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|
use clippy_utils::diagnostics::span_lint_and_sugg;
use clippy_utils::msrvs::{self, Msrv};
use clippy_utils::source::snippet_with_applicability;
use clippy_utils::ty::{is_copy, is_type_diagnostic_item, should_call_clone_as_function};
use clippy_utils::{is_diag_trait_item, peel_blocks};
use rustc_errors::Applicability;
use rustc_hir::def_id::DefId;
use rustc_hir::{self as hir, LangItem};
use rustc_lint::LateContext;
use rustc_middle::mir::Mutability;
use rustc_middle::ty;
use rustc_middle::ty::adjustment::Adjust;
use rustc_span::symbol::Ident;
use rustc_span::{Span, sym};
use super::MAP_CLONE;
// If this `map` is called on an `Option` or a `Result` and the previous call is `as_ref`, we don't
// run this lint because it would overlap with `useless_asref` which provides a better suggestion
// in this case.
fn should_run_lint(cx: &LateContext<'_>, e: &hir::Expr<'_>, method_id: DefId) -> bool {
if is_diag_trait_item(cx, method_id, sym::Iterator) {
return true;
}
// We check if it's an `Option` or a `Result`.
if let Some(id) = cx.tcx.impl_of_method(method_id) {
let identity = cx.tcx.type_of(id).instantiate_identity();
if !is_type_diagnostic_item(cx, identity, sym::Option) && !is_type_diagnostic_item(cx, identity, sym::Result) {
return false;
}
} else {
return false;
}
// We check if the previous method call is `as_ref`.
if let hir::ExprKind::MethodCall(path1, receiver, _, _) = &e.kind
&& let hir::ExprKind::MethodCall(path2, _, _, _) = &receiver.kind
{
return path2.ident.name != sym::as_ref || path1.ident.name != sym::map;
}
true
}
pub(super) fn check(cx: &LateContext<'_>, e: &hir::Expr<'_>, recv: &hir::Expr<'_>, arg: &hir::Expr<'_>, msrv: &Msrv) {
if let Some(method_id) = cx.typeck_results().type_dependent_def_id(e.hir_id)
&& should_run_lint(cx, e, method_id)
{
match arg.kind {
hir::ExprKind::Closure(&hir::Closure { body, .. }) => {
let closure_body = cx.tcx.hir_body(body);
let closure_expr = peel_blocks(closure_body.value);
match closure_body.params[0].pat.kind {
hir::PatKind::Ref(inner, Mutability::Not) => {
if let hir::PatKind::Binding(hir::BindingMode::NONE, .., name, None) = inner.kind {
if ident_eq(name, closure_expr) {
lint_explicit_closure(cx, e.span, recv.span, true, msrv);
}
}
},
hir::PatKind::Binding(hir::BindingMode::NONE, .., name, None) => {
match closure_expr.kind {
hir::ExprKind::Unary(hir::UnOp::Deref, inner) => {
if ident_eq(name, inner) {
if let ty::Ref(.., Mutability::Not) = cx.typeck_results().expr_ty(inner).kind() {
lint_explicit_closure(cx, e.span, recv.span, true, msrv);
}
}
},
hir::ExprKind::MethodCall(method, obj, [], _) => {
if ident_eq(name, obj) && method.ident.name == sym::clone
&& let Some(fn_id) = cx.typeck_results().type_dependent_def_id(closure_expr.hir_id)
&& let Some(trait_id) = cx.tcx.trait_of_item(fn_id)
&& cx.tcx.lang_items().clone_trait() == Some(trait_id)
// no autoderefs
&& !cx.typeck_results().expr_adjustments(obj).iter()
.any(|a| matches!(a.kind, Adjust::Deref(Some(..))))
{
let obj_ty = cx.typeck_results().expr_ty(obj);
if let ty::Ref(_, ty, mutability) = obj_ty.kind() {
if matches!(mutability, Mutability::Not) {
let copy = is_copy(cx, *ty);
lint_explicit_closure(cx, e.span, recv.span, copy, msrv);
}
} else {
lint_needless_cloning(cx, e.span, recv.span);
}
}
},
hir::ExprKind::Call(call, [arg]) => {
if let hir::ExprKind::Path(qpath) = call.kind
&& ident_eq(name, arg)
{
handle_path(cx, call, &qpath, e, recv);
}
},
_ => {},
}
},
_ => {},
}
},
hir::ExprKind::Path(qpath) => handle_path(cx, arg, &qpath, e, recv),
_ => {},
}
}
}
fn handle_path(
cx: &LateContext<'_>,
arg: &hir::Expr<'_>,
qpath: &hir::QPath<'_>,
e: &hir::Expr<'_>,
recv: &hir::Expr<'_>,
) {
if let Some(path_def_id) = cx.qpath_res(qpath, arg.hir_id).opt_def_id()
&& cx.tcx.lang_items().get(LangItem::CloneFn) == Some(path_def_id)
{
// The `copied` and `cloned` methods are only available on `&T` and `&mut T` in `Option`
// and `Result`.
if let ty::Adt(_, args) = cx.typeck_results().expr_ty(recv).kind()
&& let args = args.as_slice()
&& let Some(ty) = args.iter().find_map(|generic_arg| generic_arg.as_type())
&& let ty::Ref(_, ty, Mutability::Not) = ty.kind()
&& let ty::FnDef(_, lst) = cx.typeck_results().expr_ty(arg).kind()
&& lst.iter().all(|l| l.as_type() == Some(*ty))
&& !should_call_clone_as_function(cx, *ty)
{
lint_path(cx, e.span, recv.span, is_copy(cx, ty.peel_refs()));
}
}
}
fn ident_eq(name: Ident, path: &hir::Expr<'_>) -> bool {
if let hir::ExprKind::Path(hir::QPath::Resolved(None, path)) = path.kind {
path.segments.len() == 1 && path.segments[0].ident == name
} else {
false
}
}
fn lint_needless_cloning(cx: &LateContext<'_>, root: Span, receiver: Span) {
span_lint_and_sugg(
cx,
MAP_CLONE,
root.trim_start(receiver).unwrap(),
"you are needlessly cloning iterator elements",
"remove the `map` call",
String::new(),
Applicability::MachineApplicable,
);
}
fn lint_path(cx: &LateContext<'_>, replace: Span, root: Span, is_copy: bool) {
let mut applicability = Applicability::MachineApplicable;
let replacement = if is_copy { "copied" } else { "cloned" };
span_lint_and_sugg(
cx,
MAP_CLONE,
replace,
"you are explicitly cloning with `.map()`",
format!("consider calling the dedicated `{replacement}` method"),
format!(
"{}.{replacement}()",
snippet_with_applicability(cx, root, "..", &mut applicability),
),
applicability,
);
}
fn lint_explicit_closure(cx: &LateContext<'_>, replace: Span, root: Span, is_copy: bool, msrv: &Msrv) {
let mut applicability = Applicability::MachineApplicable;
let (message, sugg_method) = if is_copy && msrv.meets(msrvs::ITERATOR_COPIED) {
("you are using an explicit closure for copying elements", "copied")
} else {
("you are using an explicit closure for cloning elements", "cloned")
};
span_lint_and_sugg(
cx,
MAP_CLONE,
replace,
message,
format!("consider calling the dedicated `{sugg_method}` method"),
format!(
"{}.{sugg_method}()",
snippet_with_applicability(cx, root, "..", &mut applicability),
),
applicability,
);
}
|
