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path: root/clang/test/SemaCXX/constant-expression-cxx14.cpp
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-rw-r--r--clang/test/SemaCXX/constant-expression-cxx14.cpp1259
1 files changed, 1259 insertions, 0 deletions
diff --git a/clang/test/SemaCXX/constant-expression-cxx14.cpp b/clang/test/SemaCXX/constant-expression-cxx14.cpp
new file mode 100644
index 000000000000..016d9003c31e
--- /dev/null
+++ b/clang/test/SemaCXX/constant-expression-cxx14.cpp
@@ -0,0 +1,1259 @@
+// RUN: %clang_cc1 -std=c++2b -fsyntax-only -verify=expected,cxx20_2b %s -fcxx-exceptions -triple=x86_64-linux-gnu
+// RUN: %clang_cc1 -std=c++20 -fsyntax-only -verify=expected,cxx20_2b %s -fcxx-exceptions -triple=x86_64-linux-gnu
+// RUN: %clang_cc1 -std=c++14 -fsyntax-only -verify=expected,cxx14 %s -fcxx-exceptions -triple=x86_64-linux-gnu
+
+struct S {
+ // dummy ctor to make this a literal type
+ constexpr S(int);
+
+ S();
+
+ int arr[10];
+
+ constexpr int &get(int n) { return arr[n]; }
+ constexpr const int &get(int n) const { return arr[n]; }
+};
+
+S s = S();
+const S &sr = s;
+static_assert(&s.get(4) - &sr.get(2) == 2, "");
+
+// Compound-statements can be used in constexpr functions.
+constexpr int e() {{{{}} return 5; }}
+static_assert(e() == 5, "");
+
+// Types can be defined in constexpr functions.
+constexpr int f() {
+ enum E { e1, e2, e3 };
+
+ struct S {
+ constexpr S(E e) : e(e) {}
+ constexpr int get() { return e; }
+ E e;
+ };
+
+ return S(e2).get();
+}
+static_assert(f() == 1, "");
+
+// Variables can be declared in constexpr functions.
+constexpr int g(int k) {
+ const int n = 9;
+ int k2 = k * k;
+ int k3 = k2 * k;
+ return 3 * k3 + 5 * k2 + n * k - 20;
+}
+static_assert(g(2) == 42, "");
+constexpr int h(int n) {
+ static const int m = n; // expected-error {{static variable not permitted in a constexpr function}}
+ return m;
+}
+constexpr int i(int n) {
+ thread_local const int m = n; // expected-error {{thread_local variable not permitted in a constexpr function}}
+ return m;
+}
+
+// if-statements can be used in constexpr functions.
+constexpr int j(int k) {
+ if (k == 5)
+ return 1;
+ if (k == 1)
+ return 5;
+ else {
+ if (int n = 2 * k - 4) {
+ return n + 1;
+ return 2;
+ }
+ }
+} // expected-note 2{{control reached end of constexpr function}}
+static_assert(j(0) == -3, "");
+static_assert(j(1) == 5, "");
+static_assert(j(2), ""); // expected-error {{constant expression}} expected-note {{in call to 'j(2)'}}
+static_assert(j(3) == 3, "");
+static_assert(j(4) == 5, "");
+static_assert(j(5) == 1, "");
+
+// There can be 0 return-statements.
+constexpr void k() {
+}
+
+// If the return type is not 'void', no return statements => never a constant
+// expression, so still diagnose that case.
+[[noreturn]] constexpr int fn() { // expected-error {{no return statement in constexpr function}}
+ fn();
+}
+
+// We evaluate the body of a constexpr constructor, to check for side-effects.
+struct U {
+ constexpr U(int n) {
+ if (j(n)) {} // expected-note {{in call to 'j(2)'}}
+ }
+};
+constexpr U u1{1};
+constexpr U u2{2}; // expected-error {{constant expression}} expected-note {{in call to 'U(2)'}}
+
+// We allow expression-statements.
+constexpr int l(bool b) {
+ if (b)
+ throw "invalid value for b!"; // expected-note {{subexpression not valid}}
+ return 5;
+}
+static_assert(l(false) == 5, "");
+static_assert(l(true), ""); // expected-error {{constant expression}} expected-note {{in call to 'l(true)'}}
+
+// Potential constant expression checking is still applied where possible.
+constexpr int htonl(int x) { // expected-error {{never produces a constant expression}}
+ typedef unsigned char uchar;
+ uchar arr[4] = { uchar(x >> 24), uchar(x >> 16), uchar(x >> 8), uchar(x) };
+ return *reinterpret_cast<int*>(arr); // expected-note {{reinterpret_cast is not allowed in a constant expression}}
+}
+
+constexpr int maybe_htonl(bool isBigEndian, int x) {
+ if (isBigEndian)
+ return x;
+
+ typedef unsigned char uchar;
+ uchar arr[4] = { uchar(x >> 24), uchar(x >> 16), uchar(x >> 8), uchar(x) };
+ return *reinterpret_cast<int*>(arr); // expected-note {{reinterpret_cast is not allowed in a constant expression}}
+}
+
+constexpr int swapped = maybe_htonl(false, 123); // expected-error {{constant expression}} expected-note {{in call}}
+
+namespace NS {
+ constexpr int n = 0;
+}
+constexpr int namespace_alias() {
+ namespace N = NS;
+ return N::n;
+}
+
+namespace assign {
+ constexpr int a = 0;
+ const int b = 0;
+ int c = 0; // expected-note {{here}}
+
+ constexpr void set(const int &a, int b) {
+ const_cast<int&>(a) = b; // expected-note 3{{constant expression cannot modify an object that is visible outside that expression}}
+ }
+ constexpr int wrap(int a, int b) {
+ set(a, b);
+ return a;
+ }
+
+ static_assert((set(a, 1), a) == 1, ""); // expected-error {{constant expression}} expected-note {{in call to 'set(a, 1)'}}
+ static_assert((set(b, 1), b) == 1, ""); // expected-error {{constant expression}} expected-note {{in call to 'set(b, 1)'}}
+ static_assert((set(c, 1), c) == 1, ""); // expected-error {{constant expression}} expected-note {{in call to 'set(c, 1)'}}
+
+ static_assert(wrap(a, 1) == 1, "");
+ static_assert(wrap(b, 1) == 1, "");
+ static_assert(wrap(c, 1) == 1, ""); // expected-error {{constant expression}} expected-note {{read of non-const variable 'c'}}
+}
+
+namespace string_assign {
+ template<typename T>
+ constexpr void swap(T &a, T &b) {
+ T tmp = a;
+ a = b;
+ b = tmp;
+ }
+ template<typename Iterator>
+ constexpr void reverse(Iterator begin, Iterator end) {
+ while (begin != end && begin != --end)
+ swap(*begin++, *end);
+ }
+ template<typename Iterator1, typename Iterator2>
+ constexpr bool equal(Iterator1 a, Iterator1 ae, Iterator2 b, Iterator2 be) {
+ while (a != ae && b != be)
+ if (*a++ != *b++)
+ return false;
+ return a == ae && b == be;
+ }
+ constexpr bool test1(int n) {
+ char stuff[100] = "foobarfoo";
+ const char stuff2[100] = "oofraboof";
+ reverse(stuff, stuff + n); // expected-note {{cannot refer to element 101 of array of 100 elements}}
+ return equal(stuff, stuff + n, stuff2, stuff2 + n);
+ }
+ static_assert(!test1(1), "");
+ static_assert(test1(3), "");
+ static_assert(!test1(6), "");
+ static_assert(test1(9), "");
+ static_assert(!test1(100), "");
+ static_assert(!test1(101), ""); // expected-error {{constant expression}} expected-note {{in call to 'test1(101)'}}
+
+ 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}}
+ char foo[10] = { "z" }; // expected-note {{here}}
+ foo[10] = 'x'; // expected-warning {{past the end}}
+ }
+}
+
+namespace array_resize {
+ constexpr int do_stuff(int k1, int k2) {
+ int arr[1234] = { 1, 2, 3, 4 };
+ arr[k1] = 5; // expected-note {{past-the-end}} expected-note {{cannot refer to element 1235}} expected-note {{cannot refer to element -1}}
+ return arr[k2];
+ }
+ static_assert(do_stuff(1, 2) == 3, "");
+ static_assert(do_stuff(0, 0) == 5, "");
+ static_assert(do_stuff(1233, 1233) == 5, "");
+ static_assert(do_stuff(1233, 0) == 1, "");
+ static_assert(do_stuff(1234, 0) == 1, ""); // expected-error {{constant expression}} expected-note {{in call}}
+ static_assert(do_stuff(1235, 0) == 1, ""); // expected-error {{constant expression}} expected-note {{in call}}
+ static_assert(do_stuff(-1, 0) == 1, ""); // expected-error {{constant expression}} expected-note {{in call}}
+}
+
+namespace potential_const_expr {
+ constexpr void set(int &n) { n = 1; }
+ constexpr int div_zero_1() { int z = 0; set(z); return 100 / z; } // no error
+ constexpr int div_zero_2() { // expected-error {{never produces a constant expression}}
+ int z = 0;
+ return 100 / (set(z), 0); // expected-note {{division by zero}}
+ }
+ int n; // expected-note {{declared here}}
+ constexpr int ref() { // expected-error {{never produces a constant expression}}
+ int &r = n;
+ return r; // expected-note {{read of non-const variable 'n'}}
+ }
+}
+
+namespace subobject {
+ union A { constexpr A() : y(5) {} int x, y; };
+ struct B { A a; };
+ struct C : B {};
+ union D { constexpr D() : c() {} constexpr D(int n) : n(n) {} C c; int n; };
+ constexpr void f(D &d) {
+ d.c.a.y = 3;
+ // expected-note@-1 {{cannot modify an object that is visible outside}}
+ // expected-note@-2 {{assignment to member 'c' of union with active member 'n'}}
+ }
+ constexpr bool check(D &d) { return d.c.a.y == 3; }
+ // cxx20_2b-note@-1 {{read of member 'y' of union with active member 'x'}}
+
+ constexpr bool g() { D d; f(d); return d.c.a.y == 3; }
+ static_assert(g(), "");
+
+ D d;
+ constexpr bool h() { f(d); return check(d); } // expected-note {{in call}}
+ static_assert(h(), ""); // expected-error {{constant expression}} expected-note {{in call}}
+
+ constexpr bool i() { D d(0); f(d); return check(d); } // expected-note {{in call}}
+ static_assert(i(), ""); // expected-error {{constant expression}} expected-note {{in call}}
+
+ constexpr bool j() { D d; d.c.a.x = 3; return check(d); } // cxx14-note {{assignment to member 'x' of union with active member 'y'}}
+ // cxx20_2b-note@-1 {{in call to 'check(d)'}}
+ static_assert(j(), ""); // expected-error {{constant expression}} expected-note {{in call}}
+}
+
+namespace lifetime {
+ constexpr int &&id(int &&n) { return static_cast<int&&>(n); }
+ constexpr int &&dead() { return id(0); } // expected-note {{temporary created here}}
+ constexpr int bad() { int &&n = dead(); n = 1; return n; } // expected-note {{assignment to temporary whose lifetime has ended}}
+ static_assert(bad(), ""); // expected-error {{constant expression}} expected-note {{in call}}
+}
+
+namespace const_modify {
+ constexpr int modify(int &n) { return n = 1; } // expected-note 2 {{modification of object of const-qualified type 'const int'}}
+ constexpr int test1() { int k = 0; return modify(k); }
+ constexpr int test2() { const int k = 0; return modify(const_cast<int&>(k)); } // expected-note 2 {{in call}}
+ static_assert(test1() == 1, "");
+ static_assert(test2() == 1, ""); // expected-error {{constant expression}} expected-note {{in call}}
+ constexpr int i = test2(); // expected-error {{constant expression}} expected-note {{in call}}
+}
+
+namespace null {
+ constexpr int test(int *p) {
+ return *p = 123; // expected-note {{assignment to dereferenced null pointer}}
+ }
+ static_assert(test(0), ""); // expected-error {{constant expression}} expected-note {{in call}}
+}
+
+namespace incdec {
+ template<typename T> constexpr T &ref(T &&r) { return r; }
+ template<typename T> constexpr T postinc(T &&r) { return (r++, r); }
+ template<typename T> constexpr T postdec(T &&r) { return (r--, r); }
+
+ static_assert(++ref(0) == 1, "");
+ static_assert(ref(0)++ == 0, "");
+ static_assert(postinc(0) == 1, "");
+ static_assert(--ref(0) == -1, "");
+ static_assert(ref(0)-- == 0, "");
+ static_assert(postdec(0) == -1, "");
+
+ constexpr int overflow_int_inc_1 = ref(0x7fffffff)++; // expected-error {{constant}} expected-note {{2147483648}}
+ constexpr int overflow_int_inc_1_ok = ref(0x7ffffffe)++;
+ constexpr int overflow_int_inc_2 = ++ref(0x7fffffff); // expected-error {{constant}} expected-note {{2147483648}}
+ constexpr int overflow_int_inc_2_ok = ++ref(0x7ffffffe);
+
+ // inc/dec on short can't overflow because we promote to int first
+ static_assert(++ref<short>(0x7fff) == (int)0xffff8000u, "");
+ static_assert(--ref<short>(0x8000) == 0x7fff, "");
+
+ // inc on bool sets to true
+ static_assert(++ref(false), "");
+ // cxx14-warning@-1 {{incrementing expression of type bool}}
+ // cxx20_2b-error@-2 {{incrementing expression of type bool}}
+ static_assert(++ref(true), "");
+ // cxx14-warning@-1 {{incrementing expression of type bool}}
+ // cxx20_2b-error@-2 {{incrementing expression of type bool}}
+
+ int arr[10];
+ static_assert(++ref(&arr[0]) == &arr[1], "");
+ static_assert(++ref(&arr[9]) == &arr[10], "");
+ static_assert(++ref(&arr[10]) == &arr[11], ""); // expected-error {{constant}} expected-note {{cannot refer to element 11}}
+ static_assert(ref(&arr[0])++ == &arr[0], "");
+ static_assert(ref(&arr[10])++ == &arr[10], ""); // expected-error {{constant}} expected-note {{cannot refer to element 11}}
+ static_assert(postinc(&arr[0]) == &arr[1], "");
+ static_assert(--ref(&arr[10]) == &arr[9], "");
+ static_assert(--ref(&arr[1]) == &arr[0], "");
+ static_assert(--ref(&arr[0]) != &arr[0], ""); // expected-error {{constant}} expected-note {{cannot refer to element -1}}
+ static_assert(ref(&arr[1])-- == &arr[1], "");
+ static_assert(ref(&arr[0])-- == &arr[0], ""); // expected-error {{constant}} expected-note {{cannot refer to element -1}}
+ static_assert(postdec(&arr[1]) == &arr[0], "");
+
+ int x;
+ static_assert(++ref(&x) == &x + 1, "");
+
+ static_assert(++ref(0.0) == 1.0, "");
+ static_assert(ref(0.0)++ == 0.0, "");
+ static_assert(postinc(0.0) == 1.0, "");
+ static_assert(--ref(0.0) == -1.0, "");
+ static_assert(ref(0.0)-- == 0.0, "");
+ static_assert(postdec(0.0) == -1.0, "");
+
+ static_assert(++ref(1e100) == 1e100, "");
+ static_assert(--ref(1e100) == 1e100, "");
+
+ union U {
+ int a, b;
+ };
+ constexpr int f(U u) {
+ return ++u.b; // expected-note {{increment of member 'b' of union with active member 'a'}}
+ }
+ constexpr int wrong_member = f({0}); // expected-error {{constant}} expected-note {{in call to 'f({.a = 0})'}}
+ constexpr int vol = --ref<volatile int>(0); // expected-error {{constant}} expected-note {{decrement of volatile-qualified}}
+ // cxx20_2b-warning@-1 {{decrement of object of volatile-qualified type 'volatile int' is deprecated}}
+
+ constexpr int incr(int k) {
+ int x = k;
+ if (x++ == 100)
+ return x;
+ return incr(x);
+ }
+ static_assert(incr(0) == 101, "");
+}
+
+namespace compound_assign {
+ constexpr bool test_int() {
+ int a = 3;
+ a += 6;
+ if (a != 9) return false;
+ a -= 2;
+ if (a != 7) return false;
+ a *= 3;
+ if (a != 21) return false;
+ if (&(a /= 10) != &a) return false;
+ if (a != 2) return false;
+ a <<= 3;
+ if (a != 16) return false;
+ a %= 6;
+ if (a != 4) return false;
+ a >>= 1;
+ if (a != 2) return false;
+ a ^= 10;
+ if (a != 8) return false;
+ a |= 5;
+ if (a != 13) return false;
+ a &= 14;
+ if (a != 12) return false;
+ a += -1.2;
+ if (a != 10) return false;
+ a -= 3.1;
+ if (a != 6) return false;
+ a *= 2.2;
+ if (a != 13) return false;
+ if (&(a /= 1.5) != &a) return false;
+ if (a != 8) return false;
+ return true;
+ }
+ static_assert(test_int(), "");
+
+ constexpr bool test_float() {
+ float f = 123.;
+ f *= 2;
+ if (f != 246.) return false;
+ if ((f -= 0.5) != 245.5) return false;
+ if (f != 245.5) return false;
+ f /= 0.5;
+ if (f != 491.) return false;
+ f += -40;
+ if (f != 451.) return false;
+ return true;
+ }
+ static_assert(test_float(), "");
+
+ constexpr bool test_bool() {
+ bool b = false;
+ b |= 2;
+ if (b != true) return false;
+ b <<= 1;
+ if (b != true) return false;
+ b *= 2;
+ if (b != true) return false;
+ b -= 1;
+ if (b != false) return false;
+ b -= 1;
+ if (b != true) return false;
+ b += -1;
+ if (b != false) return false;
+ b += 1;
+ if (b != true) return false;
+ b += 1;
+ if (b != true) return false;
+ b ^= b;
+ if (b != false) return false;
+ return true;
+ }
+ static_assert(test_bool(), "");
+
+ constexpr bool test_ptr() {
+ int arr[123] = {};
+ int *p = arr;
+ if ((p += 4) != &arr[4]) return false;
+ if (p != &arr[4]) return false;
+ p += -1;
+ if (p != &arr[3]) return false;
+ if ((p -= -10) != &arr[13]) return false;
+ if (p != &arr[13]) return false;
+ p -= 11;
+ if (p != &arr[2]) return false;
+ return true;
+ }
+ static_assert(test_ptr(), "");
+
+ template<typename T>
+ constexpr bool test_overflow() {
+ T a = 1;
+ while (a != a / 2)
+ a *= 2; // expected-note {{value 2147483648 is outside the range}} expected-note {{ 9223372036854775808 }}
+ return true;
+ }
+
+ static_assert(test_overflow<int>(), ""); // expected-error {{constant}} expected-note {{call}}
+ static_assert(test_overflow<unsigned>(), ""); // ok, unsigned overflow is defined
+ static_assert(test_overflow<short>(), ""); // ok, short is promoted to int before multiplication
+ static_assert(test_overflow<unsigned short>(), ""); // ok
+ static_assert(test_overflow<unsigned long long>(), ""); // ok
+ static_assert(test_overflow<long long>(), ""); // expected-error {{constant}} expected-note {{call}}
+ static_assert(test_overflow<float>(), ""); // ok
+ static_assert(test_overflow<double>(), ""); // ok
+
+ constexpr short test_promotion(short k) {
+ short s = k;
+ s *= s;
+ return s;
+ }
+ static_assert(test_promotion(100) == 10000, "");
+ static_assert(test_promotion(200) == -25536, "");
+ static_assert(test_promotion(256) == 0, "");
+
+ constexpr const char *test_bounds(const char *p, int o) {
+ return p += o; // expected-note {{element 5 of}} expected-note {{element -1 of}} expected-note {{element 1000 of}}
+ }
+ static_assert(test_bounds("foo", 0)[0] == 'f', "");
+ static_assert(test_bounds("foo", 3)[0] == 0, "");
+ static_assert(test_bounds("foo", 4)[-3] == 'o', "");
+ static_assert(test_bounds(&"foo"[4], -4)[0] == 'f', "");
+ static_assert(test_bounds("foo", 5) != 0, ""); // expected-error {{constant}} expected-note {{call}}
+ static_assert(test_bounds("foo", -1) != 0, ""); // expected-error {{constant}} expected-note {{call}}
+ static_assert(test_bounds("foo", 1000) != 0, ""); // expected-error {{constant}} expected-note {{call}}
+}
+
+namespace loops {
+ constexpr int fib_loop(int a) {
+ int f_k = 0, f_k_plus_one = 1;
+ for (int k = 1; k != a; ++k) {
+ int f_k_plus_two = f_k + f_k_plus_one;
+ f_k = f_k_plus_one;
+ f_k_plus_one = f_k_plus_two;
+ }
+ return f_k_plus_one;
+ }
+ static_assert(fib_loop(46) == 1836311903, "");
+
+ constexpr bool breaks_work() {
+ int a = 0;
+ for (int n = 0; n != 100; ++n) {
+ ++a;
+ if (a == 5) continue;
+ if ((a % 5) == 0) break;
+ }
+
+ int b = 0;
+ while (b != 17) {
+ ++b;
+ if (b == 6) continue;
+ if ((b % 6) == 0) break;
+ }
+
+ int c = 0;
+ do {
+ ++c;
+ if (c == 7) continue;
+ if ((c % 7) == 0) break;
+ } while (c != 21);
+
+ return a == 10 && b == 12 && c == 14;
+ }
+ static_assert(breaks_work(), "");
+
+ void not_constexpr();
+ constexpr bool no_cont_after_break() {
+ for (;;) {
+ break;
+ not_constexpr();
+ }
+ while (true) {
+ break;
+ not_constexpr();
+ }
+ do {
+ break;
+ not_constexpr();
+ } while (true);
+ return true;
+ }
+ static_assert(no_cont_after_break(), "");
+
+ constexpr bool cond() {
+ for (int a = 1; bool b = a != 3; ++a) {
+ if (!b)
+ return false;
+ }
+ while (bool b = true) {
+ b = false;
+ break;
+ }
+ return true;
+ }
+ static_assert(cond(), "");
+
+ constexpr int range_for() {
+ int arr[] = { 1, 2, 3, 4, 5 };
+ int sum = 0;
+ for (int x : arr)
+ sum += x;
+ return sum;
+ }
+ static_assert(range_for() == 15, "");
+
+ template<int...N> struct ints {};
+ template<typename A, typename B> struct join_ints;
+ template<int...As, int...Bs> struct join_ints<ints<As...>, ints<Bs...>> {
+ using type = ints<As..., sizeof...(As) + Bs...>;
+ };
+ template<unsigned N> struct make_ints {
+ using type = typename join_ints<typename make_ints<N/2>::type, typename make_ints<(N+1)/2>::type>::type;
+ };
+ template<> struct make_ints<0> { using type = ints<>; };
+ template<> struct make_ints<1> { using type = ints<0>; };
+
+ struct ignore { template<typename ...Ts> constexpr ignore(Ts &&...) {} };
+
+ template<typename T, unsigned N> struct array {
+ constexpr array() : arr{} {}
+ template<typename ...X>
+ constexpr array(X ...x) : arr{} {
+ init(typename make_ints<sizeof...(X)>::type{}, x...);
+ }
+ template<int ...I, typename ...X> constexpr void init(ints<I...>, X ...x) {
+ ignore{arr[I] = x ...};
+ }
+ T arr[N];
+ struct iterator {
+ T *p;
+ constexpr explicit iterator(T *p) : p(p) {}
+ constexpr bool operator!=(iterator o) { return p != o.p; }
+ constexpr iterator &operator++() { ++p; return *this; }
+ constexpr T &operator*() { return *p; }
+ };
+ constexpr iterator begin() { return iterator(arr); }
+ constexpr iterator end() { return iterator(arr + N); }
+ };
+
+ constexpr int range_for_2() {
+ array<int, 5> arr { 1, 2, 3, 4, 5 };
+ int sum = 0;
+ for (int k : arr) {
+ sum += k;
+ if (sum > 8) break;
+ }
+ return sum;
+ }
+ static_assert(range_for_2() == 10, "");
+}
+
+namespace assignment_op {
+ struct A {
+ constexpr A() : n(5) {}
+ int n;
+ struct B {
+ int k = 1;
+ union U {
+ constexpr U() : y(4) {}
+ int x;
+ int y;
+ } u;
+ } b;
+ };
+ constexpr bool testA() {
+ A a, b;
+ a.n = 7;
+ a.b.u.y = 5;
+ b = a;
+ return b.n == 7 && b.b.u.y == 5 && b.b.k == 1;
+ }
+ static_assert(testA(), "");
+
+ struct B {
+ bool assigned = false;
+ constexpr B &operator=(const B&) {
+ assigned = true;
+ return *this;
+ }
+ };
+ struct C : B {
+ B b;
+ int n = 5;
+ };
+ constexpr bool testC() {
+ C c, d;
+ c.n = 7;
+ d = c;
+ c.n = 3;
+ return d.n == 7 && d.assigned && d.b.assigned;
+ }
+ static_assert(testC(), "");
+}
+
+namespace switch_stmt {
+ constexpr bool no_such_case(int n) {
+ switch (n) { case 1: return false; }
+ return true;
+ }
+ static_assert(no_such_case(0), "");
+
+ constexpr int f(char k) {
+ bool b = false;
+ int z = 6;
+ switch (k) {
+ return -1;
+ case 0:
+ if (false) {
+ case 1:
+ z = 1;
+ for (; b;) {
+ return 5;
+ while (0)
+ case 2: return 2;
+ case 7: z = 7;
+ do case 6: {
+ return z;
+ if (false)
+ case 3: return 3;
+ case 4: z = 4;
+ } while (1);
+ case 5: b = true;
+ case 9: z = 9;
+ }
+ return z;
+ } else if (false) case 8: z = 8;
+ else if (false) {
+ case 10:
+ z = -10;
+ break;
+ }
+ else z = 0;
+ return z;
+ default:
+ return -1;
+ }
+ return -z;
+ }
+ static_assert(f(0) == 0, "");
+ static_assert(f(1) == 1, "");
+ static_assert(f(2) == 2, "");
+ static_assert(f(3) == 3, "");
+ static_assert(f(4) == 4, "");
+ static_assert(f(5) == 5, "");
+ static_assert(f(6) == 6, "");
+ static_assert(f(7) == 7, "");
+ static_assert(f(8) == 8, "");
+ static_assert(f(9) == 9, "");
+ static_assert(f(10) == 10, "");
+
+ // Check that we can continue an outer loop from within a switch.
+ constexpr bool contin() {
+ for (int n = 0; n != 10; ++n) {
+ switch (n) {
+ case 0:
+ ++n;
+ continue;
+ case 1:
+ return false;
+ case 2:
+ return true;
+ }
+ }
+ return false;
+ }
+ static_assert(contin(), "");
+
+ constexpr bool switch_into_for() {
+ int n = 0;
+ switch (n) {
+ for (; n == 1; ++n) {
+ return n == 1;
+ case 0: ;
+ }
+ }
+ return false;
+ }
+ static_assert(switch_into_for(), "");
+
+ constexpr void duff_copy(char *a, const char *b, int n) {
+ switch ((n - 1) % 8 + 1) {
+ for ( ; n; n = (n - 1) & ~7) {
+ case 8: a[n-8] = b[n-8];
+ case 7: a[n-7] = b[n-7];
+ case 6: a[n-6] = b[n-6];
+ case 5: a[n-5] = b[n-5];
+ case 4: a[n-4] = b[n-4];
+ case 3: a[n-3] = b[n-3];
+ case 2: a[n-2] = b[n-2];
+ case 1: a[n-1] = b[n-1];
+ }
+ case 0: ;
+ }
+ }
+
+ constexpr bool test_copy(const char *str, int n) {
+ char buffer[16] = {};
+ duff_copy(buffer, str, n);
+ for (int i = 0; i != sizeof(buffer); ++i)
+ if (buffer[i] != (i < n ? str[i] : 0))
+ return false;
+ return true;
+ }
+ static_assert(test_copy("foo", 0), "");
+ static_assert(test_copy("foo", 1), "");
+ static_assert(test_copy("foo", 2), "");
+ static_assert(test_copy("hello world", 0), "");
+ static_assert(test_copy("hello world", 7), "");
+ static_assert(test_copy("hello world", 8), "");
+ static_assert(test_copy("hello world", 9), "");
+ static_assert(test_copy("hello world", 10), "");
+ static_assert(test_copy("hello world", 10), "");
+}
+
+namespace deduced_return_type {
+ constexpr auto f() { return 0; }
+ template<typename T> constexpr auto g(T t) { return t; }
+ static_assert(f() == 0, "");
+ static_assert(g(true), "");
+}
+
+namespace modify_temporary_during_construction {
+ struct A { int &&temporary; int x; int y; };
+ constexpr int f(int &r) { r *= 9; return r - 12; }
+ constexpr A a = { 6, f(a.temporary), a.temporary }; // expected-note {{temporary created here}}
+ static_assert(a.x == 42, "");
+ static_assert(a.y == 54, "");
+ constexpr int k = a.temporary++; // expected-error {{constant expression}} expected-note {{outside the expression that created the temporary}}
+}
+
+namespace std {
+ typedef decltype(sizeof(int)) size_t;
+
+ template <class _E>
+ class initializer_list
+ {
+ const _E* __begin_;
+ size_t __size_;
+
+ constexpr initializer_list(const _E* __b, size_t __s)
+ : __begin_(__b),
+ __size_(__s)
+ {}
+
+ public:
+ typedef _E value_type;
+ typedef const _E& reference;
+ typedef const _E& const_reference;
+ typedef size_t size_type;
+
+ typedef const _E* iterator;
+ typedef const _E* const_iterator;
+
+ constexpr initializer_list() : __begin_(nullptr), __size_(0) {}
+
+ constexpr size_t size() const {return __size_;}
+ constexpr const _E* begin() const {return __begin_;}
+ constexpr const _E* end() const {return __begin_ + __size_;}
+ };
+}
+
+namespace InitializerList {
+ constexpr int sum(std::initializer_list<int> ints) {
+ int total = 0;
+ for (int n : ints) total += n;
+ return total;
+ }
+ static_assert(sum({1, 2, 3, 4, 5}) == 15, "");
+}
+
+namespace StmtExpr {
+ constexpr int f(int k) {
+ switch (k) {
+ case 0:
+ return 0;
+
+ ({
+ case 1: // expected-note {{not supported}}
+ return 1;
+ });
+ }
+ }
+ static_assert(f(1) == 1, ""); // expected-error {{constant expression}} expected-note {{in call}}
+
+ constexpr int g() {
+ return ({ int n; n; }); // expected-note {{read of uninitialized object}}
+ }
+ static_assert(g() == 0, ""); // expected-error {{constant expression}} expected-note {{in call}}
+
+ // FIXME: We should handle the void statement expression case.
+ constexpr int h() { // expected-error {{never produces a constant}}
+ ({ if (true) {} }); // expected-note {{not supported}}
+ return 0;
+ }
+}
+
+namespace VirtualFromBase {
+ struct S1 {
+ virtual int f() const;
+ };
+ struct S2 {
+ virtual int f();
+ };
+ template <typename T> struct X : T {
+ constexpr X() {}
+ double d = 0.0;
+ constexpr int f() { return sizeof(T); }
+ };
+
+ // Non-virtual f(), OK.
+ constexpr X<X<S1>> xxs1;
+ constexpr X<S1> *p = const_cast<X<X<S1>>*>(&xxs1);
+ static_assert(p->f() == sizeof(S1), "");
+
+ // Virtual f(), not OK.
+ constexpr X<X<S2>> xxs2;
+ constexpr X<S2> *q = const_cast<X<X<S2>>*>(&xxs2);
+ static_assert(q->f() == sizeof(X<S2>), ""); // cxx14-error {{constant expression}} cxx14-note {{virtual function}}
+}
+
+namespace Lifetime {
+ constexpr int &get(int &&r) { return r; }
+ constexpr int f() {
+ int &r = get(123);
+ return r; // expected-note {{read of object outside its lifetime}}
+ }
+ static_assert(f() == 123, ""); // expected-error {{constant expression}} expected-note {{in call}}
+
+ constexpr int g() {
+ int *p = 0;
+ {
+ int n = 0;
+ p = &n;
+ n = 42;
+ }
+ *p = 123; // expected-note {{assignment to object outside its lifetime}}
+ return *p;
+ }
+ static_assert(g() == 42, ""); // expected-error {{constant expression}} expected-note {{in call}}
+
+ constexpr int h(int n) {
+ int *p[4] = {};
+ int &&r = 1;
+ p[0] = &r;
+ while (int a = 1) {
+ p[1] = &a;
+ for (int b = 1; int c = 1; ) {
+ p[2] = &b, p[3] = &c;
+ break;
+ }
+ break;
+ }
+ *p[n] = 0; // expected-note 3{{assignment to object outside its lifetime}}
+ return *p[n];
+ }
+ static_assert(h(0) == 0, ""); // ok, lifetime-extended
+ static_assert(h(1) == 0, ""); // expected-error {{constant expression}} expected-note {{in call}}
+ static_assert(h(2) == 0, ""); // expected-error {{constant expression}} expected-note {{in call}}
+ static_assert(h(3) == 0, ""); // expected-error {{constant expression}} expected-note {{in call}}
+
+ constexpr void lifetime_versus_loops() {
+ int *p = 0;
+ for (int i = 0; i != 2; ++i) {
+ int *q = p;
+ int n = 0;
+ p = &n;
+ if (i)
+ // This modifies the 'n' from the previous iteration of the loop outside
+ // its lifetime.
+ ++*q; // expected-note {{increment of object outside its lifetime}}
+ }
+ }
+ static_assert((lifetime_versus_loops(), true), ""); // expected-error {{constant expression}} expected-note {{in call}}
+}
+
+namespace Bitfields {
+ struct A {
+ bool b : 1;
+ int n : 4;
+ unsigned u : 5;
+ };
+ constexpr bool test() {
+ A a {};
+ a.b += 2;
+ --a.n;
+ --a.u;
+ a.n = -a.n * 3;
+ return a.b == true && a.n == 3 && a.u == 31;
+ }
+ static_assert(test(), "");
+}
+
+namespace PR17615 {
+ struct A {
+ int &&r;
+ constexpr A(int &&r) : r(static_cast<int &&>(r)) {}
+ constexpr A() : A(0) {
+ (void)+r; // expected-note {{outside its lifetime}}
+ }
+ };
+ constexpr int k = A().r; // expected-error {{constant expression}} expected-note {{in call to}}
+}
+
+namespace PR17331 {
+ template<typename T, unsigned int N>
+ constexpr T sum(const T (&arr)[N]) {
+ T result = 0;
+ for (T i : arr)
+ result += i;
+ return result;
+ }
+
+ constexpr int ARR[] = { 1, 2, 3, 4, 5 };
+ static_assert(sum(ARR) == 15, "");
+}
+
+namespace EmptyClass {
+ struct E1 {} e1;
+ union E2 {} e2; // expected-note 4{{here}}
+ struct E3 : E1 {} e3;
+
+ template<typename E>
+ constexpr int f(E &a, int kind) {
+ switch (kind) {
+ case 0: { E e(a); return 0; } // expected-note {{read}} expected-note {{in call}}
+ case 1: { E e(static_cast<E&&>(a)); return 0; } // expected-note {{read}} expected-note {{in call}}
+ case 2: { E e; e = a; return 0; } // expected-note {{read}} expected-note {{in call}}
+ case 3: { E e; e = static_cast<E&&>(a); return 0; } // expected-note {{read}} expected-note {{in call}}
+ }
+ }
+ constexpr int test1 = f(e1, 0);
+ constexpr int test2 = f(e2, 0); // expected-error {{constant expression}} expected-note {{in call}}
+ constexpr int test3 = f(e3, 0);
+ constexpr int test4 = f(e1, 1);
+ constexpr int test5 = f(e2, 1); // expected-error {{constant expression}} expected-note {{in call}}
+ constexpr int test6 = f(e3, 1);
+ constexpr int test7 = f(e1, 2);
+ constexpr int test8 = f(e2, 2); // expected-error {{constant expression}} expected-note {{in call}}
+ constexpr int test9 = f(e3, 2);
+ constexpr int testa = f(e1, 3);
+ constexpr int testb = f(e2, 3); // expected-error {{constant expression}} expected-note {{in call}}
+ constexpr int testc = f(e3, 3);
+}
+
+namespace SpeculativeEvalWrites {
+ // Ensure that we don't try to speculatively evaluate writes.
+ constexpr int f() {
+ int i = 0;
+ int a = 0;
+ // __builtin_object_size speculatively evaluates its first argument.
+ __builtin_object_size((i = 1, &a), 0);
+ return i;
+ }
+
+ static_assert(!f(), "");
+}
+
+namespace PR27989 {
+ constexpr int f(int n) {
+ int a = (n = 1, 0);
+ return n;
+ }
+ static_assert(f(0) == 1, "");
+}
+
+namespace const_char {
+template <int N>
+constexpr int sum(const char (&Arr)[N]) {
+ int S = 0;
+ for (unsigned I = 0; I != N; ++I)
+ S += Arr[I]; // expected-note 2{{read of non-constexpr variable 'Cs' is not allowed}}
+ return S;
+}
+
+// As an extension, we support evaluating some things that are `const` as though
+// they were `constexpr` when folding, but it should not be allowed in normal
+// constexpr evaluation.
+const char Cs[] = {'a', 'b'}; // expected-note 2{{declared here}}
+void foo() __attribute__((enable_if(sum(Cs) == 'a' + 'b', "")));
+void run() { foo(); }
+
+static_assert(sum(Cs) == 'a' + 'b', ""); // expected-error{{not an integral constant expression}} expected-note{{in call to 'sum(Cs)'}}
+constexpr int S = sum(Cs); // expected-error{{must be initialized by a constant expression}} expected-note{{in call}}
+}
+
+constexpr void PR28739(int n) { // expected-error {{never produces a constant}}
+ int *p = &n;
+ p += (__int128)(unsigned long)-1; // expected-note {{cannot refer to element 18446744073709551615 of non-array object in a constant expression}}
+}
+
+constexpr void Void(int n) {
+ void(n + 1);
+ void();
+}
+constexpr int void_test = (Void(0), 1);
+
+namespace PR19741 {
+constexpr void addone(int &m) { m++; }
+
+struct S {
+ int m = 0;
+ constexpr S() { addone(m); }
+};
+constexpr bool evalS() {
+ constexpr S s;
+ return s.m == 1;
+}
+static_assert(evalS(), "");
+
+struct Nested {
+ struct First { int x = 42; };
+ union {
+ First first;
+ int second;
+ };
+ int x;
+ constexpr Nested(int x) : first(), x(x) { x = 4; }
+ constexpr Nested() : Nested(42) {
+ addone(first.x);
+ x = 3;
+ }
+};
+constexpr bool evalNested() {
+ constexpr Nested N;
+ return N.first.x == 43;
+}
+static_assert(evalNested(), "");
+} // namespace PR19741
+
+namespace Mutable {
+ struct A { mutable int n; }; // expected-note 2{{here}}
+ constexpr int k = A{123}.n; // ok
+ static_assert(k == 123, "");
+
+ struct Q { A &&a; int b = a.n; };
+ constexpr Q q = { A{456} }; // expected-note {{temporary}}
+ static_assert(q.b == 456, "");
+ static_assert(q.a.n == 456, ""); // expected-error {{constant expression}} expected-note {{outside the expression that created the temporary}}
+
+ constexpr A a = {123};
+ constexpr int m = a.n; // expected-error {{constant expression}} expected-note {{mutable}}
+
+ constexpr Q r = { static_cast<A&&>(const_cast<A&>(a)) }; // expected-error {{constant expression}} expected-note@-8 {{mutable}}
+
+ struct B {
+ mutable int n; // expected-note {{here}}
+ int m;
+ constexpr B() : n(1), m(n) {} // ok
+ };
+ constexpr B b;
+ constexpr int p = b.n; // expected-error {{constant expression}} expected-note {{mutable}}
+}
+
+namespace IndirectFields {
+
+// Reference indirect field.
+struct A {
+ struct {
+ union {
+ int x = x = 3; // cxx14-note {{outside its lifetime}}
+ };
+ };
+ constexpr A() {}
+};
+static_assert(A().x == 3, ""); // cxx14-error{{not an integral constant expression}} cxx14-note{{in call to 'A()'}}
+
+// Reference another indirect field, with different 'this'.
+struct B {
+ struct {
+ union {
+ int x = 3;
+ };
+ int y = x;
+ };
+ constexpr B() {}
+};
+static_assert(B().y == 3, "");
+
+// Nested evaluation of indirect field initializers.
+struct C {
+ union {
+ int x = 1;
+ };
+};
+struct D {
+ struct {
+ C c;
+ int y = c.x + 1;
+ };
+};
+static_assert(D().y == 2, "");
+
+// Explicit 'this'.
+struct E {
+ int n = 0;
+ struct {
+ void *x = this;
+ };
+ void *y = this;
+};
+constexpr E e1 = E();
+static_assert(e1.x != e1.y, "");
+constexpr E e2 = E{0};
+static_assert(e2.x != e2.y, "");
+
+} // namespace IndirectFields
+
+constexpr bool indirect_builtin_constant_p(const char *__s) {
+ return __builtin_constant_p(*__s);
+}
+constexpr bool n = indirect_builtin_constant_p("a");
+
+__attribute__((enable_if(indirect_builtin_constant_p("a") == n, "OK")))
+int test_in_enable_if() { return 0; }
+int n2 = test_in_enable_if();
+
+template <bool n = indirect_builtin_constant_p("a")>
+int test_in_template_param() { return 0; }
+int n3 = test_in_template_param();
+
+void test_in_case(int n) {
+ switch (n) {
+ case indirect_builtin_constant_p("abc"):
+ break;
+ }
+}
+enum InEnum1 {
+ ONE = indirect_builtin_constant_p("abc")
+};
+enum InEnum2 : int {
+ TWO = indirect_builtin_constant_p("abc")
+};
+enum class InEnum3 {
+ THREE = indirect_builtin_constant_p("abc")
+};
+
+// [class.ctor]p4:
+// A constructor can be invoked for a const, volatile or const volatile
+// object. const and volatile semantics are not applied on an object under
+// construction. They come into effect when the constructor for the most
+// derived object ends.
+namespace ObjectsUnderConstruction {
+ struct A {
+ int n;
+ constexpr A() : n(1) { n = 2; }
+ };
+ struct B {
+ const A a;
+ constexpr B(bool mutate) {
+ if (mutate)
+ const_cast<A &>(a).n = 3; // expected-note {{modification of object of const-qualified type 'const int'}}
+ }
+ };
+ constexpr B b(false);
+ static_assert(b.a.n == 2, "");
+ constexpr B bad(true); // expected-error {{must be initialized by a constant expression}} expected-note {{in call to 'B(true)'}}
+
+ struct C {
+ int n;
+ constexpr C() : n(1) { n = 2; }
+ };
+ constexpr int f(bool get) {
+ volatile C c; // expected-note {{here}}
+ return get ? const_cast<int&>(c.n) : 0; // expected-note {{read of volatile object 'c'}}
+ }
+ static_assert(f(false) == 0, ""); // ok, can modify volatile c.n during c's initialization: it's not volatile then
+ static_assert(f(true) == 2, ""); // expected-error {{constant}} expected-note {{in call}}
+
+ struct Aggregate {
+ int x = 0;
+ int y = ++x;
+ };
+ constexpr Aggregate aggr1;
+ static_assert(aggr1.x == 1 && aggr1.y == 1, "");
+ // FIXME: This is not specified by the standard, but sanity requires it.
+ constexpr Aggregate aggr2 = {};
+ static_assert(aggr2.x == 1 && aggr2.y == 1, "");
+
+ // The lifetime of 'n' begins at the initialization, not before.
+ constexpr int n = ++const_cast<int&>(n); // expected-error {{constant expression}} expected-note {{increment of object outside its lifetime}}
+}
+
+namespace PR39728 {
+ struct Comment0 {
+ Comment0 &operator=(const Comment0 &) = default;
+ ~Comment0() = default;
+ };
+ constexpr void f() {
+ Comment0 a;
+ a = a;
+ }
+ static_assert((f(), true), "");
+ struct Comment1 {
+ constexpr Comment1 &operator=(const Comment1 &) = default; // OK
+ ~Comment1() = default;
+ };
+}
+
+namespace TemporaryWithBadPointer {
+ constexpr int *get_bad_pointer() {
+ int n = 0; // expected-note 2{{here}}
+ return &n; // expected-warning {{stack}}
+ }
+ constexpr int *bad_pointer = get_bad_pointer(); // expected-error {{constant expression}} expected-note {{pointer to 'n' is not a constant expression}}
+
+ struct DoBadThings { int *&&wp; int n; };
+ constexpr DoBadThings dbt = { // expected-error {{constant expression}}
+ nullptr, // expected-note {{pointer to 'n' is not a constant expression}}
+ (dbt.wp = get_bad_pointer(), 0)
+ };
+
+ constexpr DoBadThings dbt2 = { // ok
+ get_bad_pointer(),
+ (dbt2.wp = nullptr, 0)
+ };
+}