> I think "[&]" is broken.

I feel like this is consistent with the "pay for what you use" design. Why capture all variables in scope by copies when you can just capture them all as references (which might go out of scope)? If you truly need to capture other stuff, you can do so using more syntax. If "[&]" did what you describe then "wtf, why is it saying I have a deleted copy constructor for some value I'm not using" or "wtf, why is my code so slow because of unnecessary copies of large objects" would be all sorts of fun.