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factor out maybe_indirection_for_unsized

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This commit is contained in:
Taylor Yu 2021-06-01 12:35:24 -05:00
parent 2862f08b79
commit 437b2026e1
1 changed files with 47 additions and 32 deletions
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79
compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs
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@ -16,6 +16,8 @@ use rustc_errors::{pluralize, struct_span_err, Applicability, DiagnosticBuilder,
use rustc_hir as hir;
use rustc_hir::def_id::DefId;
use rustc_hir::intravisit::Visitor;
use rustc_hir::GenericParam;
use rustc_hir::Item;
use rustc_hir::Node;
use rustc_middle::mir::abstract_const::NotConstEvaluatable;
use rustc_middle::ty::error::ExpectedFound;
@ -1095,6 +1097,13 @@ trait InferCtxtPrivExt<'tcx> {
node: Node<'hir>,
);
fn maybe_indirection_for_unsized(
&self,
err: &mut DiagnosticBuilder<'tcx>,
item: &'hir Item<'hir>,
param: &'hir GenericParam<'hir>,
) -> bool;
fn is_recursive_obligation(
&self,
obligated_types: &mut Vec<&ty::TyS<'tcx>>,
@ -1821,38 +1830,7 @@ impl<'a, 'tcx> InferCtxtPrivExt<'tcx> for InferCtxt<'a, 'tcx> {
..
},
) => {
// Suggesting `T: ?Sized` is only valid in an ADT if `T` is only used in a
// borrow. `struct S<'a, T: ?Sized>(&'a T);` is valid, `struct S<T: ?Sized>(T);`
// is not.
let mut visitor = FindTypeParam {
param: param.name.ident().name,
invalid_spans: vec![],
nested: false,
};
visitor.visit_item(item);
if !visitor.invalid_spans.is_empty() {
let mut multispan: MultiSpan = param.span.into();
multispan.push_span_label(
param.span,
format!("this could be changed to `{}: ?Sized`...", param.name.ident()),
);
for sp in visitor.invalid_spans {
multispan.push_span_label(
sp,
format!(
"...if indirection were used here: `Box<{}>`",
param.name.ident(),
),
);
}
err.span_help(
multispan,
&format!(
"you could relax the implicit `Sized` bound on `{T}` if it were \
used through indirection like `&{T}` or `Box<{T}>`",
T = param.name.ident(),
),
);
if self.maybe_indirection_for_unsized(err, item, param) {
return;
}
}
@ -1872,6 +1850,43 @@ impl<'a, 'tcx> InferCtxtPrivExt<'tcx> for InferCtxt<'a, 'tcx> {
}
}
fn maybe_indirection_for_unsized(
&self,
err: &mut DiagnosticBuilder<'tcx>,
item: &'hir Item<'hir>,
param: &'hir GenericParam<'hir>,
) -> bool {
// Suggesting `T: ?Sized` is only valid in an ADT if `T` is only used in a
// borrow. `struct S<'a, T: ?Sized>(&'a T);` is valid, `struct S<T: ?Sized>(T);`
// is not.
let mut visitor =
FindTypeParam { param: param.name.ident().name, invalid_spans: vec![], nested: false };
visitor.visit_item(item);
if !visitor.invalid_spans.is_empty() {
let mut multispan: MultiSpan = param.span.into();
multispan.push_span_label(
param.span,
format!("this could be changed to `{}: ?Sized`...", param.name.ident()),
);
for sp in visitor.invalid_spans {
multispan.push_span_label(
sp,
format!("...if indirection were used here: `Box<{}>`", param.name.ident()),
);
}
err.span_help(
multispan,
&format!(
"you could relax the implicit `Sized` bound on `{T}` if it were \
used through indirection like `&{T}` or `Box<{T}>`",
T = param.name.ident(),
),
);
return true;
}
false
}
fn is_recursive_obligation(
&self,
obligated_types: &mut Vec<&ty::TyS<'tcx>>,