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Add new lint: used_underscore_items

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This commit is contained in:
WeiTheShinobi 2024-08-21 16:12:48 +08:00
parent e5a1ef0795
commit b615c82180
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6 changed files with 309 additions and 56 deletions
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1
clippy_lints/src/declared_lints.rs
View file

@ -485,6 +485,7 @@ pub static LINTS: &[&crate::LintInfo] = &[
crate::misc::SHORT_CIRCUIT_STATEMENT_INFO,
crate::misc::TOPLEVEL_REF_ARG_INFO,
crate::misc::USED_UNDERSCORE_BINDING_INFO,
crate::misc::USED_UNDERSCORE_ITEMS_INFO,
crate::misc_early::BUILTIN_TYPE_SHADOW_INFO,
crate::misc_early::DOUBLE_NEG_INFO,
crate::misc_early::DUPLICATE_UNDERSCORE_ARGUMENT_INFO,

176
clippy_lints/src/misc.rs
View file

@ -80,6 +80,45 @@ declare_clippy_lint! {
"using a binding which is prefixed with an underscore"
}
declare_clippy_lint! {
/// ### What it does
/// Checks for the use of item with a single leading
/// underscore.
///
/// ### Why is this bad?
/// A single leading underscore is usually used to indicate
/// that a item will not be used. Using such a item breaks this
/// expectation.
///
/// ### Example
/// ```no_run
/// fn _foo() {}
///
/// struct _FooStruct {}
///
/// fn main() {
/// _foo();
/// let _ = _FooStruct{};
/// }
/// ```
///
/// Use instead:
/// ```no_run
/// fn foo() {}
///
/// struct FooStruct {}
///
/// fn main() {
/// foo();
/// let _ = FooStruct{};
/// }
/// ```
#[clippy::version = "pre 1.29.0"]
pub USED_UNDERSCORE_ITEMS,
pedantic,
"using a item which is prefixed with an underscore"
}
declare_clippy_lint! {
/// ### What it does
/// Checks for the use of short circuit boolean conditions as
@ -104,6 +143,7 @@ declare_clippy_lint! {
declare_lint_pass!(LintPass => [
TOPLEVEL_REF_ARG,
USED_UNDERSCORE_BINDING,
USED_UNDERSCORE_ITEMS,
SHORT_CIRCUIT_STATEMENT,
]);
@ -205,51 +245,99 @@ impl<'tcx> LateLintPass<'tcx> for LintPass {
{
return;
}
let (definition_hir_id, ident) = match expr.kind {
ExprKind::Path(ref qpath) => {
if let QPath::Resolved(None, path) = qpath
&& let Res::Local(id) = path.res
&& is_used(cx, expr)
{
(id, last_path_segment(qpath).ident)
} else {
return;
}
},
ExprKind::Field(recv, ident) => {
if let Some(adt_def) = cx.typeck_results().expr_ty_adjusted(recv).ty_adt_def()
&& let Some(field) = adt_def.all_fields().find(|field| field.name == ident.name)
&& let Some(local_did) = field.did.as_local()
&& !cx.tcx.type_of(field.did).skip_binder().is_phantom_data()
{
(cx.tcx.local_def_id_to_hir_id(local_did), ident)
} else {
return;
}
},
_ => return,
};
let name = ident.name.as_str();
if name.starts_with('_')
&& !name.starts_with("__")
&& let definition_span = cx.tcx.hir().span(definition_hir_id)
&& !definition_span.from_expansion()
&& !fulfill_or_allowed(cx, USED_UNDERSCORE_BINDING, [expr.hir_id, definition_hir_id])
{
span_lint_and_then(
cx,
USED_UNDERSCORE_BINDING,
expr.span,
format!(
"used binding `{name}` which is prefixed with an underscore. A leading \
underscore signals that a binding will not be used"
),
|diag| {
diag.span_note(definition_span, format!("`{name}` is defined here"));
},
);
}
used_underscore_binding(cx, expr);
used_underscore_items(cx, expr);
}
}
fn used_underscore_items<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
let (def_id, ident) = match expr.kind {
ExprKind::Call(func, ..) => {
if let ExprKind::Path(QPath::Resolved(.., path)) = func.kind
&& let Some(last_segment) = path.segments.last()
&& let Res::Def(_, def_id) = last_segment.res
{
(def_id, last_segment.ident)
} else {
return;
}
},
ExprKind::MethodCall(path, ..) => {
if let Some(def_id) = cx.typeck_results().type_dependent_def_id(expr.hir_id) {
(def_id, path.ident)
} else {
return;
}
},
ExprKind::Struct(QPath::Resolved(_, path), ..) => {
if let Some(last_segment) = path.segments.last()
&& let Res::Def(_, def_id) = last_segment.res
{
(def_id, last_segment.ident)
} else {
return;
}
},
_ => return,
};
let name = ident.name.as_str();
let definition_span = cx.tcx.def_span(def_id);
if name.starts_with('_') && !name.starts_with("__") && !definition_span.from_expansion() {
span_lint_and_then(
cx,
USED_UNDERSCORE_ITEMS,
expr.span,
"used underscore-prefixed item".to_string(),
|diag| {
diag.span_note(definition_span, "item is defined here".to_string());
},
);
}
}
fn used_underscore_binding<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
let (definition_hir_id, ident) = match expr.kind {
ExprKind::Path(ref qpath) => {
if let QPath::Resolved(None, path) = qpath
&& let Res::Local(id) = path.res
&& is_used(cx, expr)
{
(id, last_path_segment(qpath).ident)
} else {
return;
}
},
ExprKind::Field(recv, ident) => {
if let Some(adt_def) = cx.typeck_results().expr_ty_adjusted(recv).ty_adt_def()
&& let Some(field) = adt_def.all_fields().find(|field| field.name == ident.name)
&& let Some(local_did) = field.did.as_local()
&& !cx.tcx.type_of(field.did).skip_binder().is_phantom_data()
{
(cx.tcx.local_def_id_to_hir_id(local_did), ident)
} else {
return;
}
},
_ => return,
};
let name = ident.name.as_str();
if name.starts_with('_')
&& !name.starts_with("__")
&& let definition_span = cx.tcx.hir().span(definition_hir_id)
&& !definition_span.from_expansion()
&& !fulfill_or_allowed(cx, USED_UNDERSCORE_BINDING, [expr.hir_id, definition_hir_id])
{
span_lint_and_then(
cx,
USED_UNDERSCORE_BINDING,
expr.span,
"used underscore-prefixed binding".to_string(),
|diag| {
diag.span_note(definition_span, "binding is defined here".to_string());
},
);
}
}