When - Timezones from the command line

Thank you for an interesting tool!

I was wondering if the following use-case would be interesting to you: I frequently want to know how much days have passed since a certain date or what would be the date + x days. IIUC, I can already calculate now + x days through 4 pm in x days but I can't do the same for the future and the past. It would certainly be nice to me since that's something I frequently do to calculate some documents processing time, etc.

Hello @mitsuhiko thanks for making this project open source. Wish I could buy you a beer or coffee.

I tried to installed it today but came across this issue:

$ cargo install when-cli

    Updating crates.io index
  Downloaded when-cli v0.4.0
error: failed to parse manifest at `/home/pathcl/.asdf/installs/rust/1.54.0/registry/src/github.com-1ecc6299db9ec823/when-cli-0.4.0/Cargo.toml`

Caused by:
  feature `edition2021` is required

  this Cargo does not support nightly features, but if you
  switch to nightly channel you can add
  `cargo-features = ["edition2021"]` to enable this feature

$ cargo --version
cargo 1.54.0 (5ae8d74b3 2021-06-22)

$ rustc --version
rustc 1.54.0 (a178d0322 2021-07-26)

Maybe I missed something in the readme?

When trying to install when-cli using cargo, I am getting this output

❯ cargo install when-cli
    Updating crates.io index
error: could not find `when-cli` in registry `crates-io` with version `*`

Can you let me know, what am I doing wrong?

I often use https://time.is to convert timezones, getting this from the CLI would be neat! However, when running cargo install when i get this:

error: there is nothing to install in `when v0.1.4`, because it has no binaries
`cargo install` is only for installing programs, and can't be used with libraries.
To use a library crate, add it as a dependency in a Cargo project instead.

Could you add a binary target to solve this? Thanks!

cargo install when-cli error:

error[E0658]: use of unstable library feature 'proc_macro_is_available'
  --> /Users/thearas/.cargo/registry/src/github.com-1ecc6299db9ec823/proc-macro2-1.0.33/src/detection.rs:28:21
   |
28 |     let available = proc_macro::is_available();
   |                     ^^^^^^^^^^^^^^^^^^^^^^^^
   |
   = note: see issue #71436 <https://github.com/rust-lang/rust/issues/71436> for more information
   = help: add `#![feature(proc_macro_is_available)]` to the crate attributes to enable

For more information about this error, try `rustc --explain E0658`.
error: could not compile `proc-macro2` due to previous error
warning: build failed, waiting for other jobs to finish...
error: failed to compile `when-cli v0.1.0`, intermediate artifacts can be found at `/var/folders/wb/ss6s2j2n1nj5jl5_v_qy2br40000gn/T/cargo-installFv9jfm`

Caused by:
  build failed

Version

rustc 1.57.0-nightly (b69fe5726 2021-09-10)

Times such as "12am" or "12pm" don't seem to work correctly now. For example, I want to compare times in Montreal and Berlin.

Behaviour for any time other than 12am/pm — works normally:

$ when "5pm in montreal -> berlin"
time: 17:00:00
date: 2021-12-04
location: Montreal (Canada)
zone: America/Toronto (-0500)

time: 23:00:00
date: 2021-12-04
location: Berlin (Germany)
zone: Europe/Berlin (+0100)

Behaviour for "12pm" — program panics:

$ when "12pm in montreal -> berlin"
thread 'main' panicked at 'called `Option::unwrap()` on a `None` value', src/parser.rs:68:22
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

Behaviour for "12am" — program treats it as 12:00 (which AFAIK is 12pm):

$ when "12am in montreal -> berlin"
time: 12:00:00
date: 2021-12-04
location: Montreal (Canada)
zone: America/Toronto (-0500)

time: 18:00:00
date: 2021-12-04
location: Berlin (Germany)
zone: Europe/Berlin (+0100)