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Rollup merge of #80763 - petrochenkov:pubusecrate, r=estebank

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resolve: Reduce scope of `pub_use_of_private_extern_crate` deprecation lint

This lint was deny-by-default since July 2017, crater showed 7 uses on crates.io back then (https://github.com/rust-lang/rust/pull/42894#issuecomment-311921147).

Unfortunately, the construction `pub use foo as bar` where `foo` is `extern crate foo;` was used by an older version `bitflags`, so turning it into an error causes too many regressions.
So, this PR reduces the scope of the lint instead of turning it into a hard error, and only turns some more rarely used components of it into errors.
This commit is contained in:
Mara 2021-03-05 10:57:15 +01:00 • committed by GitHub
commit ec2619ca62
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5 changed files with 50 additions and 39 deletions
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32
compiler/rustc_resolve/src/imports.rs
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@ -156,6 +156,21 @@ impl<'a> NameResolution<'a> {
}
}
// Reexports of the form `pub use foo as bar;` where `foo` is `extern crate foo;`
// are permitted for backward-compatibility under a deprecation lint.
fn pub_use_of_private_extern_crate_hack(import: &Import<'_>, binding: &NameBinding<'_>) -> bool {
match (&import.kind, &binding.kind) {
(
ImportKind::Single { .. },
NameBindingKind::Import {
import: Import { kind: ImportKind::ExternCrate { .. }, .. },
..
},
) => import.vis.get() == ty::Visibility::Public,
_ => false,
}
}
impl<'a> Resolver<'a> {
crate fn resolve_ident_in_module_unadjusted(
&mut self,
@ -263,10 +278,7 @@ impl<'a> Resolver<'a> {
return Err((Determined, Weak::No));
}
}
// `extern crate` are always usable for backwards compatibility, see issue #37020,
// remove this together with `PUB_USE_OF_PRIVATE_EXTERN_CRATE`.
let usable = this.is_accessible_from(binding.vis, parent_scope.module)
|| binding.is_extern_crate();
let usable = this.is_accessible_from(binding.vis, parent_scope.module);
if usable { Ok(binding) } else { Err((Determined, Weak::No)) }
};
@ -309,10 +321,7 @@ impl<'a> Resolver<'a> {
}
}
if !(self.is_accessible_from(binding.vis, parent_scope.module) ||
// Remove this together with `PUB_USE_OF_PRIVATE_EXTERN_CRATE`
(self.last_import_segment && binding.is_extern_crate()))
{
if !self.is_accessible_from(binding.vis, parent_scope.module) {
self.privacy_errors.push(PrivacyError {
ident,
binding,
@ -455,9 +464,8 @@ impl<'a> Resolver<'a> {
binding: &'a NameBinding<'a>,
import: &'a Import<'a>,
) -> &'a NameBinding<'a> {
let vis = if binding.vis.is_at_least(import.vis.get(), self) ||
// cf. `PUB_USE_OF_PRIVATE_EXTERN_CRATE`
!import.is_glob() && binding.is_extern_crate()
let vis = if binding.vis.is_at_least(import.vis.get(), self)
|| pub_use_of_private_extern_crate_hack(import, binding)
{
import.vis.get()
} else {
@ -1188,7 +1196,7 @@ impl<'a, 'b> ImportResolver<'a, 'b> {
// All namespaces must be re-exported with extra visibility for an error to occur.
if !any_successful_reexport {
let (ns, binding) = reexport_error.unwrap();
if ns == TypeNS && binding.is_extern_crate() {
if pub_use_of_private_extern_crate_hack(import, binding) {
let msg = format!(
"extern crate `{}` is private, and cannot be \
re-exported (error E0365), consider declaring with \