Auto merge of #56878 - petrochenkov:privdyn, r=arielb1

privacy: Use common `DefId` visiting infrastructure for all privacy visitors

One repeating pattern in privacy checking is going through a type, visiting all `DefId`s inside it and doing something with them.
This is the case because visibilities and reachabilities are attached to `DefId`s.

Previously various privacy visitors visited types slightly differently using their own methods, with most recently written `TypePrivacyVisitor` being the "gold standard".
This mostly worked okay, but differences could manifest in overly conservative reachability analysis, some errors being reported twice, some private-in-public lints (not errors) being wrongly reported or not reported.

This PR does something that I wanted to do since #32674 (comment) - factoring out the common visiting logic!
Now all the common logic is contained in `struct DefIdVisitorSkeleton`, with specific privacy visitors deciding only what to do with visited `DefId`s (via `trait DefIdVisitor`).

A bunch of cleanups is also applied in the process.
This area is somewhat tricky due to lots of easily miss-able details, but thankfully it's was well covered by tests in #46083 and previous PRs, so I'm relatively sure in the refactoring correctness.

Fixes #56837 (comment) in particular.
Also this will help with implementing #48054.

src/librustc/hir/mod.rs

@@ -2090,6 +2090,15 @@ impl VisibilityKind {
             VisibilityKind::Restricted { .. } => true,
         }
     }
+
+    pub fn descr(&self) -> &'static str {
+        match *self {
+            VisibilityKind::Public => "public",
+            VisibilityKind::Inherited => "private",
+            VisibilityKind::Crate(..) => "crate-visible",
+            VisibilityKind::Restricted { .. } => "restricted",
+        }
+    }
 }
 
 #[derive(Clone, RustcEncodable, RustcDecodable, Debug)]

src/librustc/util/ppaux.rs

@@ -709,6 +709,9 @@ define_print! {
 
 define_print! {
     ('tcx) ty::ExistentialTraitRef<'tcx>, (self, f, cx) {
+        display {
+            cx.parameterized(f, self.substs, self.def_id, &[])
+        }
         debug {
             ty::tls::with(|tcx| {
                 let dummy_self = tcx.mk_infer(ty::FreshTy(0));

src/libstd/sys/windows/handle.rs

@@ -160,11 +160,6 @@ impl RawHandle {
         }
     }
 
-    pub fn read_to_end(&self, buf: &mut Vec<u8>) -> io::Result<usize> {
-        let mut me = self;
-        (&mut me).read_to_end(buf)
-    }
-
     pub fn write(&self, buf: &[u8]) -> io::Result<usize> {
         let mut amt = 0;
         let len = cmp::min(buf.len(), <c::DWORD>::max_value() as usize) as c::DWORD;

src/libstd/sys/windows/stdio.rs

@@ -128,11 +128,6 @@ impl Stdin {
         // MemReader shouldn't error here since we just filled it
         utf8.read(buf)
     }
-
-    pub fn read_to_end(&self, buf: &mut Vec<u8>) -> io::Result<usize> {
-        let mut me = self;
-        (&mut me).read_to_end(buf)
-    }
 }
 
 #[unstable(reason = "not public", issue = "0", feature = "fd_read")]

src/test/ui/error-codes/E0445.rs

@@ -4,12 +4,9 @@ trait Foo {
 
 pub trait Bar : Foo {}
 //~^ ERROR private trait `Foo` in public interface [E0445]
-//~| NOTE can't leak private trait
 pub struct Bar2<T: Foo>(pub T);
 //~^ ERROR private trait `Foo` in public interface [E0445]
-//~| NOTE can't leak private trait
 pub fn foo<T: Foo> (t: T) {}
 //~^ ERROR private trait `Foo` in public interface [E0445]
-//~| NOTE can't leak private trait
 
 fn main() {}

src/test/ui/error-codes/E0445.stderr

@@ -5,13 +5,13 @@ LL | pub trait Bar : Foo {}
    | ^^^^^^^^^^^^^^^^^^^^^^ can't leak private trait
 
 error[E0445]: private trait `Foo` in public interface
-  --> $DIR/E0445.rs:8:1
+  --> $DIR/E0445.rs:7:1
    |
 LL | pub struct Bar2<T: Foo>(pub T);
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ can't leak private trait
 
 error[E0445]: private trait `Foo` in public interface
-  --> $DIR/E0445.rs:11:1
+  --> $DIR/E0445.rs:9:1
    |
 LL | pub fn foo<T: Foo> (t: T) {}
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ can't leak private trait

src/test/ui/impl-trait/issue-49376.rs

@@ -9,9 +9,11 @@ fn gen() -> impl PartialOrd + PartialEq + Debug { }
 
 struct Bar {}
 trait Foo<T = Self> {}
+trait FooNested<T = Option<Self>> {}
 impl Foo for Bar {}
+impl FooNested for Bar {}
 
-fn foo() -> impl Foo {
+fn foo() -> impl Foo + FooNested {
     Bar {}
 }
 

src/test/ui/issues/issue-18389.stderr

@@ -1,6 +1,9 @@
 error[E0445]: private trait `Private<<Self as Public>::P, <Self as Public>::R>` in public interface
   --> $DIR/issue-18389.rs:7:1
    |
+LL |   trait Private<P, R> {
+   |   - `Private<<Self as Public>::P, <Self as Public>::R>` declared as private
+...
 LL | / pub trait Public: Private<
 LL | | //~^ ERROR private trait `Private<<Self as Public>::P, <Self as Public>::R>` in public interface
 LL | |     <Self as Public>::P,

src/test/ui/privacy/associated-item-privacy-type-binding.rs

@@ -9,19 +9,19 @@ mod priv_trait {
 
     pub macro mac1() {
         let _: Box<PubTr<AssocTy = u8>>;
-        //~^ ERROR type `(dyn priv_trait::PubTr<AssocTy=u8> + '<empty>)` is private
-        //~| ERROR type `(dyn priv_trait::PubTr<AssocTy=u8> + '<empty>)` is private
+        //~^ ERROR trait `priv_trait::PrivTr` is private
+        //~| ERROR trait `priv_trait::PrivTr` is private
         type InSignatureTy2 = Box<PubTr<AssocTy = u8>>;
-        //~^ ERROR type `(dyn priv_trait::PubTr<AssocTy=u8> + 'static)` is private
+        //~^ ERROR trait `priv_trait::PrivTr` is private
         trait InSignatureTr2: PubTr<AssocTy = u8> {}
         //~^ ERROR trait `priv_trait::PrivTr` is private
     }
     pub macro mac2() {
         let _: Box<PrivTr<AssocTy = u8>>;
-        //~^ ERROR type `(dyn priv_trait::PrivTr<AssocTy=u8> + '<empty>)` is private
-        //~| ERROR type `(dyn priv_trait::PrivTr<AssocTy=u8> + '<empty>)` is private
+        //~^ ERROR trait `priv_trait::PrivTr` is private
+        //~| ERROR trait `priv_trait::PrivTr` is private
         type InSignatureTy1 = Box<PrivTr<AssocTy = u8>>;
-        //~^ ERROR type `(dyn priv_trait::PrivTr<AssocTy=u8> + 'static)` is private
+        //~^ ERROR trait `priv_trait::PrivTr` is private
         trait InSignatureTr1: PrivTr<AssocTy = u8> {}
         //~^ ERROR trait `priv_trait::PrivTr` is private
     }

src/test/ui/privacy/associated-item-privacy-type-binding.stderr

@@ -1,4 +1,4 @@
-error: type `(dyn priv_trait::PubTr<AssocTy=u8> + '<empty>)` is private
+error: trait `priv_trait::PrivTr` is private
   --> $DIR/associated-item-privacy-type-binding.rs:11:13
    |
 LL |         let _: Box<PubTr<AssocTy = u8>>;
@@ -7,7 +7,7 @@ LL |         let _: Box<PubTr<AssocTy = u8>>;
 LL |     priv_trait::mac1!();
    |     -------------------- in this macro invocation
 
-error: type `(dyn priv_trait::PubTr<AssocTy=u8> + '<empty>)` is private
+error: trait `priv_trait::PrivTr` is private
   --> $DIR/associated-item-privacy-type-binding.rs:11:16
    |
 LL |         let _: Box<PubTr<AssocTy = u8>>;
@@ -16,7 +16,7 @@ LL |         let _: Box<PubTr<AssocTy = u8>>;
 LL |     priv_trait::mac1!();
    |     -------------------- in this macro invocation
 
-error: type `(dyn priv_trait::PubTr<AssocTy=u8> + 'static)` is private
+error: trait `priv_trait::PrivTr` is private
   --> $DIR/associated-item-privacy-type-binding.rs:14:31
    |
 LL |         type InSignatureTy2 = Box<PubTr<AssocTy = u8>>;
@@ -34,7 +34,7 @@ LL |         trait InSignatureTr2: PubTr<AssocTy = u8> {}
 LL |     priv_trait::mac1!();
    |     -------------------- in this macro invocation
 
-error: type `(dyn priv_trait::PrivTr<AssocTy=u8> + '<empty>)` is private
+error: trait `priv_trait::PrivTr` is private
   --> $DIR/associated-item-privacy-type-binding.rs:20:13
    |
 LL |         let _: Box<PrivTr<AssocTy = u8>>;
@@ -43,7 +43,7 @@ LL |         let _: Box<PrivTr<AssocTy = u8>>;
 LL |     priv_trait::mac2!();
    |     -------------------- in this macro invocation
 
-error: type `(dyn priv_trait::PrivTr<AssocTy=u8> + '<empty>)` is private
+error: trait `priv_trait::PrivTr` is private
   --> $DIR/associated-item-privacy-type-binding.rs:20:16
    |
 LL |         let _: Box<PrivTr<AssocTy = u8>>;
@@ -52,7 +52,7 @@ LL |         let _: Box<PrivTr<AssocTy = u8>>;
 LL |     priv_trait::mac2!();
    |     -------------------- in this macro invocation
 
-error: type `(dyn priv_trait::PrivTr<AssocTy=u8> + 'static)` is private
+error: trait `priv_trait::PrivTr` is private
   --> $DIR/associated-item-privacy-type-binding.rs:23:31
    |
 LL |         type InSignatureTy1 = Box<PrivTr<AssocTy = u8>>;

src/test/ui/privacy/private-in-public-expr-pat.rs

@@ -0,0 +1,13 @@
+// Patterns and expressions are not interface parts and don't produce private-in-public errors.
+
+// compile-pass
+
+struct Priv1(usize);
+struct Priv2;
+
+pub struct Pub(Priv2);
+
+pub fn public_expr(_: [u8; Priv1(0).0]) {} // OK
+pub fn public_pat(Pub(Priv2): Pub) {} // OK
+
+fn main() {}

src/test/ui/privacy/private-in-public-non-principal-2.rs

@@ -0,0 +1,13 @@
+#![feature(optin_builtin_traits)]
+
+#[allow(private_in_public)]
+mod m {
+    pub trait PubPrincipal {}
+    auto trait PrivNonPrincipal {}
+    pub fn leak_dyn_nonprincipal() -> Box<PubPrincipal + PrivNonPrincipal> { loop {} }
+}
+
+fn main() {
+    m::leak_dyn_nonprincipal();
+    //~^ ERROR trait `m::PrivNonPrincipal` is private
+}

src/test/ui/privacy/private-in-public-non-principal-2.stderr

@@ -0,0 +1,8 @@
+error: trait `m::PrivNonPrincipal` is private
+  --> $DIR/private-in-public-non-principal-2.rs:11:5
+   |
+LL |     m::leak_dyn_nonprincipal();
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to previous error
+

src/test/ui/privacy/private-in-public-non-principal.rs

@@ -0,0 +1,20 @@
+#![feature(optin_builtin_traits)]
+
+pub trait PubPrincipal {}
+auto trait PrivNonPrincipal {}
+
+pub fn leak_dyn_nonprincipal() -> Box<PubPrincipal + PrivNonPrincipal> { loop {} }
+//~^ WARN private trait `PrivNonPrincipal` in public interface
+//~| WARN this was previously accepted
+
+#[deny(missing_docs)]
+fn container() {
+    impl dyn PubPrincipal {
+        pub fn check_doc_lint() {} //~ ERROR missing documentation for a method
+    }
+    impl dyn PubPrincipal + PrivNonPrincipal {
+        pub fn check_doc_lint() {} // OK, no missing doc lint
+    }
+}
+
+fn main() {}

src/test/ui/privacy/private-in-public-non-principal.stderr

@@ -0,0 +1,24 @@
+warning: private trait `PrivNonPrincipal` in public interface (error E0445)
+  --> $DIR/private-in-public-non-principal.rs:6:1
+   |
+LL | pub fn leak_dyn_nonprincipal() -> Box<PubPrincipal + PrivNonPrincipal> { loop {} }
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: #[warn(private_in_public)] on by default
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #34537 <https://github.com/rust-lang/rust/issues/34537>
+
+error: missing documentation for a method
+  --> $DIR/private-in-public-non-principal.rs:13:9
+   |
+LL |         pub fn check_doc_lint() {} //~ ERROR missing documentation for a method
+   |         ^^^^^^^^^^^^^^^^^^^^^^^
+   |
+note: lint level defined here
+  --> $DIR/private-in-public-non-principal.rs:10:8
+   |
+LL | #[deny(missing_docs)]
+   |        ^^^^^^^^^^^^
+
+error: aborting due to previous error
+

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

@@ -213,6 +213,15 @@ mod aliases_pub {
     impl PrivUseAliasTr for <Priv as PrivTr>::AssocAlias {
         type Check = Priv; //~ ERROR private type `aliases_pub::Priv` in public interface
     }
+    impl PrivUseAliasTr for Option<<Priv as PrivTr>::AssocAlias> {
+        type Check = Priv; //~ ERROR private type `aliases_pub::Priv` in public interface
+    }
+    impl PrivUseAliasTr for (<Priv as PrivTr>::AssocAlias, Priv) {
+        type Check = Priv; // OK
+    }
+    impl PrivUseAliasTr for Option<(<Priv as PrivTr>::AssocAlias, Priv)> {
+        type Check = Priv; // OK
+    }
 }
 
 mod aliases_priv {

src/test/ui/privacy/private-in-public-warn.stderr

@@ -297,33 +297,42 @@ LL |     struct Priv;
 LL |         type Check = Priv; //~ ERROR private type `aliases_pub::Priv` in public interface
    |         ^^^^^^^^^^^^^^^^^^ can't leak private type
 
+error[E0446]: private type `aliases_pub::Priv` in public interface
+  --> $DIR/private-in-public-warn.rs:217:9
+   |
+LL |     struct Priv;
+   |     - `aliases_pub::Priv` declared as private
+...
+LL |         type Check = Priv; //~ ERROR private type `aliases_pub::Priv` in public interface
+   |         ^^^^^^^^^^^^^^^^^^ can't leak private type
+
 error: private trait `aliases_priv::PrivTr1` in public interface (error E0445)
-  --> $DIR/private-in-public-warn.rs:238:5
+  --> $DIR/private-in-public-warn.rs:247:5
    |
 LL |     pub trait Tr1: PrivUseAliasTr {}
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
    = note: for more information, see issue #34537 <https://github.com/rust-lang/rust/issues/34537>
 
-error: private type `aliases_priv::Priv2` in public interface (error E0446)
-  --> $DIR/private-in-public-warn.rs:241:5
+error: private trait `aliases_priv::PrivTr1<aliases_priv::Priv2>` in public interface (error E0445)
+  --> $DIR/private-in-public-warn.rs:250:5
    |
 LL |     pub trait Tr2: PrivUseAliasTr<PrivAlias> {}
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
    = note: for more information, see issue #34537 <https://github.com/rust-lang/rust/issues/34537>
 
-error: private trait `aliases_priv::PrivTr1<aliases_priv::Priv2>` in public interface (error E0445)
-  --> $DIR/private-in-public-warn.rs:241:5
+error: private type `aliases_priv::Priv2` in public interface (error E0446)
+  --> $DIR/private-in-public-warn.rs:250:5
    |
 LL |     pub trait Tr2: PrivUseAliasTr<PrivAlias> {}
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
    = note: for more information, see issue #34537 <https://github.com/rust-lang/rust/issues/34537>
 
-error: aborting due to 35 previous errors
+error: aborting due to 36 previous errors
 
 For more information about this error, try `rustc --explain E0446`.

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

@@ -102,7 +102,7 @@ mod aliases_pub {
 
     // This should be OK, but associated type aliases are not substituted yet
     pub fn f3(arg: <Priv as PrivTr>::Assoc) {}
-    //~^ ERROR private type `<aliases_pub::Priv as aliases_pub::PrivTr>::Assoc` in public interface
+    //~^ ERROR private trait `aliases_pub::PrivTr` in public interface
     //~| ERROR private type `aliases_pub::Priv` in public interface
 
     impl PrivUseAlias {
@@ -131,7 +131,7 @@ mod aliases_priv {
     pub fn f1(arg: PrivUseAlias) {} //~ ERROR private type `aliases_priv::Priv1` in public interface
     pub fn f2(arg: PrivAlias) {} //~ ERROR private type `aliases_priv::Priv2` in public interface
     pub fn f3(arg: <Priv as PrivTr>::Assoc) {}
-    //~^ ERROR private type `<aliases_priv::Priv as aliases_priv::PrivTr>::Assoc` in public
+    //~^ ERROR private trait `aliases_priv::PrivTr` in public interface
     //~| ERROR private type `aliases_priv::Priv` in public interface
 }