core::fmt::Show vs std::fmt::Show

[kud1ing]

The trait Show and its documentation seems pretty identical:

• http://doc.rust-lang.org/core/fmt/trait.Show.html
  • given that type Result = Result<(), FormatError>; http://doc.rust-lang.org/core/fmt/type.Result.html
• http://doc.rust-lang.org/std/fmt/trait.Show.html

If there is a reason to have both, please point to each other and explain when to use which. CC @steveklabnik

If not, consider removing std::fmt::Show.

[huonw]

The std one is just a reexport of the core one, i.e. they're actually the same trait. Demonstration.

I think the solution here is just making the reexport relationships clearer (similar to #13414).

libstd is the crate that people should be using almost always; libcore is designed to the most fundamental code, with very few assumptions, suitable for use when writing operating systems etc.

[SimonSapin]

Related to #15723

[kud1ing]

Closing this in favor of the more general/specific #15723