librustc: Forbid private types in public APIs.

This breaks code like:

    struct Foo {
        ...
    }

    pub fn make_foo() -> Foo {
        ...
    }

Change this code to:

    pub struct Foo {    // note `pub`
        ...
    }

    pub fn make_foo() -> Foo {
        ...
    }

The `visible_private_types` lint has been removed, since it is now an
error to attempt to expose a private type in a public API. In its place
a `#[feature(visible_private_types)]` gate has been added.

Closes #16463.

RFC #48.

[breaking-change]

Author: pcwalton

src/libcore/any.rs

@@ -94,7 +94,7 @@ pub enum Void { }
 pub trait Any: AnyPrivate {}
 
 /// An inner trait to ensure that only this module can call `get_type_id()`.
-trait AnyPrivate {
+pub trait AnyPrivate {
     /// Get the `TypeId` of `self`
     fn get_type_id(&self) -> TypeId;
 }

src/libcore/iter.rs

@@ -2178,7 +2178,6 @@ pub type Iterate<'a, T> = Unfold<'a, T, IterateState<'a, T>>;
 
 /// Creates a new iterator that produces an infinite sequence of
 /// repeated applications of the given function `f`.
-#[allow(visible_private_types)]
 pub fn iterate<'a, T: Clone>(seed: T, f: |T|: 'a -> T) -> Iterate<'a, T> {
     Unfold::new((f, Some(seed), true), |st| {
         let &(ref mut f, ref mut val, ref mut first) = st;

src/libdebug/repr.rs

@@ -32,7 +32,7 @@ macro_rules! try( ($me:expr, $e:expr) => (
 
 /// Representations
 
-trait Repr {
+pub trait Repr {
     fn write_repr(&self, writer: &mut io::Writer) -> io::IoResult<()>;
 }
 

src/libgreen/lib.rs

@@ -218,7 +218,7 @@
 
 // NB this does *not* include globs, please keep it that way.
 #![feature(macro_rules, phase, default_type_params)]
-#![allow(visible_private_types, deprecated)]
+#![allow(deprecated)]
 
 #[cfg(test)] #[phase(plugin, link)] extern crate log;
 #[cfg(test)] extern crate rustuv;
@@ -385,7 +385,7 @@ pub struct SchedPool {
 /// keep track of how many tasks are currently running in the pool and then
 /// sending on a channel once the entire pool has been drained of all tasks.
 #[deriving(Clone)]
-struct TaskState {
+pub struct TaskState {
     cnt: Arc<AtomicUint>,
     done: Sender<()>,
 }

src/libnative/io/timer_unix.rs

@@ -66,15 +66,14 @@ pub struct Timer {
     inner: Option<Box<Inner>>,
 }
 
-struct Inner {
+pub struct Inner {
     cb: Option<Box<rtio::Callback + Send>>,
     interval: u64,
     repeat: bool,
     target: u64,
     id: uint,
 }
 
-#[allow(visible_private_types)]
 pub enum Req {
     // Add a new timer to the helper thread.
     NewTimer(Box<Inner>),

src/libregex/compile.rs

@@ -10,7 +10,6 @@
 
 // Enable this to squash warnings due to exporting pieces of the representation
 // for use with the regex! macro. See lib.rs for explanation.
-#![allow(visible_private_types)]
 
 use std::cmp;
 use parse;

src/libregex/re.rs

@@ -102,7 +102,6 @@ pub fn is_match(regex: &str, text: &str) -> Result<bool, parse::Error> {
 /// More details about the `regex!` macro can be found in the `regex` crate
 /// documentation.
 #[deriving(Clone)]
-#[allow(visible_private_types)]
 pub enum Regex {
     // The representation of `Regex` is exported to support the `regex!`
     // syntax extension. Do not rely on it.
@@ -516,7 +515,6 @@ impl Regex {
     }
 
     #[doc(hidden)]
-    #[allow(visible_private_types)]
     #[experimental]
     pub fn names_iter<'a>(&'a self) -> NamesIter<'a> {
         match *self {
@@ -534,7 +532,7 @@ impl Regex {
 
 }
 
-enum NamesIter<'a> {
+pub enum NamesIter<'a> {
     NamesIterNative(::std::slice::Items<'a, Option<&'static str>>),
     NamesIterDynamic(::std::slice::Items<'a, Option<String>>)
 }

src/librustc/lint/builtin.rs

@@ -1601,9 +1601,6 @@ declare_lint!(pub DEAD_ASSIGNMENT, Warn,
 declare_lint!(pub DEAD_CODE, Warn,
               "detect piece of code that will never be used")
 
-declare_lint!(pub VISIBLE_PRIVATE_TYPES, Warn,
-              "detect use of private types in exported type signatures")
-
 declare_lint!(pub UNREACHABLE_CODE, Warn,
               "detects unreachable code")
 
@@ -1636,7 +1633,6 @@ impl LintPass for HardwiredLints {
             UNUSED_VARIABLE,
             DEAD_ASSIGNMENT,
             DEAD_CODE,
-            VISIBLE_PRIVATE_TYPES,
             UNREACHABLE_CODE,
             WARNINGS,
             UNKNOWN_FEATURES,

src/librustc/middle/mem_categorization.rs

@@ -224,7 +224,7 @@ pub fn deref_kind(tcx: &ty::ctxt, t: ty::t) -> deref_kind {
     }
 }
 
-trait ast_node {
+pub trait ast_node {
     fn id(&self) -> ast::NodeId;
     fn span(&self) -> Span;
 }

src/librustc/middle/privacy.rs

@@ -16,7 +16,6 @@ use std::mem::replace;
 
 use metadata::csearch;
 use middle::def;
-use lint;
 use middle::resolve;
 use middle::ty;
 use middle::typeck::{MethodCall, MethodMap, MethodOrigin, MethodParam, MethodTypeParam};
@@ -1289,19 +1288,38 @@ impl<'a, 'tcx> VisiblePrivateTypesVisitor<'a, 'tcx> {
         };
         // A path can only be private if:
         // it's in this crate...
-        is_local(did) &&
-            // ... it's not exported (obviously) ...
-            !self.exported_items.contains(&did.node) &&
-            // .. and it corresponds to a type in the AST (this returns None for
-            // type parameters)
-            self.tcx.map.find(did.node).is_some()
+        if !is_local(did) {
+            return false
+        }
+        // .. and it corresponds to a private type in the AST (this returns
+        // None for type parameters)
+        match self.tcx.map.find(did.node) {
+            Some(ast_map::NodeItem(ref item)) => item.vis != ast::Public,
+            Some(_) | None => false,
+        }
     }
 
     fn trait_is_public(&self, trait_id: ast::NodeId) -> bool {
         // FIXME: this would preferably be using `exported_items`, but all
         // traits are exported currently (see `EmbargoVisitor.exported_trait`)
         self.public_items.contains(&trait_id)
     }
+
+    fn check_ty_param_bound(&self,
+                            span: Span,
+                            ty_param_bound: &ast::TyParamBound) {
+        match *ty_param_bound {
+            ast::TraitTyParamBound(ref trait_ref) => {
+                if !self.tcx.sess.features.borrow().visible_private_types &&
+                        self.path_is_private_type(trait_ref.ref_id) {
+                    self.tcx.sess.span_err(span,
+                                           "private type in exported type \
+                                            parameter bound");
+                }
+            }
+            _ => {}
+        }
+    }
 }
 
 impl<'a, 'b, 'tcx, 'v> Visitor<'v> for CheckTypeForPrivatenessVisitor<'a, 'b, 'tcx> {
@@ -1338,7 +1356,15 @@ impl<'a, 'tcx, 'v> Visitor<'v> for VisiblePrivateTypesVisitor<'a, 'tcx> {
             // namespace (the contents have their own privacies).
             ast::ItemForeignMod(_) => {}
 
-            ast::ItemTrait(..) if !self.trait_is_public(item.id) => return,
+            ast::ItemTrait(_, _, ref bounds, _) => {
+                if !self.trait_is_public(item.id) {
+                    return
+                }
+
+                for bound in bounds.iter() {
+                    self.check_ty_param_bound(item.span, bound)
+                }
+            }
 
             // impls need some special handling to try to offer useful
             // error messages without (too many) false positives
@@ -1471,6 +1497,19 @@ impl<'a, 'tcx, 'v> Visitor<'v> for VisiblePrivateTypesVisitor<'a, 'tcx> {
         visit::walk_item(self, item);
     }
 
+    fn visit_generics(&mut self, generics: &ast::Generics) {
+        for ty_param in generics.ty_params.iter() {
+            for bound in ty_param.bounds.iter() {
+                self.check_ty_param_bound(ty_param.span, bound)
+            }
+        }
+        for predicate in generics.where_clause.predicates.iter() {
+            for bound in predicate.bounds.iter() {
+                self.check_ty_param_bound(predicate.span, bound)
+            }
+        }
+    }
+
     fn visit_foreign_item(&mut self, item: &ast::ForeignItem) {
         if self.exported_items.contains(&item.id) {
             visit::walk_foreign_item(self, item)
@@ -1488,12 +1527,11 @@ impl<'a, 'tcx, 'v> Visitor<'v> for VisiblePrivateTypesVisitor<'a, 'tcx> {
     fn visit_ty(&mut self, t: &ast::Ty) {
         match t.node {
             ast::TyPath(ref p, _, path_id) => {
-                if self.path_is_private_type(path_id) {
-                    self.tcx.sess.add_lint(
-                        lint::builtin::VISIBLE_PRIVATE_TYPES,
-                        path_id, p.span,
-                        "private type in exported type \
-                         signature".to_string());
+                if !self.tcx.sess.features.borrow().visible_private_types &&
+                        self.path_is_private_type(path_id) {
+                    self.tcx.sess.span_err(p.span,
+                                           "private type in exported type \
+                                            signature");
                 }
             }
             _ => {}