.
810 constexpr X<X<S2>> xxs2;
811 constexpr X<S2> *q = const_cast<X<X<S2>>*>(&xxs2);
812 static_assert(q->f() == sizeof(X<S2>), ""); // expected-error {{constant expression}} expected-note {{virtual function call}}
816 constexpr int &get(int &&r) { return r; }
819 return r; // expected-note {{read of object outside its lifetime}}
821 static_assert(f() == 123, ""); // expected-error {{constant expression}} expected-note {{in call}}
830 *p = 123; // expected-note {{assignment to object outside its lifetime}}
833 static_assert(g() == 42, ""); // expected-error {{constant expression}} expected-note {{in call}}
835 constexpr int h(int n) {
841 for (int b = 1; int c = 1; ) {
842 p[2] = &b, p[3] = &c;
847 *p[n] = 0; // expected-note 3{{assignment to object outside its lifetime}}
850 static_assert(h(0) == 0, ""); // ok, lifetime-extended
851 static_assert(h(1) == 0, ""); // expected-error {{constant expression}} expected-note {{in call}}
852 static_assert(h(2) == 0, ""); // expected-error {{constant expression}} expected-note {{in call}}
853 static_assert(h(3) == 0, ""); // expected-error {{constant expression}} expected-note {{in call}}
855 constexpr void lifetime_versus_loops() {
857 for (int i = 0; i != 2; ++i) {
862 // This modifies the 'n' from the previous iteration of the loop outside
864 ++*q; // expected-note {{increment of object outside its lifetime}}
867 static_assert((lifetime_versus_loops(), true), ""); // expected-error {{constant expression}} expected-note {{in call}}
870 namespace Bitfields {
876 constexpr bool test() {
882 return a.b == false && a.n == 3 && a.u == 31;
884 static_assert(test(), "");
890 constexpr A(int &&r) : r(static_cast<int &&>(r)) {}
891 constexpr A() : A(0) {
892 (void)+r; // expected-note {{outside its lifetime}}
895 constexpr int k = A().r; // expected-error {{constant expression}} expected-note {{in call to}}
899 template<typename T, unsigned int N>
900 constexpr T sum(const T (&arr)[N]) {
907 constexpr int ARR[] = { 1, 2, 3, 4, 5 };
908 static_assert(sum(ARR) == 15, "");
911 namespace EmptyClass {
913 union E2 {} e2; // expected-note 4{{here}}
914 struct E3 : E1 {} e3;
917 constexpr int f(E &a, int kind) {
919 case 0: { E e(a); return 0; } // expected-note {{read}} expected-note {{in call}}
920 case 1: { E e(static_cast<E&&>(a)); return 0; } // expected-note {{read}} expected-note {{in call}}
921 case 2: { E e; e = a; return 0; } // expected-note {{read}} expected-note {{in call}}
922 case 3: { E e; e = static_cast<E&&>(a); return 0; } // expected-note {{read}} expected-note {{in call}}
925 constexpr int test1 = f(e1, 0);
926 constexpr int test2 = f(e2, 0); // expected-error {{constant expression}} expected-note {{in call}}
927 constexpr int test3 = f(e3, 0);
928 constexpr int test4 = f(e1, 1);
929 constexpr int test5 = f(e2, 1); // expected-error {{constant expression}} expected-note {{in call}}
930 constexpr int test6 = f(e3, 1);
931 constexpr int test7 = f(e1, 2);
932 constexpr int test8 = f(e2, 2); // expected-error {{constant expression}} expected-note {{in call}}
933 constexpr int test9 = f(e3, 2);
934 constexpr int testa = f(e1, 3);
935 constexpr int testb = f(e2, 3); // expected-error {{constant expression}} expected-note {{in call}}
936 constexpr int testc = f(e3, 3);
939 namespace SpeculativeEvalWrites {
940 // Ensure that we don't try to speculatively evaluate writes.
944 // __builtin_object_size speculatively evaluates its first argument.
945 __builtin_object_size((i = 1, &a), 0);
949 static_assert(!f(), "");
953 constexpr int f(int n) {
957 static_assert(f(0) == 1, "");
960 namespace const_char {
962 constexpr int sum(const char (&Arr)[N]) {
964 for (unsigned I = 0; I != N; ++I)
965 S += Arr[I]; // expected-note 2{{read of non-constexpr variable 'Cs' is not allowed}}
969 // As an extension, we support evaluating some things that are `const` as though
970 // they were `constexpr` when folding, but it should not be allowed in normal
971 // constexpr evaluation.
972 const char Cs[] = {'a', 'b'};
973 void foo() __attribute__((enable_if(sum(Cs) == 'a' + 'b', "")));
974 void run() { foo(); }
976 static_assert(sum(Cs) == 'a' + 'b', ""); // expected-error{{not an integral constant expression}} expected-note{{in call to 'sum(Cs)'}}
977 constexpr int S = sum(Cs); // expected-error{{must be initialized by a constant expression}} expected-note{{in call}}
980 constexpr void PR28739(int n) { // expected-error {{never produces a constant}}
982 p += (__int128)(unsigned long)-1; // expected-note {{cannot refer to element 18446744073709551615 of non-array object in a constant expression}}
985 constexpr void Void(int n) {
989 constexpr int void_test = (Void(0), 1);
992 constexpr void addone(int &m) { m++; }
996 constexpr S() { addone(m); }
998 constexpr bool evalS() {
1002 static_assert(evalS(), "");
1005 struct First { int x = 42; };
1011 constexpr Nested(int x) : first(), x(x) { x = 4; }
1012 constexpr Nested() : Nested(42) {
1017 constexpr bool evalNested() {
1019 return N.first.x == 43;
1021 static_assert(evalNested(), "");
1022 } // namespace PR19741
1025 struct A { mutable int n; }; // expected-note 2{{here}}
1026 constexpr int k = A{123}.n; // ok
1027 static_assert(k == 123, "");
1029 struct Q { A &&a; int b = a.n; };
1030 constexpr Q q = { A{456} }; // expected-note {{temporary}}
1031 static_assert(q.b == 456, "");
1032 static_assert(q.a.n == 456, ""); // expected-error {{constant expression}} expected-note {{outside the expression that created the temporary}}
1034 constexpr A a = {123};
1035 constexpr int m = a.n; // expected-error {{constant expression}} expected-note {{mutable}}
1037 constexpr Q r = { static_cast<A&&>(const_cast<A&>(a)) }; // expected-error {{constant expression}} expected-note@-8 {{mutable}}
1040 mutable int n; // expected-note {{here}}
1042 constexpr B() : n(1), m(n) {} // ok
1045 constexpr int p = b.n; // expected-error {{constant expression}} expected-note {{mutable}}
1048 namespace IndirectFields {
1050 // Reference indirect field.
1054 int x = x = 3; // expected-note {{outside its lifetime}}
1059 static_assert(A().x == 3, ""); // expected-error{{not an integral constant expression}} expected-note{{in call to 'A()'}}
1061 // Reference another indirect field, with different 'this'.
1071 static_assert(B().y == 3, "");
1073 // Nested evaluation of indirect field initializers.
1085 static_assert(D().y == 2, "");
1095 constexpr E e1 = E();
1096 static_assert(e1.x != e1.y, "");
1097 constexpr E e2 = E{0};
1098 static_assert(e2.x != e2.y, "");
1100 } // namespace IndirectFields