Attribute clang::lifetimebound produces no warning when assign temporary's address to pointer declared before.

[Kidsunbo]

[[clang::lifetimebound]] could be used to provide some lifetime annotation to functions. In the statement of a pointer initialization, everything works fine. But in the statement of a pointer assignment, the desired warning can not be produced.

Here is the code sample:

#include <string>

const char* get(const std::string& s [[clang::lifetimebound]]){
    return s.data();
}

int main(){
 // can be detected
 const char* s1 = get("hello"s);

 // cannot be detected
 const char* s2 = nullptr;
 s2 = get("hello"s);

 return 0;
}

Here is more code to illustrate this: https://godbolt.org/z/fhTPYTa1d

Is this intentional or a flaw of lifetime check?