feat(multiple_inherent_impl): Add config option to target specific scope

CHANGELOG.md

@@ -6874,6 +6874,7 @@ Released 2018-09-13
 [`excessive-nesting-threshold`]: https://doc.rust-lang.org/clippy/lint_configuration.html#excessive-nesting-threshold
 [`future-size-threshold`]: https://doc.rust-lang.org/clippy/lint_configuration.html#future-size-threshold
 [`ignore-interior-mutability`]: https://doc.rust-lang.org/clippy/lint_configuration.html#ignore-interior-mutability
+[`inherent-impl-lint-scope`]: https://doc.rust-lang.org/clippy/lint_configuration.html#inherent-impl-lint-scope
 [`large-error-threshold`]: https://doc.rust-lang.org/clippy/lint_configuration.html#large-error-threshold
 [`lint-commented-code`]: https://doc.rust-lang.org/clippy/lint_configuration.html#lint-commented-code
 [`literal-representation-threshold`]: https://doc.rust-lang.org/clippy/lint_configuration.html#literal-representation-threshold

book/src/lint_configuration.md

@@ -671,6 +671,16 @@ A list of paths to types that should be treated as if they do not contain interi
 * [`mutable_key_type`](https://rust-lang.github.io/rust-clippy/master/index.html#mutable_key_type)
 
 
+## `inherent-impl-lint-scope`
+Sets the scope ("crate", "file", or "module") in which duplicate inherent `impl` blocks for the same type are linted.
+
+**Default Value:** `"crate"`
+
+---
+**Affected lints:**
+* [`multiple_inherent_impl`](https://rust-lang.github.io/rust-clippy/master/index.html#multiple_inherent_impl)
+
+
 ## `large-error-threshold`
 The maximum size of the `Err`-variant in a `Result` returned from a function
 

clippy_config/src/conf.rs

@@ -1,9 +1,9 @@
 use crate::ClippyConfiguration;
 use crate::types::{
-    DisallowedPath, DisallowedPathWithoutReplacement, MacroMatcher, MatchLintBehaviour, PubUnderscoreFieldsBehaviour,
-    Rename, SourceItemOrdering, SourceItemOrderingCategory, SourceItemOrderingModuleItemGroupings,
-    SourceItemOrderingModuleItemKind, SourceItemOrderingTraitAssocItemKind, SourceItemOrderingTraitAssocItemKinds,
-    SourceItemOrderingWithinModuleItemGroupings,
+    DisallowedPath, DisallowedPathWithoutReplacement, InherentImplLintScope, MacroMatcher, MatchLintBehaviour,
+    PubUnderscoreFieldsBehaviour, Rename, SourceItemOrdering, SourceItemOrderingCategory,
+    SourceItemOrderingModuleItemGroupings, SourceItemOrderingModuleItemKind, SourceItemOrderingTraitAssocItemKind,
+    SourceItemOrderingTraitAssocItemKinds, SourceItemOrderingWithinModuleItemGroupings,
 };
 use clippy_utils::msrvs::Msrv;
 use itertools::Itertools;
@@ -663,6 +663,9 @@ fn span_from_toml_range(file: &SourceFile, span: Range<usize>) -> Span {
     /// A list of paths to types that should be treated as if they do not contain interior mutability
     #[lints(borrow_interior_mutable_const, declare_interior_mutable_const, ifs_same_cond, mutable_key_type)]
     ignore_interior_mutability: Vec<String> = Vec::from(["bytes::Bytes".into()]),
+    /// Sets the scope ("crate", "file", or "module") in which duplicate inherent `impl` blocks for the same type are linted.
+    #[lints(multiple_inherent_impl)]
+    inherent_impl_lint_scope: InherentImplLintScope = InherentImplLintScope::Crate,
     /// The maximum size of the `Err`-variant in a `Result` returned from a function
     #[lints(result_large_err)]
     large_error_threshold: u64 = 128,

clippy_config/src/types.rs

@@ -698,3 +698,11 @@ pub enum PubUnderscoreFieldsBehaviour {
     PubliclyExported,
     AllPubFields,
 }
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Deserialize, Serialize)]
+#[serde(rename_all = "lowercase")]
+pub enum InherentImplLintScope {
+    Crate,
+    File,
+    Module,
+}

clippy_lints/src/inherent_impl.rs

@@ -1,17 +1,23 @@
+use clippy_config::Conf;
+use clippy_config::types::InherentImplLintScope;
 use clippy_utils::diagnostics::span_lint_and_then;
-use clippy_utils::is_lint_allowed;
+use clippy_utils::fulfill_or_allowed;
 use rustc_data_structures::fx::FxHashMap;
-use rustc_hir::def_id::LocalDefId;
+use rustc_hir::def_id::{LocalDefId, LocalModDefId};
 use rustc_hir::{Item, ItemKind, Node};
 use rustc_lint::{LateContext, LateLintPass};
-use rustc_session::declare_lint_pass;
-use rustc_span::Span;
+use rustc_session::impl_lint_pass;
+use rustc_span::{FileName, Span};
 use std::collections::hash_map::Entry;
 
 declare_clippy_lint! {
     /// ### What it does
     /// Checks for multiple inherent implementations of a struct
     ///
+    /// The config option controls the scope in which multiple inherent `impl` blocks for the same
+    /// struct are linted, allowing values of `module` (only within the same module), `file`
+    /// (within the same file), or `crate` (anywhere in the crate, default).
+    ///
     /// ### Why restrict this?
     /// Splitting the implementation of a type makes the code harder to navigate.
     ///
@@ -41,7 +47,26 @@
     "Multiple inherent impl that could be grouped"
 }
 
-declare_lint_pass!(MultipleInherentImpl => [MULTIPLE_INHERENT_IMPL]);
+impl_lint_pass!(MultipleInherentImpl => [MULTIPLE_INHERENT_IMPL]);
+
+pub struct MultipleInherentImpl {
+    scope: InherentImplLintScope,
+}
+
+impl MultipleInherentImpl {
+    pub fn new(conf: &'static Conf) -> Self {
+        Self {
+            scope: conf.inherent_impl_lint_scope,
+        }
+    }
+}
+
+#[derive(Hash, Eq, PartialEq, Clone)]
+enum Criterion {
+    Module(LocalModDefId),
+    File(FileName),
+    Crate,
+}
 
 impl<'tcx> LateLintPass<'tcx> for MultipleInherentImpl {
     fn check_crate_post(&mut self, cx: &LateContext<'tcx>) {
@@ -55,18 +80,27 @@ fn check_crate_post(&mut self, cx: &LateContext<'tcx>) {
 
         for (&id, impl_ids) in &impls.inherent_impls {
             if impl_ids.len() < 2
-            // Check for `#[allow]` on the type definition
-            || is_lint_allowed(
+            // Check for `#[expect]` or `#[allow]` on the type definition
+            || fulfill_or_allowed(
                 cx,
                 MULTIPLE_INHERENT_IMPL,
-                cx.tcx.local_def_id_to_hir_id(id),
+                [cx.tcx.local_def_id_to_hir_id(id)],
             ) {
                 continue;
             }
 
             for impl_id in impl_ids.iter().map(|id| id.expect_local()) {
                 let impl_ty = cx.tcx.type_of(impl_id).instantiate_identity();
-                match type_map.entry(impl_ty) {
+                let hir_id = cx.tcx.local_def_id_to_hir_id(impl_id);
+                let criterion = match self.scope {
+                    InherentImplLintScope::Module => Criterion::Module(cx.tcx.parent_module(hir_id)),
+                    InherentImplLintScope::File => {
+                        let span = cx.tcx.hir_span(hir_id);
+                        Criterion::File(cx.tcx.sess.source_map().lookup_source_file(span.lo()).name.clone())
+                    },
+                    InherentImplLintScope::Crate => Criterion::Crate,
+                };
+                match type_map.entry((impl_ty, criterion)) {
                     Entry::Vacant(e) => {
                         // Store the id for the first impl block of this type. The span is retrieved lazily.
                         e.insert(IdOrSpan::Id(impl_id));
@@ -97,7 +131,6 @@ fn check_crate_post(&mut self, cx: &LateContext<'tcx>) {
             // Switching to the next type definition, no need to keep the current entries around.
             type_map.clear();
         }
-
         // `TyCtxt::crate_inherent_impls` doesn't have a defined order. Sort the lint output first.
         lint_spans.sort_by_key(|x| x.0.lo());
         for (span, first_span) in lint_spans {
@@ -125,7 +158,7 @@ fn get_impl_span(cx: &LateContext<'_>, id: LocalDefId) -> Option<Span> {
     {
         (!span.from_expansion()
             && impl_item.generics.params.is_empty()
-            && !is_lint_allowed(cx, MULTIPLE_INHERENT_IMPL, id))
+            && !fulfill_or_allowed(cx, MULTIPLE_INHERENT_IMPL, [id]))
         .then_some(span)
     } else {
         None

clippy_lints/src/lib.rs

@@ -587,7 +587,7 @@ pub fn register_lint_passes(store: &mut rustc_lint::LintStore, conf: &'static Co
     store.register_early_pass(|| Box::new(suspicious_operation_groupings::SuspiciousOperationGroupings));
     store.register_late_pass(|_| Box::new(suspicious_trait_impl::SuspiciousImpl));
     store.register_late_pass(|_| Box::new(map_unit_fn::MapUnit));
-    store.register_late_pass(|_| Box::new(inherent_impl::MultipleInherentImpl));
+    store.register_late_pass(move |_| Box::new(inherent_impl::MultipleInherentImpl::new(conf)));
     store.register_late_pass(|_| Box::new(neg_cmp_op_on_partial_ord::NoNegCompOpForPartialOrd));
     store.register_late_pass(move |_| Box::new(unwrap::Unwrap::new(conf)));
     store.register_late_pass(move |_| Box::new(indexing_slicing::IndexingSlicing::new(conf)));

tests/ui-cargo/multiple_inherent_impl/config_fail/Cargo.stderr

@@ -0,0 +1,7 @@
+error: error reading Clippy's configuration file: unknown variant `FooBar`, expected one of `crate`, `file`, `module`
+ --> $DIR/tests/ui-cargo/multiple_inherent_impl/config_fail/clippy.toml:1:28
+  |
+1 | inherent-impl-lint-scope = "FooBar"
+  |                            ^^^^^^^^
+
+error: could not compile `config_fail` (bin "config_fail") due to 1 previous error

tests/ui-cargo/multiple_inherent_impl/config_fail/Cargo.toml

@@ -0,0 +1,7 @@
+[package]
+name = "config_fail"
+version = "0.1.0"
+edition = "2024"
+publish = false
+
+[dependencies]

tests/ui-cargo/multiple_inherent_impl/config_fail/clippy.toml

@@ -0,0 +1 @@
+inherent-impl-lint-scope = "FooBar"

tests/ui-cargo/multiple_inherent_impl/config_fail/src/main.rs

@@ -0,0 +1,3 @@
+#![allow(dead_code)]
+#![deny(clippy::multiple_inherent_impl)]
+fn main() {}

tests/ui-cargo/multiple_inherent_impl/crate_fail/Cargo.stderr

@@ -0,0 +1,57 @@
+error: multiple implementations of this structure
+  --> src/main.rs:11:1
+   |
+11 | / impl S {
+12 | |     //^ Must trigger
+13 | |     fn second() {}
+14 | | }
+   | |_^
+   |
+note: first implementation here
+  --> src/main.rs:7:1
+   |
+ 7 | / impl S {
+ 8 | |     fn first() {}
+ 9 | | }
+   | |_^
+note: the lint level is defined here
+  --> src/main.rs:2:9
+   |
+ 2 | #![deny(clippy::multiple_inherent_impl)]
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: multiple implementations of this structure
+  --> src/main.rs:22:5
+   |
+22 | /     impl T {
+23 | |         //^ Must trigger
+24 | |         fn second() {}
+25 | |     }
+   | |_____^
+   |
+note: first implementation here
+  --> src/main.rs:16:1
+   |
+16 | / impl T {
+17 | |     fn first() {}
+18 | | }
+   | |_^
+
+error: multiple implementations of this structure
+  --> src/main.rs:36:1
+   |
+36 | / impl b::T {
+37 | |     //^ Must trigger
+38 | |     fn second() {}
+39 | | }
+   | |_^
+   |
+note: first implementation here
+  --> src/b.rs:4:1
+   |
+ 4 | / impl T {
+ 5 | |     fn first() {}
+ 6 | | }
+   | |_^
+
+error: could not compile `crate_fail` (bin "crate_fail") due to 3 previous errors

tests/ui-cargo/multiple_inherent_impl/crate_fail/Cargo.toml

@@ -0,0 +1,7 @@
+[package]
+name = "crate_fail"
+version = "0.1.0"
+edition = "2024"
+publish = false
+
+[dependencies]

tests/ui-cargo/multiple_inherent_impl/crate_fail/clippy.toml

@@ -0,0 +1 @@
+inherent-impl-lint-scope = "crate"

tests/ui-cargo/multiple_inherent_impl/crate_fail/src/b.rs

@@ -0,0 +1,6 @@
+pub struct S;
+pub struct T;
+
+impl T {
+    fn first() {}
+}

tests/ui-cargo/multiple_inherent_impl/crate_fail/src/main.rs

@@ -0,0 +1,41 @@
+#![allow(dead_code)]
+#![deny(clippy::multiple_inherent_impl)]
+
+struct S;
+struct T;
+
+impl S {
+    fn first() {}
+}
+
+impl S {
+    //^ Must trigger
+    fn second() {}
+}
+
+impl T {
+    fn first() {}
+}
+
+mod a {
+    use super::T;
+    impl T {
+        //^ Must trigger
+        fn second() {}
+    }
+}
+
+mod b;
+
+impl b::S {
+    //^ Must NOT trigger
+    fn first() {}
+    fn second() {}
+}
+
+impl b::T {
+    //^ Must trigger
+    fn second() {}
+}
+
+fn main() {}

tests/ui-cargo/multiple_inherent_impl/file_fail/Cargo.stderr

@@ -0,0 +1,58 @@
+error: multiple implementations of this structure
+  --> src/main.rs:13:5
+   |
+13 | /     impl S {
+14 | |         //^ Must trigger
+15 | |         fn second() {}
+16 | |     }
+   | |_____^
+   |
+note: first implementation here
+  --> src/main.rs:6:1
+   |
+ 6 | / impl S {
+ 7 | |     fn first() {}
+ 8 | | }
+   | |_^
+note: the lint level is defined here
+  --> src/main.rs:2:9
+   |
+ 2 | #![deny(clippy::multiple_inherent_impl)]
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: multiple implementations of this structure
+  --> src/main.rs:26:5
+   |
+26 | /     impl S {
+27 | |         //^ Must trigger
+28 | |
+29 | |         fn second() {}
+30 | |     }
+   | |_____^
+   |
+note: first implementation here
+  --> src/main.rs:22:5
+   |
+22 | /     impl S {
+23 | |         fn first() {}
+24 | |     }
+   | |_____^
+
+error: multiple implementations of this structure
+  --> src/c.rs:17:5
+   |
+17 | /     impl T {
+18 | |         //^ Must trigger
+19 | |         fn second() {}
+20 | |     }
+   | |_____^
+   |
+note: first implementation here
+  --> src/c.rs:10:5
+   |
+10 | /     impl T {
+11 | |         fn first() {}
+12 | |     }
+   | |_____^
+
+error: could not compile `file_fail` (bin "file_fail") due to 3 previous errors

tests/ui-cargo/multiple_inherent_impl/file_fail/Cargo.toml

@@ -0,0 +1,7 @@
+[package]
+name = "file_fail"
+version = "0.1.0"
+edition = "2024"
+publish = false
+
+[dependencies]

tests/ui-cargo/multiple_inherent_impl/file_fail/clippy.toml

@@ -0,0 +1 @@
+inherent-impl-lint-scope = "file"

tests/ui-cargo/multiple_inherent_impl/file_fail/src/c.rs

@@ -0,0 +1,21 @@
+pub struct S;
+struct T;
+
+impl S {
+    fn first() {}
+}
+
+mod d {
+    use super::T;
+    impl T {
+        fn first() {}
+    }
+}
+
+mod e {
+    use super::T;
+    impl T {
+        //^ Must trigger
+        fn second() {}
+    }
+}

tests/ui-cargo/multiple_inherent_impl/file_fail/src/main.rs

@@ -0,0 +1,40 @@
+#![allow(dead_code)]
+#![deny(clippy::multiple_inherent_impl)]
+
+struct S;
+
+impl S {
+    fn first() {}
+}
+
+mod a {
+    use super::S;
+
+    impl S {
+        //^ Must trigger
+        fn second() {}
+    }
+}
+
+mod b {
+    struct S;
+
+    impl S {
+        fn first() {}
+    }
+
+    impl S {
+        //^ Must trigger
+
+        fn second() {}
+    }
+}
+
+mod c;
+
+impl c::S {
+    //^ Must NOT trigger
+    fn second() {}
+}
+
+fn main() {}

tests/ui-cargo/multiple_inherent_impl/module_fail/Cargo.stderr

@@ -0,0 +1,41 @@
+error: multiple implementations of this structure
+  --> src/main.rs:26:5
+   |
+26 | /     impl S {
+27 | |         //^ Must trigger
+28 | |
+29 | |         fn second() {}
+30 | |     }
+   | |_____^
+   |
+note: first implementation here
+  --> src/main.rs:22:5
+   |
+22 | /     impl S {
+23 | |         fn first() {}
+24 | |     }
+   | |_____^
+note: the lint level is defined here
+  --> src/main.rs:2:9
+   |
+ 2 | #![deny(clippy::multiple_inherent_impl)]
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: multiple implementations of this structure
+  --> src/c.rs:12:1
+   |
+12 | / impl T {
+13 | |     //^ Must trigger
+14 | |     fn second() {}
+15 | | }
+   | |_^
+   |
+note: first implementation here
+  --> src/c.rs:8:1
+   |
+ 8 | / impl T {
+ 9 | |     fn first() {}
+10 | | }
+   | |_^
+
+error: could not compile `module_fail` (bin "module_fail") due to 2 previous errors

tests/ui-cargo/multiple_inherent_impl/module_fail/Cargo.toml

@@ -0,0 +1,7 @@
+[package]
+name = "module_fail"
+version = "0.1.0"
+edition = "2024"
+publish = false
+
+[dependencies]

tests/ui-cargo/multiple_inherent_impl/module_fail/clippy.toml

@@ -0,0 +1 @@
+inherent-impl-lint-scope = "module"

tests/ui-cargo/multiple_inherent_impl/module_fail/src/c.rs

@@ -0,0 +1,15 @@
+pub struct S;
+struct T;
+
+impl S {
+    fn first() {}
+}
+
+impl T {
+    fn first() {}
+}
+
+impl T {
+    //^ Must trigger
+    fn second() {}
+}

tests/ui-cargo/multiple_inherent_impl/module_fail/src/main.rs

@@ -0,0 +1,40 @@
+#![allow(dead_code)]
+#![deny(clippy::multiple_inherent_impl)]
+
+struct S;
+
+impl S {
+    fn first() {}
+}
+
+mod a {
+    use super::S;
+
+    impl S {
+        //^ Must NOT trigger
+        fn second() {}
+    }
+}
+
+mod b {
+    struct S;
+
+    impl S {
+        fn first() {}
+    }
+
+    impl S {
+        //^ Must trigger
+
+        fn second() {}
+    }
+}
+
+mod c;
+
+impl c::S {
+    //^ Must NOT trigger
+    fn second() {}
+}
+
+fn main() {}

tests/ui-toml/toml_unknown_key/conf_unknown_key.stderr

@@ -49,6 +49,7 @@ error: error reading Clippy's configuration file: unknown field `foobar`, expect
            excessive-nesting-threshold
            future-size-threshold
            ignore-interior-mutability
+           inherent-impl-lint-scope
            large-error-threshold
            lint-commented-code
            literal-representation-threshold
@@ -144,6 +145,7 @@ error: error reading Clippy's configuration file: unknown field `barfoo`, expect
            excessive-nesting-threshold
            future-size-threshold
            ignore-interior-mutability
+           inherent-impl-lint-scope
            large-error-threshold
            lint-commented-code
            literal-representation-threshold
@@ -239,6 +241,7 @@ error: error reading Clippy's configuration file: unknown field `allow_mixed_uni
            excessive-nesting-threshold
            future-size-threshold
            ignore-interior-mutability
+           inherent-impl-lint-scope
            large-error-threshold
            lint-commented-code
            literal-representation-threshold

tests/ui/impl.rs

@@ -68,7 +68,20 @@ impl AllowedImpl {}
 impl OneAllowedImpl {}
 #[allow(clippy::multiple_inherent_impl)]
 impl OneAllowedImpl {}
-impl OneAllowedImpl {} // Lint, only one of the three blocks is allowed.
+impl OneAllowedImpl {}
+//~^ multiple_inherent_impl
+
+#[expect(clippy::multiple_inherent_impl)]
+struct ExpectedFulfilled;
+
+impl ExpectedFulfilled {}
+impl ExpectedFulfilled {}
+
+struct OneExpected;
+impl OneExpected {}
+#[expect(clippy::multiple_inherent_impl)]
+impl OneExpected {}
+impl OneExpected {}
 //~^ multiple_inherent_impl
 
 fn main() {}

tests/ui/impl.stderr

@@ -57,7 +57,7 @@ LL | | }
 error: multiple implementations of this structure
   --> tests/ui/impl.rs:71:1
    |
-LL | impl OneAllowedImpl {} // Lint, only one of the three blocks is allowed.
+LL | impl OneAllowedImpl {}
    | ^^^^^^^^^^^^^^^^^^^^^^
    |
 note: first implementation here
@@ -66,5 +66,17 @@ note: first implementation here
 LL | impl OneAllowedImpl {}
    | ^^^^^^^^^^^^^^^^^^^^^^
 
-error: aborting due to 4 previous errors
+error: multiple implementations of this structure
+  --> tests/ui/impl.rs:84:1
+   |
+LL | impl OneExpected {}
+   | ^^^^^^^^^^^^^^^^^^^
+   |
+note: first implementation here
+  --> tests/ui/impl.rs:81:1
+   |
+LL | impl OneExpected {}
+   | ^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to 5 previous errors