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Suggest unit struct and constants.

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This commit is contained in:
Camille Gillot
2025-09-07 02:17:13 +00:00
parent ca0379d6cd
commit c653430714
6 changed files with 237 additions and 26 deletions
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2
compiler/rustc_mir_transform/messages.ftl
View File

@@ -104,3 +104,5 @@ mir_transform_unused_variable = unused variable: `{$name}`
mir_transform_unused_variable_args_in_macro = `{$name}` is captured in macro and introduced a unused variable
mir_transform_unused_variable_try_ignore = try ignoring the field
mir_transform_unused_variable_typo = you might have meant to pattern match on the similarly named {$kind} `{$item_name}`

18
compiler/rustc_mir_transform/src/errors.rs
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@@ -170,6 +170,8 @@ pub(crate) struct UnusedCaptureMaybeCaptureRef {
#[note]
pub(crate) struct UnusedVarAssignedOnly {
pub name: Symbol,
#[subdiagnostic]
pub typo: Option<PatternTypo>,
}
#[derive(LintDiagnostic)]
@@ -235,6 +237,8 @@ pub(crate) enum UnusedVariableSugg {
#[suggestion_part(code = "_{name}")]
spans: Vec<Span>,
name: Symbol,
#[subdiagnostic]
typo: Option<PatternTypo>,
},
#[help(mir_transform_unused_variable_args_in_macro)]
@@ -266,6 +270,20 @@ impl Subdiagnostic for UnusedVariableStringInterp {
}
}
#[derive(Subdiagnostic)]
#[multipart_suggestion(
mir_transform_unused_variable_typo,
style = "verbose",
applicability = "maybe-incorrect"
)]
pub(crate) struct PatternTypo {
#[suggestion_part(code = "{code}")]
pub span: Span,
pub code: String,
pub item_name: Symbol,
pub kind: &'static str,
}
pub(crate) struct MustNotSupend<'a, 'tcx> {
pub tcx: TyCtxt<'tcx>,
pub yield_sp: Span,

88
compiler/rustc_mir_transform/src/liveness.rs
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@@ -1,8 +1,8 @@
use rustc_abi::FieldIdx;
use rustc_data_structures::fx::{FxHashSet, FxIndexMap, IndexEntry};
use rustc_hir::attrs::AttributeKind;
use rustc_hir::def::DefKind;
use rustc_hir::def_id::LocalDefId;
use rustc_hir::def::{CtorKind, DefKind};
use rustc_hir::def_id::{DefId, LocalDefId};
use rustc_hir::find_attr;
use rustc_index::IndexVec;
use rustc_index::bit_set::DenseBitSet;
@@ -11,11 +11,13 @@ use rustc_middle::mir::visit::{
MutatingUseContext, NonMutatingUseContext, NonUseContext, PlaceContext, Visitor,
};
use rustc_middle::mir::*;
use rustc_middle::ty::print::with_no_trimmed_paths;
use rustc_middle::ty::{self, Ty, TyCtxt};
use rustc_mir_dataflow::fmt::DebugWithContext;
use rustc_mir_dataflow::{Analysis, Backward, ResultsCursor};
use rustc_session::lint;
use rustc_span::Span;
use rustc_span::edit_distance::find_best_match_for_name;
use rustc_span::symbol::{Symbol, kw, sym};
use crate::errors;
@@ -201,6 +203,62 @@ fn maybe_suggest_literal_matching_name(
finder.found
}
/// Give a diagnostic when an unused variable may be a typo of a unit variant or a struct.
fn maybe_suggest_unit_pattern_typo<'tcx>(
tcx: TyCtxt<'tcx>,
body_def_id: DefId,
name: Symbol,
span: Span,
ty: Ty<'tcx>,
) -> Option<errors::PatternTypo> {
if let ty::Adt(adt_def, _) = ty.peel_refs().kind() {
let variant_names: Vec<_> = adt_def
.variants()
.iter()
.filter(|v| matches!(v.ctor, Some((CtorKind::Const, _))))
.map(|v| v.name)
.collect();
if let Some(name) = find_best_match_for_name(&variant_names, name, None)
&& let Some(variant) = adt_def
.variants()
.iter()
.find(|v| v.name == name && matches!(v.ctor, Some((CtorKind::Const, _))))
{
return Some(errors::PatternTypo {
span,
code: with_no_trimmed_paths!(tcx.def_path_str(variant.def_id)),
kind: tcx.def_descr(variant.def_id),
item_name: variant.name,
});
}
}
// Look for consts of the same type with similar names as well,
// not just unit structs and variants.
let constants = tcx
.hir_body_owners()
.filter(|&def_id| {
matches!(tcx.def_kind(def_id), DefKind::Const)
&& tcx.type_of(def_id).instantiate_identity() == ty
&& tcx.visibility(def_id).is_accessible_from(body_def_id, tcx)
})
.collect::<Vec<_>>();
let names = constants.iter().map(|&def_id| tcx.item_name(def_id)).collect::<Vec<_>>();
if let Some(item_name) = find_best_match_for_name(&names, name, None)
&& let Some(position) = names.iter().position(|&n| n == item_name)
&& let Some(&def_id) = constants.get(position)
{
return Some(errors::PatternTypo {
span,
code: with_no_trimmed_paths!(tcx.def_path_str(def_id)),
kind: "constant",
item_name,
});
}
None
}
/// Return whether we should consider the current place as a drop guard and skip reporting.
fn maybe_drop_guard<'tcx>(
tcx: TyCtxt<'tcx>,
@@ -855,12 +913,27 @@ impl<'a, 'tcx> AssignmentResult<'a, 'tcx> {
let from_macro = def_span.from_expansion()
&& introductions.iter().any(|intro| intro.span.eq_ctxt(def_span));
let maybe_suggest_typo = || {
if let LocalKind::Arg = self.body.local_kind(local) {
None
} else {
maybe_suggest_unit_pattern_typo(
tcx,
self.body.source.def_id(),
name,
def_span,
decl.ty,
)
}
};
let statements = &mut self.assignments[index];
if statements.is_empty() {
let sugg = if from_macro {
errors::UnusedVariableSugg::NoSugg { span: def_span, name }
} else {
errors::UnusedVariableSugg::TryPrefix { spans: vec![def_span], name }
let typo = maybe_suggest_typo();
errors::UnusedVariableSugg::TryPrefix { spans: vec![def_span], name, typo }
};
tcx.emit_node_span_lint(
lint::builtin::UNUSED_VARIABLES,
@@ -909,11 +982,12 @@ impl<'a, 'tcx> AssignmentResult<'a, 'tcx> {
continue;
}
let typo = maybe_suggest_typo();
tcx.emit_node_span_lint(
lint::builtin::UNUSED_VARIABLES,
hir_id,
def_span,
errors::UnusedVarAssignedOnly { name },
errors::UnusedVarAssignedOnly { name, typo },
);
continue;
}
@@ -944,9 +1018,11 @@ impl<'a, 'tcx> AssignmentResult<'a, 'tcx> {
} else if from_macro {
errors::UnusedVariableSugg::NoSugg { span: def_span, name }
} else if !introductions.is_empty() {
errors::UnusedVariableSugg::TryPrefix { name, spans: spans.clone() }
let typo = maybe_suggest_typo();
errors::UnusedVariableSugg::TryPrefix { name, typo, spans: spans.clone() }
} else {
errors::UnusedVariableSugg::TryPrefix { name, spans: vec![def_span] }
let typo = maybe_suggest_typo();
errors::UnusedVariableSugg::TryPrefix { name, typo, spans: vec![def_span] }
};
tcx.emit_node_span_lint(

21
tests/ui/lint/non-snake-case/lint-uppercase-variables.stderr
View File

@@ -16,7 +16,7 @@ warning: unused variable: `Foo`
--> $DIR/lint-uppercase-variables.rs:22:9
|
LL | Foo => {}
| ^^^ help: if this is intentional, prefix it with an underscore: `_Foo`
| ^^^
|
note: the lint level is defined here
--> $DIR/lint-uppercase-variables.rs:1:9
@@ -24,12 +24,29 @@ note: the lint level is defined here
LL | #![warn(unused)]
| ^^^^^^
= note: `#[warn(unused_variables)]` implied by `#[warn(unused)]`
help: you might have meant to pattern match on the similarly named variant `Foo`
|
LL | foo::Foo::Foo => {}
| ++++++++++
help: if this is intentional, prefix it with an underscore
|
LL | _Foo => {}
| +
warning: unused variable: `Foo`
--> $DIR/lint-uppercase-variables.rs:28:9
|
LL | let Foo = foo::Foo::Foo;
| ^^^ help: if this is intentional, prefix it with an underscore: `_Foo`
| ^^^
|
help: you might have meant to pattern match on the similarly named variant `Foo`
|
LL | let foo::Foo::Foo = foo::Foo::Foo;
| ++++++++++
help: if this is intentional, prefix it with an underscore
|
LL | let _Foo = foo::Foo::Foo;
| +
error[E0170]: pattern binding `Foo` is named the same as one of the variants of the type `foo::Foo`
--> $DIR/lint-uppercase-variables.rs:33:17

16
tests/ui/or-patterns/binding-typo-2.rs
View File

@@ -16,8 +16,8 @@ fn foo(x: (Lol, Lol)) {
//~| HELP: you might have meant to use the similarly named previously used binding `Bar`
//~| NOTE: pattern doesn't bind `Ban`
//~| NOTE: variable not in all patterns
//~| ERROR: variable `Ban` is assigned to, but never used
//~| NOTE: consider using `_Ban` instead
//~| ERROR: unused variable: `Ban`
//~| HELP: if this is intentional, prefix it with an underscore
//~| HELP: you might have meant to pattern match on the similarly named
_ => {}
}
@@ -27,8 +27,8 @@ fn foo(x: (Lol, Lol)) {
//~| HELP: you might have meant to use the similarly named unit variant `Bar`
//~| NOTE: pattern doesn't bind `Ban`
//~| NOTE: variable not in all patterns
//~| ERROR: variable `Ban` is assigned to, but never used
//~| NOTE: consider using `_Ban` instead
//~| ERROR: unused variable: `Ban`
//~| HELP: if this is intentional, prefix it with an underscore
//~| HELP: you might have meant to pattern match on the similarly named
_ => {}
}
@@ -73,8 +73,8 @@ fn bar(x: (Lol, Lol)) {
//~| HELP: you might have meant to use the similarly named constant `Bat`
//~| NOTE: pattern doesn't bind `Ban`
//~| NOTE: variable not in all patterns
//~| ERROR: variable `Ban` is assigned to, but never used
//~| NOTE: consider using `_Ban` instead
//~| ERROR: unused variable: `Ban`
//~| HELP: if this is intentional, prefix it with an underscore
//~| HELP: you might have meant to pattern match on the similarly named
_ => {}
}
@@ -89,8 +89,8 @@ fn baz(x: (Lol, Lol)) {
//~| HELP: you might have meant to use the similarly named constant `Bat`
//~| NOTE: pattern doesn't bind `Ban`
//~| NOTE: variable not in all patterns
//~| ERROR: variable `Ban` is assigned to, but never used
//~| NOTE: consider using `_Ban` instead
//~| ERROR: unused variable: `Ban`
//~| HELP: if this is intentional, prefix it with an underscore
//~| HELP: you might have meant to pattern match on the similarly named
_ => {}
}

118
tests/ui/or-patterns/binding-typo-2.stderr
View File

@@ -101,67 +101,165 @@ error: unused variable: `Ban`
--> $DIR/binding-typo-2.rs:14:23
|
LL | (Foo, Bar) | (Ban, Foo) => {}
| ^^^ help: if this is intentional, prefix it with an underscore: `_Ban`
| ^^^
|
note: the lint level is defined here
--> $DIR/binding-typo-2.rs:2:9
|
LL | #![deny(unused_variables)]
| ^^^^^^^^^^^^^^^^
help: you might have meant to pattern match on the similarly named variant `Bar`
|
LL - (Foo, Bar) | (Ban, Foo) => {}
LL + (Foo, Bar) | (Lol::Bar, Foo) => {}
|
help: if this is intentional, prefix it with an underscore
|
LL | (Foo, Bar) | (_Ban, Foo) => {}
| +
error: unused variable: `Ban`
--> $DIR/binding-typo-2.rs:25:21
|
LL | (Foo, _) | (Ban, Foo) => {}
| ^^^ help: if this is intentional, prefix it with an underscore: `_Ban`
| ^^^
|
help: you might have meant to pattern match on the similarly named variant `Bar`
|
LL - (Foo, _) | (Ban, Foo) => {}
LL + (Foo, _) | (Lol::Bar, Foo) => {}
|
help: if this is intentional, prefix it with an underscore
|
LL | (Foo, _) | (_Ban, Foo) => {}
| +
error: unused variable: `Non`
--> $DIR/binding-typo-2.rs:37:9
|
LL | Non => {}
| ^^^ help: if this is intentional, prefix it with an underscore: `_Non`
| ^^^
|
help: you might have meant to pattern match on the similarly named variant `None`
|
LL - Non => {}
LL + std::prelude::v1::None => {}
|
help: if this is intentional, prefix it with an underscore
|
LL | _Non => {}
| +
error: unused variable: `Non`
--> $DIR/binding-typo-2.rs:44:9
|
LL | Non | None => {}
| ^^^ help: if this is intentional, prefix it with an underscore: `_Non`
| ^^^
|
help: you might have meant to pattern match on the similarly named variant `None`
|
LL - Non | None => {}
LL + std::prelude::v1::None | None => {}
|
help: if this is intentional, prefix it with an underscore
|
LL | _Non | None => {}
| +
error: unused variable: `Non`
--> $DIR/binding-typo-2.rs:54:9
|
LL | Non | Some(_) => {}
| ^^^ help: if this is intentional, prefix it with an underscore: `_Non`
| ^^^
|
help: you might have meant to pattern match on the similarly named variant `None`
|
LL - Non | Some(_) => {}
LL + std::prelude::v1::None | Some(_) => {}
|
help: if this is intentional, prefix it with an underscore
|
LL | _Non | Some(_) => {}
| +
error: unused variable: `Ban`
--> $DIR/binding-typo-2.rs:69:21
|
LL | (Foo, _) | (Ban, Foo) => {}
| ^^^ help: if this is intentional, prefix it with an underscore: `_Ban`
| ^^^
|
help: you might have meant to pattern match on the similarly named variant `Bar`
|
LL - (Foo, _) | (Ban, Foo) => {}
LL + (Foo, _) | (Lol::Bar, Foo) => {}
|
help: if this is intentional, prefix it with an underscore
|
LL | (Foo, _) | (_Ban, Foo) => {}
| +
error: unused variable: `Ban`
--> $DIR/binding-typo-2.rs:86:21
|
LL | (Foo, _) | (Ban, Foo) => {}
| ^^^ help: if this is intentional, prefix it with an underscore: `_Ban`
| ^^^
|
help: you might have meant to pattern match on the similarly named variant `Bar`
|
LL - (Foo, _) | (Ban, Foo) => {}
LL + (Foo, _) | (Lol::Bar, Foo) => {}
|
help: if this is intentional, prefix it with an underscore
|
LL | (Foo, _) | (_Ban, Foo) => {}
| +
error: unused variable: `Ban`
--> $DIR/binding-typo-2.rs:98:10
|
LL | (Ban, _) => {}
| ^^^ help: if this is intentional, prefix it with an underscore: `_Ban`
| ^^^
|
help: you might have meant to pattern match on the similarly named variant `Bar`
|
LL - (Ban, _) => {}
LL + (Lol::Bar, _) => {}
|
help: if this is intentional, prefix it with an underscore
|
LL | (_Ban, _) => {}
| +
error: unused variable: `Ban`
--> $DIR/binding-typo-2.rs:104:9
|
LL | Ban => {}
| ^^^ help: if this is intentional, prefix it with an underscore: `_Ban`
| ^^^
|
help: you might have meant to pattern match on the similarly named struct `Bay`
|
LL - Ban => {}
LL + Bay => {}
|
help: if this is intentional, prefix it with an underscore
|
LL | _Ban => {}
| +
error: unused variable: `Batery`
--> $DIR/binding-typo-2.rs:110:9
|
LL | Batery => {}
| ^^^^^^ help: if this is intentional, prefix it with an underscore: `_Batery`
| ^^^^^^
|
help: you might have meant to pattern match on the similarly named constant `Battery`
|
LL | Battery => {}
| +
help: if this is intentional, prefix it with an underscore
|
LL | _Batery => {}
| +
error: aborting due to 16 previous errors