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Rollup merge of #99686 - vincenzopalazzo:macros/impl_on_ptr, r=compiler-errors
add suggestion when there is a impl of external trait on pointer with wrong coherence rules Closes https://github.com/rust-lang/rust/issues/99572 This will try to improve the node in the error message by suggesting a general solution because the solution, in this case, is application depended. I'm not super happy regarding the code quality, but I'm happy to have feedback on it. `@rustbot` r? `@compiler-errors`
This commit is contained in:
commit
a573adf3cb
@ -3,7 +3,7 @@
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use rustc_data_structures::fx::FxHashSet;
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use rustc_errors::struct_span_err;
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use rustc_errors::ErrorGuaranteed;
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use rustc_errors::{Diagnostic, ErrorGuaranteed};
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use rustc_hir as hir;
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use rustc_infer::infer::TyCtxtInferExt;
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use rustc_middle::ty::subst::GenericArgKind;
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@ -107,6 +107,7 @@ fn do_orphan_check_impl<'tcx>(
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Err(err) => emit_orphan_check_error(
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tcx,
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sp,
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item.span,
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tr.path.span,
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trait_ref.self_ty(),
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impl_.self_ty.span,
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@ -207,6 +208,7 @@ fn do_orphan_check_impl<'tcx>(
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fn emit_orphan_check_error<'tcx>(
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tcx: TyCtxt<'tcx>,
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sp: Span,
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full_impl_span: Span,
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trait_span: Span,
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self_ty: Ty<'tcx>,
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self_ty_span: Span,
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@ -247,8 +249,20 @@ fn emit_orphan_check_error<'tcx>(
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ty::Slice(_) => (this, " because slices are always foreign"),
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ty::Array(..) => (this, " because arrays are always foreign"),
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ty::Tuple(..) => (this, " because tuples are always foreign"),
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ty::RawPtr(ptr_ty) => {
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emit_newtype_suggestion_for_raw_ptr(
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full_impl_span,
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self_ty,
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self_ty_span,
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ptr_ty,
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&mut err,
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);
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(format!("`{}`", ty), " because raw pointers are always foreign")
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}
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_ => (format!("`{}`", ty), ""),
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};
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let msg = format!("{} is not defined in the current crate{}", ty, postfix);
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if *is_target_ty {
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// Point at `D<A>` in `impl<A, B> for C<B> in D<A>`
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@ -330,6 +344,27 @@ fn emit_orphan_check_error<'tcx>(
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})
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}
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fn emit_newtype_suggestion_for_raw_ptr(
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full_impl_span: Span,
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self_ty: Ty<'_>,
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self_ty_span: Span,
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ptr_ty: &ty::TypeAndMut<'_>,
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diag: &mut Diagnostic,
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) {
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if !self_ty.needs_subst() {
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let mut_key = if ptr_ty.mutbl == rustc_middle::mir::Mutability::Mut { "mut " } else { "" };
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let msg_sugg = "consider introducing a new wrapper type".to_owned();
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let sugg = vec![
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(
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full_impl_span.shrink_to_lo(),
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format!("struct WrapperType(*{}{});\n\n", mut_key, ptr_ty.ty),
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),
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(self_ty_span, "WrapperType".to_owned()),
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];
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diag.multipart_suggestion(msg_sugg, sugg, rustc_errors::Applicability::MaybeIncorrect);
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}
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}
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/// Lint impls of auto traits if they are likely to have
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/// unsound or surprising effects on auto impls.
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fn lint_auto_trait_impl<'tcx>(
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25
src/test/ui/errors/issue-99572-impl-trait-on-pointer.rs
Normal file
25
src/test/ui/errors/issue-99572-impl-trait-on-pointer.rs
Normal file
@ -0,0 +1,25 @@
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// Emit additional suggestion to correct the trait implementation
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// on a pointer
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use std::{fmt, marker};
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struct LocalType;
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impl fmt::Display for *mut LocalType {
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//~^ ERROR only traits defined in the current crate can be implemented for arbitrary types
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//~| NOTE impl doesn't use only types from inside the current crate
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//~| NOTE `*mut LocalType` is not defined in the current crate because raw pointers are always foreign
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//~| NOTE define and implement a trait or new type instead
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//~| HELP consider introducing a new wrapper type
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fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
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write!(f, "This not compile")
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}
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}
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impl<T> marker::Copy for *mut T {
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//~^ ERROR only traits defined in the current crate can be implemented for arbitrary types
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//~| NOTE impl doesn't use only types from inside the current crate
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//~| NOTE `*mut T` is not defined in the current crate because raw pointers are always foreign
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//~| NOTE define and implement a trait or new type instead
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}
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fn main() {}
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31
src/test/ui/errors/issue-99572-impl-trait-on-pointer.stderr
Normal file
31
src/test/ui/errors/issue-99572-impl-trait-on-pointer.stderr
Normal file
@ -0,0 +1,31 @@
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error[E0117]: only traits defined in the current crate can be implemented for arbitrary types
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--> $DIR/issue-99572-impl-trait-on-pointer.rs:7:1
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LL | impl fmt::Display for *mut LocalType {
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| ^^^^^^^^^^^^^^^^^^^^^^--------------
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| | |
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| | `*mut LocalType` is not defined in the current crate because raw pointers are always foreign
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| impl doesn't use only types from inside the current crate
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= note: define and implement a trait or new type instead
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help: consider introducing a new wrapper type
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LL + struct WrapperType(*mut LocalType);
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LL +
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LL ~ impl fmt::Display for WrapperType {
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error[E0117]: only traits defined in the current crate can be implemented for arbitrary types
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--> $DIR/issue-99572-impl-trait-on-pointer.rs:18:1
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LL | impl<T> marker::Copy for *mut T {
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| ^^^^^^^^^^^^^^^^^^^^^^^^^------
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| | |
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| | `*mut T` is not defined in the current crate because raw pointers are always foreign
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| impl doesn't use only types from inside the current crate
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= note: define and implement a trait or new type instead
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error: aborting due to 2 previous errors
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For more information about this error, try `rustc --explain E0117`.
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