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@estebank
estebank committed Oct 15, 2019
1 parent 8cabb42 commit 9c525ee
Showing 1 changed file with 51 additions and 59 deletions.
110 changes: 51 additions & 59 deletions src/librustc/traits/error_reporting.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -969,9 +969,10 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
trait_ref: &ty::PolyTraitRef<'_>,
body_id: hir::HirId,
) {
let (param_ty, projection) = match &trait_ref.self_ty().kind {
ty::Param(param_ty) => (Some(param_ty), None),
ty::Projection(projection) => (None, Some(projection)),
let self_ty = trait_ref.self_ty();
let (param_ty, projection) = match &self_ty.kind {
ty::Param(_) => (true, None),
ty::Projection(projection) => (false, Some(projection)),
_ => return,
};

Expand All @@ -997,17 +998,10 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
let mut hir_id = body_id;
while let Some(node) = self.tcx.hir().find(hir_id) {
match node {
hir::Node::Item(hir::Item {
kind: hir::ItemKind::Fn(_, _, generics, _), ..
}) |
hir::Node::TraitItem(hir::TraitItem {
generics,
kind: hir::TraitItemKind::Method(..), ..
}) |
hir::Node::ImplItem(hir::ImplItem {
generics,
kind: hir::ImplItemKind::Method(..), ..
}) if param_ty.map_or(false, |p| p.name.as_str() == "Self") => {
}) if param_ty && self_ty == self.tcx.types.self_param => {
// Restricting `Self` for a single method.
suggest_restriction(&generics, "`Self`");
return;
Expand Down Expand Up @@ -1058,12 +1052,12 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
}) |
hir::Node::TraitItem(hir::TraitItem { generics, span, .. }) |
hir::Node::ImplItem(hir::ImplItem { generics, span, .. })
if param_ty.is_some() => {
if param_ty => {
// Missing generic type parameter bound.
let restrict_msg = "consider further restricting this bound";
let param_name = param_ty.unwrap().name.as_str();
let param_name = self_ty.to_string();
for param in generics.params.iter().filter(|p| {
param_name == p.name.ident().as_str()
&param_name == p.name.ident().as_str()
}) {
if param_name.starts_with("impl ") {
// `impl Trait` in argument:
Expand All @@ -1075,53 +1069,51 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
format!("{} + {}", param.name.ident(), trait_ref),
Applicability::MachineApplicable,
);
} else {
if generics.where_clause.predicates.is_empty() &&
} else if generics.where_clause.predicates.is_empty() &&
param.bounds.is_empty()
{
// If there are no bounds whatsoever, suggest adding a constraint
// to the type parameter:
// `fn foo<T>(t: T) {}` → `fn foo<T: Trait>(t: T) {}`
err.span_suggestion(
param.span,
"consider restricting this bound",
format!("{}", trait_ref.to_predicate()),
Applicability::MachineApplicable,
);
} else if !generics.where_clause.predicates.is_empty() {
// There is a `where` clause, so suggest expanding it:
// `fn foo<T>(t: T) where T: Debug {}` →
// `fn foo<T(t: T) where T: Debug, Trait {}`
err.span_suggestion(
generics.where_clause.span().unwrap().shrink_to_hi(),
&format!(
"consider further restricting type parameter `{}`",
param_name,
),
format!(", {}", trait_ref.to_predicate()),
Applicability::MachineApplicable,
);
{
// If there are no bounds whatsoever, suggest adding a constraint
// to the type parameter:
// `fn foo<T>(t: T) {}` → `fn foo<T: Trait>(t: T) {}`
err.span_suggestion(
param.span,
"consider restricting this bound",
format!("{}", trait_ref.to_predicate()),
Applicability::MachineApplicable,
);
} else if !generics.where_clause.predicates.is_empty() {
// There is a `where` clause, so suggest expanding it:
// `fn foo<T>(t: T) where T: Debug {}` →
// `fn foo<T>(t: T) where T: Debug, T: Trait {}`
err.span_suggestion(
generics.where_clause.span().unwrap().shrink_to_hi(),
&format!(
"consider further restricting type parameter `{}`",
param_name,
),
format!(", {}", trait_ref.to_predicate()),
Applicability::MachineApplicable,
);
} else {
// If there is no `where` clause lean towards constraining to the
// type parameter:
// `fn foo<X: Bar, T>(t: T, x: X) {}` → `fn foo<T: Trait>(t: T) {}`
// `fn foo<T: Bar>(t: T) {}` → `fn foo<T: Bar + Trait>(t: T) {}`
let sp = param.span.with_hi(span.hi());
let span = self.tcx.sess.source_map()
.span_through_char(sp, ':');
if sp != param.span && sp != span {
// Only suggest if we have high certainty that the span
// covers the colon in `foo<T: Trait>`.
err.span_suggestion(span, restrict_msg, format!(
"{} + ",
trait_ref.to_predicate(),
), Applicability::MachineApplicable);
} else {
// If there is no `where` clause lean towards constraining to the
// type parameter:
// `fn foo<X: Bar, T>(t: T, x: X) {}` → `fn foo<T: Trait>(t: T) {}`
// `fn foo<T: Bar>(t: T) {}` → `fn foo<T: Bar + Trait>(t: T) {}`
let sp = param.span.with_hi(span.hi());
let span = self.tcx.sess.source_map()
.span_through_char(sp, ':');
if sp != param.span && sp != span {
// Only suggest if we have high certainty that the span
// covers the colon in `foo<T: Trait>`.
err.span_suggestion(span, restrict_msg, format!(
"{} + ",
trait_ref.to_predicate(),
), Applicability::MachineApplicable);
} else {
err.span_label(param.span, &format!(
"consider adding a `where {}` bound",
trait_ref.to_predicate(),
));
}
err.span_label(param.span, &format!(
"consider adding a `where {}` bound",
trait_ref.to_predicate(),
));
}
}
return;
Expand Down

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