[[lifetimebound]] assignment seems to interfere with tracking

[DenisYaroshevskiy]

The following example is not caught

#include <string>
#include <string_view>
#include <iostream>

struct S {
  std::string s;

  std::string_view f() const [[clang::lifetimebound]] {
    return s;
  }
};

void test() {
  std::string_view thisIsAnIssue;
  thisIsAnIssue = S{}.f();
  std::cout << thisIsAnIssue << std::endl;
}

https://godbolt.org/z/onnPjPo95

While this one is

void test() {
  std::string_view thisIsAnIssue = S{}.f();
  std::cout << thisIsAnIssue << std::endl;
}

https://godbolt.org/z/q57nhWYaT

Could they both be caught?

[yndx-melkov]

There are many problems with std::span and string_view. [[clang::lifetimebound]] can not be directly used with non-eliminated constructors, assignment operators, and also with stuff like subspan, because it will bind to the source span object itself rather than the objects it is pointing to.

Might it be possible to allow the application of [[clang::lifetimebound]] to entire class, so it would be treated like a pointer?

• When constructed from another [[clang::lifetimebound]] object, it would point to the target that object points to.
• When a method returns a [[clang::lifetimebound]] object, it would point to the targets the original object is pointing to.