Enforce crate naming rules of rustc

[sanmai-NL]

Actual behavior

Creating a new crate:

cargo new --bin 'UPPERcase_name'

No issue.

Compiling it:

 cargo build

warning: crate `UPPERcase_name` should have a snake case name such as `uppercase_name`, #[warn(non_snake_case)] on by default

Expected behavior

Cargo should only create crates with names that raise rustc warnings if forced.

Meta

  rustc --version --verbose
rustc 1.8.0
binary: rustc
commit-hash: unknown
commit-date: unknown
host: x86_64-unknown-linux-gnu
release: 1.8.0

  cargo --version
cargo 0.10.0 (10ddd7d 2016-04-08)

[gsurrel]

I would say that it should warn before creation that it's not according to rules and offer the following options:

1. Edit the name
2. Continue
3. Continue and add the ignore directive where needed

[shnaramn]

Can I try a fix for this? I've just started learning rust/cargo and this feels like a good first fix.

There are several validations for crate name at function check_name in cargo_new.rs. Will adding a warning (similar to the existing ones) about the casing be a good fix? The existing validations don't prompt for a new name. Want to be consistent with the existing behavior.

[epage]

So long as its only a warning, I feel that is the most we should do. My main concern about a warning is making sure we get the language right to give people a heads up without coming across to strong (since they can just allow it or ignore it). I wonder if we should also check the status of the warning in the lints table (#12115).

[sanmai-NL]

Rather than warning or not warning you could just be informative. Something like this name doesn't match the naming rules standard X, please see documentation blah blah blah blah.

[epage]

How is that different from a warning?

[sanmai-NL]

A warning is a value judgment.

[shnaramn]

If this change looks good, I can start a PR:
master...shnaramn:cargo:WarnAboutNameCase

Using the language mentioned in RFC 430.

I've not added the link to API naming guidelines since it still stays unclear for naming convention for crates.

The fix reuses the method that checks for snake_case when building.

[epage]

Theres details to work out in a PR but that is the general direction of what I'd expect.