matrixcompare uses num_traits::Float without std

[0ncorhynchus]

This is a bug report.

I tried to use matrixcompare as a dependency with a tiny sample Cargo.toml shown as the below:

[package]
name = "tmp"
version = "0.1.0"
edition = "2018"

[dependencies]
matrixcompare = "0.1.3"

However, cargo check failed with the message like:

$ cargo check
    Checking matrixcompare v0.1.3
error[E0432]: unresolved import `num_traits::Float`
 --> /home/kato/.cargo/registry/src/gh.neting.cc-1ecc6299db9ec823/matrixcompare-0.1.3/src/comparators.rs:5:18
  |
5 | use num_traits::{Float, Num};
  |                  ^^^^^
  |                  |
  |                  no `Float` in the root
  |                  help: a similar name exists in the module (notice the capitalization): `float`

error: aborting due to previous error

For more information about this error, try `rustc --explain E0432`.
error: could not compile `matrixcompare`.

To learn more, run the command again with --verbose.

This is caused by that matrixcompare uses num_traits::Float without the std feature of num-traits.
I found out from Cargo.toml of this crate that it is expected behavior to use num-traits without the std feature.

matrixcompare/Cargo.toml

Line 13 in 8fa1ad3

num-traits = { version = "0.2", default-features = false }

On the other hand, num-traits doesn't export Float without std or libm features.

So, matrixcompare tries to use num_traits::Float, which is not exported.

By the way, matrixcompare is successfully built on the CI now. This is due to the bug of cargo.
matrixcompare uses proptest as a dev-dependency. (and it uses num-traits with the default features including std!)
This is the reason that cargo uses num-traits with the std feature when building matrixcompare as a root crate.
At the last, when I tried to build matrixcompare with the nightly version of cargo, building failed:

$ cargo +nightly -Z features=dev_dep check
   Compiling autocfg v1.0.1
    Checking matrixcompare-core v0.1.0 (/home/kato/wrk/develop/matrixcompare/matrixcompare-core)
   Compiling num-traits v0.2.12
    Checking matrixcompare v0.1.3 (/home/kato/wrk/develop/matrixcompare)
error[E0432]: unresolved import `num_traits::Float`
 --> src/comparators.rs:5:18
  |
5 | use num_traits::{Float, Num};
  |                  ^^^^^
  |                  |
  |                  no `Float` in the root
  |                  help: a similar name exists in the module (notice the capitalization): `float`

error: aborting due to previous error

For more information about this error, try `rustc --explain E0432`.
error: could not compile `matrixcompare`.

To learn more, run the command again with --verbose.

[Andlon]

Hi @0ncorhynchus, thanks for figuring this out! I'm sorry I didn't get back to you sooner, I don't recall having being notified of this issue, so I unfortunately missed it. I will take a look at your PR now and publish an updated release shortly!

[Andlon]

In addition to merging your PR, I added the compilation of a "hello world" crate (basically your example) to the CI, to prevent future regressions. Thanks again for notifying me of the issue!

(For some reason, notifications were not enabled on this repo for me, which is why I did not notice your issue before now. In the future, I should hopefully receive notifications in a timely manner.)

[0ncorhynchus]

Don't worry about it 😃
I thank you for your good project!