privacy: Substitute type aliases in private-in-public checker

src/librustc_privacy/lib.rs

@@ -873,12 +873,6 @@ impl<'a, 'tcx: 'a> SearchInterfaceForPrivateItemsVisitor<'a, 'tcx> {
     // Return the visibility of the type alias's least visible component type when substituted
     fn substituted_alias_visibility(&self, item: &hir::Item, path: &hir::Path)
                                     -> Option<ty::Visibility> {
-        // We substitute type aliases only when determining impl publicity
-        // FIXME: This will probably change and all type aliases will be substituted,
-        // requires an amendment to RFC 136.
-        if self.required_visibility != ty::Visibility::PrivateExternal {
-            return None;
-        }
         // Type alias is considered public if the aliased type is
         // public, even if the type alias itself is private. So, something
         // like `type A = u8; pub fn f() -> A {...}` doesn't cause an error.

src/test/compile-fail/private-in-public-warn.rs

@@ -205,11 +205,10 @@ mod aliases_pub {
     }
 
     pub fn f1(arg: PrivUseAlias) {} // OK
+    pub fn f2(arg: PrivAlias) {} // OK
 
     pub trait Tr1: PrivUseAliasTr {} // OK
-    // This should be OK, if type aliases are substituted
-    pub trait Tr2: PrivUseAliasTr<PrivAlias> {} //~ WARN private type in public interface
-        //~^ WARNING hard error
+    pub trait Tr2: PrivUseAliasTr<PrivAlias> {} // OK
 
     impl PrivAlias {
         pub fn f(arg: Priv) {} //~ WARN private type in public interface
@@ -246,6 +245,8 @@ mod aliases_priv {
     use self::Priv1 as PrivUseAlias;
     use self::PrivTr1 as PrivUseAliasTr;
     type PrivAlias = Priv2;
+    //~^ WARN private type in public interface
+    //~| WARNING hard error
     trait PrivTr {
         type AssocAlias;
     }
@@ -285,6 +286,8 @@ mod aliases_params {
     struct Priv;
     type PrivAliasGeneric<T = Priv> = T;
     type Result<T> = ::std::result::Result<T, Priv>;
+
+    pub fn f1(arg: PrivAliasGeneric<u8>) {} // OK, not an error
 }
 
 #[rustc_error]

src/test/compile-fail/private-in-public.rs

@@ -105,8 +105,6 @@ mod aliases_pub {
     }
     impl PrivTr for Priv {}
 
-    // This should be OK, if type aliases are substituted
-    pub fn f2(arg: PrivAlias) {} //~ ERROR private type in public interface
     // This should be OK, but associated type aliases are not substituted yet
     pub fn f3(arg: <Priv as PrivTr>::AssocAlias) {} //~ ERROR private type in public interface
 
@@ -143,8 +141,6 @@ mod aliases_params {
     type PrivAliasGeneric<T = Priv> = T;
     type Result<T> = ::std::result::Result<T, Priv>;
 
-    // This should be OK, if type aliases are substituted
-    pub fn f1(arg: PrivAliasGeneric<u8>) {} //~ ERROR private type in public interface
     pub fn f2(arg: PrivAliasGeneric) {} //~ ERROR private type in public interface
     pub fn f3(arg: Result<u8>) {} //~ ERROR private type in public interface
 }