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|
use super::ObjectSafetyViolation;
use crate::infer::InferCtxt;
use rustc_data_structures::fx::FxIndexSet;
use rustc_errors::{struct_span_err, DiagnosticBuilder, ErrorGuaranteed, MultiSpan};
use rustc_hir as hir;
use rustc_hir::def_id::{DefId, LocalDefId};
use rustc_middle::ty::TyCtxt;
use rustc_span::Span;
use std::fmt;
use std::iter;
impl<'tcx> InferCtxt<'tcx> {
pub fn report_extra_impl_obligation(
&self,
error_span: Span,
impl_item_def_id: LocalDefId,
trait_item_def_id: DefId,
requirement: &dyn fmt::Display,
) -> DiagnosticBuilder<'tcx, ErrorGuaranteed> {
let mut err = struct_span_err!(
self.tcx.sess,
error_span,
E0276,
"impl has stricter requirements than trait"
);
if let Some(span) = self.tcx.hir().span_if_local(trait_item_def_id) {
let item_name = self.tcx.item_name(impl_item_def_id.to_def_id());
err.span_label(span, format!("definition of `{}` from trait", item_name));
}
err.span_label(error_span, format!("impl has extra requirement {}", requirement));
err
}
}
pub fn report_object_safety_error<'tcx>(
tcx: TyCtxt<'tcx>,
span: Span,
trait_def_id: DefId,
violations: &[ObjectSafetyViolation],
) -> DiagnosticBuilder<'tcx, ErrorGuaranteed> {
let trait_str = tcx.def_path_str(trait_def_id);
let trait_span = tcx.hir().get_if_local(trait_def_id).and_then(|node| match node {
hir::Node::Item(item) => Some(item.ident.span),
_ => None,
});
let mut err = struct_span_err!(
tcx.sess,
span,
E0038,
"the trait `{}` cannot be made into an object",
trait_str
);
err.span_label(span, format!("`{}` cannot be made into an object", trait_str));
let mut reported_violations = FxIndexSet::default();
let mut multi_span = vec![];
let mut messages = vec![];
for violation in violations {
if let ObjectSafetyViolation::SizedSelf(sp) = &violation && !sp.is_empty() {
// Do not report `SizedSelf` without spans pointing at `SizedSelf` obligations
// with a `Span`.
reported_violations.insert(ObjectSafetyViolation::SizedSelf(vec![].into()));
}
if reported_violations.insert(violation.clone()) {
let spans = violation.spans();
let msg = if trait_span.is_none() || spans.is_empty() {
format!("the trait cannot be made into an object because {}", violation.error_msg())
} else {
format!("...because {}", violation.error_msg())
};
if spans.is_empty() {
err.note(&msg);
} else {
for span in spans {
multi_span.push(span);
messages.push(msg.clone());
}
}
}
}
let has_multi_span = !multi_span.is_empty();
let mut note_span = MultiSpan::from_spans(multi_span.clone());
if let (Some(trait_span), true) = (trait_span, has_multi_span) {
note_span.push_span_label(trait_span, "this trait cannot be made into an object...");
}
for (span, msg) in iter::zip(multi_span, messages) {
note_span.push_span_label(span, msg);
}
err.span_note(
note_span,
"for a trait to be \"object safe\" it needs to allow building a vtable to allow the call \
to be resolvable dynamically; for more information visit \
<https://doc.rust-lang.org/reference/items/traits.html#object-safety>",
);
if trait_span.is_some() {
let mut reported_violations: Vec<_> = reported_violations.into_iter().collect();
reported_violations.sort();
for violation in reported_violations {
// Only provide the help if its a local trait, otherwise it's not actionable.
violation.solution(&mut err);
}
}
err
}
|
