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Tracking issue for visible_private_types feature #29627

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aturon opened this issue Nov 5, 2015 · 0 comments
Closed

Tracking issue for visible_private_types feature #29627

aturon opened this issue Nov 5, 2015 · 0 comments
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B-unstable Blocker: Implemented in the nightly compiler and unstable. T-lang Relevant to the language team, which will review and decide on the PR/issue.

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@aturon
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aturon commented Nov 5, 2015

The visible_private_types feature allows exposing private types in public signatures (in contravention of RFC 136). This feature should probably be removed.

@aturon aturon added T-lang Relevant to the language team, which will review and decide on the PR/issue. B-unstable Blocker: Implemented in the nightly compiler and unstable. labels Nov 5, 2015
bors added a commit that referenced this issue Dec 18, 2015
Some notes:
This patch enforces the rules from [RFC 136](https://github.com/rust-lang/rfcs/blob/master/text/0136-no-privates-in-public.md) and makes "private in public" a module-level concept and not crate-level. Only `pub` annotations are used by the new algorithm, crate-level exported node set produced by `EmbargoVisitor` is not used. The error messages are tweaked accordingly and don't use the word "exported" to avoid confusing people (#29668).

The old algorithm tried to be extra smart with impls, but it mostly led to unpredictable behavior and bugs like #28325.
The new algorithm tries to be as simple as possible - an impl is considered public iff its type is public and its trait is public (if presents).
A type or trait is considered public if all its components are public, [complications](https://internals.rust-lang.org/t/limits-of-type-inference-smartness/2919) with private types leaking to other crates/modules through trait impls and type inference are deliberately ignored so far.

The new algorithm is not recursive and uses the nice new facility `Crate::visit_all_items`!

Obsolete pre-1.0 feature `visible_private_types` is removed.

This is a [breaking-change].
The two main vectors of breakage are type aliases (#28450) and impls (#28325).
I need some statistics from a crater run (cc @alexcrichton) to decide on the breakage mitigation strategy.
UPDATE: All the new errors are reported as warnings controlled by a lint `private_in_public` and lint group `future_incompatible`, but the intent is to make them hard errors eventually.

Closes #28325
Closes #28450
Closes #29524
Closes #29627
Closes #29668
Closes #30055

r? @nikomatsakis
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Labels
B-unstable Blocker: Implemented in the nightly compiler and unstable. T-lang Relevant to the language team, which will review and decide on the PR/issue.
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