| Issue |
60936
|
| Summary |
Aggregate construction of an lvalue class object not considered constant _expression_
|
| Labels |
new issue
|
| Assignees |
|
| Reporter |
danakj
|
Construction as an rvalue works, but not as an lvalue.
https://godbolt.org/z/r3d17jMjM
```cpp
struct S {
// Clang cant constexpr construct this as an lvalue without the constructor.
// constexpr S(int i) : i(i) {}
int i;
int *p = &i;
constexpr const int* ptr() const { return &i; }
};
// Not constant _expression_ in GCC.
static_assert(S{2}.ptr() != nullptr);
static_assert(S{2}.p != nullptr);
// Is a constant _expression_.
static_assert(*S{2}.ptr() == 2);
static_assert(*S{2}.p == 2);
static_assert([]() constexpr {
// Not a constant _expression_ in Clang without a user-defined constructor.
auto r = S{2};
// Is a constant _expression_.
return r.ptr() != nullptr && r.p != nullptr;
}());
```
Generates a compiler error that the lambda is not a constant _expression_.
Uncommenting the constructor in S makes the example compile. GCC and MSVC accept this without the constructor.
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