Print a clear warning when including untracked files in package

[bluss]

Print a clear warning when including untracked files in package.

Admonition the user to track or ignore these files in git.

See issue #1584.

Cargo should help the author for two reasons:

• If the file is untracked, it might be lost and an important part of a working package is lost
• It might alert the author to junk. It happens easily, perf.data, files you saved to test, logs

If it's about empty directories, tell the crate author to use the standard workaround (.gitignore inside to make it non-empty).

[bluss]

Some food for thought, I downloaded all packages from crates.io, and I'm grepping for junk and filing bugs. Mostly the bugs will help everyone because we don't have to download things like 10 MB of perf.data files or a random 10 MB mp4 file that a developer had lying around, or some extra 160 MB database directory they had..

issues:

• Junk in the cargo package source meh/rust-lzma#1
• Junk in the cargo source huonw/simple_parallel#6
• Junk in the cargo package source Aatch/ramp#18
• Junk in the cargo package source rust-bakery/nom#67
• Junk in the cargo package source mongodb/bson-rust#12 — 161 MB
• Junk in the cargo package source jethrogb/namedlock-rs#1 — 21 MB
• Docs in the cargo package source clog-tool/clog-cli#68 — 17 MB
• Large files in cargo package source aatxe/markov#8 — 11 MB
• Large files in cargo package source jamesmunns/cobs.rs#1 — 21 MB
• Large files in cargo package source maidsafe-archive/sodiumoxide#16 — 6 MB

Edit: Everyone responded. Well done team!

[codyps]

This came up on IRC #rust recently.

I'd prefer:

• exclude untracked files by default
• require special additions to Cargo.toml for the special cases that need to ship non-tracked files

Because:

• by the time we get warnings, we're moments away from uploading anyhow
• including untracked files is probably not widely used

[rillian]

See also #2063. I'd prefer cargo not package anything not explicitly traceable from the crate sources and Cargo.toml, but limiting it to VCS-tracked files would definitely help.

[bluss]

Issue rust-bakery/nom/issues/117 is another “victim”