`From<proc_macro::Span>` is missing for `proc_macro2::Span` when `DOCS_RS=1`#501

wtdcode wants to merge 2 commits intodtolnay:masterdtolnay/proc-macro2:masterfrom

wtdcode:impl-proc-macro-spanwtdcode/proc-macro2:impl-proc-macro-spanCopy head branch name to clipboard