Allow more !Copy impls

Author: fmease

compiler/rustc_typeck/src/coherence/builtin.rs

@@ -70,23 +70,21 @@ fn visit_implementation_of_copy(tcx: TyCtxt<'_>, impl_did: LocalDefId) {
  let self_type = tcx.type_of(impl_did);
  debug!("visit_implementation_of_copy: self_type={:?} (bound)", self_type);
 
- let span = tcx.hir().span(impl_hir_id);
  let param_env = tcx.param_env(impl_did);
  assert!(!self_type.has_escaping_bound_vars());
 
  debug!("visit_implementation_of_copy: self_type={:?} (free)", self_type);
 
+ let span = match tcx.hir().expect_item(impl_did).kind {
+ ItemKind::Impl(hir::Impl { polarity: hir::ImplPolarity::Negative(_), .. }) => return,
+ ItemKind::Impl(impl_) => impl_.self_ty.span,
+ _ => bug!("expected Copy impl item"),
+ };
+
  let cause = traits::ObligationCause::misc(span, impl_hir_id);
  match can_type_implement_copy(tcx, param_env, self_type, cause) {
  Ok(()) => {}
  Err(CopyImplementationError::InfrigingFields(fields)) => {
- let item = tcx.hir().expect_item(impl_did);
- let span = if let ItemKind::Impl(hir::Impl { of_trait: Some(ref tr), .. }) = item.kind {
- tr.path.span
- } else {
- span
- };
-
  let mut err = struct_span_err!(
  tcx.sess,
  span,
@@ -166,10 +164,6 @@ fn visit_implementation_of_copy(tcx: TyCtxt<'_>, impl_did: LocalDefId) {
  err.emit();
  }
  Err(CopyImplementationError::NotAnAdt) => {
- let item = tcx.hir().expect_item(impl_did);
- let span =
- if let ItemKind::Impl(ref impl_) = item.kind { impl_.self_ty.span } else { span };
-
  tcx.sess.emit_err(CopyImplOnNonAdt { span });
  }
  Err(CopyImplementationError::HasDestructor) => {

src/test/ui/coherence/coherence-negative-impls-copy-bad.rs

@@ -0,0 +1,11 @@
+#![feature(negative_impls)]
+#![crate_type = "lib"]
+
+impl !Copy for str {}
+//~^ ERROR only traits defined in the current crate can be implemented
+
+impl !Copy for fn() {}
+//~^ ERROR only traits defined in the current crate can be implemented
+
+impl !Copy for () {}
+//~^ ERROR only traits defined in the current crate can be implemented

src/test/ui/coherence/coherence-negative-impls-copy-bad.stderr

@@ -0,0 +1,36 @@
+error[E0117]: only traits defined in the current crate can be implemented for arbitrary types
+ --> $DIR/coherence-negative-impls-copy-bad.rs:4:1
+ |
+LL | impl !Copy for str {}
+ | ^^^^^^^^^^^^^^^---
+ | | |
+ | | `str` is not defined in the current crate
+ | impl doesn't use only types from inside the current crate
+ |
+ = note: define and implement a trait or new type instead
+
+error[E0117]: only traits defined in the current crate can be implemented for arbitrary types
+ --> $DIR/coherence-negative-impls-copy-bad.rs:7:1
+ |
+LL | impl !Copy for fn() {}
+ | ^^^^^^^^^^^^^^^----
+ | | |
+ | | `fn()` is not defined in the current crate
+ | impl doesn't use only types from inside the current crate
+ |
+ = note: define and implement a trait or new type instead
+
+error[E0117]: only traits defined in the current crate can be implemented for arbitrary types
+ --> $DIR/coherence-negative-impls-copy-bad.rs:10:1
+ |
+LL | impl !Copy for () {}
+ | ^^^^^^^^^^^^^^^--
+ | | |
+ | | this is not defined in the current crate because tuples are always foreign
+ | impl doesn't use only types from inside the current crate
+ |
+ = note: define and implement a trait or new type instead
+
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0117`.

src/test/ui/coherence/coherence-negative-impls-copy.rs

@@ -0,0 +1,29 @@
+// check-pass
+// regression test for issue #101836
+
+#![feature(negative_impls, extern_types)]
+#![crate_type = "lib"]
+
+struct NonCopy;
+struct NeverCopy(NonCopy);
+
+impl !Copy for NeverCopy {}
+
+
+struct WithDrop;
+impl Drop for WithDrop { fn drop(&mut self) {} }
+
+impl !Copy for WithDrop {}
+
+
+struct Type;
+trait Trait {}
+extern {
+ type ExternType;
+}
+
+impl !Copy for &mut Type {}
+
+impl !Copy for dyn Trait {}
+
+impl !Copy for ExternType {}

src/test/ui/coherence/deep-bad-copy-reason.stderr

@@ -1,11 +1,11 @@
 error[E0204]: the trait `Copy` may not be implemented for this type
- --> $DIR/deep-bad-copy-reason.rs:33:15
+ --> $DIR/deep-bad-copy-reason.rs:33:24
  |
 LL | pub struct List<'tcx, T>(Interned<'tcx, ListS<T>>);
  | ------------------------ this field does not implement `Copy`
 ...
 LL | impl<'tcx, T> Copy for List<'tcx, T> {}
- | ^^^^
+ |  ^^^^^^^^^^^^^
  |
 note: the `Copy` impl for `Interned<'tcx, ListS<T>>` requires that `OpaqueListContents: Sized`
  --> $DIR/deep-bad-copy-reason.rs:23:26

src/test/ui/opt-in-copy.stderr

@@ -1,20 +1,20 @@
 error[E0204]: the trait `Copy` may not be implemented for this type
- --> $DIR/opt-in-copy.rs:7:6
+ --> $DIR/opt-in-copy.rs:7:15
  |
 LL | but_i_cant: CantCopyThis,
  | ------------------------ this field does not implement `Copy`
 ...
 LL | impl Copy for IWantToCopyThis {}
- | ^^^^
+ |  ^^^^^^^^^^^^^^^
 
 error[E0204]: the trait `Copy` may not be implemented for this type
- --> $DIR/opt-in-copy.rs:19:6
+ --> $DIR/opt-in-copy.rs:19:15
  |
 LL | ButICant(CantCopyThisEither),
  | ------------------ this field does not implement `Copy`
 ...
 LL | impl Copy for IWantToCopyThisToo {}
- | ^^^^
+ |  ^^^^^^^^^^^^^^^^^^
 
 error: aborting due to 2 previous errors
 

src/test/ui/span/E0204.stderr

@@ -1,11 +1,11 @@
 error[E0204]: the trait `Copy` may not be implemented for this type
- --> $DIR/E0204.rs:5:6
+ --> $DIR/E0204.rs:5:15
  |
 LL | foo: Vec<u32>,
  | ------------- this field does not implement `Copy`
 ...
 LL | impl Copy for Foo { }
- | ^^^^
+ |  ^^^
 
 error[E0204]: the trait `Copy` may not be implemented for this type
  --> $DIR/E0204.rs:7:10
@@ -19,13 +19,13 @@ LL | ty: &'a mut bool,
  = note: this error originates in the derive macro `Copy` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error[E0204]: the trait `Copy` may not be implemented for this type
- --> $DIR/E0204.rs:17:6
+ --> $DIR/E0204.rs:17:15
  |
 LL | Bar { x: Vec<u32> },
  | ----------- this field does not implement `Copy`
 ...
 LL | impl Copy for EFoo { }
- | ^^^^
+ |  ^^^^
 
 error[E0204]: the trait `Copy` may not be implemented for this type
  --> $DIR/E0204.rs:19:10

src/test/ui/suggestions/missing-bound-in-manual-copy-impl-2.stderr

@@ -1,11 +1,11 @@
 error[E0204]: the trait `Copy` may not be implemented for this type
- --> $DIR/missing-bound-in-manual-copy-impl-2.rs:16:9
+ --> $DIR/missing-bound-in-manual-copy-impl-2.rs:16:18
  |
 LL | struct Wrapper<T>(T);
  | - this field does not implement `Copy`
 ...
 LL | impl<S> Copy for Wrapper<OnlyCopyIfDisplay<S>> {}
- | ^^^^
+ |  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  |
 note: the `Copy` impl for `OnlyCopyIfDisplay<S>` requires that `S: std::fmt::Display`
  --> $DIR/missing-bound-in-manual-copy-impl-2.rs:4:19

src/test/ui/suggestions/missing-bound-in-manual-copy-impl.stderr

@@ -1,11 +1,11 @@
 error[E0204]: the trait `Copy` may not be implemented for this type
- --> $DIR/missing-bound-in-manual-copy-impl.rs:6:9
+ --> $DIR/missing-bound-in-manual-copy-impl.rs:6:18
  |
 LL | struct Wrapper<T>(T);
  | - this field does not implement `Copy`
 LL |
 LL | impl<S> Copy for Wrapper<S> {}
- | ^^^^
+ |  ^^^^^^^^^^
  |
 help: consider restricting type parameter `S`
  |

src/test/ui/traits/copy-impl-cannot-normalize.stderr

@@ -1,8 +1,8 @@
 error[E0277]: the trait bound `T: TraitFoo` is not satisfied
- --> $DIR/copy-impl-cannot-normalize.rs:22:1
+ --> $DIR/copy-impl-cannot-normalize.rs:22:18
  |
 LL | impl<T> Copy for Foo<T> {}
- | ^^^^^^^^^^^^^^^^^^^^^^^ the trait `TraitFoo` is not implemented for `T`
+ |  ^^^^^^ the trait `TraitFoo` is not implemented for `T`
  |
 help: consider restricting type parameter `T`
  |