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99 lines
3.9 KiB
Rust
99 lines
3.9 KiB
Rust
//! Unsafety checker: every impl either implements a trait defined in this
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//! crate or pertains to a type defined in this crate.
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use rustc_errors::{codes::*, struct_span_code_err};
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use rustc_hir::Safety;
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use rustc_middle::ty::print::PrintTraitRefExt as _;
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use rustc_middle::ty::{ImplPolarity::*, ImplTraitHeader, TraitDef, TyCtxt};
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use rustc_span::def_id::LocalDefId;
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use rustc_span::ErrorGuaranteed;
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pub(super) fn check_item(
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tcx: TyCtxt<'_>,
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def_id: LocalDefId,
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trait_header: ImplTraitHeader<'_>,
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trait_def: &TraitDef,
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) -> Result<(), ErrorGuaranteed> {
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let unsafe_attr =
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tcx.generics_of(def_id).own_params.iter().find(|p| p.pure_wrt_drop).map(|_| "may_dangle");
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let trait_ref = trait_header.trait_ref.instantiate_identity();
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match (trait_def.safety, unsafe_attr, trait_header.safety, trait_header.polarity) {
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(Safety::Safe, None, Safety::Unsafe, Positive | Reservation) => {
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let span = tcx.def_span(def_id);
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return Err(struct_span_code_err!(
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tcx.dcx(),
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tcx.def_span(def_id),
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E0199,
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"implementing the trait `{}` is not unsafe",
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trait_ref.print_trait_sugared()
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)
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.with_span_suggestion_verbose(
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span.with_hi(span.lo() + rustc_span::BytePos(7)),
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"remove `unsafe` from this trait implementation",
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"",
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rustc_errors::Applicability::MachineApplicable,
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)
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.emit());
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}
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(Safety::Unsafe, _, Safety::Safe, Positive | Reservation) => {
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let span = tcx.def_span(def_id);
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return Err(struct_span_code_err!(
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tcx.dcx(),
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span,
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E0200,
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"the trait `{}` requires an `unsafe impl` declaration",
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trait_ref.print_trait_sugared()
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)
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.with_note(format!(
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"the trait `{}` enforces invariants that the compiler can't check. \
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Review the trait documentation and make sure this implementation \
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upholds those invariants before adding the `unsafe` keyword",
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trait_ref.print_trait_sugared()
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))
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.with_span_suggestion_verbose(
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span.shrink_to_lo(),
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"add `unsafe` to this trait implementation",
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"unsafe ",
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rustc_errors::Applicability::MaybeIncorrect,
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)
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.emit());
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}
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(Safety::Safe, Some(attr_name), Safety::Safe, Positive | Reservation) => {
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let span = tcx.def_span(def_id);
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return Err(struct_span_code_err!(
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tcx.dcx(),
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span,
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E0569,
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"requires an `unsafe impl` declaration due to `#[{}]` attribute",
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attr_name
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)
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.with_note(format!(
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"the trait `{}` enforces invariants that the compiler can't check. \
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Review the trait documentation and make sure this implementation \
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upholds those invariants before adding the `unsafe` keyword",
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trait_ref.print_trait_sugared()
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))
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.with_span_suggestion_verbose(
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span.shrink_to_lo(),
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"add `unsafe` to this trait implementation",
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"unsafe ",
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rustc_errors::Applicability::MaybeIncorrect,
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)
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.emit());
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}
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(_, _, Safety::Unsafe, Negative) => {
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// Reported in AST validation
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assert!(tcx.dcx().has_errors().is_some(), "unsafe negative impl");
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Ok(())
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}
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(_, _, Safety::Safe, Negative)
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| (Safety::Unsafe, _, Safety::Unsafe, Positive | Reservation)
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| (Safety::Safe, Some(_), Safety::Unsafe, Positive | Reservation)
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| (Safety::Safe, None, Safety::Safe, _) => Ok(()),
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}
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}
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