Add configurable threshold for type_repetition_in_bounds lint

Author: ThibsG

clippy_lints/src/lib.rs

@@ -996,7 +996,8 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
     store.register_late_pass(|| box checked_conversions::CheckedConversions);
     store.register_late_pass(|| box integer_division::IntegerDivision);
     store.register_late_pass(|| box inherent_to_string::InherentToString);
-    store.register_late_pass(|| box trait_bounds::TraitBounds);
+    let max_trait_bounds = conf.max_trait_bounds;
+    store.register_late_pass(move || box trait_bounds::TraitBounds::new(max_trait_bounds));
     store.register_late_pass(|| box comparison_chain::ComparisonChain);
     store.register_late_pass(|| box mut_key::MutableKeyType);
     store.register_late_pass(|| box modulo_arithmetic::ModuloArithmetic);
@@ -1033,7 +1034,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
     let array_size_threshold = conf.array_size_threshold;
     store.register_late_pass(move || box large_stack_arrays::LargeStackArrays::new(array_size_threshold));
     store.register_late_pass(move || box large_const_arrays::LargeConstArrays::new(array_size_threshold));
-    store.register_late_pass(move || box floating_point_arithmetic::FloatingPointArithmetic);
+    store.register_late_pass(|| box floating_point_arithmetic::FloatingPointArithmetic);
     store.register_early_pass(|| box as_conversions::AsConversions);
     store.register_early_pass(|| box utils::internal_lints::ProduceIce);
     store.register_late_pass(|| box let_underscore::LetUnderscore);

clippy_lints/src/trait_bounds.rs

@@ -5,9 +5,6 @@ use rustc_hir::{GenericBound, Generics, WherePredicate};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_session::{declare_tool_lint, impl_lint_pass};
 
-#[derive(Copy, Clone)]
-pub struct TraitBounds;
-
 declare_clippy_lint! {
     /// **What it does:** This lint warns about unnecessary type repetitions in trait bounds
     ///
@@ -29,6 +26,18 @@ declare_clippy_lint! {
     "Types are repeated unnecessary in trait bounds use `+` instead of using `T: _, T: _`"
 }
 
+#[derive(Copy, Clone)]
+pub struct TraitBounds {
+    max_trait_bounds: u64,
+}
+
+impl TraitBounds {
+    #[must_use]
+    pub fn new(max_trait_bounds: u64) -> Self {
+        Self { max_trait_bounds }
+    }
+}
+
 impl_lint_pass!(TraitBounds => [TYPE_REPETITION_IN_BOUNDS]);
 
 impl<'tcx> LateLintPass<'tcx> for TraitBounds {
@@ -45,6 +54,9 @@ impl<'tcx> LateLintPass<'tcx> for TraitBounds {
         let mut applicability = Applicability::MaybeIncorrect;
         for bound in gen.where_clause.predicates {
             if let WherePredicate::BoundPredicate(ref p) = bound {
+                if p.bounds.len() as u64 > self.max_trait_bounds {
+                    return;
+                }
                 let h = hash(&p.bounded_ty);
                 if let Some(ref v) = map.insert(h, p.bounds.iter().collect::<Vec<_>>()) {
                     let mut hint_string = format!(

clippy_lints/src/utils/conf.rs

@@ -156,6 +156,8 @@ define_Conf! {
     (array_size_threshold, "array_size_threshold": u64, 512_000),
     /// Lint: VEC_BOX. The size of the boxed type in bytes, where boxing in a `Vec` is allowed
     (vec_box_size_threshold, "vec_box_size_threshold": u64, 4096),
+    /// Lint: TYPE_REPETITION_IN_BOUNDS. The maximum number of bounds a trait can have to be linted
+    (max_trait_bounds, "max_trait_bounds": u64, 3),
     /// Lint: STRUCT_EXCESSIVE_BOOLS. The maximum number of bools a struct can have
     (max_struct_bools, "max_struct_bools": u64, 3),
     /// Lint: FN_PARAMS_EXCESSIVE_BOOLS. The maximum number of bools function parameters can have

tests/ui-toml/toml_unknown_key/conf_unknown_key.stderr

@@ -1,4 +1,4 @@
-error: error reading Clippy's configuration file `$DIR/clippy.toml`: unknown field `foobar`, expected one of `blacklisted-names`, `cognitive-complexity-threshold`, `cyclomatic-complexity-threshold`, `doc-valid-idents`, `too-many-arguments-threshold`, `type-complexity-threshold`, `single-char-binding-names-threshold`, `too-large-for-stack`, `enum-variant-name-threshold`, `enum-variant-size-threshold`, `verbose-bit-mask-threshold`, `literal-representation-threshold`, `trivial-copy-size-limit`, `too-many-lines-threshold`, `array-size-threshold`, `vec-box-size-threshold`, `max-struct-bools`, `max-fn-params-bools`, `warn-on-all-wildcard-imports`, `third-party` at line 5 column 1
+error: error reading Clippy's configuration file `$DIR/clippy.toml`: unknown field `foobar`, expected one of `blacklisted-names`, `cognitive-complexity-threshold`, `cyclomatic-complexity-threshold`, `doc-valid-idents`, `too-many-arguments-threshold`, `type-complexity-threshold`, `single-char-binding-names-threshold`, `too-large-for-stack`, `enum-variant-name-threshold`, `enum-variant-size-threshold`, `verbose-bit-mask-threshold`, `literal-representation-threshold`, `trivial-copy-size-limit`, `too-many-lines-threshold`, `array-size-threshold`, `vec-box-size-threshold`, `max-trait-bounds`, `max-struct-bools`, `max-fn-params-bools`, `warn-on-all-wildcard-imports`, `third-party` at line 5 column 1
 
 error: aborting due to previous error
 

tests/ui/type_repetition_in_bounds.rs

@@ -1,4 +1,6 @@
-#[deny(clippy::type_repetition_in_bounds)]
+#![deny(clippy::type_repetition_in_bounds)]
+
+use std::ops::{Add, AddAssign, Div, DivAssign, Mul, MulAssign, Sub, SubAssign};
 
 pub fn foo<T>(_t: T)
 where
@@ -16,4 +18,21 @@ where
     unimplemented!();
 }
 
+trait LintBounds
+where
+    Self: Clone,
+    Self: Copy + Default + Ord,
+    Self: Add<Output = Self> + AddAssign + Sub<Output = Self> + SubAssign,
+    Self: Mul<Output = Self> + MulAssign + Div<Output = Self> + DivAssign,
+{
+}
+
+trait LotsOfBounds
+where
+    Self: Clone + Copy + Default + Ord,
+    Self: Add<Output = Self> + AddAssign + Sub<Output = Self> + SubAssign,
+    Self: Mul<Output = Self> + MulAssign + Div<Output = Self> + DivAssign,
+{
+}
+
 fn main() {}

tests/ui/type_repetition_in_bounds.stderr

@@ -1,15 +1,23 @@
 error: this type has already been used as a bound predicate
-  --> $DIR/type_repetition_in_bounds.rs:6:5
+  --> $DIR/type_repetition_in_bounds.rs:8:5
    |
 LL |     T: Clone,
    |     ^^^^^^^^
    |
 note: the lint level is defined here
-  --> $DIR/type_repetition_in_bounds.rs:1:8
+  --> $DIR/type_repetition_in_bounds.rs:1:9
    |
-LL | #[deny(clippy::type_repetition_in_bounds)]
-   |        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+LL | #![deny(clippy::type_repetition_in_bounds)]
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    = help: consider combining the bounds: `T: Copy + Clone`
 
-error: aborting due to previous error
+error: this type has already been used as a bound predicate
+  --> $DIR/type_repetition_in_bounds.rs:24:5
+   |
+LL |     Self: Copy + Default + Ord,
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = help: consider combining the bounds: `Self: Clone + Copy + Default + Ord`
+
+error: aborting due to 2 previous errors