While std::string_view is fantastic for avoiding string allocations during read-only operations, it does NOT own the underlying character buffer:

std::string_view GetPrefix() {
    std::string s = "https://example.com";
    return s.substr(0, 5); // DANGLING STRING_VIEW!
}

When GetPrefix() exits, the local std::string s is deallocated. The returned std::string_view now points to freed memory, leading to garbage output or access violation crashes when dereferenced.

AddressSanitizer (-fsanitize=address) catches these stack-use-after-scope bugs instantly at runtime.

Rule of thumb: Use std::string_view for function parameters, but rarely as return types unless borrowing from a parameter with matching lifetime.