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8 - Make more use of let_chains #94484

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Mar 3, 2022
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8 - Make more use of let_chains #94484

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77 changes: 35 additions & 42 deletions compiler/rustc_infer/src/infer/error_reporting/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -606,17 +606,16 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
// don't show type `_`
err.span_label(span, format!("this expression has type `{}`", ty));
}
if let Some(ty::error::ExpectedFound { found, .. }) = exp_found {
if ty.is_box() && ty.boxed_ty() == found {
if let Ok(snippet) = self.tcx.sess.source_map().span_to_snippet(span) {
err.span_suggestion(
span,
"consider dereferencing the boxed value",
format!("*{}", snippet),
Applicability::MachineApplicable,
);
}
}
if let Some(ty::error::ExpectedFound { found, .. }) = exp_found
&& ty.is_box() && ty.boxed_ty() == found
&& let Ok(snippet) = self.tcx.sess.source_map().span_to_snippet(span)
{
err.span_suggestion(
span,
"consider dereferencing the boxed value",
format!("*{}", snippet),
Applicability::MachineApplicable,
);
}
}
ObligationCauseCode::Pattern { origin_expr: false, span: Some(span), .. } => {
Expand Down Expand Up @@ -1748,13 +1747,12 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
self.check_and_note_conflicting_crates(diag, terr);
self.tcx.note_and_explain_type_err(diag, terr, cause, span, body_owner_def_id.to_def_id());

if let Some(ValuePairs::PolyTraitRefs(exp_found)) = values {
if let ty::Closure(def_id, _) = exp_found.expected.skip_binder().self_ty().kind() {
if let Some(def_id) = def_id.as_local() {
let span = self.tcx.def_span(def_id);
diag.span_note(span, "this closure does not fulfill the lifetime requirements");
}
}
if let Some(ValuePairs::PolyTraitRefs(exp_found)) = values
&& let ty::Closure(def_id, _) = exp_found.expected.skip_binder().self_ty().kind()
&& let Some(def_id) = def_id.as_local()
{
let span = self.tcx.def_span(def_id);
diag.span_note(span, "this closure does not fulfill the lifetime requirements");
}

// It reads better to have the error origin as the final
Expand Down Expand Up @@ -2046,19 +2044,16 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
// containing a single character, perhaps the user meant to write `'c'` to
// specify a character literal (issue #92479)
(ty::Char, ty::Ref(_, r, _)) if r.is_str() => {
if let Ok(code) = self.tcx.sess().source_map().span_to_snippet(span) {
if let Some(code) =
code.strip_prefix('"').and_then(|s| s.strip_suffix('"'))
{
if code.chars().count() == 1 {
err.span_suggestion(
span,
"if you meant to write a `char` literal, use single quotes",
format!("'{}'", code),
Applicability::MachineApplicable,
);
}
}
if let Ok(code) = self.tcx.sess().source_map().span_to_snippet(span)
&& let Some(code) = code.strip_prefix('"').and_then(|s| s.strip_suffix('"'))
&& code.chars().count() == 1
{
err.span_suggestion(
span,
"if you meant to write a `char` literal, use single quotes",
format!("'{}'", code),
Applicability::MachineApplicable,
);
}
}
// If a string was expected and the found expression is a character literal,
Expand All @@ -2080,18 +2075,16 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
_ => {}
}
}
if let MatchExpressionArm(box MatchExpressionArmCause { source, .. }) =
*trace.cause.code()
let code = trace.cause.code();
if let &MatchExpressionArm(box MatchExpressionArmCause { source, .. }) = code
&& let hir::MatchSource::TryDesugar = source
&& let Some((expected_ty, found_ty)) = self.values_str(trace.values)
{
if let hir::MatchSource::TryDesugar = source {
if let Some((expected_ty, found_ty)) = self.values_str(trace.values) {
err.note(&format!(
"`?` operator cannot convert from `{}` to `{}`",
found_ty.content(),
expected_ty.content(),
));
}
}
err.note(&format!(
"`?` operator cannot convert from `{}` to `{}`",
found_ty.content(),
expected_ty.content(),
));
}
err
}
Expand Down
89 changes: 41 additions & 48 deletions compiler/rustc_infer/src/infer/error_reporting/need_type_info.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -114,28 +114,25 @@ impl<'a, 'tcx> Visitor<'tcx> for FindHirNodeVisitor<'a, 'tcx> {
}

fn visit_expr(&mut self, expr: &'tcx Expr<'tcx>) {
if let ExprKind::Match(scrutinee, [_, arm], MatchSource::ForLoopDesugar) = expr.kind {
if let Some(pat) = arm.pat.for_loop_some() {
if let Some(ty) = self.node_ty_contains_target(pat.hir_id) {
self.found_for_loop_iter = Some(scrutinee);
self.found_node_ty = Some(ty);
return;
}
}
if let ExprKind::Match(scrutinee, [_, arm], MatchSource::ForLoopDesugar) = expr.kind
&& let Some(pat) = arm.pat.for_loop_some()
&& let Some(ty) = self.node_ty_contains_target(pat.hir_id)
{
self.found_for_loop_iter = Some(scrutinee);
self.found_node_ty = Some(ty);
return;
}
if let ExprKind::MethodCall(segment, exprs, _) = expr.kind {
if segment.ident.span == self.target_span
&& Some(self.target)
== self.infcx.in_progress_typeck_results.and_then(|typeck_results| {
typeck_results
.borrow()
.node_type_opt(exprs.first().unwrap().hir_id)
.map(Into::into)
})
{
self.found_exact_method_call = Some(&expr);
return;
}
if let ExprKind::MethodCall(segment, exprs, _) = expr.kind
&& segment.ident.span == self.target_span
&& Some(self.target) == self.infcx.in_progress_typeck_results.and_then(|typeck_results| {
typeck_results
.borrow()
.node_type_opt(exprs.first().unwrap().hir_id)
.map(Into::into)
})
{
self.found_exact_method_call = Some(&expr);
return;
}

// FIXME(const_generics): Currently, any uninferred `const` generics arguments
Expand Down Expand Up @@ -602,10 +599,8 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
);

let use_diag = local_visitor.found_use_diagnostic.as_ref();
if let Some(use_diag) = use_diag {
if use_diag.applies_to(err_span) {
use_diag.attach_note(&mut err);
}
if let Some(use_diag) = use_diag && use_diag.applies_to(err_span) {
use_diag.attach_note(&mut err);
}

let param_type = arg_data.kind.descr();
Expand Down Expand Up @@ -736,29 +731,27 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
// | help: specify type like: `<Impl as Into<u32>>::into(foo_impl)`
// |
// = note: cannot satisfy `Impl: Into<_>`
if !impl_candidates.is_empty() && e.span.contains(span) {
if let Some(expr) = exprs.first() {
if let ExprKind::Path(hir::QPath::Resolved(_, path)) = expr.kind {
if let [path_segment] = path.segments {
let candidate_len = impl_candidates.len();
let suggestions = impl_candidates.iter().map(|candidate| {
format!(
"{}::{}({})",
candidate, segment.ident, path_segment.ident
)
});
err.span_suggestions(
e.span,
&format!(
"use the fully qualified path for the potential candidate{}",
pluralize!(candidate_len),
),
suggestions,
Applicability::MaybeIncorrect,
);
}
}
};
if !impl_candidates.is_empty() && e.span.contains(span)
&& let Some(expr) = exprs.first()
&& let ExprKind::Path(hir::QPath::Resolved(_, path)) = expr.kind
&& let [path_segment] = path.segments
{
let candidate_len = impl_candidates.len();
let suggestions = impl_candidates.iter().map(|candidate| {
format!(
"{}::{}({})",
candidate, segment.ident, path_segment.ident
)
});
err.span_suggestions(
e.span,
&format!(
"use the fully qualified path for the potential candidate{}",
pluralize!(candidate_len),
),
suggestions,
Applicability::MaybeIncorrect,
);
}
// Suggest specifying type params or point out the return type of the call:
//
Expand Down
47 changes: 22 additions & 25 deletions compiler/rustc_infer/src/infer/error_reporting/nice_region_error/static_impl_trait.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -223,35 +223,32 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
let fn_returns = tcx.return_type_impl_or_dyn_traits(anon_reg_sup.def_id);

let mut override_error_code = None;
if let SubregionOrigin::Subtype(box TypeTrace { cause, .. }) = &sup_origin {
if let ObligationCauseCode::UnifyReceiver(ctxt) = cause.code() {
// Handle case of `impl Foo for dyn Bar { fn qux(&self) {} }` introducing a
// `'static` lifetime when called as a method on a binding: `bar.qux()`.
if self.find_impl_on_dyn_trait(&mut err, param.param_ty, &ctxt) {
override_error_code = Some(ctxt.assoc_item.name);
}
}
if let SubregionOrigin::Subtype(box TypeTrace { cause, .. }) = &sup_origin
&& let ObligationCauseCode::UnifyReceiver(ctxt) = cause.code()
// Handle case of `impl Foo for dyn Bar { fn qux(&self) {} }` introducing a
// `'static` lifetime when called as a method on a binding: `bar.qux()`.
&& self.find_impl_on_dyn_trait(&mut err, param.param_ty, &ctxt)
{
override_error_code = Some(ctxt.assoc_item.name);
}
if let SubregionOrigin::Subtype(box TypeTrace { cause, .. }) = &sub_origin {
let code = match cause.code() {

if let SubregionOrigin::Subtype(box TypeTrace { cause, .. }) = &sub_origin
&& let code = match cause.code() {
ObligationCauseCode::MatchImpl(parent, ..) => parent.code(),
_ => cause.code(),
};
if let (ObligationCauseCode::ItemObligation(item_def_id), None) =
(code, override_error_code)
}
&& let (ObligationCauseCode::ItemObligation(item_def_id), None) = (code, override_error_code)
{
// Same case of `impl Foo for dyn Bar { fn qux(&self) {} }` introducing a `'static`
// lifetime as above, but called using a fully-qualified path to the method:
// `Foo::qux(bar)`.
let mut v = TraitObjectVisitor(FxHashSet::default());
v.visit_ty(param.param_ty);
if let Some((ident, self_ty)) =
self.get_impl_ident_and_self_ty_from_trait(*item_def_id, &v.0)
&& self.suggest_constrain_dyn_trait_in_impl(&mut err, &v.0, ident, self_ty)
{
// Same case of `impl Foo for dyn Bar { fn qux(&self) {} }` introducing a `'static`
// lifetime as above, but called using a fully-qualified path to the method:
// `Foo::qux(bar)`.
let mut v = TraitObjectVisitor(FxHashSet::default());
v.visit_ty(param.param_ty);
if let Some((ident, self_ty)) =
self.get_impl_ident_and_self_ty_from_trait(*item_def_id, &v.0)
{
if self.suggest_constrain_dyn_trait_in_impl(&mut err, &v.0, ident, self_ty) {
override_error_code = Some(ident.name);
}
}
override_error_code = Some(ident.name);
}
}
if let (Some(ident), true) = (override_error_code, fn_returns.is_empty()) {
Expand Down
64 changes: 26 additions & 38 deletions compiler/rustc_infer/src/infer/error_reporting/nice_region_error/trait_impl_difference.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -23,51 +23,39 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
let error = self.error.as_ref()?;
debug!("try_report_impl_not_conforming_to_trait {:?}", error);
if let RegionResolutionError::SubSupConflict(
_,
var_origin,
sub_origin,
_sub,
sup_origin,
_sup,
_,
) = error.clone()
_, var_origin, sub_origin, _sub, sup_origin, _sup, _,
) = error.clone()
&& let (&Subtype(ref sup_trace), &Subtype(ref sub_trace)) = (&sup_origin, &sub_origin)
&& let (
sub_expected_found @ Some((sub_expected, sub_found)),
sup_expected_found @ Some(_),
CompareImplMethodObligation { trait_item_def_id, .. },
) = (sub_trace.values.ty(), sup_trace.values.ty(), sub_trace.cause.code())
&& sup_expected_found == sub_expected_found
{
if let (&Subtype(ref sup_trace), &Subtype(ref sub_trace)) = (&sup_origin, &sub_origin) {
if let (
sub_expected_found @ Some((sub_expected, sub_found)),
sup_expected_found @ Some(_),
CompareImplMethodObligation { trait_item_def_id, .. },
) = (&sub_trace.values.ty(), &sup_trace.values.ty(), sub_trace.cause.code())
{
if sup_expected_found == sub_expected_found {
self.emit_err(
var_origin.span(),
*sub_expected,
*sub_found,
*trait_item_def_id,
);
return Some(ErrorGuaranteed);
}
}
}
self.emit_err(
var_origin.span(),
sub_expected,
sub_found,
*trait_item_def_id,
);
return Some(ErrorGuaranteed);
}
if let RegionResolutionError::ConcreteFailure(origin, _, _)
| RegionResolutionError::GenericBoundFailure(origin, _, _) = error.clone()
{
if let SubregionOrigin::CompareImplTypeObligation {
| RegionResolutionError::GenericBoundFailure(origin, _, _) = error.clone()
&& let SubregionOrigin::CompareImplTypeObligation {
span,
impl_item_def_id,
trait_item_def_id,
} = origin
{
self.emit_associated_type_err(
span,
self.infcx.tcx.item_name(impl_item_def_id),
impl_item_def_id,
trait_item_def_id,
);
return Some(ErrorGuaranteed);
}
{
self.emit_associated_type_err(
span,
self.infcx.tcx.item_name(impl_item_def_id),
impl_item_def_id,
trait_item_def_id,
);
return Some(ErrorGuaranteed);
}
None
}
Expand Down
10 changes: 4 additions & 6 deletions compiler/rustc_infer/src/infer/fudge.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -220,12 +220,10 @@ impl<'a, 'tcx> TypeFolder<'tcx> for InferenceFudger<'a, 'tcx> {
}

fn fold_region(&mut self, r: ty::Region<'tcx>) -> ty::Region<'tcx> {
if let ty::ReVar(vid) = *r {
if self.region_vars.0.contains(&vid) {
let idx = vid.index() - self.region_vars.0.start.index();
let origin = self.region_vars.1[idx];
return self.infcx.next_region_var(origin);
}
if let ty::ReVar(vid) = *r && self.region_vars.0.contains(&vid) {
let idx = vid.index() - self.region_vars.0.start.index();
let origin = self.region_vars.1[idx];
return self.infcx.next_region_var(origin);
}
r
}
Expand Down
12 changes: 4 additions & 8 deletions compiler/rustc_infer/src/infer/lexical_region_resolve/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -304,10 +304,8 @@ impl<'cx, 'tcx> LexicalResolver<'cx, 'tcx> {
// check below for a common case, here purely as an
// optimization.
let b_universe = self.var_infos[b_vid].universe;
if let ReEmpty(a_universe) = *a_region {
if a_universe == b_universe {
return false;
}
if let ReEmpty(a_universe) = *a_region && a_universe == b_universe {
return false;
}

let mut lub = self.lub_concrete_regions(a_region, cur_region);
Expand All @@ -324,10 +322,8 @@ impl<'cx, 'tcx> LexicalResolver<'cx, 'tcx> {
// tighter bound than `'static`.
//
// (This might e.g. arise from being asked to prove `for<'a> { 'b: 'a }`.)
if let ty::RePlaceholder(p) = *lub {
if b_universe.cannot_name(p.universe) {
lub = self.tcx().lifetimes.re_static;
}
if let ty::RePlaceholder(p) = *lub && b_universe.cannot_name(p.universe) {
lub = self.tcx().lifetimes.re_static;
}

debug!("Expanding value of {:?} from {:?} to {:?}", b_vid, cur_region, lub);
Expand Down
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