Tracking issue for `--extern priv`

[ehuss]

This is a tracking issue for the priv CLI option for --extern.

• Docs: https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/extern-options.html
• RFC: https://rust-lang.github.io/rfcs/1977-public-private-dependencies.html

This option marks the given crate as "private" which is used by the exported_private_dependencies lint.

The syntax is [opts ':'] name ['=' path] where opts is a comma separated list of options:

--extern priv:foo=/path/to/libfoo.rlib

See also #98398 and #98400 which share this syntax extension.

About tracking issues

Tracking issues are used to record the overall progress of implementation.
They are also used as hubs connecting to other relevant issues, e.g., bugs or open design questions.
A tracking issue is however not meant for large scale discussion, questions, or bug reports about a feature.
Instead, open a dedicated issue for the specific matter and add the relevant feature gate label.

Steps

• Implementation: Add options to --extern flag. #67074
• Adjust documentation (see instructions on rustc-dev-guide)
• Stabilization PR (see instructions on rustc-dev-guide)

Unresolved Questions

• The syntax for adding options to --extern flags was added without much bikeshedding or discussion. It may need adjusting to be more flexible for more complex options.

Implementation history

• Add options to --extern flag. #67074

[petrochenkov]

Stabilization blocked on "Tracking Issue --extern crate modifiers".