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map_identity: simplify lint emission (#15797)

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Instead of calling `span_lint_and_*` in multiple places, call
`span_lint_and_then` once and then use the `Diag` methods.

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This commit is contained in:
Alejandra González 2025-10-01 16:27:32 +00:00 • committed by GitHub
commit 12e0c4c637
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1 changed files with 35 additions and 45 deletions
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80
clippy_lints/src/methods/map_identity.rs
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@ -1,4 +1,4 @@
use clippy_utils::diagnostics::{span_lint_and_sugg, span_lint_and_then};
use clippy_utils::diagnostics::span_lint_and_then;
use clippy_utils::source::snippet_with_applicability;
use clippy_utils::ty::{is_copy, is_type_diagnostic_item};
use clippy_utils::{is_expr_untyped_identity_function, is_mutable, is_trait_method, path_to_local_with_projections};
@ -27,48 +27,46 @@ pub(super) fn check(
&& is_expr_untyped_identity_function(cx, map_arg)
&& let Some(call_span) = expr.span.trim_start(caller.span)
{
let main_sugg = (call_span, String::new());
let mut app = if is_copy(cx, caller_ty) {
// there is technically a behavioral change here for `Copy` iterators, where
// `iter.map(|x| x).next()` would mutate a temporary copy of the iterator and
// changing it to `iter.next()` mutates iter directly
Applicability::Unspecified
} else {
Applicability::MachineApplicable
};
span_lint_and_then(cx, MAP_IDENTITY, call_span, MSG, |diag| {
let main_sugg = (call_span, String::new());
let mut app = if is_copy(cx, caller_ty) {
// there is technically a behavioral change here for `Copy` iterators, where
// `iter.map(|x| x).next()` would mutate a temporary copy of the iterator and
// changing it to `iter.next()` mutates iter directly
Applicability::Unspecified
} else {
Applicability::MachineApplicable
};
let needs_to_be_mutable = cx.typeck_results().expr_ty_adjusted(expr).is_mutable_ptr();
if needs_to_be_mutable && !is_mutable(cx, caller) {
if let Some(hir_id) = path_to_local_with_projections(caller)
&& let Node::Pat(pat) = cx.tcx.hir_node(hir_id)
&& let PatKind::Binding(_, _, ident, _) = pat.kind
{
// We can reach the binding -- suggest making it mutable
let suggs = vec![main_sugg, (ident.span.shrink_to_lo(), String::from("mut "))];
let needs_to_be_mutable = cx.typeck_results().expr_ty_adjusted(expr).is_mutable_ptr();
if needs_to_be_mutable && !is_mutable(cx, caller) {
if let Some(hir_id) = path_to_local_with_projections(caller)
&& let Node::Pat(pat) = cx.tcx.hir_node(hir_id)
&& let PatKind::Binding(_, _, ident, _) = pat.kind
{
// We can reach the binding -- suggest making it mutable
let suggs = vec![main_sugg, (ident.span.shrink_to_lo(), String::from("mut "))];
let ident = snippet_with_applicability(cx.sess(), ident.span, "_", &mut app);
let ident = snippet_with_applicability(cx.sess(), ident.span, "_", &mut app);
span_lint_and_then(cx, MAP_IDENTITY, call_span, MSG, |diag| {
diag.multipart_suggestion(
format!("remove the call to `{name}`, and make `{ident}` mutable"),
suggs,
app,
);
});
} else {
// If we can't make the binding mutable, prevent the suggestion from being automatically applied,
// and add a complementary help message.
app = Applicability::Unspecified;
let method_requiring_mut = if let Node::Expr(expr) = cx.tcx.parent_hir_node(expr.hir_id)
&& let ExprKind::MethodCall(method, ..) = expr.kind
{
Some(method.ident)
} else {
None
};
// If we can't make the binding mutable, prevent the suggestion from being automatically applied,
// and add a complementary help message.
app = Applicability::Unspecified;
let method_requiring_mut = if let Node::Expr(expr) = cx.tcx.parent_hir_node(expr.hir_id)
&& let ExprKind::MethodCall(method, ..) = expr.kind
{
Some(method.ident)
} else {
None
};
span_lint_and_then(cx, MAP_IDENTITY, call_span, MSG, |diag| {
diag.span_suggestion(main_sugg.0, format!("remove the call to `{name}`"), main_sugg.1, app);
let note = if let Some(method_requiring_mut) = method_requiring_mut {
@ -77,18 +75,10 @@ pub(super) fn check(
"this must be made mutable".to_string()
};
diag.span_note(caller.span, note);
});
}
} else {
diag.span_suggestion(main_sugg.0, format!("remove the call to `{name}`"), main_sugg.1, app);
}
} else {
span_lint_and_sugg(
cx,
MAP_IDENTITY,
main_sugg.0,
MSG,
format!("remove the call to `{name}`"),
main_sugg.1,
app,
);
}
});
}
}