auto merge of #13398 : nick29581/rust/unsized-enum, r=nikomatsakis

Now with proper checking of enums and allows unsized fields as the last field in a struct or variant. This PR only checks passing of unsized types and distinguishing them from sized ones. To be safe we also need to control storage.

Closes issues #12969 and #13121, supersedes #13375 (all the discussion there is valid here too).

Author: bors

src/librustc/front/config.rs

@@ -103,12 +103,12 @@ fn fold_item_underscore(cx: &mut Context, item: &ast::Item_) -> ast::Item_ {
                 .map(|x| *x).collect();
             ast::ItemImpl((*a).clone(), (*b).clone(), c, methods)
         }
-        ast::ItemTrait(ref a, ref b, ref methods) => {
+        ast::ItemTrait(ref a, b, ref c, ref methods) => {
             let methods = methods.iter()
                                  .filter(|m| trait_method_in_cfg(cx, *m) )
                                  .map(|x| (*x).clone())
                                  .collect();
-            ast::ItemTrait((*a).clone(), (*b).clone(), methods)
+            ast::ItemTrait((*a).clone(), b, (*c).clone(), methods)
         }
         ast::ItemStruct(def, ref generics) => {
             ast::ItemStruct(fold_struct(cx, def), generics.clone())

src/librustc/metadata/common.rs

@@ -170,6 +170,7 @@ pub static tag_lang_items_item_node_id: uint = 0x73;
 
 pub static tag_item_unnamed_field: uint = 0x74;
 pub static tag_items_data_item_visibility: uint = 0x76;
+pub static tag_items_data_item_sized: uint = 0x77;
 
 pub static tag_item_method_tps: uint = 0x79;
 pub static tag_item_method_fty: uint = 0x7a;

src/librustc/metadata/decoder.rs

@@ -164,6 +164,19 @@ fn item_visibility(item: ebml::Doc) -> ast::Visibility {
     }
 }
 
+fn item_sized(item: ebml::Doc) -> ast::Sized {
+    match reader::maybe_get_doc(item, tag_items_data_item_sized) {
+        None => ast::StaticSize,
+        Some(sized_doc) => {
+            match reader::doc_as_u8(sized_doc) as char {
+                'd' => ast::DynSize,
+                's' => ast::StaticSize,
+                _ => fail!("unknown sized-ness character")
+            }
+        }
+    }
+}
+
 fn item_method_sort(item: ebml::Doc) -> char {
     let mut ret = 'r';
     reader::tagged_docs(item, tag_item_trait_method_sort, |doc| {
@@ -371,6 +384,7 @@ pub fn get_trait_def(cdata: Cmd,
     let tp_defs = item_ty_param_defs(item_doc, tcx, cdata,
                                      tag_items_data_item_ty_param_bounds);
     let rp_defs = item_region_param_defs(item_doc, cdata);
+    let sized = item_sized(item_doc);
     let mut bounds = ty::EmptyBuiltinBounds();
     // Collect the builtin bounds from the encoded supertraits.
     // FIXME(#8559): They should be encoded directly.
@@ -382,6 +396,13 @@ pub fn get_trait_def(cdata: Cmd,
         });
         true
     });
+    // Turn sized into a bound, FIXME(#8559).
+    if sized == ast::StaticSize {
+        tcx.lang_items.to_builtin_kind(tcx.lang_items.sized_trait().unwrap()).map(|bound| {
+            bounds.add(bound);
+        });
+    }
+
     ty::TraitDef {
         generics: ty::Generics {type_param_defs: tp_defs,
                                 region_param_defs: rp_defs},

src/librustc/metadata/encoder.rs

@@ -832,6 +832,16 @@ fn encode_extension_implementations(ecx: &EncodeContext,
     }
 }
 
+fn encode_sized(ebml_w: &mut Encoder, sized: Sized) {
+    ebml_w.start_tag(tag_items_data_item_sized);
+    let ch = match sized {
+        DynSize => 'd',
+        StaticSize => 's',
+    };
+    ebml_w.wr_str(str::from_char(ch));
+    ebml_w.end_tag();
+}
+
 fn encode_info_for_item(ecx: &EncodeContext,
                         ebml_w: &mut Encoder,
                         item: &Item,
@@ -1070,7 +1080,7 @@ fn encode_info_for_item(ecx: &EncodeContext,
                                    ast_method)
         }
       }
-      ItemTrait(_, ref super_traits, ref ms) => {
+      ItemTrait(_, sized, ref super_traits, ref ms) => {
         add_to_index(item, ebml_w, index);
         ebml_w.start_tag(tag_items_data_item);
         encode_def_id(ebml_w, def_id);
@@ -1084,6 +1094,9 @@ fn encode_info_for_item(ecx: &EncodeContext,
         encode_trait_ref(ebml_w, ecx, &*trait_def.trait_ref, tag_item_trait_ref);
         encode_name(ebml_w, item.ident.name);
         encode_attributes(ebml_w, item.attrs.as_slice());
+        // When we fix the rest of the supertrait nastiness (FIXME(#8559)), we
+        // should no longer need this ugly little hack either.
+        encode_sized(ebml_w, sized);
         encode_visibility(ebml_w, vis);
         for &method_def_id in ty::trait_method_def_ids(tcx, def_id).iter() {
             ebml_w.start_tag(tag_item_trait_method);

src/librustc/middle/privacy.rs

@@ -79,7 +79,7 @@ impl Visitor<()> for ParentVisitor {
             // method to the root. In this case, if the trait is private, then
             // parent all the methods to the trait to indicate that they're
             // private.
-            ast::ItemTrait(_, _, ref methods) if item.vis != ast::Public => {
+            ast::ItemTrait(_, _, _, ref methods) if item.vis != ast::Public => {
                 for m in methods.iter() {
                     match *m {
                         ast::Provided(ref m) => self.parents.insert(m.id, item.id),
@@ -274,7 +274,7 @@ impl<'a> Visitor<()> for EmbargoVisitor<'a> {
 
             // Default methods on traits are all public so long as the trait
             // is public
-            ast::ItemTrait(_, _, ref methods) if public_first => {
+            ast::ItemTrait(_, _, _, ref methods) if public_first => {
                 for method in methods.iter() {
                     match *method {
                         ast::Provided(ref m) => {
@@ -1082,7 +1082,7 @@ impl<'a> SanePrivacyVisitor<'a> {
                 }
             }
 
-            ast::ItemTrait(_, _, ref methods) => {
+            ast::ItemTrait(_, _, _, ref methods) => {
                 for m in methods.iter() {
                     match *m {
                         ast::Provided(ref m) => {
@@ -1142,7 +1142,7 @@ impl<'a> SanePrivacyVisitor<'a> {
 
             ast::ItemStruct(ref def, _) => check_struct(def),
 
-            ast::ItemTrait(_, _, ref methods) => {
+            ast::ItemTrait(_, _, _, ref methods) => {
                 for m in methods.iter() {
                     match *m {
                         ast::Required(..) => {}

src/librustc/middle/resolve.rs

@@ -1326,7 +1326,7 @@ impl<'a> Resolver<'a> {
 
             ItemImpl(_, Some(_), _, _) => parent,
 
-            ItemTrait(_, _, ref methods) => {
+            ItemTrait(_, _, _, ref methods) => {
                 let name_bindings =
                     self.add_child(ident, parent.clone(), ForbidDuplicateTypes, sp);
 
@@ -3579,7 +3579,7 @@ impl<'a> Resolver<'a> {
                                             methods.as_slice());
             }
 
-            ItemTrait(ref generics, ref traits, ref methods) => {
+            ItemTrait(ref generics, _, ref traits, ref methods) => {
                 // Create a new rib for the self type.
                 let self_type_rib = Rib::new(NormalRibKind);
                 // plain insert (no renaming)
@@ -3787,9 +3787,8 @@ impl<'a> Resolver<'a> {
                 }
                 Some(declaration) => {
                     for argument in declaration.inputs.iter() {
-                        let binding_mode = ArgumentIrrefutableMode;
                         this.resolve_pattern(argument.pat,
-                                             binding_mode,
+                                             ArgumentIrrefutableMode,
                                              None);
 
                         this.resolve_type(argument.ty);

src/librustc/middle/resolve_lifetime.rs

@@ -84,7 +84,7 @@ impl<'a, 'b> Visitor<Scope<'a>> for LifetimeContext<'b> {
             ast::ItemEnum(_, ref generics) |
             ast::ItemStruct(_, ref generics) |
             ast::ItemImpl(ref generics, _, _, _) |
-            ast::ItemTrait(ref generics, _, _) => {
+            ast::ItemTrait(ref generics, _, _, _) => {
                 self.check_lifetime_names(&generics.lifetimes);
                 EarlyScope(0, &generics.lifetimes, &root)
             }

src/librustc/middle/ty.rs

@@ -2595,18 +2595,7 @@ pub fn type_is_machine(ty: t) -> bool {
 // Is the type's representation size known at compile time?
 #[allow(dead_code)] // leaving in for DST
 pub fn type_is_sized(cx: &ctxt, ty: ty::t) -> bool {
-    match get(ty).sty {
-        // FIXME(#6308) add trait, vec, str, etc here.
-        ty_param(p) => {
-            let ty_param_defs = cx.ty_param_defs.borrow();
-            let param_def = ty_param_defs.get(&p.def_id.node);
-            if param_def.bounds.builtin_bounds.contains_elem(BoundSized) {
-                return true;
-            }
-            return false;
-        },
-        _ => return true,
-    }
+    type_contents(cx, ty).is_sized(cx)
 }
 
 // Whether a type is enum like, that is an enum type with only nullary
@@ -3500,7 +3489,7 @@ pub fn provided_trait_methods(cx: &ctxt, id: ast::DefId) -> Vec<Rc<Method>> {
         match cx.map.find(id.node) {
             Some(ast_map::NodeItem(item)) => {
                 match item.node {
-                    ItemTrait(_, _, ref ms) => {
+                    ItemTrait(_, _, _, ref ms) => {
                         let (_, p) = ast_util::split_trait_methods(ms.as_slice());
                         p.iter().map(|m| method(cx, ast_util::local_def(m.id))).collect()
                     }