diff options
Diffstat (limited to 'compiler/rustc_infer/src/infer/error_reporting/note.rs')
| -rw-r--r-- | compiler/rustc_infer/src/infer/error_reporting/note.rs | 414 |
1 files changed, 414 insertions, 0 deletions
diff --git a/compiler/rustc_infer/src/infer/error_reporting/note.rs b/compiler/rustc_infer/src/infer/error_reporting/note.rs new file mode 100644 index 000000000..c1940c5c0 --- /dev/null +++ b/compiler/rustc_infer/src/infer/error_reporting/note.rs @@ -0,0 +1,414 @@ +use crate::infer::error_reporting::{note_and_explain_region, ObligationCauseExt}; +use crate::infer::{self, InferCtxt, SubregionOrigin}; +use rustc_errors::{struct_span_err, Diagnostic, DiagnosticBuilder, ErrorGuaranteed}; +use rustc_middle::traits::ObligationCauseCode; +use rustc_middle::ty::error::TypeError; +use rustc_middle::ty::{self, Region}; + +impl<'a, 'tcx> InferCtxt<'a, 'tcx> { + pub(super) fn note_region_origin(&self, err: &mut Diagnostic, origin: &SubregionOrigin<'tcx>) { + let mut label_or_note = |span, msg: &str| { + let sub_count = err.children.iter().filter(|d| d.span.is_dummy()).count(); + let expanded_sub_count = err.children.iter().filter(|d| !d.span.is_dummy()).count(); + let span_is_primary = err.span.primary_spans().iter().all(|&sp| sp == span); + if span_is_primary && sub_count == 0 && expanded_sub_count == 0 { + err.span_label(span, msg); + } else if span_is_primary && expanded_sub_count == 0 { + err.note(msg); + } else { + err.span_note(span, msg); + } + }; + match *origin { + infer::Subtype(ref trace) => { + if let Some((expected, found)) = self.values_str(trace.values) { + label_or_note( + trace.cause.span, + &format!("...so that the {}", trace.cause.as_requirement_str()), + ); + + err.note_expected_found(&"", expected, &"", found); + } else { + // FIXME: this really should be handled at some earlier stage. Our + // handling of region checking when type errors are present is + // *terrible*. + + label_or_note( + trace.cause.span, + &format!("...so that {}", trace.cause.as_requirement_str()), + ); + } + } + infer::Reborrow(span) => { + label_or_note(span, "...so that reference does not outlive borrowed content"); + } + infer::ReborrowUpvar(span, ref upvar_id) => { + let var_name = self.tcx.hir().name(upvar_id.var_path.hir_id); + label_or_note(span, &format!("...so that closure can access `{}`", var_name)); + } + infer::RelateObjectBound(span) => { + label_or_note(span, "...so that it can be closed over into an object"); + } + infer::DataBorrowed(ty, span) => { + label_or_note( + span, + &format!( + "...so that the type `{}` is not borrowed for too long", + self.ty_to_string(ty) + ), + ); + } + infer::ReferenceOutlivesReferent(ty, span) => { + label_or_note( + span, + &format!( + "...so that the reference type `{}` does not outlive the data it points at", + self.ty_to_string(ty) + ), + ); + } + infer::RelateParamBound(span, t, opt_span) => { + label_or_note( + span, + &format!( + "...so that the type `{}` will meet its required lifetime bounds{}", + self.ty_to_string(t), + if opt_span.is_some() { "..." } else { "" }, + ), + ); + if let Some(span) = opt_span { + err.span_note(span, "...that is required by this bound"); + } + } + infer::RelateRegionParamBound(span) => { + label_or_note( + span, + "...so that the declared lifetime parameter bounds are satisfied", + ); + } + infer::CompareImplItemObligation { span, .. } => { + label_or_note( + span, + "...so that the definition in impl matches the definition from the trait", + ); + } + infer::CheckAssociatedTypeBounds { ref parent, .. } => { + self.note_region_origin(err, &parent); + } + } + } + + pub(super) fn report_concrete_failure( + &self, + origin: SubregionOrigin<'tcx>, + sub: Region<'tcx>, + sup: Region<'tcx>, + ) -> DiagnosticBuilder<'tcx, ErrorGuaranteed> { + match origin { + infer::Subtype(box trace) => { + let terr = TypeError::RegionsDoesNotOutlive(sup, sub); + let mut err = self.report_and_explain_type_error(trace, &terr); + match (*sub, *sup) { + (ty::RePlaceholder(_), ty::RePlaceholder(_)) => {} + (ty::RePlaceholder(_), _) => { + note_and_explain_region( + self.tcx, + &mut err, + "", + sup, + " doesn't meet the lifetime requirements", + None, + ); + } + (_, ty::RePlaceholder(_)) => { + note_and_explain_region( + self.tcx, + &mut err, + "the required lifetime does not necessarily outlive ", + sub, + "", + None, + ); + } + _ => { + note_and_explain_region(self.tcx, &mut err, "", sup, "...", None); + note_and_explain_region( + self.tcx, + &mut err, + "...does not necessarily outlive ", + sub, + "", + None, + ); + } + } + err + } + infer::Reborrow(span) => { + let mut err = struct_span_err!( + self.tcx.sess, + span, + E0312, + "lifetime of reference outlives lifetime of borrowed content..." + ); + note_and_explain_region( + self.tcx, + &mut err, + "...the reference is valid for ", + sub, + "...", + None, + ); + note_and_explain_region( + self.tcx, + &mut err, + "...but the borrowed content is only valid for ", + sup, + "", + None, + ); + err + } + infer::ReborrowUpvar(span, ref upvar_id) => { + let var_name = self.tcx.hir().name(upvar_id.var_path.hir_id); + let mut err = struct_span_err!( + self.tcx.sess, + span, + E0313, + "lifetime of borrowed pointer outlives lifetime of captured variable `{}`...", + var_name + ); + note_and_explain_region( + self.tcx, + &mut err, + "...the borrowed pointer is valid for ", + sub, + "...", + None, + ); + note_and_explain_region( + self.tcx, + &mut err, + &format!("...but `{}` is only valid for ", var_name), + sup, + "", + None, + ); + err + } + infer::RelateObjectBound(span) => { + let mut err = struct_span_err!( + self.tcx.sess, + span, + E0476, + "lifetime of the source pointer does not outlive lifetime bound of the \ + object type" + ); + note_and_explain_region( + self.tcx, + &mut err, + "object type is valid for ", + sub, + "", + None, + ); + note_and_explain_region( + self.tcx, + &mut err, + "source pointer is only valid for ", + sup, + "", + None, + ); + err + } + infer::RelateParamBound(span, ty, opt_span) => { + let mut err = struct_span_err!( + self.tcx.sess, + span, + E0477, + "the type `{}` does not fulfill the required lifetime", + self.ty_to_string(ty) + ); + match *sub { + ty::ReStatic => note_and_explain_region( + self.tcx, + &mut err, + "type must satisfy ", + sub, + if opt_span.is_some() { " as required by this binding" } else { "" }, + opt_span, + ), + _ => note_and_explain_region( + self.tcx, + &mut err, + "type must outlive ", + sub, + if opt_span.is_some() { " as required by this binding" } else { "" }, + opt_span, + ), + } + err + } + infer::RelateRegionParamBound(span) => { + let mut err = + struct_span_err!(self.tcx.sess, span, E0478, "lifetime bound not satisfied"); + note_and_explain_region( + self.tcx, + &mut err, + "lifetime parameter instantiated with ", + sup, + "", + None, + ); + note_and_explain_region( + self.tcx, + &mut err, + "but lifetime parameter must outlive ", + sub, + "", + None, + ); + err + } + infer::DataBorrowed(ty, span) => { + let mut err = struct_span_err!( + self.tcx.sess, + span, + E0490, + "a value of type `{}` is borrowed for too long", + self.ty_to_string(ty) + ); + note_and_explain_region( + self.tcx, + &mut err, + "the type is valid for ", + sub, + "", + None, + ); + note_and_explain_region( + self.tcx, + &mut err, + "but the borrow lasts for ", + sup, + "", + None, + ); + err + } + infer::ReferenceOutlivesReferent(ty, span) => { + let mut err = struct_span_err!( + self.tcx.sess, + span, + E0491, + "in type `{}`, reference has a longer lifetime than the data it references", + self.ty_to_string(ty) + ); + note_and_explain_region( + self.tcx, + &mut err, + "the pointer is valid for ", + sub, + "", + None, + ); + note_and_explain_region( + self.tcx, + &mut err, + "but the referenced data is only valid for ", + sup, + "", + None, + ); + err + } + infer::CompareImplItemObligation { span, impl_item_def_id, trait_item_def_id } => self + .report_extra_impl_obligation( + span, + impl_item_def_id, + trait_item_def_id, + &format!("`{}: {}`", sup, sub), + ), + infer::CheckAssociatedTypeBounds { impl_item_def_id, trait_item_def_id, parent } => { + let mut err = self.report_concrete_failure(*parent, sub, sup); + + let trait_item_span = self.tcx.def_span(trait_item_def_id); + let item_name = self.tcx.item_name(impl_item_def_id.to_def_id()); + err.span_label( + trait_item_span, + format!("definition of `{}` from trait", item_name), + ); + + let trait_predicates = self.tcx.explicit_predicates_of(trait_item_def_id); + let impl_predicates = self.tcx.explicit_predicates_of(impl_item_def_id); + + let impl_predicates: rustc_data_structures::fx::FxHashSet<_> = + impl_predicates.predicates.into_iter().map(|(pred, _)| pred).collect(); + let clauses: Vec<_> = trait_predicates + .predicates + .into_iter() + .filter(|&(pred, _)| !impl_predicates.contains(pred)) + .map(|(pred, _)| format!("{}", pred)) + .collect(); + + if !clauses.is_empty() { + let generics = self.tcx.hir().get_generics(impl_item_def_id).unwrap(); + let where_clause_span = generics.tail_span_for_predicate_suggestion(); + + let suggestion = format!( + "{} {}", + generics.add_where_or_trailing_comma(), + clauses.join(", "), + ); + err.span_suggestion( + where_clause_span, + &format!( + "try copying {} from the trait", + if clauses.len() > 1 { "these clauses" } else { "this clause" } + ), + suggestion, + rustc_errors::Applicability::MaybeIncorrect, + ); + } + + err + } + } + } + + pub(super) fn report_placeholder_failure( + &self, + placeholder_origin: SubregionOrigin<'tcx>, + sub: Region<'tcx>, + sup: Region<'tcx>, + ) -> DiagnosticBuilder<'tcx, ErrorGuaranteed> { + // I can't think how to do better than this right now. -nikomatsakis + debug!(?placeholder_origin, ?sub, ?sup, "report_placeholder_failure"); + match placeholder_origin { + infer::Subtype(box ref trace) + if matches!( + &trace.cause.code().peel_derives(), + ObligationCauseCode::BindingObligation(..) + ) => + { + // Hack to get around the borrow checker because trace.cause has an `Rc`. + if let ObligationCauseCode::BindingObligation(_, span) = + &trace.cause.code().peel_derives() + { + let span = *span; + let mut err = self.report_concrete_failure(placeholder_origin, sub, sup); + err.span_note(span, "the lifetime requirement is introduced here"); + err + } else { + unreachable!() + } + } + infer::Subtype(box trace) => { + let terr = TypeError::RegionsPlaceholderMismatch; + return self.report_and_explain_type_error(trace, &terr); + } + _ => return self.report_concrete_failure(placeholder_origin, sub, sup), + } + } +} |