-use crate::utils::span_lint;
+use clippy_utils::diagnostics::span_lint;
use rustc_hir::{BorrowKind, Expr, ExprKind, Mutability};
use rustc_lint::{LateContext, LateLintPass};
use rustc_middle::ty::subst::Subst;
use rustc_middle::ty::{self, Ty};
use rustc_session::{declare_lint_pass, declare_tool_lint};
+use std::iter;
declare_clippy_lint! {
- /// **What it does:** Detects passing a mutable reference to a function that only
+ /// ### What it does
+ /// Detects passing a mutable reference to a function that only
/// requires an immutable reference.
///
- /// **Why is this bad?** The immutable reference rules out all other references
- /// to the value. Also the code misleads about the intent of the call site.
+ /// ### Why is this bad?
+ /// The mutable reference rules out all other references to
+ /// the value. Also the code misleads about the intent of the call site.
///
- /// **Known problems:** None.
- ///
- /// **Example:**
+ /// ### Example
/// ```ignore
/// // Bad
/// my_vec.push(&mut value)
/// // Good
/// my_vec.push(&value)
/// ```
+ #[clippy::version = "pre 1.29.0"]
pub UNNECESSARY_MUT_PASSED,
style,
"an argument passed as a mutable reference although the callee only demands an immutable reference"
impl<'tcx> LateLintPass<'tcx> for UnnecessaryMutPassed {
fn check_expr(&mut self, cx: &LateContext<'tcx>, e: &'tcx Expr<'_>) {
match e.kind {
- ExprKind::Call(ref fn_expr, ref arguments) => {
+ ExprKind::Call(fn_expr, arguments) => {
if let ExprKind::Path(ref path) = fn_expr.kind {
check_arguments(
cx,
arguments,
cx.typeck_results().expr_ty(fn_expr),
&rustc_hir_pretty::to_string(rustc_hir_pretty::NO_ANN, |s| s.print_qpath(path, false)),
+ "function",
);
}
},
- ExprKind::MethodCall(ref path, _, ref arguments, _) => {
+ ExprKind::MethodCall(path, arguments, _) => {
let def_id = cx.typeck_results().type_dependent_def_id(e.hir_id).unwrap();
let substs = cx.typeck_results().node_substs(e.hir_id);
let method_type = cx.tcx.type_of(def_id).subst(cx.tcx, substs);
- check_arguments(cx, arguments, method_type, &path.ident.as_str())
+ check_arguments(cx, arguments, method_type, path.ident.as_str(), "method");
},
_ => (),
}
}
}
-fn check_arguments<'tcx>(cx: &LateContext<'tcx>, arguments: &[Expr<'_>], type_definition: Ty<'tcx>, name: &str) {
- match type_definition.kind {
+fn check_arguments<'tcx>(
+ cx: &LateContext<'tcx>,
+ arguments: &[Expr<'_>],
+ type_definition: Ty<'tcx>,
+ name: &str,
+ fn_kind: &str,
+) {
+ match type_definition.kind() {
ty::FnDef(..) | ty::FnPtr(_) => {
let parameters = type_definition.fn_sig(cx.tcx).skip_binder().inputs();
- for (argument, parameter) in arguments.iter().zip(parameters.iter()) {
- match parameter.kind {
+ for (argument, parameter) in iter::zip(arguments, parameters) {
+ match parameter.kind() {
ty::Ref(_, _, Mutability::Not)
| ty::RawPtr(ty::TypeAndMut {
mutbl: Mutability::Not, ..
cx,
UNNECESSARY_MUT_PASSED,
argument.span,
- &format!("The function/method `{}` doesn't need a mutable reference", name),
+ &format!("the {} `{}` doesn't need a mutable reference", fn_kind, name),
);
}
},