excessive_bools, do not lint in trait impls

Should not lint because the trait might not be changeable by the user
We only lint in the trait definition

Author: kraktus

clippy_lints/src/excessive_bools.rs

@@ -1,5 +1,5 @@
 use clippy_utils::diagnostics::span_lint_and_help;
-use clippy_utils::{has_repr_attr, is_bool};
+use clippy_utils::{get_parent_as_impl, has_repr_attr, is_bool};
 use rustc_hir::intravisit::FnKind;
 use rustc_hir::{Body, FnDecl, HirId, Item, ItemKind, Ty};
 use rustc_lint::{LateContext, LateLintPass};
@@ -159,11 +159,16 @@ impl<'tcx> LateLintPass<'tcx> for ExcessiveBools {
         fn_decl: &'tcx FnDecl<'tcx>,
         _: &'tcx Body<'tcx>,
         span: Span,
-        _: HirId,
+        hir_id: HirId,
     ) {
         if let Some(fn_header) = fn_kind.header()
             && fn_header.abi == Abi::Rust
-            && !span.from_expansion() {
+            && !span.from_expansion()
+            && get_parent_as_impl(cx.tcx, hir_id)
+                .map_or(true,
+                    |impl_item| impl_item.of_trait.is_none()
+                )
+            {
             self.check_fn_sig(cx, fn_decl, span);
         }
     }

tests/ui/fn_params_excessive_bools.rs

@@ -35,6 +35,8 @@ impl S {
 }
 
 impl Trait for S {
+    // Should not lint because the trait might not be changeable by the user
+    // We only lint in the trait definition
     fn f(_: bool, _: bool, _: bool, _: bool) {}
     fn g(_: bool, _: bool, _: bool, _: Vec<u32>) {}
 }

tests/ui/fn_params_excessive_bools.stderr

@@ -24,15 +24,7 @@ LL |     fn f(&self, _: bool, _: bool, _: bool, _: bool) {}
    = help: consider refactoring bools into two-variant enums
 
 error: more than 3 bools in function parameters
-  --> $DIR/fn_params_excessive_bools.rs:38:5
-   |
-LL |     fn f(_: bool, _: bool, _: bool, _: bool) {}
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = help: consider refactoring bools into two-variant enums
-
-error: more than 3 bools in function parameters
-  --> $DIR/fn_params_excessive_bools.rs:43:5
+  --> $DIR/fn_params_excessive_bools.rs:45:5
    |
 LL | /     fn n(_: bool, _: u32, _: bool, _: Box<u32>, _: bool, _: bool) {
 LL | |         fn nn(_: bool, _: bool, _: bool, _: bool) {}
@@ -42,12 +34,12 @@ LL | |     }
    = help: consider refactoring bools into two-variant enums
 
 error: more than 3 bools in function parameters
-  --> $DIR/fn_params_excessive_bools.rs:44:9
+  --> $DIR/fn_params_excessive_bools.rs:46:9
    |
 LL |         fn nn(_: bool, _: bool, _: bool, _: bool) {}
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = help: consider refactoring bools into two-variant enums
 
-error: aborting due to 6 previous errors
+error: aborting due to 5 previous errors