Auto merge of #111801 - Bryanskiy:lints1, r=petrochenkov

Private-in-public lints implementation

Next part of RFC #48054.

r? `@petrochenkov`

compiler/rustc_lint_defs/src/builtin.rs

@@ -3372,7 +3372,9 @@ declare_lint_pass! {
         OVERLAPPING_RANGE_ENDPOINTS,
         PATTERNS_IN_FNS_WITHOUT_BODY,
         POINTER_STRUCTURAL_MATCH,
+        PRIVATE_BOUNDS,
         PRIVATE_IN_PUBLIC,
+        PRIVATE_INTERFACES,
         PROC_MACRO_BACK_COMPAT,
         PROC_MACRO_DERIVE_RESOLUTION_FALLBACK,
         PUB_USE_OF_PRIVATE_EXTERN_CRATE,
@@ -3399,6 +3401,7 @@ declare_lint_pass! {
         UNINHABITED_STATIC,
         UNKNOWN_CRATE_TYPES,
         UNKNOWN_LINTS,
+        UNNAMEABLE_TYPES,
         UNREACHABLE_CODE,
         UNREACHABLE_PATTERNS,
         UNSAFE_OP_IN_UNSAFE_FN,
@@ -4251,3 +4254,95 @@ declare_lint! {
     Warn,
     "\"invalid_parameter\" isn't a valid argument for `#[macro_export]`",
 }
+
+declare_lint! {
+    /// The `private_interfaces` lint detects types in a primary interface of an item,
+    /// that are more private than the item itself. Primary interface of an item is all
+    /// its interface except for bounds on generic parameters and where clauses.
+    ///
+    /// ### Example
+    ///
+    /// ```rust,compile_fail
+    /// # #![allow(unused)]
+    /// # #![allow(private_in_public)]
+    /// #![deny(private_interfaces)]
+    /// struct SemiPriv;
+    ///
+    /// mod m1 {
+    ///     struct Priv;
+    ///     impl crate::SemiPriv {
+    ///         pub fn f(_: Priv) {}
+    ///     }
+    /// }
+    ///
+    /// # fn main() {}
+    /// ```
+    ///
+    /// {{produces}}
+    ///
+    /// ### Explanation
+    ///
+    /// Having something private in primary interface guarantees that
+    /// the item will be unusable from outer modules due to type privacy.
+    pub PRIVATE_INTERFACES,
+    Allow,
+    "private type in primary interface of an item",
+}
+
+declare_lint! {
+    /// The `private_bounds` lint detects types in a secondary interface of an item,
+    /// that are more private than the item itself. Secondary interface of an item consists of
+    /// bounds on generic parameters and where clauses, including supertraits for trait items.
+    ///
+    /// ### Example
+    ///
+    /// ```rust,compile_fail
+    /// # #![allow(private_in_public)]
+    /// # #![allow(unused)]
+    /// #![deny(private_bounds)]
+    ///
+    /// struct PrivTy;
+    /// pub struct S
+    ///     where PrivTy:
+    /// {}
+    /// # fn main() {}
+    /// ```
+    ///
+    /// {{produces}}
+    ///
+    /// ### Explanation
+    ///
+    /// Having private types or traits in item bounds makes it less clear what interface
+    /// the item actually provides.
+    pub PRIVATE_BOUNDS,
+    Allow,
+    "private type in secondary interface of an item"
+}
+
+declare_lint! {
+    /// The `unnameable_types` lint detects types for which you can get objects of that type,
+    /// but cannot name the type itself.
+    ///
+    /// ### Example
+    ///
+    /// ```rust,compile_fail
+    /// # #![allow(unused)]
+    /// #![deny(unnameable_types)]
+    /// mod m {
+    ///     pub struct S;
+    /// }
+    ///
+    /// pub fn get_voldemort() -> m::S { m::S }
+    /// # fn main() {}
+    /// ```
+    ///
+    /// {{produces}}
+    ///
+    /// ### Explanation
+    ///
+    /// It is often expected that if you can obtain an object of type `T`, then
+    /// you can name the type `T` as well, this lint attempts to enforce this rule.
+    pub UNNAMEABLE_TYPES,
+    Allow,
+    "effective visibility of a type is larger than the area in which it can be named"
+}

compiler/rustc_privacy/messages.ftl

@@ -17,7 +17,14 @@ privacy_private_in_public_lint =
         *[other] E0446
     })
 
+privacy_private_interface_or_bounds_lint = {$ty_kind} `{$ty_descr}` is more private than the item `{$item_descr}`
+    .item_note = {$item_kind} `{$item_descr}` is reachable at visibility `{$item_vis_descr}`
+    .ty_note = but {$ty_kind} `{$ty_descr}` is only usable at visibility `{$ty_vis_descr}`
+
 privacy_report_effective_visibility = {$descr}
 
+privacy_unnameable_types_lint = {$kind} `{$descr}` is reachable but cannot be named
+    .label = reachable at visibility `{$reachable_vis}`, but can only be named at visibility `{$reexported_vis}`
+
 privacy_unnamed_item_is_private = {$kind} is private
     .label = private {$kind}

compiler/rustc_privacy/src/errors.rs

@@ -98,3 +98,32 @@ pub struct PrivateInPublicLint<'a> {
     pub kind: &'a str,
     pub descr: DiagnosticArgFromDisplay<'a>,
 }
+
+#[derive(LintDiagnostic)]
+#[diag(privacy_unnameable_types_lint)]
+pub struct UnnameableTypesLint<'a> {
+    #[label]
+    pub span: Span,
+    pub kind: &'a str,
+    pub descr: DiagnosticArgFromDisplay<'a>,
+    pub reachable_vis: &'a str,
+    pub reexported_vis: &'a str,
+}
+
+// Used for `private_interfaces` and `private_bounds` lints.
+// They will replace private-in-public errors and compatibility lints in future.
+// See https://rust-lang.github.io/rfcs/2145-type-privacy.html for more details.
+#[derive(LintDiagnostic)]
+#[diag(privacy_private_interface_or_bounds_lint)]
+pub struct PrivateInterfacesOrBoundsLint<'a> {
+    #[note(privacy_item_note)]
+    pub item_span: Span,
+    pub item_kind: &'a str,
+    pub item_descr: DiagnosticArgFromDisplay<'a>,
+    pub item_vis_descr: &'a str,
+    #[note(privacy_ty_note)]
+    pub ty_span: Span,
+    pub ty_kind: &'a str,
+    pub ty_descr: DiagnosticArgFromDisplay<'a>,
+    pub ty_vis_descr: &'a str,
+}