| Issue |
123637
|
| Summary |
Bad error trace for issue with unique_ptr
|
| Labels |
new issue
|
| Assignees |
|
| Reporter |
JVApen
|
The following is reduced from a build with clang-cl and the MS stl implementation:
````
#include <vector>
#include <memory>
#include <type_traits>
template <class _Ty>
struct ms_default_delete { // default deleter for unique_ptr
constexpr ms_default_delete() noexcept = default;
template <class _Ty2, std::enable_if_t<std::is_convertible_v<_Ty2*, _Ty*>, int> = 0>
ms_default_delete(const ms_default_delete<_Ty2>&) noexcept {}
void operator()(_Ty* _Ptr) const noexcept /* strengthened */ { // delete a pointer
static_assert(0 < sizeof(_Ty), "can't delete an incomplete type");
delete _Ptr;
}
};
struct FWD;
struct S
{
~S() = default;
std::vector<std::unique_ptr<FWD, ms_default_delete<FWD>>> member;
};
int main(int, char**){
S s;
}
````
https://compiler-explorer.com/z/6K8ebK3E1
This gives the error:
````
<source>:13:27: error: invalid application of 'sizeof' to an incomplete type 'FWD'
13 | static_assert(0 < sizeof(_Ty), "can't delete an incomplete type");
| ^~~~~~~~~~~
/opt/compiler-explorer/clang-trunk-20250120/bin/../include/c++/v1/__memory/unique_ptr.h:300:7: note: in instantiation of member function 'ms_default_delete<FWD>::operator()' requested here
300 | __deleter_(__tmp);
| ^
/opt/compiler-explorer/clang-trunk-20250120/bin/../include/c++/v1/__memory/unique_ptr.h:269:71: note: in instantiation of member function 'std::unique_ptr<FWD, ms_default_delete<FWD>>::reset' requested here
269 | _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 ~unique_ptr() { reset(); }
| ^
/opt/compiler-explorer/clang-trunk-20250120/bin/../include/c++/v1/__memory/construct_at.h:66:11: note: in instantiation of member function 'std::unique_ptr<FWD, ms_default_delete<FWD>>::~unique_ptr' requested here
66 | __loc->~_Tp();
| ^
<source>:17:8: note: forward declaration of 'FWD'
17 | struct FWD;
| ^
1 error generated.
````
In this trace, this mentions the location of the `static_assert`, it mentions the location of the forward declare.
Though what is missing in this trace is the location that started the initialization. (The inline destructor of struct `S`)
This last is especially useful if you have the output of multiple compilations together without explicit mention of the file that was compiled.
(Like a multi-process build via CMake, a CI system that runs clang-tidy on multiple files and puts all results together ...)
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