Auto merge of #32688 - jseyfried:ast_groundwork_for_1422, r=pnkfelix

[breaking-batch] Add support for `pub(restricted)` syntax in the AST

This PR allows the AST to represent the `pub(restricted)` syntax from RFC 1422 (cc #32409).

More specifically, it makes `ast::Visibility` non-`Copy` and adds two new variants, `Visibility::Crate` for `pub(crate)` and `Visitibility::Restricted { path: P<Path>, id: NodeId }` for `pub(path)`.

plugin-[breaking-change] cc #31645
r? @pnkfelix

src/librustc_front/lowering.rs

@@ -761,7 +761,7 @@ pub fn lower_impl_item(lctx: &LoweringContext, i: &ImplItem) -> hir::ImplItem {
         id: i.id,
         name: i.ident.name,
         attrs: lower_attrs(lctx, &i.attrs),
-        vis: lower_visibility(lctx, i.vis),
+        vis: lower_visibility(lctx, &i.vis),
         defaultness: lower_defaultness(lctx, i.defaultness),
         node: match i.node {
             ImplItemKind::Const(ref ty, ref expr) => {
@@ -839,7 +839,7 @@ pub fn lower_item(lctx: &LoweringContext, i: &Item) -> hir::Item {
         name: i.ident.name,
         attrs: lower_attrs(lctx, &i.attrs),
         node: node,
-        vis: lower_visibility(lctx, i.vis),
+        vis: lower_visibility(lctx, &i.vis),
         span: i.span,
     }
 }
@@ -857,7 +857,7 @@ pub fn lower_foreign_item(lctx: &LoweringContext, i: &ForeignItem) -> hir::Forei
                 hir::ForeignItemStatic(lower_ty(lctx, t), m)
             }
         },
-        vis: lower_visibility(lctx, i.vis),
+        vis: lower_visibility(lctx, &i.vis),
         span: i.span,
     }
 }
@@ -1706,10 +1706,11 @@ pub fn lower_capture_clause(_lctx: &LoweringContext, c: CaptureBy) -> hir::Captu
     }
 }
 
-pub fn lower_visibility(_lctx: &LoweringContext, v: Visibility) -> hir::Visibility {
-    match v {
+pub fn lower_visibility(lctx: &LoweringContext, v: &Visibility) -> hir::Visibility {
+    match *v {
         Visibility::Public => hir::Public,
         Visibility::Inherited => hir::Inherited,
+        _ => panic!(lctx.diagnostic().fatal("pub(restricted) is not implemented yet!"))
     }
 }
 

src/libsyntax/ast.rs

@@ -1868,21 +1868,14 @@ pub struct PolyTraitRef {
     pub span: Span,
 }
 
-#[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
+#[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 pub enum Visibility {
     Public,
+    Crate,
+    Restricted { path: P<Path>, id: NodeId },
     Inherited,
 }
 
-impl Visibility {
-    pub fn inherit_from(&self, parent_visibility: Visibility) -> Visibility {
-        match *self {
-            Visibility::Inherited => parent_visibility,
-            Visibility::Public => *self
-        }
-    }
-}
-
 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 pub struct StructField_ {
     pub kind: StructFieldKind,
@@ -1902,7 +1895,7 @@ impl StructField_ {
 
 pub type StructField = Spanned<StructField_>;
 
-#[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
+#[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 pub enum StructFieldKind {
     NamedField(Ident, Visibility),
     /// Element of a tuple-like struct
@@ -1917,9 +1910,9 @@ impl StructFieldKind {
         }
     }
 
-    pub fn visibility(&self) -> Visibility {
+    pub fn visibility(&self) -> &Visibility {
         match *self {
-            NamedField(_, vis) | UnnamedField(vis) => vis
+            NamedField(_, ref vis) | UnnamedField(ref vis) => vis
         }
     }
 }

src/libsyntax/ast_util.rs

@@ -247,7 +247,7 @@ impl<'a, 'v, O: IdVisitingOperation> Visitor<'v> for IdVisitor<'a, O> {
             FnKind::ItemFn(_, generics, _, _, _, _) => {
                 self.visit_generics_helper(generics)
             }
-            FnKind::Method(_, sig, _) => {
+            FnKind::Method(_, ref sig, _) => {
                 self.visit_generics_helper(&sig.generics)
             }
             FnKind::Closure => {}

src/libsyntax/fold.rs

@@ -288,6 +288,10 @@ pub trait Folder : Sized {
         noop_fold_where_predicate(where_predicate, self)
     }
 
+    fn fold_vis(&mut self, vis: Visibility) -> Visibility {
+        noop_fold_vis(vis, self)
+    }
+
     fn new_id(&mut self, i: NodeId) -> NodeId {
         i
     }
@@ -992,7 +996,7 @@ pub fn noop_fold_impl_item<T: Folder>(i: ImplItem, folder: &mut T)
         id: folder.new_id(i.id),
         ident: folder.fold_ident(i.ident),
         attrs: fold_attrs(i.attrs, folder),
-        vis: i.vis,
+        vis: folder.fold_vis(i.vis),
         defaultness: i.defaultness,
         node: match i.node  {
             ast::ImplItemKind::Const(ty, expr) => {
@@ -1082,7 +1086,7 @@ pub fn noop_fold_item_simple<T: Folder>(Item {id, ident, attrs, node, vis, span}
         ident: folder.fold_ident(ident),
         attrs: fold_attrs(attrs, folder),
         node: node,
-        vis: vis,
+        vis: folder.fold_vis(vis),
         span: folder.new_span(span)
     }
 }
@@ -1100,7 +1104,7 @@ pub fn noop_fold_foreign_item<T: Folder>(ni: ForeignItem, folder: &mut T) -> For
                 ForeignItemKind::Static(folder.fold_ty(t), m)
             }
         },
-        vis: ni.vis,
+        vis: folder.fold_vis(ni.vis),
         span: folder.new_span(ni.span)
     }
 }
@@ -1391,6 +1395,16 @@ pub fn noop_fold_stmt<T: Folder>(Spanned {node, span}: Stmt, folder: &mut T)
     }
 }
 
+pub fn noop_fold_vis<T: Folder>(vis: Visibility, folder: &mut T) -> Visibility {
+    match vis {
+        Visibility::Restricted { path, id } => Visibility::Restricted {
+            path: path.map(|path| folder.fold_path(path)),
+            id: folder.new_id(id)
+        },
+        _ => vis,
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use std::io;

src/libsyntax/parse/parser.rs

@@ -3842,7 +3842,7 @@ impl<'a> Parser<'a> {
                          attrs: Vec<Attribute> ) -> PResult<'a, StructField> {
         let lo = match pr {
             Visibility::Inherited => self.span.lo,
-            Visibility::Public => self.last_span.lo,
+            _ => self.last_span.lo,
         };
         let name = self.parse_ident()?;
         self.expect(&token::Colon)?;
@@ -4952,7 +4952,7 @@ impl<'a> Parser<'a> {
             self.commit_expr_expecting(&expr, token::Semi)?;
             (name, ast::ImplItemKind::Const(typ, expr))
         } else {
-            let (name, inner_attrs, node) = self.parse_impl_method(vis)?;
+            let (name, inner_attrs, node) = self.parse_impl_method(&vis)?;
             attrs.extend(inner_attrs);
             (name, node)
         };
@@ -4968,9 +4968,10 @@ impl<'a> Parser<'a> {
         })
     }
 
-    fn complain_if_pub_macro(&mut self, visa: Visibility, span: Span) {
-        match visa {
-            Visibility::Public => {
+    fn complain_if_pub_macro(&mut self, visa: &Visibility, span: Span) {
+        match *visa {
+            Visibility::Inherited => (),
+            _ => {
                 let is_macro_rules: bool = match self.token {
                     token::Ident(sid, _) => sid.name == intern("macro_rules"),
                     _ => false,
@@ -4988,12 +4989,11 @@ impl<'a> Parser<'a> {
                                      .emit();
                 }
             }
-            Visibility::Inherited => (),
         }
     }
 
     /// Parse a method or a macro invocation in a trait impl.
-    fn parse_impl_method(&mut self, vis: Visibility)
+    fn parse_impl_method(&mut self, vis: &Visibility)
                          -> PResult<'a, (Ident, Vec<ast::Attribute>, ast::ImplItemKind)> {
         // code copied from parse_macro_use_or_failure... abstraction!
         if !self.token.is_any_keyword()
@@ -5003,7 +5003,7 @@ impl<'a> Parser<'a> {
             // method macro.
 
             let last_span = self.last_span;
-            self.complain_if_pub_macro(vis, last_span);
+            self.complain_if_pub_macro(&vis, last_span);
 
             let lo = self.span.lo;
             let pth = self.parse_path(NoTypesAllowed)?;
@@ -6045,7 +6045,7 @@ impl<'a> Parser<'a> {
             // MACRO INVOCATION ITEM
 
             let last_span = self.last_span;
-            self.complain_if_pub_macro(visibility, last_span);
+            self.complain_if_pub_macro(&visibility, last_span);
 
             let mac_lo = self.span.lo;
 
@@ -6096,7 +6096,7 @@ impl<'a> Parser<'a> {
         // FAILURE TO PARSE ITEM
         match visibility {
             Visibility::Inherited => {}
-            Visibility::Public => {
+            _ => {
                 let last_span = self.last_span;
                 return Err(self.span_fatal(last_span, "unmatched visibility `pub`"));
             }