Auto merge of #38152 - arielb1:special-copy, r=nikomatsakis

Fix associated types in copy implementations

Fixes an ICE and an error in checking copy implementations.

r? @nikomatsakis

Author: bors

src/libcore/marker.rs

@@ -234,12 +234,10 @@ pub trait Unsize<T: ?Sized> {
 /// Generalizing the latter case, any type implementing [`Drop`] can't be `Copy`, because it's
 /// managing some resource besides its own [`size_of::<T>()`] bytes.
 ///
-/// If you try to implement `Copy` on a struct or enum containing non-`Copy` data, you will get a
-/// compile-time error. Specifically, with structs you'll get [E0204] and with enums you'll get
-/// [E0205].
+/// If you try to implement `Copy` on a struct or enum containing non-`Copy` data, you will get
+/// the error [E0204].
 ///
 /// [E0204]: ../../error-index.html#E0204
-/// [E0205]: ../../error-index.html#E0205
 ///
 /// ## When *should* my type be `Copy`?
 ///

src/librustc/ty/util.rs

@@ -15,7 +15,7 @@ use hir::map::DefPathData;
 use infer::InferCtxt;
 use hir::map as ast_map;
 use traits::{self, Reveal};
-use ty::{self, Ty, AdtKind, TyCtxt, TypeAndMut, TypeFlags, TypeFoldable};
+use ty::{self, Ty, TyCtxt, TypeAndMut, TypeFlags, TypeFoldable};
 use ty::{Disr, ParameterEnvironment};
 use ty::fold::TypeVisitor;
 use ty::layout::{Layout, LayoutError};
@@ -120,9 +120,8 @@ impl IntTypeExt for attr::IntType {
 
 
 #[derive(Copy, Clone)]
-pub enum CopyImplementationError {
-    InfrigingField(Name),
-    InfrigingVariant(Name),
+pub enum CopyImplementationError<'tcx> {
+    InfrigingField(&'tcx ty::FieldDef),
     NotAnAdt,
     HasDestructor
 }
@@ -145,37 +144,30 @@ pub enum Representability {
 impl<'tcx> ParameterEnvironment<'tcx> {
     pub fn can_type_implement_copy<'a>(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>,
                                        self_type: Ty<'tcx>, span: Span)
-                                       -> Result<(),CopyImplementationError> {
+                                       -> Result<(), CopyImplementationError> {
         // FIXME: (@jroesch) float this code up
-        tcx.infer_ctxt(None, Some(self.clone()), Reveal::ExactMatch).enter(|infcx| {
-            let adt = match self_type.sty {
-                ty::TyAdt(adt, substs) => match adt.adt_kind() {
-                    AdtKind::Struct | AdtKind::Union => {
-                        for field in adt.all_fields() {
-                            let field_ty = field.ty(tcx, substs);
-                            if infcx.type_moves_by_default(field_ty, span) {
-                                return Err(CopyImplementationError::InfrigingField(
-                                    field.name))
-                            }
-                        }
-                        adt
-                    }
-                    AdtKind::Enum => {
-                        for variant in &adt.variants {
-                            for field in &variant.fields {
-                                let field_ty = field.ty(tcx, substs);
-                                if infcx.type_moves_by_default(field_ty, span) {
-                                    return Err(CopyImplementationError::InfrigingVariant(
-                                        variant.name))
-                                }
-                            }
-                        }
-                        adt
-                    }
-                },
+        tcx.infer_ctxt(None, Some(self.clone()), Reveal::NotSpecializable).enter(|infcx| {
+            let (adt, substs) = match self_type.sty {
+                ty::TyAdt(adt, substs) => (adt, substs),
                 _ => return Err(CopyImplementationError::NotAnAdt)
             };
 
+            let field_implements_copy = |field: &ty::FieldDef| {
+                let cause = traits::ObligationCause::dummy();
+                match traits::fully_normalize(&infcx, cause, &field.ty(tcx, substs)) {
+                    Ok(ty) => !infcx.type_moves_by_default(ty, span),
+                    Err(..) => false
+                }
+            };
+
+            for variant in &adt.variants {
+                for field in &variant.fields {
+                    if !field_implements_copy(field) {
+                        return Err(CopyImplementationError::InfrigingField(field));
+                    }
+                }
+            }
+
             if adt.has_dtor() {
                 return Err(CopyImplementationError::HasDestructor);
             }