| Issue |
109442
|
| Summary |
-Wdangling-gsl does not work consistently with span across STL
|
| Labels |
new issue
|
| Assignees |
|
| Reporter |
marco-antognini-sonarsource
|
I'm checking the behavior of Clang 19 vs 18 and I noticed that @hokein's https://github.com/llvm/llvm-project/pull/99622 introduces some nice warnings thanks to the added attributes on `std::span`.
However, it does not work with libc++.
Here is an example:
```cpp
#include <span>
#include <string>
struct SpanAggr {
std::span<char const> sv;
};
void test() {
// No issue raised in 18.1
// Issue raised from 19.1 thanks to https://github.com/llvm/llvm-project/pull/99622
// but not with libc++
SpanAggr a1{std::span<char const>{std::string{}}};
}
```
https://godbolt.org/z/Yfe78nsdb
IIUC, the problem boils down to the fact `std::span` is defined with a template specialization for dynamic extent and the `ClassTemplatePartialSpecializationDecl` does not get the `PointerAttr`:
```cpp
namespace std {
inline constexpr size_t dynamic_extent = -1;
template <typename _Tp, size_t _Extent = dynamic_extent>
class span;
template <typename _Tp, size_t _Extent>
struct span {
// Bla
};
template <typename _Tp>
struct span<_Tp, dynamic_extent> {
// Bla
};
} // namespace std
```
https://godbolt.org/z/nh1j4a7xE
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