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librustc error_reporting.rs cleanup. #39977

Merged
merged 8 commits into from
Feb 28, 2017
Merged

librustc error_reporting.rs cleanup. #39977

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7e0c3de
Remove `else`, unindent.
frewsxcv Feb 19, 2017
de2f7e1
Rewrite `match` to use combinators.
frewsxcv Feb 19, 2017
83fe48d
Remove `else`, unindent.
frewsxcv Feb 19, 2017
a97aed7
Remove unnecessary logic when finding simpilar `impl` candidates.
frewsxcv Feb 19, 2017
2436d73
Extract out error message generation.
frewsxcv Feb 19, 2017
10639d7
Add early return, remove `else`, unindent.
frewsxcv Feb 19, 2017
23d9211
Flatten `for` loop using iterator combinators.
frewsxcv Feb 19, 2017
a754ea6
Move `TraitRef` `impl` next to `struct` definition.
frewsxcv Feb 20, 2017
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246 changes: 106 additions & 140 deletions src/librustc/traits/error_reporting.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -359,34 +359,9 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
}

fn report_similar_impl_candidates(&self,
trait_ref: ty::PolyTraitRef<'tcx>,
impl_candidates: Vec<ty::TraitRef<'tcx>>,
err: &mut DiagnosticBuilder)
{
let simp = fast_reject::simplify_type(self.tcx,
trait_ref.skip_binder().self_ty(),
true);
let mut impl_candidates = Vec::new();
let trait_def = self.tcx.lookup_trait_def(trait_ref.def_id());

match simp {
Some(simp) => trait_def.for_each_impl(self.tcx, |def_id| {
let imp = self.tcx.impl_trait_ref(def_id).unwrap();
let imp_simp = fast_reject::simplify_type(self.tcx,
imp.self_ty(),
true);
if let Some(imp_simp) = imp_simp {
if simp != imp_simp {
return;
}
}
impl_candidates.push(imp);
}),
None => trait_def.for_each_impl(self.tcx, |def_id| {
impl_candidates.push(
self.tcx.impl_trait_ref(def_id).unwrap());
})
};

if impl_candidates.is_empty() {
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Was all of this duplicated from find_similar_impl_candidates? 😆

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Yeeeppppppp

return;
}
Expand Down Expand Up @@ -525,127 +500,118 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
lint_id)
.emit();
return;
} else {
match obligation.predicate {
ty::Predicate::Trait(ref trait_predicate) => {
let trait_predicate =
self.resolve_type_vars_if_possible(trait_predicate);

if self.tcx.sess.has_errors() && trait_predicate.references_error() {
return;
} else {
let trait_ref = trait_predicate.to_poly_trait_ref();
let (post_message, pre_message) = match self.get_parent_trait_ref(
&obligation.cause.code)
{
Some(t) => {
(format!(" in `{}`", t), format!("within `{}`, ", t))
}
None => (String::new(), String::new()),
};
let mut err = struct_span_err!(
self.tcx.sess,
span,
E0277,
"the trait bound `{}` is not satisfied{}",
trait_ref.to_predicate(),
post_message);
err.span_label(span,
&format!("{}the trait `{}` is not \
implemented for `{}`",
pre_message,
trait_ref,
trait_ref.self_ty()));

// Try to report a help message

if !trait_ref.has_infer_types() &&
self.predicate_can_apply(trait_ref) {
// If a where-clause may be useful, remind the
// user that they can add it.
//
// don't display an on-unimplemented note, as
// these notes will often be of the form
// "the type `T` can't be frobnicated"
// which is somewhat confusing.
err.help(&format!("consider adding a `where {}` bound",
trait_ref.to_predicate()));
} else if let Some(s) = self.on_unimplemented_note(trait_ref,
obligation) {
// If it has a custom "#[rustc_on_unimplemented]"
// error message, let's display it!
err.note(&s);
} else {
// If we can't show anything useful, try to find
// similar impls.
let impl_candidates =
self.find_similar_impl_candidates(trait_ref);
if impl_candidates.len() > 0 {
self.report_similar_impl_candidates(trait_ref, &mut err);
}
}
err
}
}
}
match obligation.predicate {
ty::Predicate::Trait(ref trait_predicate) => {
let trait_predicate =
self.resolve_type_vars_if_possible(trait_predicate);

ty::Predicate::Equate(ref predicate) => {
let predicate = self.resolve_type_vars_if_possible(predicate);
let err = self.equality_predicate(&obligation.cause,
&predicate).err().unwrap();
struct_span_err!(self.tcx.sess, span, E0278,
"the requirement `{}` is not satisfied (`{}`)",
predicate, err)
if self.tcx.sess.has_errors() && trait_predicate.references_error() {
return;
}

ty::Predicate::RegionOutlives(ref predicate) => {
let predicate = self.resolve_type_vars_if_possible(predicate);
let err = self.region_outlives_predicate(&obligation.cause,
&predicate).err().unwrap();
struct_span_err!(self.tcx.sess, span, E0279,
"the requirement `{}` is not satisfied (`{}`)",
predicate, err)
let trait_ref = trait_predicate.to_poly_trait_ref();
let (post_message, pre_message) =
self.get_parent_trait_ref(&obligation.cause.code)
.map(|t| (format!(" in `{}`", t), format!("within `{}`, ", t)))
.unwrap_or((String::new(), String::new()));
let mut err = struct_span_err!(
self.tcx.sess,
span,
E0277,
"the trait bound `{}` is not satisfied{}",
trait_ref.to_predicate(),
post_message);
err.span_label(span,
&format!("{}the trait `{}` is not \
implemented for `{}`",
pre_message,
trait_ref,
trait_ref.self_ty()));

// Try to report a help message

if !trait_ref.has_infer_types() &&
self.predicate_can_apply(trait_ref) {
// If a where-clause may be useful, remind the
// user that they can add it.
//
// don't display an on-unimplemented note, as
// these notes will often be of the form
// "the type `T` can't be frobnicated"
// which is somewhat confusing.
err.help(&format!("consider adding a `where {}` bound",
trait_ref.to_predicate()));
} else if let Some(s) = self.on_unimplemented_note(trait_ref,
obligation) {
// If it has a custom "#[rustc_on_unimplemented]"
// error message, let's display it!
err.note(&s);
} else {
// If we can't show anything useful, try to find
// similar impls.
let impl_candidates = self.find_similar_impl_candidates(trait_ref);
self.report_similar_impl_candidates(impl_candidates, &mut err);
}
err
}

ty::Predicate::Projection(..) | ty::Predicate::TypeOutlives(..) => {
let predicate =
self.resolve_type_vars_if_possible(&obligation.predicate);
struct_span_err!(self.tcx.sess, span, E0280,
"the requirement `{}` is not satisfied",
predicate)
}
ty::Predicate::Equate(ref predicate) => {
let predicate = self.resolve_type_vars_if_possible(predicate);
let err = self.equality_predicate(&obligation.cause,
&predicate).err().unwrap();
struct_span_err!(self.tcx.sess, span, E0278,
"the requirement `{}` is not satisfied (`{}`)",
predicate, err)
}

ty::Predicate::ObjectSafe(trait_def_id) => {
let violations = self.tcx.object_safety_violations(trait_def_id);
self.tcx.report_object_safety_error(span,
trait_def_id,
violations)
}
ty::Predicate::RegionOutlives(ref predicate) => {
let predicate = self.resolve_type_vars_if_possible(predicate);
let err = self.region_outlives_predicate(&obligation.cause,
&predicate).err().unwrap();
struct_span_err!(self.tcx.sess, span, E0279,
"the requirement `{}` is not satisfied (`{}`)",
predicate, err)
}

ty::Predicate::ClosureKind(closure_def_id, kind) => {
let found_kind = self.closure_kind(closure_def_id).unwrap();
let closure_span = self.tcx.hir.span_if_local(closure_def_id).unwrap();
let mut err = struct_span_err!(
self.tcx.sess, closure_span, E0525,
"expected a closure that implements the `{}` trait, \
but this closure only implements `{}`",
kind,
found_kind);
err.span_note(
obligation.cause.span,
&format!("the requirement to implement \
`{}` derives from here", kind));
err.emit();
return;
}
ty::Predicate::Projection(..) | ty::Predicate::TypeOutlives(..) => {
let predicate =
self.resolve_type_vars_if_possible(&obligation.predicate);
struct_span_err!(self.tcx.sess, span, E0280,
"the requirement `{}` is not satisfied",
predicate)
}

ty::Predicate::WellFormed(ty) => {
// WF predicates cannot themselves make
// errors. They can only block due to
// ambiguity; otherwise, they always
// degenerate into other obligations
// (which may fail).
span_bug!(span, "WF predicate not satisfied for {:?}", ty);
}
ty::Predicate::ObjectSafe(trait_def_id) => {
let violations = self.tcx.object_safety_violations(trait_def_id);
self.tcx.report_object_safety_error(span,
trait_def_id,
violations)
}

ty::Predicate::ClosureKind(closure_def_id, kind) => {
let found_kind = self.closure_kind(closure_def_id).unwrap();
let closure_span = self.tcx.hir.span_if_local(closure_def_id).unwrap();
let mut err = struct_span_err!(
self.tcx.sess, closure_span, E0525,
"expected a closure that implements the `{}` trait, \
but this closure only implements `{}`",
kind,
found_kind);
err.span_note(
obligation.cause.span,
&format!("the requirement to implement \
`{}` derives from here", kind));
err.emit();
return;
}

ty::Predicate::WellFormed(ty) => {
// WF predicates cannot themselves make
// errors. They can only block due to
// ambiguity; otherwise, they always
// degenerate into other obligations
// (which may fail).
span_bug!(span, "WF predicate not satisfied for {:?}", ty);
}
}
}
Expand Down