privacy: Account for associated existential types

src/test/ui/privacy/private-in-public-assoc-ty.rs

@@ -1,7 +1,7 @@
 // Private types and traits are not allowed in interfaces of associated types.
 // This test also ensures that the checks are performed even inside private modules.
 
-#![feature(associated_type_defaults)]
+#![feature(associated_type_defaults, existential_type)]
 
 mod m {
     struct Priv;
@@ -23,10 +23,17 @@ mod m {
 
         type Alias4 = Priv;
         //~^ ERROR private type `m::Priv` in public interface
+
+        type Exist;
+        fn infer_exist() -> Self::Exist;
     }
     impl PubTr for u8 {
         type Alias1 = Priv;
         //~^ ERROR private type `m::Priv` in public interface
+
+        existential type Exist: PrivTr;
+        //~^ ERROR private trait `m::PrivTr` in public interface
+        fn infer_exist() -> Self::Exist { Priv }
     }
 }
 

src/test/ui/privacy/private-in-public-assoc-ty.stderr

@@ -6,7 +6,7 @@ LL | |         //~^ WARN private trait `m::PrivTr` in public interface
 LL | |         //~| WARN this was previously accepted
 LL | |         //~| WARN private type `m::Priv` in public interface
 ...  |
-LL | |         //~^ ERROR private type `m::Priv` in public interface
+LL | |         fn infer_exist() -> Self::Exist;
 LL | |     }
    | |_____^
    |
@@ -22,7 +22,7 @@ LL | |         //~^ WARN private trait `m::PrivTr` in public interface
 LL | |         //~| WARN this was previously accepted
 LL | |         //~| WARN private type `m::Priv` in public interface
 ...  |
-LL | |         //~^ ERROR private type `m::Priv` in public interface
+LL | |         fn infer_exist() -> Self::Exist;
 LL | |     }
    | |_____^
    |
@@ -39,7 +39,7 @@ LL |         type Alias4 = Priv;
    |         ^^^^^^^^^^^^^^^^^^^ can't leak private type
 
 error[E0446]: private type `m::Priv` in public interface
-  --> $DIR/private-in-public-assoc-ty.rs:28:9
+  --> $DIR/private-in-public-assoc-ty.rs:31:9
    |
 LL |     struct Priv;
    |     - `m::Priv` declared as private
@@ -47,6 +47,16 @@ LL |     struct Priv;
 LL |         type Alias1 = Priv;
    |         ^^^^^^^^^^^^^^^^^^^ can't leak private type
 
-error: aborting due to 2 previous errors
+error[E0445]: private trait `m::PrivTr` in public interface
+  --> $DIR/private-in-public-assoc-ty.rs:34:9
+   |
+LL |     trait PrivTr {}
+   |     - `m::PrivTr` declared as private
+...
+LL |         existential type Exist: PrivTr;
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ can't leak private trait
 
-For more information about this error, try `rustc --explain E0446`.
+error: aborting due to 3 previous errors
+
+Some errors occurred: E0445, E0446.
+For more information about an error, try `rustc --explain E0445`.

src/test/ui/privacy/private-in-public-existential.rs

@@ -12,4 +12,14 @@ fn check() -> Pub {
     Priv
 }
 
+pub trait Trait {
+    type Pub: Default;
+    fn method() -> Self::Pub;
+}
+
+impl Trait for u8 {
+    existential type Pub: Default;
+    fn method() -> Self::Pub { Priv }
+}
+
 fn main() {}