Remove wfcheck for auto traits, remove dead error codes

The WF checks are now done as an AST validation.

Author: leoyvens

src/librustc_passes/ast_validation.rs

@@ -247,16 +247,16 @@ impl<'a> Visitor<'a> for AstValidator<'a> {
                 if is_auto == IsAuto::Yes {
                     // Auto traits cannot have generics, super traits nor contain items.
                     if generics.is_parameterized() {
-                        self.err_handler().span_err(item.span,
-                                                    "auto traits cannot have generics");
+                        struct_span_err!(self.session, item.span, E0567,
+                                        "Auto traits cannot have generic parameters").emit();
                     }
                     if !bounds.is_empty() {
-                        self.err_handler().span_err(item.span,
-                                                    "auto traits cannot have super traits");
+                        struct_span_err!(self.session, item.span, E0568,
+                                        "Auto traits cannot have predicates").emit();
                     }
                     if !trait_items.is_empty() {
-                        self.err_handler().span_err(item.span,
-                                                    "auto traits cannot contain items");
+                        struct_span_err!(self.session, item.span, E0380,
+                                "Auto traits cannot have methods or associated items").emit();
                     }
                 }
                 self.no_questions_in_bounds(bounds, "supertraits", true);

src/librustc_passes/diagnostics.rs

@@ -150,6 +150,13 @@ Trait methods cannot be declared `const` by design. For more information, see
 [RFC 911]: https://github.com/rust-lang/rfcs/pull/911
 "##,
 
+E0380: r##"
+Auto traits cannot have methods or associated items.
+For more information see the [opt-in builtin traits RFC][RFC 19].
+
+[RFC 19]: https://github.com/rust-lang/rfcs/blob/master/text/0019-opt-in-builtin-traits.md
+"##,
+
 E0449: r##"
 A visibility qualifier was used when it was unnecessary. Erroneous code
 examples:
@@ -264,5 +271,7 @@ register_diagnostics! {
     E0226, // only a single explicit lifetime bound is permitted
     E0472, // asm! is unsupported on this target
     E0561, // patterns aren't allowed in function pointer types
+    E0567, // auto traits can not have type parameters
+    E0568, // auto traits can not have predicates
     E0642, // patterns aren't allowed in methods without bodies
 }

src/librustc_typeck/check/wfcheck.rs

@@ -275,74 +275,8 @@ impl<'a, 'gcx> CheckTypeWellFormedVisitor<'a, 'gcx> {
         });
     }
 
-    fn check_auto_trait(&mut self, trait_def_id: DefId, span: Span) {
-        // We want to ensure:
-        //
-        // 1) that there are no items contained within
-        // the trait definition
-        //
-        // 2) that the definition doesn't violate the no-super trait rule
-        // for auto traits.
-        //
-        // 3) that the trait definition does not have any type parameters
-
-        let predicates = self.tcx.predicates_of(trait_def_id);
-
-        // We must exclude the Self : Trait predicate contained by all
-        // traits.
-        let has_predicates =
-            predicates.predicates.iter().any(|predicate| {
-                match predicate {
-                    &ty::Predicate::Trait(ref poly_trait_ref) => {
-                        let self_ty = poly_trait_ref.0.self_ty();
-                        !(self_ty.is_self() && poly_trait_ref.def_id() == trait_def_id)
-                    },
-                    _ => true,
-                }
-            });
-
-        let has_ty_params = self.tcx.generics_of(trait_def_id).types.len() > 1;
-
-        // We use an if-else here, since the generics will also trigger
-        // an extraneous error message when we find predicates like
-        // `T : Sized` for a trait like: `trait Magic<T>`.
-        //
-        // We also put the check on the number of items here,
-        // as it seems confusing to report an error about
-        // extraneous predicates created by things like
-        // an associated type inside the trait.
-        let mut err = None;
-        if !self.tcx.associated_item_def_ids(trait_def_id).is_empty() {
-            error_380(self.tcx, span);
-        } else if has_ty_params {
-            err = Some(struct_span_err!(self.tcx.sess, span, E0567,
-                "traits with auto impls (`e.g. impl \
-                    Trait for ..`) can not have type parameters"));
-        } else if has_predicates {
-            err = Some(struct_span_err!(self.tcx.sess, span, E0568,
-                "traits with auto impls (`e.g. impl \
-                    Trait for ..`) cannot have predicates"));
-        }
-
-        // Finally if either of the above conditions apply we should add a note
-        // indicating that this error is the result of a recent soundness fix.
-        match err {
-            None => {},
-            Some(mut e) => {
-                e.note("the new auto trait rules are the result of a \
-                          recent soundness fix; see #29859 for more details");
-                e.emit();
-            }
-        }
-    }
-
     fn check_trait(&mut self, item: &hir::Item) {
         let trait_def_id = self.tcx.hir.local_def_id(item.id);
-
-        if self.tcx.trait_is_auto(trait_def_id) {
-            self.check_auto_trait(trait_def_id, item.span);
-        }
-
         self.for_item(item).with_fcx(|fcx, this| {
             let predicates = fcx.tcx.predicates_of(trait_def_id).instantiate_identity(fcx.tcx);
             let predicates = fcx.normalize_associated_types_in(item.span, &predicates);
@@ -733,12 +667,6 @@ fn error_192(tcx: TyCtxt, span: Span) {
                default impls (e.g., `Send` and `Sync`)")
 }
 
-fn error_380(tcx: TyCtxt, span: Span) {
-    span_err!(tcx.sess, span, E0380,
-              "traits with default impls (`e.g. impl \
-               Trait for ..`) must have no methods or associated items")
-}
-
 fn error_392<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, span: Span, param_name: ast::Name)
                        -> DiagnosticBuilder<'tcx> {
     let mut err = struct_span_err!(tcx.sess, span, E0392,

src/librustc_typeck/collect.rs

@@ -712,9 +712,9 @@ fn trait_def<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
     let node_id = tcx.hir.as_local_node_id(def_id).unwrap();
     let item = tcx.hir.expect_item(node_id);
 
-    let unsafety = match item.node {
-        hir::ItemTrait(_, unsafety, ..) => unsafety,
-        hir::ItemTraitAlias(..) => hir::Unsafety::Normal,
+    let (is_auto, unsafety) = match item.node {
+        hir::ItemTrait(is_auto, unsafety, ..) => (is_auto == hir::IsAuto::Yes, unsafety),
+        hir::ItemTraitAlias(..) => (hir::IsAuto::No, hir::Unsafety::Normal),
         _ => span_bug!(item.span, "trait_def_of_item invoked on non-trait"),
     };
 
@@ -731,10 +731,6 @@ fn trait_def<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
     }
 
     let def_path_hash = tcx.def_path_hash(def_id);
-    let is_auto = match item.node {
-        hir::ItemTrait(hir::IsAuto::Yes, ..) => true,
-        _ => tcx.hir.trait_is_auto(def_id),
-    };
     let def = ty::TraitDef::new(def_id,
                                 unsafety,
                                 paren_sugar,

src/librustc_typeck/diagnostics.rs

@@ -2531,13 +2531,6 @@ struct Bar<S, T> { x: Foo<S, T> }
 ```
 "##,
 
-E0318: r##"
-Default impls for a trait must be located in the same crate where the trait was
-defined. For more information see the [opt-in builtin traits RFC][RFC 19].
-
-[RFC 19]: https://github.com/rust-lang/rfcs/blob/master/text/0019-opt-in-builtin-traits.md
-"##,
-
 E0321: r##"
 A cross-crate opt-out trait was implemented on something which wasn't a struct
 or enum type. Erroneous code example:
@@ -3170,13 +3163,6 @@ containing the unsized type is the last and only unsized type field in the
 struct.
 "##,
 
-E0380: r##"
-Default impls are only allowed for traits with no methods or associated items.
-For more information see the [opt-in builtin traits RFC][RFC 19].
-
-[RFC 19]: https://github.com/rust-lang/rfcs/blob/master/text/0019-opt-in-builtin-traits.md
-"##,
-
 E0390: r##"
 You tried to implement methods for a primitive type. Erroneous code example:
 
@@ -4729,13 +4715,10 @@ register_diagnostics! {
 //  E0372, // coherence not object safe
     E0377, // the trait `CoerceUnsized` may only be implemented for a coercion
            // between structures with the same definition
-    E0521, // redundant auto implementations of trait
     E0533, // `{}` does not name a unit variant, unit struct or a constant
 //  E0563, // cannot determine a type for this `impl Trait`: {} // removed in 6383de15
     E0564, // only named lifetimes are allowed in `impl Trait`,
            // but `{}` was found in the type `{}`
-    E0567, // auto traits can not have type parameters
-    E0568, // auto-traits can not have predicates,
     E0587, // struct has conflicting packed and align representation hints
     E0588, // packed struct cannot transitively contain a `[repr(align)]` struct
     E0592, // duplicate definitions with name `{}`

src/test/compile-fail/auto-trait-validation.rs

@@ -11,12 +11,9 @@
 #![feature(optin_builtin_traits)]
 
 auto trait Generic<T> {}
-//~^ ERROR auto traits cannot have generics
-//~^^ traits with auto impls (`e.g. impl Trait for ..`) can not have type parameters
+//~^ Auto traits cannot have type parameters [E0567]
 auto trait Bound : Copy {}
-//~^ ERROR auto traits cannot have super traits
-//~^^ traits with auto impls (`e.g. impl Trait for ..`) cannot have predicates
+//~^ Auto traits cannot have predicates [E0568]
 auto trait MyTrait { fn foo() {} }
-//~^ ERROR auto traits cannot contain items
-//~^^ traits with default impls (`e.g. impl Trait for ..`) must have no methods or associated items
+//~^ Auto traits cannot have methods or associated items [E0380]
 fn main() {}

src/test/compile-fail/coherence-default-trait-impl.rs

@@ -14,13 +14,11 @@ auto trait MySafeTrait {}
 
 struct Foo;
 
-#[allow(auto_impl)]
 unsafe impl MySafeTrait for Foo {}
 //~^ ERROR implementing the trait `MySafeTrait` is not unsafe
 
 unsafe auto trait MyUnsafeTrait {}
 
-#[allow(auto_impl)]
 impl MyUnsafeTrait for Foo {}
 //~^ ERROR the trait `MyUnsafeTrait` requires an `unsafe impl` declaration
 

src/test/compile-fail/issue-23080-2.rs

@@ -22,4 +22,5 @@ fn call_method<T: Trait>(x: T) {}
 fn main() {
     // ICE
     call_method(());
+    //~^ ERROR
 }

src/test/compile-fail/traits-inductive-overflow-supertrait-oibit.rs

@@ -22,6 +22,6 @@ fn copy<T: Magic>(x: T) -> (T, T) { (x, x) }
 struct NoClone;
 
 fn main() {
-    let (a, b) = copy(NoClone);
+    let (a, b) = copy(NoClone); //~ ERROR
     println!("{:?} {:?}", a, b);
 }