1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
|
// RUN: %clang_cc1 -fexperimental-new-constant-interpreter -verify=expected,both %s
// RUN: %clang_cc1 -fexperimental-new-constant-interpreter -std=c++20 -verify=expected,both %s
// RUN: %clang_cc1 -verify=ref,both %s
// RUN: %clang_cc1 -verify=ref,both -std=c++20 %s
constexpr int m = 3;
constexpr const int *foo[][5] = {
{nullptr, &m, nullptr, nullptr, nullptr},
{nullptr, nullptr, &m, nullptr, nullptr},
{nullptr, nullptr, nullptr, &m, nullptr},
};
static_assert(foo[0][0] == nullptr, "");
static_assert(foo[0][1] == &m, "");
static_assert(foo[0][2] == nullptr, "");
static_assert(foo[0][3] == nullptr, "");
static_assert(foo[0][4] == nullptr, "");
static_assert(foo[1][0] == nullptr, "");
static_assert(foo[1][1] == nullptr, "");
static_assert(foo[1][2] == &m, "");
static_assert(foo[1][3] == nullptr, "");
static_assert(foo[1][4] == nullptr, "");
static_assert(foo[2][0] == nullptr, "");
static_assert(foo[2][1] == nullptr, "");
static_assert(foo[2][2] == nullptr, "");
static_assert(foo[2][3] == &m, "");
static_assert(foo[2][4] == nullptr, "");
constexpr int SomeInt[] = {1};
constexpr int getSomeInt() { return *SomeInt; }
static_assert(getSomeInt() == 1, "");
/// A init list for a primitive value.
constexpr int f{5};
static_assert(f == 5, "");
constexpr int getElement(int i) {
int values[] = {1, 4, 9, 16, 25, 36};
return values[i];
}
static_assert(getElement(1) == 4, "");
static_assert(getElement(5) == 36, "");
constexpr int data[] = {5, 4, 3, 2, 1};
constexpr int getElement(const int *Arr, int index) {
return *(Arr + index);
}
constexpr int derefPtr(const int *d) {
return *d;
}
static_assert(derefPtr(data) == 5, "");
constexpr int storePtr() {
int b[] = {1,2,3,4};
int *c = b;
*c = 4;
return *c;
}
static_assert(storePtr() == 4, "");
static_assert(getElement(data, 1) == 4, "");
static_assert(getElement(data, 4) == 1, "");
constexpr int getElementFromEnd(const int *Arr, int size, int index) {
return *(Arr + size - index - 1);
}
static_assert(getElementFromEnd(data, 5, 0) == 1, "");
static_assert(getElementFromEnd(data, 5, 4) == 5, "");
constexpr int getFirstElem(const int *a) {
return a[0]; // both-note {{read of dereferenced null pointer}}
}
static_assert(getFirstElem(nullptr) == 1, ""); // both-error {{not an integral constant expression}} \
// both-note {{in call to}}
constexpr static int arr[2] = {1,2};
constexpr static int arr2[2] = {3,4};
constexpr int *p1 = nullptr;
constexpr int *p2 = p1 + 1; // both-error {{must be initialized by a constant expression}} \
// both-note {{cannot perform pointer arithmetic on null pointer}}
constexpr int *p3 = p1 + 0;
constexpr int *p4 = p1 - 0;
constexpr int *p5 = 0 + p1;
constexpr int *p6 = 0 - p1; // both-error {{invalid operands to binary expression}}
constexpr int const * ap1 = &arr[0];
constexpr int const * ap2 = ap1 + 3; // both-error {{must be initialized by a constant expression}} \
// both-note {{cannot refer to element 3 of array of 2}}
constexpr auto ap3 = arr - 1; // both-error {{must be initialized by a constant expression}} \
// both-note {{cannot refer to element -1}}
constexpr int k1 = &arr[1] - &arr[0];
static_assert(k1 == 1, "");
static_assert((&arr[0] - &arr[1]) == -1, "");
constexpr int k2 = &arr2[1] - &arr[0]; // both-error {{must be initialized by a constant expression}}
static_assert((arr + 0) == arr, "");
static_assert(&arr[0] == arr, "");
static_assert(*(&arr[0]) == 1, "");
static_assert(*(&arr[1]) == 2, "");
constexpr const int *OOB = (arr + 3) - 3; // both-error {{must be initialized by a constant expression}} \
// both-note {{cannot refer to element 3 of array of 2}}
template<typename T>
constexpr T getElementOf(T* array, int i) {
return array[i];
}
static_assert(getElementOf(foo[0], 1) == &m, "");
template <typename T, int N>
constexpr T& getElementOfArray(T (&array)[N], int I) {
return array[I];
}
static_assert(getElementOfArray(foo[2], 3) == &m, "");
static_assert(data[0] == 4, ""); // both-error{{failed}} \
// both-note{{5 == 4}}
constexpr int dynamic[] = {
f, 3, 2 + 5, data[3], *getElementOf(foo[2], 3)
};
static_assert(dynamic[0] == f, "");
static_assert(dynamic[3] == 2, "");
constexpr int dependent[4] = {
0, 1, dependent[0], dependent[1]
};
static_assert(dependent[2] == dependent[0], "");
static_assert(dependent[3] == dependent[1], "");
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wc99-extensions"
#pragma clang diagnostic ignored "-Winitializer-overrides"
constexpr int DI[] = {
[0] = 10,
[1] = 20,
30,
40,
[1] = 50
};
static_assert(DI[0] == 10, "");
static_assert(DI[1] == 50, "");
static_assert(DI[2] == 30, "");
static_assert(DI[3] == 40, "");
constexpr int addThreeElements(const int v[3]) {
return v[0] + v[1] + v[2];
}
constexpr int is[] = {10, 20, 30 };
static_assert(addThreeElements(is) == 60, "");
struct fred {
char s [6];
int n;
};
struct fred y [] = { [0] = { .s[0] = 'q' } };
#pragma clang diagnostic pop
namespace indices {
constexpr int first[] = {1};
constexpr int firstValue = first[2]; // both-error {{must be initialized by a constant expression}} \
// both-note {{cannot refer to element 2 of array of 1}}
constexpr int second[10] = {17};
constexpr int secondValue = second[10];// both-error {{must be initialized by a constant expression}} \
// both-note {{read of dereferenced one-past-the-end pointer}} \
constexpr int negative = second[-2]; // both-error {{must be initialized by a constant expression}} \
// both-note {{cannot refer to element -2 of array of 10}}
};
namespace DefaultInit {
template <typename T, unsigned N>
struct B {
T a[N];
};
int f() {
constexpr B<int,10> arr = {};
constexpr int x = arr.a[0];
}
};
class A {
public:
int a;
constexpr A(int m = 2) : a(10 + m) {}
};
class AU {
public:
int a;
constexpr AU() : a(5 / 0) {} // both-warning {{division by zero is undefined}} \
// both-note 2{{division by zero}} \
// both-error {{never produces a constant expression}}
};
class B {
public:
A a[2];
constexpr B() {}
};
constexpr B b;
static_assert(b.a[0].a == 12, "");
static_assert(b.a[1].a == 12, "");
class BU {
public:
AU a[2];
constexpr BU() {} // both-note {{in call to 'AU()'}}
};
constexpr BU bu; // both-error {{must be initialized by a constant expression}} \
// both-note {{in call to 'BU()'}}
namespace IncDec {
constexpr int getNextElem(const int *A, int I) {
const int *B = (A + I);
++B;
return *B;
}
constexpr int E[] = {1,2,3,4};
static_assert(getNextElem(E, 1) == 3, "");
constexpr int getFirst() {
const int *e = E;
return *(e++);
}
static_assert(getFirst() == 1, "");
constexpr int getFirst2() {
const int *e = E;
e++;
return *e;
}
static_assert(getFirst2() == 2, "");
constexpr int getSecond() {
const int *e = E;
return *(++e);
}
static_assert(getSecond() == 2, "");
constexpr int getSecond2() {
const int *e = E;
++e;
return *e;
}
static_assert(getSecond2() == 2, "");
constexpr int getLast() {
const int *e = E + 3;
return *(e--);
}
static_assert(getLast() == 4, "");
constexpr int getLast2() {
const int *e = E + 3;
e--;
return *e;
}
static_assert(getLast2() == 3, "");
constexpr int getSecondToLast() {
const int *e = E + 3;
return *(--e);
}
static_assert(getSecondToLast() == 3, "");
constexpr int getSecondToLast2() {
const int *e = E + 3;
--e;
return *e;
}
static_assert(getSecondToLast2() == 3, "");
constexpr int bad1() { // both-error {{never produces a constant expression}}
const int *e = E + 3;
e++; // This is fine because it's a one-past-the-end pointer
return *e; // both-note 2{{read of dereferenced one-past-the-end pointer}}
}
static_assert(bad1() == 0, ""); // both-error {{not an integral constant expression}} \
// both-note {{in call to}}
constexpr int bad2() { // both-error {{never produces a constant expression}}
const int *e = E + 4;
e++; // both-note 2{{cannot refer to element 5 of array of 4 elements}}
return *e; // This is UB as well
}
static_assert(bad2() == 0, ""); // both-error {{not an integral constant expression}} \
// both-note {{in call to}}
constexpr int bad3() { // both-error {{never produces a constant expression}}
const int *e = E;
e--; // both-note 2{{cannot refer to element -1 of array of 4 elements}}
return *e; // This is UB as well
}
static_assert(bad3() == 0, ""); // both-error {{not an integral constant expression}} \
// both-note {{in call to}}
constexpr int nullptr1(bool Pre) {
int *a = nullptr;
if (Pre)
++a; // both-note {{arithmetic on null pointer}}
else
a++; // both-note {{arithmetic on null pointer}}
return 1;
}
static_assert(nullptr1(true) == 1, ""); // both-error {{not an integral constant expression}} \
// both-note {{in call to}}
static_assert(nullptr1(false) == 1, ""); // both-error {{not an integral constant expression}} \
// both-note {{in call to}}
};
namespace ZeroInit {
struct A {
int *p[2];
};
constexpr A a = {};
static_assert(a.p[0] == nullptr, "");
static_assert(a.p[1] == nullptr, "");
struct B {
double f[2];
};
constexpr B b = {};
static_assert(b.f[0] == 0.0, "");
static_assert(b.f[1] == 0.0, "");
}
namespace ArrayInitLoop {
struct X {
int arr[3];
};
constexpr X f(int &r) {
return {++r, ++r, ++r};
}
constexpr int g() {
int n = 0;
auto [a, b, c] = f(n).arr;
return a + b + c;
}
static_assert(g() == 6, "");
}
namespace StringZeroFill {
struct A {
char c[6];
};
constexpr A a = { "abc" };
static_assert(a.c[0] == 'a', "");
static_assert(a.c[1] == 'b', "");
static_assert(a.c[2] == 'c', "");
static_assert(a.c[3] == '\0', "");
static_assert(a.c[4] == '\0', "");
static_assert(a.c[5] == '\0', "");
constexpr char b[6] = "foo";
static_assert(b[0] == 'f', "");
static_assert(b[1] == 'o', "");
static_assert(b[2] == 'o', "");
static_assert(b[3] == '\0', "");
static_assert(b[4] == '\0', "");
static_assert(b[5] == '\0', "");
}
namespace NoInitMapLeak {
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wdivision-by-zero"
#pragma clang diagnostic ignored "-Wc++20-extensions"
constexpr int testLeak() { // both-error {{never produces a constant expression}}
int a[2];
a[0] = 1;
// interrupts interpretation.
(void)(1 / 0); // both-note 2{{division by zero}}
return 1;
}
#pragma clang diagnostic pop
static_assert(testLeak() == 1, ""); // both-error {{not an integral constant expression}} \
// both-note {{in call to 'testLeak()'}}
constexpr int a[] = {1,2,3,4/0,5}; // both-error {{must be initialized by a constant expression}} \
// both-note {{division by zero}} \
// ref-note {{declared here}}
/// FIXME: This should fail in the new interpreter as well.
constexpr int b = a[0]; // ref-error {{must be initialized by a constant expression}} \
// ref-note {{is not a constant expression}} \
// ref-note {{declared here}}
static_assert(b == 1, ""); // ref-error {{not an integral constant expression}} \
// ref-note {{not a constant expression}}
constexpr int f() { // both-error {{never produces a constant expression}}
int a[] = {19,2,3/0,4}; // both-note 2{{division by zero}} \
// both-warning {{is undefined}}
return 1;
}
static_assert(f() == 1, ""); // both-error {{not an integral constant expression}} \
// both-note {{in call to}}
}
namespace Incomplete {
struct Foo {
char c;
int a[];
};
constexpr Foo F{};
constexpr const int *A = F.a; // both-error {{must be initialized by a constant expression}} \
// both-note {{array-to-pointer decay of array member without known bound}}
constexpr const int *B = F.a + 1; // both-error {{must be initialized by a constant expression}} \
// both-note {{array-to-pointer decay of array member without known bound}}
constexpr int C = *F.a; // both-error {{must be initialized by a constant expression}} \
// both-note {{array-to-pointer decay of array member without known bound}}
/// These are from test/SemaCXX/constant-expression-cxx11.cpp
/// and are the only tests using the 'indexing of array without known bound' diagnostic.
/// We currently diagnose them differently.
extern int arr[]; // expected-note 3{{declared here}}
constexpr int *c = &arr[1]; // both-error {{must be initialized by a constant expression}} \
// ref-note {{indexing of array without known bound}} \
// expected-note {{read of non-constexpr variable 'arr'}}
constexpr int *d = &arr[1]; // both-error {{must be initialized by a constant expression}} \
// ref-note {{indexing of array without known bound}} \
// expected-note {{read of non-constexpr variable 'arr'}}
constexpr int *e = arr + 1; // both-error {{must be initialized by a constant expression}} \
// ref-note {{indexing of array without known bound}} \
// expected-note {{read of non-constexpr variable 'arr'}}
}
namespace GH69115 {
/// This used to crash because we were trying to emit destructors for the
/// array.
constexpr int foo() {
int arr[2][2] = {1, 2, 3, 4};
return 0;
}
static_assert(foo() == 0, "");
/// Test that we still emit the destructors for multi-dimensional
/// composite arrays.
#if __cplusplus >= 202002L
constexpr void assert(bool C) {
if (C)
return;
// Invalid in constexpr.
(void)(1 / 0); // both-warning {{undefined}}
}
class F {
public:
int a;
int *dtor;
int &idx;
constexpr F(int a, int *dtor, int &idx) : a(a), dtor(dtor), idx(idx) {}
constexpr ~F() noexcept(false){
dtor[idx] = a;
++idx;
}
};
constexpr int foo2() {
int dtorIndices[] = {0, 0, 0, 0};
int idx = 0;
{
F arr[2][2] = {F(1, dtorIndices, idx),
F(2, dtorIndices, idx),
F(3, dtorIndices, idx),
F(4, dtorIndices, idx)};
}
/// Reverse-reverse order.
assert(idx == 4);
assert(dtorIndices[0] == 4);
assert(dtorIndices[1] == 3);
assert(dtorIndices[2] == 2);
assert(dtorIndices[3] == 1);
return 0;
}
static_assert(foo2() == 0, "");
#endif
}
namespace NonConstReads {
#if __cplusplus >= 202002L
void *p = nullptr; // both-note {{declared here}}
int arr[!p]; // both-error {{not allowed at file scope}} \
// both-warning {{variable length arrays}} \
// both-note {{read of non-constexpr variable 'p'}}
int z; // both-note {{declared here}}
int a[z]; // both-error {{not allowed at file scope}} \
// both-warning {{variable length arrays}} \
// both-note {{read of non-const variable 'z'}}
#else
void *p = nullptr;
int arr[!p]; // ref-error {{not allowed at file scope}} \
// expected-error {{not allowed at file scope}}
int z;
int a[z]; // ref-error {{not allowed at file scope}} \
// expected-error {{not allowed at file scope}}
#endif
const int y = 0;
int yy[y];
}
namespace SelfComparison {
struct S {
int field;
static int static_field;
int array[4];
};
struct T {
int field;
static int static_field;
int array[4];
S s;
};
int struct_test(S s1, S s2, S *s3, T t) {
return s3->array[t.field] == s3->array[t.field]; // both-warning {{self-comparison always evaluates to true}}
};
}
namespace LocalIndex {
void test() {
const int const_subscript = 3;
int array[2]; // both-note {{declared here}}
array[const_subscript] = 0; // both-warning {{array index 3 is past the end of the array (that has type 'int[2]')}}
}
}
namespace LocalVLA {
struct Foo {
int x;
Foo(int x) : x(x) {}
};
struct Elidable {
Elidable();
};
void foo(int size) {
Elidable elidableDynArray[size];
#if __cplusplus >= 202002L
// both-note@-3 {{declared here}}
// both-warning@-3 {{variable length array}}
// both-note@-4 {{function parameter 'size' with unknown value}}
#endif
}
}
char melchizedek[2200000000];
typedef decltype(melchizedek[1] - melchizedek[0]) ptrdiff_t;
constexpr ptrdiff_t d1 = &melchizedek[0x7fffffff] - &melchizedek[0]; // ok
constexpr ptrdiff_t d3 = &melchizedek[0] - &melchizedek[0x80000000u]; // ok
|