warning: pub extern crate does not work as expected and should not be used #189

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1. cuviper commented on Apr 29, 2016

   

   cuviper

   on Apr 29, 2016

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   Ideally, I wouldn't want these public at all, rather just the renamed pub use num_traits as traits. But IIRC nightly then complains about a public export of something private. So we're left living with a warning on stable.
2. briansmith commented on Apr 29, 2016

   

   briansmith

   on Apr 29, 2016

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   Are people supposed to use the new crates directly instead of using num? I did make a patch to modify ring to do that but it was quite cumbersome to use num_bigint since the traits I needed were split into two other crates, e.g.:

   use num_bigint;
   use num_integer::Integer as Integral;
   use num_traits::{FromPrimitive, Num, One, Signed, ToPrimitive, Zero};

   And then three crate references in Cargo.toml. Maybe I'm doing something silly, though?

   In any case, if the warnings are intended to be ignored then maybe you can use #[allow] to suppress them?
3. cuviper commented on Apr 29, 2016

   

   cuviper

   on Apr 29, 2016

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   Your exact suggestion doesn't work:

   error: an extern crate named `num_traits` has already been imported in this module
   

   If I just drop the pub from the crate, leaving pub use num_traits as traits below, it says:

   warning: extern crate `num_traits` is private, and cannot be reexported (error E0364), consider declaring with `pub`, #[warn(private_in_public)] on by default
   warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
   

   Both 1.8.0 and nightly say that right now, and they're perfectly happy when pub extern crate is used. Only 1.4 through 1.7 complain about pub extern crate, but seem to work AFAICT.

   As for how to use all this, please feel free to continue using num as before. I don't plan to remove this supercrate any time soon. I'm fine with adding #[allow], although the message doesn't say what the lint name is.
4. bluss commented on Apr 29, 2016

   

   bluss

   on Apr 29, 2016

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   another reexporting technique that's sometimes used is:

   extern crate num_traits;
   
   pub mod traits {
       pub use num_traits::*;
   }

   but I actually don't know what caveats or bugs might apply to this form.
5. cuviper commented on Apr 29, 2016

   

   cuviper

   on Apr 29, 2016

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   Hmm, I could have sworn I tried that, but it does appear to work.
6. cuviper

   added a commit that references this issue on Apr 29, 2016

   num: remove `pub` from sub-crates

   ...

   This issue will close once commit 865c491 is merged into the 'main' branch.

   865c491
7. cuviper commented on May 3, 2016

   

   cuviper

   on May 3, 2016

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   In case you missed it, I opened #190 removing pub extern crate. Please let me know if you find any issues with this, or else I'll merge it soon.
8. homu

   closed this as completedin #190on May 12, 2016
9. homu

   added a commit that references this issue on May 12, 2016

   Auto merge of #190 - rust-num:private-crates, r=cuviper

   ...

   This issue will close once commit 4bbc34b is merged into the 'main' branch.

   4bbc34b