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add byref checking for the guard's local

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This commit is contained in:
mojave2 2023-09-13 11:13:51 +08:00
parent 69fcbfdac0
commit 7f870201d3
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4 changed files with 176 additions and 21 deletions
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77
clippy_lints/src/matches/redundant_guards.rs
View file

@ -34,24 +34,45 @@ pub(super) fn check<'tcx>(cx: &LateContext<'tcx>, arms: &'tcx [Arm<'tcx>]) {
],
MatchSource::Normal,
) = if_expr.kind
&& let Some((binding_span, is_field, is_byref)) = get_pat_binding(cx, scrutinee, outer_arm)
{
if is_field && is_byref { return; }
let pat_span = if let PatKind::Ref(pat, _) = arm.pat.kind {
if is_byref { pat.span } else { continue; }
} else {
if is_byref { continue; }
arm.pat.span
};
emit_redundant_guards(
cx,
outer_arm,
if_expr.span,
scrutinee,
arm.pat.span,
pat_span,
binding_span,
is_field,
arm.guard,
);
}
// `Some(x) if let Some(2) = x`
else if let Guard::IfLet(let_expr) = guard {
else if let Guard::IfLet(let_expr) = guard
&& let Some((binding_span, is_field, is_byref)) = get_pat_binding(cx, let_expr.init, outer_arm)
{
if is_field && is_byref { return; }
let pat_span = if let PatKind::Ref(pat, _) = let_expr.pat.kind {
if is_byref && !is_field { pat.span } else { continue; }
} else {
if is_byref { continue; }
let_expr.pat.span
};
emit_redundant_guards(
cx,
outer_arm,
let_expr.span,
let_expr.init,
let_expr.pat.span,
pat_span,
binding_span,
is_field,
None,
);
}
@ -67,31 +88,48 @@ pub(super) fn check<'tcx>(cx: &LateContext<'tcx>, arms: &'tcx [Arm<'tcx>]) {
//
// This isn't necessary in the other two checks, as they must be a pattern already.
&& cx.typeck_results().expr_ty(local) == cx.typeck_results().expr_ty(pat)
&& let Some((binding_span, is_field, is_byref)) = get_pat_binding(cx, local, outer_arm)
{
if is_field && is_byref { return; }
let pat_span = if let ExprKind::AddrOf(rustc_ast::BorrowKind::Ref, _, expr) = pat.kind {
if is_byref { expr.span } else { continue; }
} else {
if is_byref { continue; }
pat.span
};
emit_redundant_guards(
cx,
outer_arm,
if_expr.span,
local,
pat.span,
pat_span,
binding_span,
is_field,
None,
);
}
}
}
fn get_pat_binding<'tcx>(cx: &LateContext<'tcx>, guard_expr: &Expr<'_>, outer_arm: &Arm<'tcx>) -> Option<(Span, bool)> {
fn get_pat_binding<'tcx>(
cx: &LateContext<'tcx>,
guard_expr: &Expr<'_>,
outer_arm: &Arm<'tcx>,
) -> Option<(Span, bool, bool)> {
if let Some(local) = path_to_local(guard_expr) && !is_local_used(cx, outer_arm.body, local) {
let mut span = None;
let mut multiple_bindings = false;
let mut is_byref = false;
// `each_binding` gives the `HirId` of the `Pat` itself, not the binding
outer_arm.pat.walk(|pat| {
if let PatKind::Binding(_, hir_id, _, _) = pat.kind
if let PatKind::Binding(bind_annot, hir_id, _, _) = pat.kind
&& hir_id == local
&& span.replace(pat.span).is_some()
{
multiple_bindings = true;
return false;
is_byref = matches!(bind_annot.0, rustc_ast::ByRef::Yes);
if span.replace(pat.span).is_some() {
multiple_bindings = true;
return false;
}
}
true
@ -102,7 +140,8 @@ fn get_pat_binding<'tcx>(cx: &LateContext<'tcx>, guard_expr: &Expr<'_>, outer_ar
return span.map(|span| {
(
span,
!matches!(cx.tcx.hir().get_parent(local), Node::PatField(_)),
matches!(cx.tcx.hir().get_parent(local), Node::PatField(_)),
is_byref,
)
});
}
@ -115,14 +154,12 @@ fn emit_redundant_guards<'tcx>(
cx: &LateContext<'tcx>,
outer_arm: &Arm<'tcx>,
guard_span: Span,
local: &Expr<'_>,
pat_span: Span,
binding_span: Span,
field_binding: bool,
inner_guard: Option<Guard<'_>>,
) {
let mut app = Applicability::MaybeIncorrect;
let Some((pat_binding, can_use_shorthand)) = get_pat_binding(cx, local, outer_arm) else {
return;
};
span_lint_and_then(
cx,
@ -134,10 +171,10 @@ fn emit_redundant_guards<'tcx>(
diag.multipart_suggestion_verbose(
"try",
vec![
if can_use_shorthand {
(pat_binding, binding_replacement.into_owned())
if field_binding {
(binding_span.shrink_to_hi(), format!(": {binding_replacement}"))
} else {
(pat_binding.shrink_to_hi(), format!(": {binding_replacement}"))
(binding_span, binding_replacement.into_owned())
},
(
guard_span.source_callsite().with_lo(outer_arm.pat.span.hi()),