How to return unique_ptr of an array created inside my function?

I've tried various ways of writing my function, all of them failing with some kind of error.

First I tried a straight forward const auto type on my unique pointer (same result as const unique_ptr<char[]>):

export unique_ptr<char[]> mem_new_dup(const char* data, const size_t length)
{
    const auto mem = make_unique<char[]>(length);
    memcpy(mem.get(), data, length);
    return mem;  // error is on this line
}

// error:
//1>F:\gitrepos\ve2\ve2\utilities.ixx(10,1): error C2280: 'std::unique_ptr<char [],std::default_delete<char []>>::unique_ptr(const std::unique_ptr<char [],std::default_delete<char []>> &)': attempting to reference a deleted function
//1>D:\a01\_work\2\s\binaries\x86ret\inc\memory(2686): message : see declaration of 'std::unique_ptr<char [],std::default_delete<char []>>::unique_ptr'
//1>D:\a01\_work\2\s\binaries\x86ret\inc\memory(2686,5): message : 'std::unique_ptr<char [],std::default_delete<char []>>::unique_ptr(const std::unique_ptr<char [],std::default_delete<char []>> &)': function was explicitly deleted

Then I tried to remove the const from the unique pointer (even though it is constant):

export unique_ptr<char[]> mem_new_dup(const char* data, const size_t length)
{
    auto mem = make_unique<char[]>(length);
    memcpy(mem.get(), data, length);
    return mem;
}

// error
//1>D:\a01\_work\2\s\binaries\x86ret\inc\memory(2536,1): error C2070: '_Ty': illegal sizeof operand
//1>        with
//1>        [
//1>            _Ty=char []
//1>        ]
//1>D:\a01\_work\2\s\binaries\x86ret\inc\memory(2535): message : while compiling class template member function 'void std::default_delete<char []>::operator ()(_Ty (*)) noexcept const'
//1>        with
//1>        [
//1>            _Ty=char []
//1>        ]
//1>D:\a01\_work\2\s\binaries\x86ret\inc\memory(2647): message : see reference to function template instantiation 'void std::default_delete<char []>::operator ()(_Ty (*)) noexcept const' being compiled
//1>        with
//1>        [
//1>            _Ty=char []
//1>        ]
//1>D:\a01\_work\2\s\binaries\x86ret\inc\memory(2574): message : see reference to class template instantiation 'std::default_delete<char []>' being compiled
//1>F:\gitrepos\ve2\ve2\utilities.ixx(7): message : see reference to class template instantiation 'std::unique_ptr<char [],std::default_delete<char []>>' being compiled
//1>D:\a01\_work\2\s\binaries\x86ret\inc\memory(2536,25): error C2338: can't delete an incomplete type
//1>D:\a01\_work\2\s\binaries\x86ret\inc\memory(2537,1): warning C4156: deletion of an array expression without using the array form of 'delete'; array form substituted

So how can I correctly write my function?

Solution

Turns out that the problem was related to C++20 modules, I was doing an import std.core; above this code and for some reason it was importing the clang memory module instead of the MSVC module. Using #include <memory> as usual fixes the problem.