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Rollup merge of rust-lang#94465 - c410-f3r:more-let-chains, r=Dylan-DPC
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6 - Make more use of `let_chains`

Continuation of rust-lang#94376.

cc rust-lang#53667
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@matthiaskrgr
matthiaskrgr authored Mar 1, 2022
2 parents c531b01 + fe94f78 commit a0baf25
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Showing 8 changed files with 97 additions and 118 deletions.
28 changes: 13 additions & 15 deletions compiler/rustc_mir_build/src/build/expr/stmt.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -116,22 +116,20 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
// it is usually better to focus on `the_value` rather
// than the entirety of block(s) surrounding it.
let adjusted_span = (|| {
if let ExprKind::Block { body } = &expr.kind {
if let Some(tail_expr) = body.expr {
let mut expr = &this.thir[tail_expr];
while let ExprKind::Block {
body: Block { expr: Some(nested_expr), .. },
}
| ExprKind::Scope { value: nested_expr, .. } = expr.kind
{
expr = &this.thir[nested_expr];
}
this.block_context.push(BlockFrame::TailExpr {
tail_result_is_ignored: true,
span: expr.span,
});
return Some(expr.span);
if let ExprKind::Block { body } = &expr.kind && let Some(tail_ex) = body.expr {
let mut expr = &this.thir[tail_ex];
while let ExprKind::Block {
body: Block { expr: Some(nested_expr), .. },
}
| ExprKind::Scope { value: nested_expr, .. } = expr.kind
{
expr = &this.thir[nested_expr];
}
this.block_context.push(BlockFrame::TailExpr {
tail_result_is_ignored: true,
span: expr.span,
});
return Some(expr.span);
}
None
})();
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12 changes: 5 additions & 7 deletions compiler/rustc_mir_build/src/build/matches/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1597,13 +1597,11 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
}

// Insert a Shallow borrow of any places that is switched on.
if let Some(fb) = fake_borrows {
if let Ok(match_place_resolved) =
match_place.clone().try_upvars_resolved(self.tcx, self.typeck_results)
{
let resolved_place = match_place_resolved.into_place(self.tcx, self.typeck_results);
fb.insert(resolved_place);
}
if let Some(fb) = fake_borrows && let Ok(match_place_resolved) =
match_place.clone().try_upvars_resolved(self.tcx, self.typeck_results)
{
let resolved_place = match_place_resolved.into_place(self.tcx, self.typeck_results);
fb.insert(resolved_place);
}

// perform the test, branching to one of N blocks. For each of
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14 changes: 6 additions & 8 deletions compiler/rustc_mir_build/src/build/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -877,14 +877,12 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
let arg_local = self.local_decls.push(LocalDecl::with_source_info(ty, source_info));

// If this is a simple binding pattern, give debuginfo a nice name.
if let Some(arg) = arg_opt {
if let Some(ident) = arg.pat.simple_ident() {
self.var_debug_info.push(VarDebugInfo {
name: ident.name,
source_info,
value: VarDebugInfoContents::Place(arg_local.into()),
});
}
if let Some(arg) = arg_opt && let Some(ident) = arg.pat.simple_ident() {
self.var_debug_info.push(VarDebugInfo {
name: ident.name,
source_info,
value: VarDebugInfoContents::Place(arg_local.into()),
});
}
}

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34 changes: 15 additions & 19 deletions compiler/rustc_mir_build/src/check_unsafety.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -416,23 +416,21 @@ impl<'a, 'tcx> Visitor<'a, 'tcx> for UnsafetyVisitor<'a, 'tcx> {
}
ExprKind::Field { lhs, .. } => {
let lhs = &self.thir[lhs];
if let ty::Adt(adt_def, _) = lhs.ty.kind() {
if adt_def.is_union() {
if let Some((assigned_ty, assignment_span)) = self.assignment_info {
// To avoid semver hazard, we only consider `Copy` and `ManuallyDrop` non-dropping.
if !(assigned_ty
.ty_adt_def()
.map_or(false, |adt| adt.is_manually_drop())
|| assigned_ty
.is_copy_modulo_regions(self.tcx.at(expr.span), self.param_env))
{
self.requires_unsafe(assignment_span, AssignToDroppingUnionField);
} else {
// write to non-drop union field, safe
}
if let ty::Adt(adt_def, _) = lhs.ty.kind() && adt_def.is_union() {
if let Some((assigned_ty, assignment_span)) = self.assignment_info {
// To avoid semver hazard, we only consider `Copy` and `ManuallyDrop` non-dropping.
if !(assigned_ty
.ty_adt_def()
.map_or(false, |adt| adt.is_manually_drop())
|| assigned_ty
.is_copy_modulo_regions(self.tcx.at(expr.span), self.param_env))
{
self.requires_unsafe(assignment_span, AssignToDroppingUnionField);
} else {
self.requires_unsafe(expr.span, AccessToUnionField);
// write to non-drop union field, safe
}
} else {
self.requires_unsafe(expr.span, AccessToUnionField);
}
}
}
Expand Down Expand Up @@ -476,10 +474,8 @@ impl<'a, 'tcx> Visitor<'a, 'tcx> for UnsafetyVisitor<'a, 'tcx> {
}
ExprKind::Let { expr: expr_id, .. } => {
let let_expr = &self.thir[expr_id];
if let ty::Adt(adt_def, _) = let_expr.ty.kind() {
if adt_def.is_union() {
self.requires_unsafe(expr.span, AccessToUnionField);
}
if let ty::Adt(adt_def, _) = let_expr.ty.kind() && adt_def.is_union() {
self.requires_unsafe(expr.span, AccessToUnionField);
}
}
_ => {}
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7 changes: 4 additions & 3 deletions compiler/rustc_mir_build/src/lib.rs
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Original file line number Diff line number Diff line change
@@ -1,15 +1,16 @@
//! Construction of MIR from HIR.
//!
//! This crate also contains the match exhaustiveness and usefulness checking.
#![allow(rustc::potential_query_instability)]
#![feature(bool_to_option)]
#![feature(box_patterns)]
#![feature(control_flow_enum)]
#![feature(crate_visibility_modifier)]
#![feature(bool_to_option)]
#![feature(let_chains)]
#![feature(let_else)]
#![feature(once_cell)]
#![feature(min_specialization)]
#![feature(once_cell)]
#![recursion_limit = "256"]
#![allow(rustc::potential_query_instability)]

#[macro_use]
extern crate tracing;
Expand Down
78 changes: 36 additions & 42 deletions compiler/rustc_mir_build/src/thir/pattern/check_match.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -315,47 +315,43 @@ fn check_for_bindings_named_same_as_variants(
rf: RefutableFlag,
) {
pat.walk_always(|p| {
if let hir::PatKind::Binding(_, _, ident, None) = p.kind {
if let Some(ty::BindByValue(hir::Mutability::Not)) =
if let hir::PatKind::Binding(_, _, ident, None) = p.kind
&& let Some(ty::BindByValue(hir::Mutability::Not)) =
cx.typeck_results.extract_binding_mode(cx.tcx.sess, p.hir_id, p.span)
{
let pat_ty = cx.typeck_results.pat_ty(p).peel_refs();
if let ty::Adt(edef, _) = pat_ty.kind() {
if edef.is_enum()
&& edef.variants.iter().any(|variant| {
variant.ident(cx.tcx) == ident && variant.ctor_kind == CtorKind::Const
})
{
let variant_count = edef.variants.len();
cx.tcx.struct_span_lint_hir(
BINDINGS_WITH_VARIANT_NAME,
p.hir_id,
&& let pat_ty = cx.typeck_results.pat_ty(p).peel_refs()
&& let ty::Adt(edef, _) = pat_ty.kind()
&& edef.is_enum()
&& edef.variants.iter().any(|variant| {
variant.ident(cx.tcx) == ident && variant.ctor_kind == CtorKind::Const
})
{
let variant_count = edef.variants.len();
cx.tcx.struct_span_lint_hir(
BINDINGS_WITH_VARIANT_NAME,
p.hir_id,
p.span,
|lint| {
let ty_path = cx.tcx.def_path_str(edef.did);
let mut err = lint.build(&format!(
"pattern binding `{}` is named the same as one \
of the variants of the type `{}`",
ident, ty_path
));
err.code(error_code!(E0170));
// If this is an irrefutable pattern, and there's > 1 variant,
// then we can't actually match on this. Applying the below
// suggestion would produce code that breaks on `check_irrefutable`.
if rf == Refutable || variant_count == 1 {
err.span_suggestion(
p.span,
|lint| {
let ty_path = cx.tcx.def_path_str(edef.did);
let mut err = lint.build(&format!(
"pattern binding `{}` is named the same as one \
of the variants of the type `{}`",
ident, ty_path
));
err.code(error_code!(E0170));
// If this is an irrefutable pattern, and there's > 1 variant,
// then we can't actually match on this. Applying the below
// suggestion would produce code that breaks on `check_irrefutable`.
if rf == Refutable || variant_count == 1 {
err.span_suggestion(
p.span,
"to match on the variant, qualify the path",
format!("{}::{}", ty_path, ident),
Applicability::MachineApplicable,
);
}
err.emit();
},
)
"to match on the variant, qualify the path",
format!("{}::{}", ty_path, ident),
Applicability::MachineApplicable,
);
}
}
}
err.emit();
},
)
}
});
}
Expand Down Expand Up @@ -622,10 +618,8 @@ fn maybe_point_at_variant<'a, 'p: 'a, 'tcx: 'a>(
let mut covered = vec![];
for pattern in patterns {
if let Variant(variant_index) = pattern.ctor() {
if let ty::Adt(this_def, _) = pattern.ty().kind() {
if this_def.did != def.did {
continue;
}
if let ty::Adt(this_def, _) = pattern.ty().kind() && this_def.did != def.did {
continue;
}
let sp = def.variants[*variant_index].ident(cx.tcx).span;
if covered.contains(&sp) {
Expand Down
24 changes: 10 additions & 14 deletions compiler/rustc_mir_build/src/thir/pattern/deconstruct_pat.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -680,27 +680,23 @@ impl<'tcx> Constructor<'tcx> {
///
/// This means that the variant has a stdlib unstable feature marking it.
pub(super) fn is_unstable_variant(&self, pcx: PatCtxt<'_, '_, 'tcx>) -> bool {
if let Constructor::Variant(idx) = self {
if let ty::Adt(adt, _) = pcx.ty.kind() {
let variant_def_id = adt.variants[*idx].def_id;
// Filter variants that depend on a disabled unstable feature.
return matches!(
pcx.cx.tcx.eval_stability(variant_def_id, None, DUMMY_SP, None),
EvalResult::Deny { .. }
);
}
if let Constructor::Variant(idx) = self && let ty::Adt(adt, _) = pcx.ty.kind() {
let variant_def_id = adt.variants[*idx].def_id;
// Filter variants that depend on a disabled unstable feature.
return matches!(
pcx.cx.tcx.eval_stability(variant_def_id, None, DUMMY_SP, None),
EvalResult::Deny { .. }
);
}
false
}

/// Checks if the `Constructor` is a `Constructor::Variant` with a `#[doc(hidden)]`
/// attribute.
pub(super) fn is_doc_hidden_variant(&self, pcx: PatCtxt<'_, '_, 'tcx>) -> bool {
if let Constructor::Variant(idx) = self {
if let ty::Adt(adt, _) = pcx.ty.kind() {
let variant_def_id = adt.variants[*idx].def_id;
return pcx.cx.tcx.is_doc_hidden(variant_def_id);
}
if let Constructor::Variant(idx) = self && let ty::Adt(adt, _) = pcx.ty.kind() {
let variant_def_id = adt.variants[*idx].def_id;
return pcx.cx.tcx.is_doc_hidden(variant_def_id);
}
false
}
Expand Down
18 changes: 8 additions & 10 deletions compiler/rustc_mir_build/src/thir/pattern/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -790,16 +790,14 @@ crate fn compare_const_vals<'tcx>(
};
}

if let ty::Str = ty.kind() {
if let (
ty::ConstKind::Value(a_val @ ConstValue::Slice { .. }),
ty::ConstKind::Value(b_val @ ConstValue::Slice { .. }),
) = (a.val(), b.val())
{
let a_bytes = get_slice_bytes(&tcx, a_val);
let b_bytes = get_slice_bytes(&tcx, b_val);
return from_bool(a_bytes == b_bytes);
}
if let ty::Str = ty.kind() && let (
ty::ConstKind::Value(a_val @ ConstValue::Slice { .. }),
ty::ConstKind::Value(b_val @ ConstValue::Slice { .. }),
) = (a.val(), b.val())
{
let a_bytes = get_slice_bytes(&tcx, a_val);
let b_bytes = get_slice_bytes(&tcx, b_val);
return from_bool(a_bytes == b_bytes);
}
fallback()
}

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