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Reorganize code in mem_replace.rs

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Make each lint be more self-contained, and trigger only the next lint
when the previous one didn't already rewrite the expression.
This commit is contained in:
Samuel Tardieu 2025-02-12 17:15:27 +01:00
parent ff87bead4f
commit 39bde6d46a
1 changed files with 50 additions and 36 deletions
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86
clippy_lints/src/mem_replace.rs
View file

@ -103,26 +103,31 @@ declare_clippy_lint! {
impl_lint_pass!(MemReplace =>
[MEM_REPLACE_OPTION_WITH_NONE, MEM_REPLACE_WITH_UNINIT, MEM_REPLACE_WITH_DEFAULT]);
fn check_replace_option_with_none(cx: &LateContext<'_>, dest: &Expr<'_>, expr_span: Span) {
// Since this is a late pass (already type-checked),
// and we already know that the second argument is an
// `Option`, we do not need to check the first
// argument's type. All that's left is to get
// the replacee's expr after peeling off the `&mut`
let sugg_expr = peel_ref_operators(cx, dest);
let mut applicability = Applicability::MachineApplicable;
span_lint_and_sugg(
cx,
MEM_REPLACE_OPTION_WITH_NONE,
expr_span,
"replacing an `Option` with `None`",
"consider `Option::take()` instead",
format!(
"{}.take()",
Sugg::hir_with_context(cx, sugg_expr, expr_span.ctxt(), "", &mut applicability).maybe_par()
),
applicability,
);
fn check_replace_option_with_none(cx: &LateContext<'_>, src: &Expr<'_>, dest: &Expr<'_>, expr_span: Span) -> bool {
if is_res_lang_ctor(cx, path_res(cx, src), OptionNone) {
// Since this is a late pass (already type-checked),
// and we already know that the second argument is an
// `Option`, we do not need to check the first
// argument's type. All that's left is to get
// the replacee's expr after peeling off the `&mut`
let sugg_expr = peel_ref_operators(cx, dest);
let mut applicability = Applicability::MachineApplicable;
span_lint_and_sugg(
cx,
MEM_REPLACE_OPTION_WITH_NONE,
expr_span,
"replacing an `Option` with `None`",
"consider `Option::take()` instead",
format!(
"{}.take()",
Sugg::hir_with_context(cx, sugg_expr, expr_span.ctxt(), "", &mut applicability).maybe_par()
),
applicability,
);
true
} else {
false
}
}
fn check_replace_with_uninit(cx: &LateContext<'_>, src: &Expr<'_>, dest: &Expr<'_>, expr_span: Span) {
@ -181,27 +186,34 @@ fn check_replace_with_uninit(cx: &LateContext<'_>, src: &Expr<'_>, dest: &Expr<'
}
}
fn check_replace_with_default(cx: &LateContext<'_>, src: &Expr<'_>, dest: &Expr<'_>, expr_span: Span) {
// disable lint for primitives
let expr_type = cx.typeck_results().expr_ty_adjusted(src);
if is_non_aggregate_primitive_type(expr_type) {
return;
}
if is_default_equivalent(cx, src) && !expr_span.in_external_macro(cx.tcx.sess.source_map()) {
let Some(top_crate) = std_or_core(cx) else { return };
fn check_replace_with_default(
cx: &LateContext<'_>,
src: &Expr<'_>,
dest: &Expr<'_>,
expr: &Expr<'_>,
msrv: &Msrv,
) -> bool {
if msrv.meets(msrvs::MEM_TAKE) && is_expr_used_or_unified(cx.tcx, expr)
// disable lint for primitives
&& let expr_type = cx.typeck_results().expr_ty_adjusted(src)
&& !is_non_aggregate_primitive_type(expr_type)
&& is_default_equivalent(cx, src)
&& !expr.span.in_external_macro(cx.tcx.sess.source_map())
&& let Some(top_crate) = std_or_core(cx)
{
span_lint_and_then(
cx,
MEM_REPLACE_WITH_DEFAULT,
expr_span,
expr.span,
format!(
"replacing a value of type `T` with `T::default()` is better expressed using `{top_crate}::mem::take`"
),
|diag| {
if !expr_span.from_expansion() {
if !expr.span.from_expansion() {
let suggestion = format!("{top_crate}::mem::take({})", snippet(cx, dest.span, ""));
diag.span_suggestion(
expr_span,
expr.span,
"consider using",
suggestion,
Applicability::MachineApplicable,
@ -209,6 +221,9 @@ fn check_replace_with_default(cx: &LateContext<'_>, src: &Expr<'_>, dest: &Expr<
}
},
);
true
} else {
false
}
}
@ -233,12 +248,11 @@ impl<'tcx> LateLintPass<'tcx> for MemReplace {
&& cx.tcx.is_diagnostic_item(sym::mem_replace, def_id)
{
// Check that second argument is `Option::None`
if is_res_lang_ctor(cx, path_res(cx, src), OptionNone) {
check_replace_option_with_none(cx, dest, expr.span);
} else if self.msrv.meets(msrvs::MEM_TAKE) && is_expr_used_or_unified(cx.tcx, expr) {
check_replace_with_default(cx, src, dest, expr.span);
if !check_replace_option_with_none(cx, src, dest, expr.span)
&& !check_replace_with_default(cx, src, dest, expr, &self.msrv)
{
check_replace_with_uninit(cx, src, dest, expr.span);
}
check_replace_with_uninit(cx, src, dest, expr.span);
}
}
extract_msrv_attr!(LateContext);