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Update error message

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This commit is contained in:
Ryan Levick 2021-01-11 11:47:16 +01:00 committed by Ryan Levick
parent 16c4afbde4
commit 95e330bd01
4 changed files with 30 additions and 15 deletions
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9
compiler/rustc_lint/src/noop_method_call.rs
View File

@ -39,7 +39,7 @@
impl<'tcx> LateLintPass<'tcx> for NoopMethodCall {
fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
// We only care about method calls
if let ExprKind::MethodCall(..) = expr.kind {
if let ExprKind::MethodCall(call, ..) = expr.kind {
// Get the `DefId` only when dealing with an `AssocFn`
if let Some((DefKind::AssocFn, did)) =
cx.typeck_results().type_dependent_def(expr.hir_id)
@ -55,7 +55,7 @@ fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
}
let substs = cx.typeck_results().node_substs(expr.hir_id);
// We can't resolve on types that recursively require monomorphization,
// We can't resolve on types that require monomorphization,
// so check that we don't need to perfom substitution
if !substs.needs_subst() {
let param_env = cx.tcx.param_env(trait_id);
@ -73,9 +73,12 @@ fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
let expr_span = expr.span;
cx.struct_span_lint(NOOP_METHOD_CALL, expr_span, |lint| {
let message = "call to method that does nothing";
let method = &call.ident.name;
let message = format!("call to `.{}()` on a reference in this situation does nothing", &method);
lint.build(&message)
.span_label(expr_span, "unnecessary method call")
.note("the type the method is being called on and the return type are functionally equivalent.")
.note("therefore, the method call doesn't actually do anything and can be removed.")
.emit()
});
}

8
src/test/ui/issues/issue-11820.rs
View File

@ -6,9 +6,9 @@
struct NoClone;
fn main() {
let rnc = &NoClone;
let rsnc = &Some(NoClone);
let rnc = &NoClone;
let rsnc = &Some(NoClone);
let _: &NoClone = rnc.clone();
let _: &Option<NoClone> = rsnc.clone();
let _: &NoClone = rnc.clone();
let _: &Option<NoClone> = rsnc.clone();
}

9
src/test/ui/lint/noop-method-call.rs
View File

@ -22,21 +22,21 @@ fn deref(&self) -> &Self::Target {
fn main() {
let foo = &Foo(1u32);
let foo_clone: &Foo<u32> = foo.clone();
//~^ WARNING call to method that does nothing [noop_method_call]
//~^ WARNING call to `.clone()` on a reference in this situation does nothing [noop_method_call]
let bar = &Bar(1u32);
let bar_clone: Bar<u32> = bar.clone();
let deref = &&DerefExample(12u32);
let derefed: &DerefExample<u32> = deref.deref();
//~^ WARNING call to method that does nothing [noop_method_call]
//~^ WARNING call to `.deref()` on a reference in this situation does nothing [noop_method_call]
let deref = &DerefExample(12u32);
let derefed: &u32 = deref.deref();
let a = &&Foo(1u32);
let borrowed: &Foo<u32> = a.borrow();
//~^ WARNING call to method that does nothing [noop_method_call]
//~^ WARNING call to `.borrow()` on a reference in this situation does nothing [noop_method_call]
}
fn generic<T>(foo: &Foo<T>) {
@ -44,5 +44,6 @@ fn generic<T>(foo: &Foo<T>) {
}
fn non_generic(foo: &Foo<u32>) {
foo.clone(); //~ WARNING call to method that does nothing [noop_method_call]
foo.clone();
//~^ WARNING call to `.clone()` on a reference in this situation does nothing [noop_method_call]
}

19
src/test/ui/lint/noop-method-call.stderr
View File

@ -1,28 +1,39 @@
warning: call to method that does nothing
warning: call to `.clone()` on a reference in this situation does nothing
--> $DIR/noop-method-call.rs:24:32
|
LL | let foo_clone: &Foo<u32> = foo.clone();
| ^^^^^^^^^^^ unnecessary method call
|
= note: `#[warn(noop_method_call)]` on by default
= note: the type the method is being called on and the return type are functionally equivalent.
= note: therefore, the method call doesn't actually do anything and can be removed.
warning: call to method that does nothing
warning: call to `.deref()` on a reference in this situation does nothing
--> $DIR/noop-method-call.rs:31:39
|
LL | let derefed: &DerefExample<u32> = deref.deref();
| ^^^^^^^^^^^^^ unnecessary method call
|
= note: the type the method is being called on and the return type are functionally equivalent.
= note: therefore, the method call doesn't actually do anything and can be removed.
warning: call to method that does nothing
warning: call to `.borrow()` on a reference in this situation does nothing
--> $DIR/noop-method-call.rs:38:31
|
LL | let borrowed: &Foo<u32> = a.borrow();
| ^^^^^^^^^^ unnecessary method call
|
= note: the type the method is being called on and the return type are functionally equivalent.
= note: therefore, the method call doesn't actually do anything and can be removed.
warning: call to method that does nothing
warning: call to `.clone()` on a reference in this situation does nothing
--> $DIR/noop-method-call.rs:47:5
|
LL | foo.clone();
| ^^^^^^^^^^^ unnecessary method call
|
= note: the type the method is being called on and the return type are functionally equivalent.
= note: therefore, the method call doesn't actually do anything and can be removed.
warning: 4 warnings emitted