Not to detract from your general point, but are you sure your example corrupts memory? AsciiStrToUpper returns a std::string (it has to), which in your example becomes a temporary object. Temporaries are destructed at the end of the containing full-expression, which in this case is the whole assignment expression. So StripAsciiWhitespace returns a view into a still-living temporary, and foo2's constructor allocates memory and makes a copy. Only then is the temporary deallocated.

Now, if you wrote absl::string_view foo2 = etc., you'd have a dangling view for sure. In practical industrial usage, you'd build with an address sanitizer (it's built into clang: -fsanitize=address), which should catch that issue.