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Auto merge of #5892 - matthiaskrgr:redundant_mut, r=flip1995
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unnecessary-mut-passed: make lint message say if fn is a function or a method

changelog: refine "unnecessary-mut-passed" lint message
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bors committed Aug 11, 2020
2 parents 09bd400 + b8713e3 commit 3337f79
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Showing 2 changed files with 13 additions and 6 deletions.
13 changes: 10 additions & 3 deletions clippy_lints/src/mut_reference.rs
Original file line number Diff line number Diff line change
Expand Up @@ -39,21 +39,28 @@ impl<'tcx> LateLintPass<'tcx> for UnnecessaryMutPassed {
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, _) => {
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) {
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();
Expand All @@ -68,7 +75,7 @@ fn check_arguments<'tcx>(cx: &LateContext<'tcx>, arguments: &[Expr<'_>], type_de
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),
);
}
},
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6 changes: 3 additions & 3 deletions tests/ui/mut_reference.stderr
Original file line number Diff line number Diff line change
@@ -1,18 +1,18 @@
error: The function/method `takes_an_immutable_reference` doesn't need a mutable reference
error: the function `takes_an_immutable_reference` doesn't need a mutable reference
--> $DIR/mut_reference.rs:17:34
|
LL | takes_an_immutable_reference(&mut 42);
| ^^^^^^^
|
= note: `-D clippy::unnecessary-mut-passed` implied by `-D warnings`

error: The function/method `as_ptr` doesn't need a mutable reference
error: the function `as_ptr` doesn't need a mutable reference
--> $DIR/mut_reference.rs:19:12
|
LL | as_ptr(&mut 42);
| ^^^^^^^

error: The function/method `takes_an_immutable_reference` doesn't need a mutable reference
error: the method `takes_an_immutable_reference` doesn't need a mutable reference
--> $DIR/mut_reference.rs:23:44
|
LL | my_struct.takes_an_immutable_reference(&mut 42);
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