Do not substitute type aliases during error reporting

Type aliases are still substituted when determining impl publicity

src/librustc_privacy/lib.rs

@@ -1463,6 +1463,12 @@ struct SearchInterfaceForPrivateItemsVisitor<'a, 'tcx: 'a> {
 impl<'a, 'tcx: 'a> SearchInterfaceForPrivateItemsVisitor<'a, 'tcx> {
     // Check if the type alias contain private types when substituted
     fn is_public_type_alias(&self, item: &hir::Item, path: &hir::Path) -> bool {
+        // 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.is_quiet {
+            return false
+        }
         // 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/librustc_trans/back/msvc/registry.rs

@@ -14,7 +14,7 @@ use std::os::windows::prelude::*;
 use std::ptr;
 use libc::{c_void, c_long};
 
-type DWORD = u32;
+pub type DWORD = u32;
 type LPCWSTR = *const u16;
 type LONG = c_long;
 type LPDWORD = *mut DWORD;

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

@@ -175,10 +175,10 @@ mod aliases_pub {
     impl PrivTr for Priv {}
 
     pub fn f1(arg: PrivUseAlias) {} // OK
-    pub fn f2(arg: PrivAlias) {} // OK
 
     pub trait Tr1: PrivUseAliasTr {} // OK
-    pub trait Tr2: PrivUseAliasTr<PrivAlias> {} // OK
+    // This should be OK, if type aliases are substituted
+    pub trait Tr2: PrivUseAliasTr<PrivAlias> {} //~ WARN private type in public interface
 
     impl PrivAlias {
         pub fn f(arg: Priv) {} //~ WARN private type in public interface
@@ -211,7 +211,6 @@ mod aliases_priv {
     use self::Priv1 as PrivUseAlias;
     use self::PrivTr1 as PrivUseAliasTr;
     type PrivAlias = Priv2;
-    //~^ WARN private type in public interface
     trait PrivTr {
         type AssocAlias = Priv3;
     }
@@ -246,8 +245,6 @@ 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

@@ -105,6 +105,8 @@ 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
 
@@ -141,6 +143,8 @@ 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
 }