From a98f4d3b9c41c950f33b38f050fff6492864b58f Mon Sep 17 00:00:00 2001
From: Deadbeef <ent3rm4n@gmail.com>
Date: Wed, 24 May 2023 16:05:42 +0000
Subject: [PATCH 1/3] make `noop_method_call` warn by default
---
compiler/rustc_lint/src/noop_method_call.rs | 3 +--
tests/ui/issues/issue-11820.rs | 2 ++
tests/ui/lint/noop-method-call.rs | 1 -
tests/ui/lint/noop-method-call.stderr | 22 +++++++++------------
tests/ui/underscore-imports/cycle.rs | 2 ++
tests/ui/underscore-imports/hygiene.rs | 1 +
6 files changed, 15 insertions(+), 16 deletions(-)
diff --git a/compiler/rustc_lint/src/noop_method_call.rs b/compiler/rustc_lint/src/noop_method_call.rs
index d054966459d85..ad67a3ce0e6eb 100644
--- a/compiler/rustc_lint/src/noop_method_call.rs
+++ b/compiler/rustc_lint/src/noop_method_call.rs
@@ -16,7 +16,6 @@ declare_lint! {
///
/// ```rust
/// # #![allow(unused)]
- /// #![warn(noop_method_call)]
/// struct Foo;
/// let foo = &Foo;
/// let clone: &Foo = foo.clone();
@@ -32,7 +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,
- Allow,
+ Warn,
"detects the use of well-known noop methods"
}
diff --git a/tests/ui/issues/issue-11820.rs b/tests/ui/issues/issue-11820.rs
index 7ffe9652797cf..dc6349b10ee58 100644
--- a/tests/ui/issues/issue-11820.rs
+++ b/tests/ui/issues/issue-11820.rs
@@ -1,6 +1,8 @@
// run-pass
// pretty-expanded FIXME #23616
+#![allow(noop_method_call)]
+
struct NoClone;
fn main() {
diff --git a/tests/ui/lint/noop-method-call.rs b/tests/ui/lint/noop-method-call.rs
index dbcf2a5131b5b..8ce6c859b2480 100644
--- a/tests/ui/lint/noop-method-call.rs
+++ b/tests/ui/lint/noop-method-call.rs
@@ -1,7 +1,6 @@
// check-pass
#![allow(unused)]
-#![warn(noop_method_call)]
use std::borrow::Borrow;
use std::ops::Deref;
diff --git a/tests/ui/lint/noop-method-call.stderr b/tests/ui/lint/noop-method-call.stderr
index 37cd1a0fc18ea..ae61913f99381 100644
--- a/tests/ui/lint/noop-method-call.stderr
+++ b/tests/ui/lint/noop-method-call.stderr
@@ -1,18 +1,14 @@
warning: call to `.clone()` on a reference in this situation does nothing
- --> $DIR/noop-method-call.rs:16:71
+ --> $DIR/noop-method-call.rs:15:71
|
LL | let non_clone_type_ref_clone: &PlainType<u32> = non_clone_type_ref.clone();
| ^^^^^^^^ unnecessary method call
|
= note: the type `&PlainType<u32>` which `clone` is being called on is the same as the type returned from `clone`, so the method call does not do anything and can be removed
-note: the lint level is defined here
- --> $DIR/noop-method-call.rs:4:9
- |
-LL | #![warn(noop_method_call)]
- | ^^^^^^^^^^^^^^^^
+ = note: `#[warn(noop_method_call)]` on by default
warning: using `.clone()` on a double reference, which returns `&CloneType<u32>` instead of cloning the inner type
- --> $DIR/noop-method-call.rs:23:63
+ --> $DIR/noop-method-call.rs:22:63
|
LL | let clone_type_ref_clone: &CloneType<u32> = clone_type_ref.clone();
| ^^^^^^^^
@@ -20,7 +16,7 @@ LL | let clone_type_ref_clone: &CloneType<u32> = clone_type_ref.clone();
= note: `#[warn(suspicious_double_ref_op)]` on by default
warning: call to `.deref()` on a reference in this situation does nothing
- --> $DIR/noop-method-call.rs:27:63
+ --> $DIR/noop-method-call.rs:26:63
|
LL | let non_deref_type_deref: &PlainType<u32> = non_deref_type.deref();
| ^^^^^^^^ unnecessary method call
@@ -28,13 +24,13 @@ LL | let non_deref_type_deref: &PlainType<u32> = non_deref_type.deref();
= note: the type `&PlainType<u32>` which `deref` is being called on is the same as the type returned from `deref`, so the method call does not do anything and can be removed
warning: using `.deref()` on a double reference, which returns `&PlainType<u32>` instead of dereferencing the inner type
- --> $DIR/noop-method-call.rs:31:63
+ --> $DIR/noop-method-call.rs:30:63
|
LL | let non_deref_type_deref: &PlainType<u32> = non_deref_type.deref();
| ^^^^^^^^
warning: call to `.borrow()` on a reference in this situation does nothing
- --> $DIR/noop-method-call.rs:35:66
+ --> $DIR/noop-method-call.rs:34:66
|
LL | let non_borrow_type_borrow: &PlainType<u32> = non_borrow_type.borrow();
| ^^^^^^^^^ unnecessary method call
@@ -42,13 +38,13 @@ LL | let non_borrow_type_borrow: &PlainType<u32> = non_borrow_type.borrow();
= note: the type `&PlainType<u32>` which `borrow` is being called on is the same as the type returned from `borrow`, so the method call does not do anything and can be removed
warning: using `.clone()` on a double reference, which returns `&str` instead of cloning the inner type
- --> $DIR/noop-method-call.rs:43:44
+ --> $DIR/noop-method-call.rs:42:44
|
LL | let _v: Vec<&str> = xs.iter().map(|x| x.clone()).collect(); // could use `*x` instead
| ^^^^^^^^
warning: call to `.clone()` on a reference in this situation does nothing
- --> $DIR/noop-method-call.rs:48:19
+ --> $DIR/noop-method-call.rs:47:19
|
LL | non_clone_type.clone();
| ^^^^^^^^ unnecessary method call
@@ -56,7 +52,7 @@ LL | non_clone_type.clone();
= note: the type `&PlainType<T>` which `clone` is being called on is the same as the type returned from `clone`, so the method call does not do anything and can be removed
warning: call to `.clone()` on a reference in this situation does nothing
- --> $DIR/noop-method-call.rs:53:19
+ --> $DIR/noop-method-call.rs:52:19
|
LL | non_clone_type.clone();
| ^^^^^^^^ unnecessary method call
diff --git a/tests/ui/underscore-imports/cycle.rs b/tests/ui/underscore-imports/cycle.rs
index bacf9b2d5a96a..c8a293687878f 100644
--- a/tests/ui/underscore-imports/cycle.rs
+++ b/tests/ui/underscore-imports/cycle.rs
@@ -2,6 +2,8 @@
// check-pass
+#![allow(noop_method_call)]
+
mod x {
pub use crate::y::*;
pub use std::ops::Deref as _;
diff --git a/tests/ui/underscore-imports/hygiene.rs b/tests/ui/underscore-imports/hygiene.rs
index c4db65245386f..7795ccb797199 100644
--- a/tests/ui/underscore-imports/hygiene.rs
+++ b/tests/ui/underscore-imports/hygiene.rs
@@ -3,6 +3,7 @@
// check-pass
#![feature(decl_macro)]
+#![allow(noop_method_call)]
mod x {
pub use std::ops::Deref as _;
From b5e49153aca523a9c26600154337462e9214928b Mon Sep 17 00:00:00 2001
From: Deadbeef <ent3rm4n@gmail.com>
Date: Thu, 25 May 2023 05:21:44 +0000
Subject: [PATCH 2/3] fix
---
compiler/rustc_lint/messages.ftl | 2 +-
compiler/rustc_lint/src/lints.rs | 3 +-
compiler/rustc_lint/src/noop_method_call.rs | 29 +++++++++----------
.../src/traits/error_reporting/suggestions.rs | 3 +-
library/core/benches/iter.rs | 1 +
.../tests/ui/explicit_deref_methods.fixed | 1 +
.../clippy/tests/ui/explicit_deref_methods.rs | 1 +
.../tests/ui/explicit_deref_methods.stderr | 24 +++++++--------
src/tools/compiletest/src/lib.rs | 2 +-
tests/ui/lint/noop-method-call.stderr | 10 +++----
tests/ui/lint/suspicious-double-ref-op.stderr | 4 +--
11 files changed, 40 insertions(+), 40 deletions(-)
diff --git a/compiler/rustc_lint/messages.ftl b/compiler/rustc_lint/messages.ftl
index 98fe3821947d5..cb8fe4735c0e2 100644
--- a/compiler/rustc_lint/messages.ftl
+++ b/compiler/rustc_lint/messages.ftl
@@ -405,7 +405,7 @@ lint_non_upper_case_global = {$sort} `{$name}` should have an upper case name
lint_noop_method_call = call to `.{$method}()` on a reference in this situation does nothing
.label = unnecessary method call
- .note = the type `{$receiver_ty}` which `{$method}` is being called on is the same as the type returned from `{$method}`, so the method call does not do anything and can be removed
+ .note = the type `{$orig_ty}` does not implement `{$trait_}`, so calling `{$method}` on `&{$orig_ty}` copies the reference, which does not do anything and can be removed
lint_only_cast_u8_to_char = only `u8` can be cast into `char`
.suggestion = use a `char` literal instead
diff --git a/compiler/rustc_lint/src/lints.rs b/compiler/rustc_lint/src/lints.rs
index fd15f7952023a..5d9971acfc3c3 100644
--- a/compiler/rustc_lint/src/lints.rs
+++ b/compiler/rustc_lint/src/lints.rs
@@ -1206,7 +1206,8 @@ pub enum NonUpperCaseGlobalSub {
#[note]
pub struct NoopMethodCallDiag<'a> {
pub method: Symbol,
- pub receiver_ty: Ty<'a>,
+ pub orig_ty: Ty<'a>,
+ pub trait_: Symbol,
#[label]
pub label: Span,
}
diff --git a/compiler/rustc_lint/src/noop_method_call.rs b/compiler/rustc_lint/src/noop_method_call.rs
index ad67a3ce0e6eb..7207492e342f7 100644
--- a/compiler/rustc_lint/src/noop_method_call.rs
+++ b/compiler/rustc_lint/src/noop_method_call.rs
@@ -75,21 +75,16 @@ impl<'tcx> LateLintPass<'tcx> for NoopMethodCall {
// We only care about method calls corresponding to the `Clone`, `Deref` and `Borrow`
// traits and ignore any other method call.
- let did = match cx.typeck_results().type_dependent_def(expr.hir_id) {
- // Verify we are dealing with a method/associated function.
- 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 matches!(
- cx.tcx.get_diagnostic_name(trait_id),
- Some(sym::Borrow | sym::Clone | sym::Deref)
- ) =>
- {
- did
- }
- _ => return,
- },
- _ => return,
+ //
+ // Verify we are dealing with a method/associated function, and check that we're dealing
+ // with a trait method for one of the traits we care about.
+ let (did, trait_) = if let Some((DefKind::AssocFn, did)) = cx.typeck_results().type_dependent_def(expr.hir_id)
+ && let Some(trait_id) = cx.tcx.trait_of_item(did)
+ && let Some(trait_ @ (sym::Borrow | sym::Clone | sym::Deref)) = cx.tcx.get_diagnostic_name(trait_id)
+ {
+ (did, trait_)
+ } else {
+ return;
};
let substs = cx
.tcx
@@ -121,11 +116,13 @@ impl<'tcx> LateLintPass<'tcx> for NoopMethodCall {
let expr_span = expr.span;
let span = expr_span.with_lo(receiver.span.hi());
+ let orig_ty = expr_ty.peel_refs();
+
if receiver_ty == expr_ty {
cx.emit_spanned_lint(
NOOP_METHOD_CALL,
span,
- NoopMethodCallDiag { method: call.ident.name, receiver_ty, label: span },
+ NoopMethodCallDiag { method: call.ident.name, orig_ty, trait_, label: span },
);
} else {
cx.emit_spanned_lint(
diff --git a/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs b/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
index 42038dbc3d82e..ed6f6ede7381b 100644
--- a/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
+++ b/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
@@ -40,7 +40,6 @@ use rustc_span::{BytePos, DesugaringKind, ExpnKind, MacroKind, Span, DUMMY_SP};
use rustc_target::spec::abi;
use std::borrow::Cow;
use std::iter;
-use std::ops::Deref;
use super::InferCtxtPrivExt;
use crate::infer::InferCtxtExt as _;
@@ -3466,7 +3465,7 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
// to an associated type (as seen from `trait_pred`) in the predicate. Like in
// trait_pred `S: Sum<<Self as Iterator>::Item>` and predicate `i32: Sum<&()>`
let mut type_diffs = vec![];
- if let ObligationCauseCode::ExprBindingObligation(def_id, _, _, idx) = parent_code.deref()
+ if let ObligationCauseCode::ExprBindingObligation(def_id, _, _, idx) = parent_code
&& let Some(node_substs) = typeck_results.node_substs_opt(call_hir_id)
&& let where_clauses = self.tcx.predicates_of(def_id).instantiate(self.tcx, node_substs)
&& let Some(where_pred) = where_clauses.predicates.get(*idx)
diff --git a/library/core/benches/iter.rs b/library/core/benches/iter.rs
index 60ef83223d104..4d68960431c7a 100644
--- a/library/core/benches/iter.rs
+++ b/library/core/benches/iter.rs
@@ -421,6 +421,7 @@ fn bench_next_chunk_copied(b: &mut Bencher) {
/// Exercises the TrustedRandomAccess specialization in ArrayChunks
#[bench]
+#[allow(noop_method_call)]
fn bench_next_chunk_trusted_random_access(b: &mut Bencher) {
let v = vec![1u8; 1024];
diff --git a/src/tools/clippy/tests/ui/explicit_deref_methods.fixed b/src/tools/clippy/tests/ui/explicit_deref_methods.fixed
index 60482c66da7c4..f5510461a40aa 100644
--- a/src/tools/clippy/tests/ui/explicit_deref_methods.fixed
+++ b/src/tools/clippy/tests/ui/explicit_deref_methods.fixed
@@ -4,6 +4,7 @@
#![allow(
clippy::borrow_deref_ref,
suspicious_double_ref_op,
+ noop_method_call,
clippy::explicit_auto_deref,
clippy::needless_borrow,
clippy::uninlined_format_args
diff --git a/src/tools/clippy/tests/ui/explicit_deref_methods.rs b/src/tools/clippy/tests/ui/explicit_deref_methods.rs
index e3613e216bb22..9b67308b91f1b 100644
--- a/src/tools/clippy/tests/ui/explicit_deref_methods.rs
+++ b/src/tools/clippy/tests/ui/explicit_deref_methods.rs
@@ -4,6 +4,7 @@
#![allow(
clippy::borrow_deref_ref,
suspicious_double_ref_op,
+ noop_method_call,
clippy::explicit_auto_deref,
clippy::needless_borrow,
clippy::uninlined_format_args
diff --git a/src/tools/clippy/tests/ui/explicit_deref_methods.stderr b/src/tools/clippy/tests/ui/explicit_deref_methods.stderr
index 4b10ed1377b0d..809a94ddccd83 100644
--- a/src/tools/clippy/tests/ui/explicit_deref_methods.stderr
+++ b/src/tools/clippy/tests/ui/explicit_deref_methods.stderr
@@ -1,5 +1,5 @@
error: explicit `deref` method call
- --> $DIR/explicit_deref_methods.rs:36:19
+ --> $DIR/explicit_deref_methods.rs:37:19
|
LL | let b: &str = a.deref();
| ^^^^^^^^^ help: try this: `&*a`
@@ -7,67 +7,67 @@ LL | let b: &str = a.deref();
= note: `-D clippy::explicit-deref-methods` implied by `-D warnings`
error: explicit `deref_mut` method call
- --> $DIR/explicit_deref_methods.rs:38:23
+ --> $DIR/explicit_deref_methods.rs:39:23
|
LL | let b: &mut str = a.deref_mut();
| ^^^^^^^^^^^^^ help: try this: `&mut **a`
error: explicit `deref` method call
- --> $DIR/explicit_deref_methods.rs:41:39
+ --> $DIR/explicit_deref_methods.rs:42:39
|
LL | let b: String = format!("{}, {}", a.deref(), a.deref());
| ^^^^^^^^^ help: try this: `&*a`
error: explicit `deref` method call
- --> $DIR/explicit_deref_methods.rs:41:50
+ --> $DIR/explicit_deref_methods.rs:42:50
|
LL | let b: String = format!("{}, {}", a.deref(), a.deref());
| ^^^^^^^^^ help: try this: `&*a`
error: explicit `deref` method call
- --> $DIR/explicit_deref_methods.rs:43:20
+ --> $DIR/explicit_deref_methods.rs:44:20
|
LL | println!("{}", a.deref());
| ^^^^^^^^^ help: try this: `&*a`
error: explicit `deref` method call
- --> $DIR/explicit_deref_methods.rs:46:11
+ --> $DIR/explicit_deref_methods.rs:47:11
|
LL | match a.deref() {
| ^^^^^^^^^ help: try this: `&*a`
error: explicit `deref` method call
- --> $DIR/explicit_deref_methods.rs:50:28
+ --> $DIR/explicit_deref_methods.rs:51:28
|
LL | let b: String = concat(a.deref());
| ^^^^^^^^^ help: try this: `&*a`
error: explicit `deref` method call
- --> $DIR/explicit_deref_methods.rs:52:13
+ --> $DIR/explicit_deref_methods.rs:53:13
|
LL | let b = just_return(a).deref();
| ^^^^^^^^^^^^^^^^^^^^^^ help: try this: `just_return(a)`
error: explicit `deref` method call
- --> $DIR/explicit_deref_methods.rs:54:28
+ --> $DIR/explicit_deref_methods.rs:55:28
|
LL | let b: String = concat(just_return(a).deref());
| ^^^^^^^^^^^^^^^^^^^^^^ help: try this: `just_return(a)`
error: explicit `deref` method call
- --> $DIR/explicit_deref_methods.rs:56:19
+ --> $DIR/explicit_deref_methods.rs:57:19
|
LL | let b: &str = a.deref().deref();
| ^^^^^^^^^^^^^^^^^ help: try this: `&**a`
error: explicit `deref` method call
- --> $DIR/explicit_deref_methods.rs:59:13
+ --> $DIR/explicit_deref_methods.rs:60:13
|
LL | let b = opt_a.unwrap().deref();
| ^^^^^^^^^^^^^^^^^^^^^^ help: try this: `&*opt_a.unwrap()`
error: explicit `deref` method call
- --> $DIR/explicit_deref_methods.rs:85:31
+ --> $DIR/explicit_deref_methods.rs:86:31
|
LL | let b: &str = expr_deref!(a.deref());
| ^^^^^^^^^ help: try this: `&*a`
diff --git a/src/tools/compiletest/src/lib.rs b/src/tools/compiletest/src/lib.rs
index fc48d0159905b..1a765477fe501 100644
--- a/src/tools/compiletest/src/lib.rs
+++ b/src/tools/compiletest/src/lib.rs
@@ -1119,7 +1119,7 @@ fn check_overlapping_tests(found_paths: &BTreeSet<PathBuf>) {
for path in found_paths {
for ancestor in path.ancestors().skip(1) {
if found_paths.contains(ancestor) {
- collisions.push((path, ancestor.clone()));
+ collisions.push((path, ancestor));
}
}
}
diff --git a/tests/ui/lint/noop-method-call.stderr b/tests/ui/lint/noop-method-call.stderr
index ae61913f99381..fb02c6f361e0a 100644
--- a/tests/ui/lint/noop-method-call.stderr
+++ b/tests/ui/lint/noop-method-call.stderr
@@ -4,7 +4,7 @@ warning: call to `.clone()` on a reference in this situation does nothing
LL | let non_clone_type_ref_clone: &PlainType<u32> = non_clone_type_ref.clone();
| ^^^^^^^^ unnecessary method call
|
- = note: the type `&PlainType<u32>` which `clone` is being called on is the same as the type returned from `clone`, so the method call does not do anything and can be removed
+ = note: the type `PlainType<u32>` does not implement `Clone`, so calling `clone` on `&PlainType<u32>` copies the reference, which does not do anything and can be removed
= note: `#[warn(noop_method_call)]` on by default
warning: using `.clone()` on a double reference, which returns `&CloneType<u32>` instead of cloning the inner type
@@ -21,7 +21,7 @@ warning: call to `.deref()` on a reference in this situation does nothing
LL | let non_deref_type_deref: &PlainType<u32> = non_deref_type.deref();
| ^^^^^^^^ unnecessary method call
|
- = note: the type `&PlainType<u32>` which `deref` is being called on is the same as the type returned from `deref`, so the method call does not do anything and can be removed
+ = note: the type `PlainType<u32>` does not implement `Deref`, so calling `deref` on `&PlainType<u32>` copies the reference, which does not do anything and can be removed
warning: using `.deref()` on a double reference, which returns `&PlainType<u32>` instead of dereferencing the inner type
--> $DIR/noop-method-call.rs:30:63
@@ -35,7 +35,7 @@ warning: call to `.borrow()` on a reference in this situation does nothing
LL | let non_borrow_type_borrow: &PlainType<u32> = non_borrow_type.borrow();
| ^^^^^^^^^ unnecessary method call
|
- = note: the type `&PlainType<u32>` which `borrow` is being called on is the same as the type returned from `borrow`, so the method call does not do anything and can be removed
+ = note: the type `PlainType<u32>` does not implement `Borrow`, so calling `borrow` on `&PlainType<u32>` copies the reference, which does not do anything and can be removed
warning: using `.clone()` on a double reference, which returns `&str` instead of cloning the inner type
--> $DIR/noop-method-call.rs:42:44
@@ -49,7 +49,7 @@ warning: call to `.clone()` on a reference in this situation does nothing
LL | non_clone_type.clone();
| ^^^^^^^^ unnecessary method call
|
- = note: the type `&PlainType<T>` which `clone` is being called on is the same as the type returned from `clone`, so the method call does not do anything and can be removed
+ = note: the type `PlainType<T>` does not implement `Clone`, so calling `clone` on `&PlainType<T>` copies the reference, which does not do anything and can be removed
warning: call to `.clone()` on a reference in this situation does nothing
--> $DIR/noop-method-call.rs:52:19
@@ -57,7 +57,7 @@ warning: call to `.clone()` on a reference in this situation does nothing
LL | non_clone_type.clone();
| ^^^^^^^^ unnecessary method call
|
- = note: the type `&PlainType<u32>` which `clone` is being called on is the same as the type returned from `clone`, so the method call does not do anything and can be removed
+ = note: the type `PlainType<u32>` does not implement `Clone`, so calling `clone` on `&PlainType<u32>` copies the reference, which does not do anything and can be removed
warning: 8 warnings emitted
diff --git a/tests/ui/lint/suspicious-double-ref-op.stderr b/tests/ui/lint/suspicious-double-ref-op.stderr
index d15487ca23865..f2128f2a0edad 100644
--- a/tests/ui/lint/suspicious-double-ref-op.stderr
+++ b/tests/ui/lint/suspicious-double-ref-op.stderr
@@ -16,7 +16,7 @@ error: call to `.clone()` on a reference in this situation does nothing
LL | let _ = &mut encoded.clone();
| ^^^^^^^^ unnecessary method call
|
- = note: the type `&[u8]` which `clone` is being called on is the same as the type returned from `clone`, so the method call does not do anything and can be removed
+ = note: the type `[u8]` does not implement `Clone`, so calling `clone` on `&[u8]` copies the reference, which does not do anything and can be removed
note: the lint level is defined here
--> $DIR/suspicious-double-ref-op.rs:2:35
|
@@ -29,7 +29,7 @@ error: call to `.clone()` on a reference in this situation does nothing
LL | let _ = &encoded.clone();
| ^^^^^^^^ unnecessary method call
|
- = note: the type `&[u8]` which `clone` is being called on is the same as the type returned from `clone`, so the method call does not do anything and can be removed
+ = note: the type `[u8]` does not implement `Clone`, so calling `clone` on `&[u8]` copies the reference, which does not do anything and can be removed
error: aborting due to 3 previous errors
From 59b2ca3c43255983f71961a7145f11a9dadee9ac Mon Sep 17 00:00:00 2001
From: Deadbeef <ent3rm4n@gmail.com>
Date: Sun, 4 Jun 2023 15:04:23 +0000
Subject: [PATCH 3/3] deny noop method call
---
compiler/rustc_lint/src/noop_method_call.rs | 2 +-
tests/ui/lint/noop-method-call.rs | 1 +
tests/ui/lint/noop-method-call.stderr | 22 ++++++++++++---------
3 files changed, 15 insertions(+), 10 deletions(-)
diff --git a/compiler/rustc_lint/src/noop_method_call.rs b/compiler/rustc_lint/src/noop_method_call.rs
index 7207492e342f7..6546f979ef9fa 100644
--- a/compiler/rustc_lint/src/noop_method_call.rs
+++ b/compiler/rustc_lint/src/noop_method_call.rs
@@ -31,7 +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,
+ Deny,
"detects the use of well-known noop methods"
}
diff --git a/tests/ui/lint/noop-method-call.rs b/tests/ui/lint/noop-method-call.rs
index 8ce6c859b2480..dbcf2a5131b5b 100644
--- a/tests/ui/lint/noop-method-call.rs
+++ b/tests/ui/lint/noop-method-call.rs
@@ -1,6 +1,7 @@
// check-pass
#![allow(unused)]
+#![warn(noop_method_call)]
use std::borrow::Borrow;
use std::ops::Deref;
diff --git a/tests/ui/lint/noop-method-call.stderr b/tests/ui/lint/noop-method-call.stderr
index fb02c6f361e0a..cb0777775a0ec 100644
--- a/tests/ui/lint/noop-method-call.stderr
+++ b/tests/ui/lint/noop-method-call.stderr
@@ -1,14 +1,18 @@
warning: call to `.clone()` on a reference in this situation does nothing
- --> $DIR/noop-method-call.rs:15:71
+ --> $DIR/noop-method-call.rs:16:71
|
LL | let non_clone_type_ref_clone: &PlainType<u32> = non_clone_type_ref.clone();
| ^^^^^^^^ unnecessary method call
|
= note: the type `PlainType<u32>` does not implement `Clone`, so calling `clone` on `&PlainType<u32>` copies the reference, which does not do anything and can be removed
- = note: `#[warn(noop_method_call)]` on by default
+note: the lint level is defined here
+ --> $DIR/noop-method-call.rs:4:9
+ |
+LL | #![warn(noop_method_call)]
+ | ^^^^^^^^^^^^^^^^
warning: using `.clone()` on a double reference, which returns `&CloneType<u32>` instead of cloning the inner type
- --> $DIR/noop-method-call.rs:22:63
+ --> $DIR/noop-method-call.rs:23:63
|
LL | let clone_type_ref_clone: &CloneType<u32> = clone_type_ref.clone();
| ^^^^^^^^
@@ -16,7 +20,7 @@ LL | let clone_type_ref_clone: &CloneType<u32> = clone_type_ref.clone();
= note: `#[warn(suspicious_double_ref_op)]` on by default
warning: call to `.deref()` on a reference in this situation does nothing
- --> $DIR/noop-method-call.rs:26:63
+ --> $DIR/noop-method-call.rs:27:63
|
LL | let non_deref_type_deref: &PlainType<u32> = non_deref_type.deref();
| ^^^^^^^^ unnecessary method call
@@ -24,13 +28,13 @@ LL | let non_deref_type_deref: &PlainType<u32> = non_deref_type.deref();
= note: the type `PlainType<u32>` does not implement `Deref`, so calling `deref` on `&PlainType<u32>` copies the reference, which does not do anything and can be removed
warning: using `.deref()` on a double reference, which returns `&PlainType<u32>` instead of dereferencing the inner type
- --> $DIR/noop-method-call.rs:30:63
+ --> $DIR/noop-method-call.rs:31:63
|
LL | let non_deref_type_deref: &PlainType<u32> = non_deref_type.deref();
| ^^^^^^^^
warning: call to `.borrow()` on a reference in this situation does nothing
- --> $DIR/noop-method-call.rs:34:66
+ --> $DIR/noop-method-call.rs:35:66
|
LL | let non_borrow_type_borrow: &PlainType<u32> = non_borrow_type.borrow();
| ^^^^^^^^^ unnecessary method call
@@ -38,13 +42,13 @@ LL | let non_borrow_type_borrow: &PlainType<u32> = non_borrow_type.borrow();
= note: the type `PlainType<u32>` does not implement `Borrow`, so calling `borrow` on `&PlainType<u32>` copies the reference, which does not do anything and can be removed
warning: using `.clone()` on a double reference, which returns `&str` instead of cloning the inner type
- --> $DIR/noop-method-call.rs:42:44
+ --> $DIR/noop-method-call.rs:43:44
|
LL | let _v: Vec<&str> = xs.iter().map(|x| x.clone()).collect(); // could use `*x` instead
| ^^^^^^^^
warning: call to `.clone()` on a reference in this situation does nothing
- --> $DIR/noop-method-call.rs:47:19
+ --> $DIR/noop-method-call.rs:48:19
|
LL | non_clone_type.clone();
| ^^^^^^^^ unnecessary method call
@@ -52,7 +56,7 @@ LL | non_clone_type.clone();
= note: the type `PlainType<T>` does not implement `Clone`, so calling `clone` on `&PlainType<T>` copies the reference, which does not do anything and can be removed
warning: call to `.clone()` on a reference in this situation does nothing
- --> $DIR/noop-method-call.rs:52:19
+ --> $DIR/noop-method-call.rs:53:19
|
LL | non_clone_type.clone();
| ^^^^^^^^ unnecessary method call