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9 - Make more use of let_chains
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Continuation of rust-lang#94376.

cc rust-lang#53667
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c410-f3r committed Mar 1, 2022
1 parent f0c4da4 commit a7b4d66
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Showing 8 changed files with 176 additions and 218 deletions.
9 changes: 5 additions & 4 deletions compiler/rustc_trait_selection/src/lib.rs
Original file line number Diff line number Diff line change
Expand Up @@ -10,19 +10,20 @@
//!
//! This API is completely unstable and subject to change.
#![allow(rustc::potential_query_instability)]
#![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
#![feature(bool_to_option)]
#![feature(box_patterns)]
#![feature(drain_filter)]
#![feature(control_flow_enum)]
#![feature(crate_visibility_modifier)]
#![feature(derive_default_enum)]
#![feature(drain_filter)]
#![feature(hash_drain_filter)]
#![feature(label_break_value)]
#![feature(let_chains)]
#![feature(let_else)]
#![feature(never_type)]
#![feature(crate_visibility_modifier)]
#![feature(control_flow_enum)]
#![recursion_limit = "512"] // For rustdoc
#![allow(rustc::potential_query_instability)]

#[macro_use]
extern crate rustc_macros;
Expand Down
90 changes: 44 additions & 46 deletions compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs
Original file line number Diff line number Diff line change
Expand Up @@ -1098,42 +1098,43 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
);
}
}
if let &[ArgKind::Tuple(_, ref fields)] = &expected_args[..] {
if fields.len() == found_args.len() && is_closure {
let sugg = format!(
"|({}){}|",
found_args
.iter()
.map(|arg| match arg {
ArgKind::Arg(name, _) => name.to_owned(),
_ => "_".to_owned(),
})
.collect::<Vec<String>>()
.join(", "),
// add type annotations if available
if found_args.iter().any(|arg| match arg {
ArgKind::Arg(_, ty) => ty != "_",
_ => false,
}) {
format!(
": ({})",
fields
.iter()
.map(|(_, ty)| ty.to_owned())
.collect::<Vec<String>>()
.join(", ")
)
} else {
String::new()
},
);
err.span_suggestion_verbose(
found_span,
"change the closure to accept a tuple instead of individual arguments",
sugg,
Applicability::MachineApplicable,
);
}
if let &[ArgKind::Tuple(_, ref fields)] = &expected_args[..]
&& fields.len() == found_args.len()
&& is_closure
{
let sugg = format!(
"|({}){}|",
found_args
.iter()
.map(|arg| match arg {
ArgKind::Arg(name, _) => name.to_owned(),
_ => "_".to_owned(),
})
.collect::<Vec<String>>()
.join(", "),
// add type annotations if available
if found_args.iter().any(|arg| match arg {
ArgKind::Arg(_, ty) => ty != "_",
_ => false,
}) {
format!(
": ({})",
fields
.iter()
.map(|(_, ty)| ty.to_owned())
.collect::<Vec<String>>()
.join(", ")
)
} else {
String::new()
},
);
err.span_suggestion_verbose(
found_span,
"change the closure to accept a tuple instead of individual arguments",
sugg,
Applicability::MachineApplicable,
);
}
}

Expand Down Expand Up @@ -2231,16 +2232,13 @@ impl<'a, 'tcx> InferCtxtPrivExt<'a, 'tcx> for InferCtxt<'a, 'tcx> {
if obligated_types.iter().any(|ot| ot == &self_ty) {
return true;
}
if let ty::Adt(def, substs) = self_ty.kind() {
if let [arg] = &substs[..] {
if let ty::subst::GenericArgKind::Type(ty) = arg.unpack() {
if let ty::Adt(inner_def, _) = ty.kind() {
if inner_def == def {
return true;
}
}
}
}
if let ty::Adt(def, substs) = self_ty.kind()
&& let [arg] = &substs[..]
&& let ty::subst::GenericArgKind::Type(ty) = arg.unpack()
&& let ty::Adt(inner_def, _) = ty.kind()
&& inner_def == def
{
return true;
}
}
false
Expand Down
Original file line number Diff line number Diff line change
Expand Up @@ -891,23 +891,20 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
}
if let Some(typeck_results) =
self.in_progress_typeck_results.map(|t| t.borrow())
&& let ty = typeck_results.expr_ty_adjusted(base)
&& let ty::FnDef(def_id, _substs) = ty.kind()
&& let Some(hir::Node::Item(hir::Item { span, ident, .. })) =
hir.get_if_local(*def_id)
{
let ty = typeck_results.expr_ty_adjusted(base);
if let ty::FnDef(def_id, _substs) = ty.kind() {
if let Some(hir::Node::Item(hir::Item { span, ident, .. })) =
hir.get_if_local(*def_id)
{
err.span_suggestion_verbose(
span.shrink_to_lo(),
&format!(
"alternatively, consider making `fn {}` asynchronous",
ident
),
"async ".to_string(),
Applicability::MaybeIncorrect,
);
}
}
err.span_suggestion_verbose(
span.shrink_to_lo(),
&format!(
"alternatively, consider making `fn {}` asynchronous",
ident
),
"async ".to_string(),
Applicability::MaybeIncorrect,
);
}
}
}
Expand Down Expand Up @@ -1000,34 +997,24 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
span: Span,
trait_pred: ty::PolyTraitPredicate<'tcx>,
) {
let is_empty_tuple =
|ty: ty::Binder<'tcx, Ty<'_>>| *ty.skip_binder().kind() == ty::Tuple(ty::List::empty());

let hir = self.tcx.hir();
let parent_node = hir.get_parent_node(obligation.cause.body_id);
let node = hir.find(parent_node);
if let Some(hir::Node::Item(hir::Item {
kind: hir::ItemKind::Fn(sig, _, body_id), ..
})) = node
if let Some(hir::Node::Item(hir::Item { kind: hir::ItemKind::Fn(sig, _, body_id), .. })) = node
&& let body = hir.body(*body_id)
&& let hir::ExprKind::Block(blk, _) = &body.value.kind
&& sig.decl.output.span().overlaps(span)
&& blk.expr.is_none()
&& *trait_pred.self_ty().skip_binder().kind() == ty::Tuple(ty::List::empty())
// FIXME(estebank): When encountering a method with a trait
// bound not satisfied in the return type with a body that has
// no return, suggest removal of semicolon on last statement.
// Once that is added, close #54771.
&& let Some(stmt) = blk.stmts.last()
&& let hir::StmtKind::Semi(_) = stmt.kind
{
let body = hir.body(*body_id);
if let hir::ExprKind::Block(blk, _) = &body.value.kind {
if sig.decl.output.span().overlaps(span)
&& blk.expr.is_none()
&& is_empty_tuple(trait_pred.self_ty())
{
// FIXME(estebank): When encountering a method with a trait
// bound not satisfied in the return type with a body that has
// no return, suggest removal of semicolon on last statement.
// Once that is added, close #54771.
if let Some(ref stmt) = blk.stmts.last() {
if let hir::StmtKind::Semi(_) = stmt.kind {
let sp = self.tcx.sess.source_map().end_point(stmt.span);
err.span_label(sp, "consider removing this semicolon");
}
}
}
}
let sp = self.tcx.sess.source_map().end_point(stmt.span);
err.span_label(sp, "consider removing this semicolon");
}
}

Expand Down Expand Up @@ -2481,17 +2468,15 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
debug!("suggest_await_before_try: try_trait_obligation {:?}", try_obligation);
if self.predicate_may_hold(&try_obligation)
&& impls_future.must_apply_modulo_regions()
&& let Ok(snippet) = self.tcx.sess.source_map().span_to_snippet(span)
&& snippet.ends_with('?')
{
if let Ok(snippet) = self.tcx.sess.source_map().span_to_snippet(span) {
if snippet.ends_with('?') {
err.span_suggestion_verbose(
span.with_hi(span.hi() - BytePos(1)).shrink_to_hi(),
"consider `await`ing on the `Future`",
".await".to_string(),
Applicability::MaybeIncorrect,
);
}
}
err.span_suggestion_verbose(
span.with_hi(span.hi() - BytePos(1)).shrink_to_hi(),
"consider `await`ing on the `Future`",
".await".to_string(),
Applicability::MaybeIncorrect,
);
}
}
}
Expand Down
38 changes: 17 additions & 21 deletions compiler/rustc_trait_selection/src/traits/on_unimplemented.rs
Original file line number Diff line number Diff line change
Expand Up @@ -91,10 +91,8 @@ impl<'tcx> OnUnimplementedDirective {
)
})?;
attr::eval_condition(cond, &tcx.sess.parse_sess, Some(tcx.features()), &mut |item| {
if let Some(symbol) = item.value_str() {
if parse_value(symbol).is_err() {
errored = true;
}
if let Some(symbol) = item.value_str() && parse_value(symbol).is_err() {
errored = true;
}
true
});
Expand Down Expand Up @@ -232,24 +230,22 @@ impl<'tcx> OnUnimplementedDirective {
options.iter().filter_map(|(k, v)| v.as_ref().map(|v| (*k, v.to_owned()))).collect();

for command in self.subcommands.iter().chain(Some(self)).rev() {
if let Some(ref condition) = command.condition {
if !attr::eval_condition(
condition,
&tcx.sess.parse_sess,
Some(tcx.features()),
&mut |c| {
c.ident().map_or(false, |ident| {
let value = c.value_str().map(|s| {
OnUnimplementedFormatString(s).format(tcx, trait_ref, &options_map)
});
if let Some(ref condition) = command.condition && !attr::eval_condition(
condition,
&tcx.sess.parse_sess,
Some(tcx.features()),
&mut |c| {
c.ident().map_or(false, |ident| {
let value = c.value_str().map(|s| {
OnUnimplementedFormatString(s).format(tcx, trait_ref, &options_map)
});

options.contains(&(ident.name, value))
})
},
) {
debug!("evaluate: skipping {:?} due to condition", command);
continue;
}
options.contains(&(ident.name, value))
})
},
) {
debug!("evaluate: skipping {:?} due to condition", command);
continue;
}
debug!("evaluate: {:?} succeeded", command);
if let Some(ref message_) = command.message {
Expand Down
28 changes: 13 additions & 15 deletions compiler/rustc_trait_selection/src/traits/query/dropck_outlives.rs
Original file line number Diff line number Diff line change
Expand Up @@ -43,21 +43,19 @@ impl<'cx, 'tcx> AtExt<'tcx> for At<'cx, 'tcx> {
let c_ty = self.infcx.canonicalize_query(self.param_env.and(ty), &mut orig_values);
let span = self.cause.span;
debug!("c_ty = {:?}", c_ty);
if let Ok(result) = tcx.dropck_outlives(c_ty) {
if result.is_proven() {
if let Ok(InferOk { value, obligations }) =
self.infcx.instantiate_query_response_and_region_obligations(
self.cause,
self.param_env,
&orig_values,
result,
)
{
let ty = self.infcx.resolve_vars_if_possible(ty);
let kinds = value.into_kinds_reporting_overflows(tcx, span, ty);
return InferOk { value: kinds, obligations };
}
}
if let Ok(result) = tcx.dropck_outlives(c_ty)
&& result.is_proven()
&& let Ok(InferOk { value, obligations }) =
self.infcx.instantiate_query_response_and_region_obligations(
self.cause,
self.param_env,
&orig_values,
result,
)
{
let ty = self.infcx.resolve_vars_if_possible(ty);
let kinds = value.into_kinds_reporting_overflows(tcx, span, ty);
return InferOk { value: kinds, obligations };
}

// Errors and ambiuity in dropck occur in two cases:
Expand Down
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