no function or associated item named `from_str` found for struct `proc_macro::Literal` in the current scope toolchain: `nightly-2021-05-16-x86_64-unknown-linux-gnu` proc-macro2: 1.0.29 https://github.com/dtolnay/proc-macro2/issues/297 should fix #37 for newer toolchain support, or specify the use of proc-macro2 previous version?