[LifetimeSafety] False-positive for aliases to reference variable

[usx95]

https://godbolt.org/z/cGxozPYWj

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

void foo() {
    std::vector<std::string> v;
    std::string_view view;
    for (const auto& s : v) {
        view = s; // warning: 's' does not live long enough.
    }
    (void)view; // note: later used here.
}

void bar(const std::string& s) {
    std::string_view view;
    {
        const std::string& ref = s; // 's' does not live long enough.
        view = ref;
    }
    (void)view; // later used here.
}

[llvmbot]

@llvm/issue-subscribers-clang-temporal-safety

Author: Utkarsh Saxena (usx95)

https://godbolt.org/z/GEvfvxvG6

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

void foo() {
    std::vector<std::string> v;
    std::string_view view;
    for (const auto& s : v) {
        view = s; // warning: 's' does not live long enough.
    }
    (void)view; // note: later used here.
}