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Rollup merge of #78002 - estebank:issue-77598, r=oli-obk

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Tweak "object unsafe" errors

CC #77598.
This commit is contained in:
Yuki Okushi 2020-10-21 13:59:35 +09:00 • committed by GitHub
commit 9583029a2d
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57 changed files with 759 additions and 480 deletions
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111
compiler/rustc_trait_selection/src/traits/object_safety.rs
View file

@ -13,7 +13,7 @@ use super::elaborate_predicates;
use crate::infer::TyCtxtInferExt;
use crate::traits::query::evaluate_obligation::InferCtxtExt;
use crate::traits::{self, Obligation, ObligationCause};
use rustc_errors::{Applicability, FatalError};
use rustc_errors::FatalError;
use rustc_hir as hir;
use rustc_hir::def_id::DefId;
use rustc_middle::ty::subst::{GenericArg, InternalSubsts, Subst};
@ -21,7 +21,7 @@ use rustc_middle::ty::{self, Ty, TyCtxt, TypeFoldable, TypeVisitor, WithConstnes
use rustc_middle::ty::{Predicate, ToPredicate};
use rustc_session::lint::builtin::WHERE_CLAUSES_OBJECT_SAFETY;
use rustc_span::symbol::Symbol;
use rustc_span::Span;
use rustc_span::{MultiSpan, Span};
use smallvec::SmallVec;
use std::array;
@ -100,49 +100,7 @@ fn object_safety_violations_for_trait(
span,
) = violation
{
// Using `CRATE_NODE_ID` is wrong, but it's hard to get a more precise id.
// It's also hard to get a use site span, so we use the method definition span.
tcx.struct_span_lint_hir(
WHERE_CLAUSES_OBJECT_SAFETY,
hir::CRATE_HIR_ID,
*span,
|lint| {
let mut err = lint.build(&format!(
"the trait `{}` cannot be made into an object",
tcx.def_path_str(trait_def_id)
));
let node = tcx.hir().get_if_local(trait_def_id);
let msg = if let Some(hir::Node::Item(item)) = node {
err.span_label(
item.ident.span,
"this trait cannot be made into an object...",
);
format!("...because {}", violation.error_msg())
} else {
format!(
"the trait cannot be made into an object because {}",
violation.error_msg()
)
};
err.span_label(*span, &msg);
match (node, violation.solution()) {
(Some(_), Some((note, None))) => {
err.help(&note);
}
(Some(_), Some((note, Some((sugg, span))))) => {
err.span_suggestion(
span,
&note,
sugg,
Applicability::MachineApplicable,
);
}
// Only provide the help if its a local trait, otherwise it's not actionable.
_ => {}
}
err.emit();
},
);
lint_object_unsafe_trait(tcx, *span, trait_def_id, violation);
false
} else {
true
@ -180,6 +138,51 @@ fn object_safety_violations_for_trait(
violations
}
/// Lint object-unsafe trait.
fn lint_object_unsafe_trait(
tcx: TyCtxt<'_>,
span: Span,
trait_def_id: DefId,
violation: &ObjectSafetyViolation,
) {
// Using `CRATE_NODE_ID` is wrong, but it's hard to get a more precise id.
// It's also hard to get a use site span, so we use the method definition span.
tcx.struct_span_lint_hir(WHERE_CLAUSES_OBJECT_SAFETY, hir::CRATE_HIR_ID, span, |lint| {
let mut err = lint.build(&format!(
"the trait `{}` cannot be made into an object",
tcx.def_path_str(trait_def_id)
));
let node = tcx.hir().get_if_local(trait_def_id);
let mut spans = MultiSpan::from_span(span);
if let Some(hir::Node::Item(item)) = node {
spans.push_span_label(
item.ident.span,
"this trait cannot be made into an object...".into(),
);
spans.push_span_label(span, format!("...because {}", violation.error_msg()));
} else {
spans.push_span_label(
span,
format!(
"the trait cannot be made into an object because {}",
violation.error_msg()
),
);
};
err.span_note(
spans,
"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 node.is_some() {
// Only provide the help if its a local trait, otherwise it's not
violation.solution(&mut err);
}
err.emit();
});
}
fn sized_trait_bound_spans<'tcx>(
tcx: TyCtxt<'tcx>,
bounds: hir::GenericBounds<'tcx>,
@ -385,6 +388,8 @@ fn virtual_call_violation_for_method<'tcx>(
trait_def_id: DefId,
method: &ty::AssocItem,
) -> Option<MethodViolationCode> {
let sig = tcx.fn_sig(method.def_id);
// The method's first parameter must be named `self`
if !method.fn_has_self_parameter {
// We'll attempt to provide a structured suggestion for `Self: Sized`.
@ -395,11 +400,21 @@ fn virtual_call_violation_for_method<'tcx>(
[.., pred] => (", Self: Sized", pred.span().shrink_to_hi()),
},
);
return Some(MethodViolationCode::StaticMethod(sugg));
// Get the span pointing at where the `self` receiver should be.
let sm = tcx.sess.source_map();
let self_span = method.ident.span.to(tcx
.hir()
.span_if_local(method.def_id)
.unwrap_or_else(|| sm.next_point(method.ident.span))
.shrink_to_hi());
let self_span = sm.span_through_char(self_span, '(').shrink_to_hi();
return Some(MethodViolationCode::StaticMethod(
sugg,
self_span,
!sig.inputs().skip_binder().is_empty(),
));
}
let sig = tcx.fn_sig(method.def_id);
for (i, input_ty) in sig.skip_binder().inputs()[1..].iter().enumerate() {
if contains_illegal_self_type_reference(tcx, trait_def_id, input_ty) {
return Some(MethodViolationCode::ReferencesSelfInput(i));