Tracking Issue for default-visibility

This is a tracking issue for default-visibility, which allows setting the visibility of symbols when building a shared object / dylib.

MCP: https://github.com/rust-lang/compiler-team/issues/782

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.
Discussion comments will get marked as off-topic or deleted.
Repeated discussions on the tracking issue may lead to the tracking issue getting locked.

Steps

• Implement the flag as -Z default-visibility
• Stabilize as -C default-visibility

Unresolved Questions

• Are we happy with the naming of the flag and its options?
• What should the default be?

Implementation history

• https://github.com/rust-lang/rust/pull/130005

Start with the MCP at compiler-team issue 782 and the implementation history in rust-lang/rust#130005. Review the tracking checklist and unresolved questions before deciding on work. Done means implementing -Z default-visibility, stabilizing it as -C default-visibility, and resolving the naming and default-value questions.