Broken Dependency: proc-macro2 ... again ...

[Zhengmian Hu]

Local compiler:
rustc --version
rustc 1.31.0 (abe02cefd 2018-12-04)
rustc +nightly --version
rustc 1.32.0-nightly (f4a421ee3 2018-12-13)

errors:

error[E0658]: use of unstable library feature 'proc_macro_span' (see issue #54725)
   --> /home/xiaoniu/.cargo/registry/src/github.com-1ecc6299db9ec823/proc-macro2-0.4.6/src/unstable.rs:284:13
    |
284 |     Nightly(proc_macro::SourceFile, FileName),
    |             ^^^^^^^^^^^^^^^^^^^^^^
    |
    = help: add #![feature(proc_macro_span)] to the crate attributes to enable

error[E0658]: use of unstable library feature 'proc_macro_span' (see issue #54725)
   --> /home/xiaoniu/.cargo/registry/src/github.com-1ecc6299db9ec823/proc-macro2-0.4.6/src/unstable.rs:289:20
    |
289 |     fn nightly(sf: proc_macro::SourceFile) -> Self {
    |                    ^^^^^^^^^^^^^^^^^^^^^^
    |
    = help: add #![feature(proc_macro_span)] to the crate attributes to enable

[Zhengmian Hu]

after regenerating Cargo.lock, above errors vanished.

Instead other errors emerge.

error[E0557]: feature has been removed
 --> src/main.rs:1:36               
  |          
1 | #![feature(proc_macro, generators, proc_macro_non_items)]
  |                                    ^^^^^^^^^^^^^^^^^^^^
  |                                                                              
note: subsumed by `#![feature(proc_macro_hygiene)]`
 --> src/main.rs:1:36                                                               
  |                       
1 | #![feature(proc_macro, generators, proc_macro_non_items)]
  |                                    ^^^^^^^^^^^^^^^^^^^^                                                                                                                                  

error[E0658]: procedural macros cannot be expanded to expressions (see issue #54727)
  --> src/checker.rs:13:15
   |
13 |       let lop = async_block! {
   |  _______________^
14 | |         #[async]
15 | |         for _ in Interval::new(Duration::from_secs(12 * 60 * 60), &handle)
16 | |             .expect("failed to start checker loop")
...  |
62 | |         Ok(())
63 | |     }.map_err(|e: ::std::io::Error| error!("checker loop: {}", e));
   | |_____^
   |
   = help: add #![feature(proc_macro_hygiene)] to the crate attributes to enable

[iovxw]

README is outdated, please use cargo build --release and don't regenerate Cargo.lock