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Fix borrow and deref

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This commit is contained in:
Ryan Levick 2021-02-16 22:39:05 +01:00
parent da3995f0ec
commit 1999a3147f
11 changed files with 67 additions and 32 deletions
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18
compiler/rustc_lint/src/noop_method_call.rs
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@ -15,6 +15,7 @@ declare_lint! {
///
/// ```rust
/// # #![allow(unused)]
/// #![deny(noop_method_call)]
/// struct Foo;
/// let foo = &Foo;
/// let clone: &Foo = foo.clone();
@ -30,7 +31,7 @@ declare_lint! {
/// calling `clone` on a `&T` where `T` does not implement clone, actually doesn't do anything
/// as references are copy. This lint detects these calls and warns the user about them.
pub NOOP_METHOD_CALL,
Warn,
Allow,
"detects the use of well-known noop methods"
}
@ -50,7 +51,9 @@ impl<'tcx> LateLintPass<'tcx> for NoopMethodCall {
Some((DefKind::AssocFn, did)) => match cx.tcx.trait_of_item(did) {
// Check that we're dealing with a trait method for one of the traits we care about.
Some(trait_id)
if [sym::Clone].iter().any(|s| cx.tcx.is_diagnostic_item(*s, trait_id)) =>
if [sym::Clone, sym::Deref, sym::Borrow]
.iter()
.any(|s| cx.tcx.is_diagnostic_item(*s, trait_id)) =>
{
(trait_id, did)
}
@ -71,20 +74,11 @@ impl<'tcx> LateLintPass<'tcx> for NoopMethodCall {
_ => return,
};
// (Re)check that it implements the noop diagnostic.
for (s, peel_ref) in [(sym::noop_method_clone, false)].iter() {
for s in [sym::noop_method_clone, sym::noop_method_deref, sym::noop_method_borrow].iter() {
if cx.tcx.is_diagnostic_item(*s, i.def_id()) {
let method = &call.ident.name;
let receiver = &elements[0];
let receiver_ty = cx.typeck_results().expr_ty(receiver);
let receiver_ty = match receiver_ty.kind() {
// Remove one borrow from the receiver if appropriate to positively verify that
// the receiver `&self` type and the return type are the same, depending on the
// involved trait being checked.
ty::Ref(_, ty, _) if *peel_ref => ty,
// When it comes to `Clone` we need to check the `receiver_ty` directly.
// FIXME: we must come up with a better strategy for this.
_ => receiver_ty,
};
let expr_ty = cx.typeck_results().expr_ty_adjusted(expr);
if receiver_ty != expr_ty {
// This lint will only trigger if the receiver type and resulting expression \