Auto merge of #5428 - dtolnay:cognitive, r=flip1995

Move cognitive_complexity to nursery

As discussed in #5418 (comment); Clippy's current understanding of cognitive complexity is not good enough yet at analyzing code for understandability to have this lint be enabled by default.

changelog: Remove cognitive_complexity from default set of enabled lints

Author: bors

clippy_lints/src/assign_ops.rs

@@ -77,7 +77,6 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for AssignOps {
             },
             hir::ExprKind::Assign(assignee, e, _) => {
                 if let hir::ExprKind::Binary(op, l, r) = &e.kind {
-                    #[allow(clippy::cognitive_complexity)]
                     let lint = |assignee: &hir::Expr<'_>, rhs: &hir::Expr<'_>| {
                         let ty = cx.tables.expr_ty(assignee);
                         let rty = cx.tables.expr_ty(rhs);

clippy_lints/src/cognitive_complexity.rs

@@ -22,7 +22,7 @@ declare_clippy_lint! {
     ///
     /// **Example:** No. You'll see it when you get the warning.
     pub COGNITIVE_COMPLEXITY,
-    complexity,
+    nursery,
     "functions that should be split up into multiple functions"
 }
 

clippy_lints/src/lib.rs

@@ -1174,7 +1174,6 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         LintId::of(&booleans::LOGIC_BUG),
         LintId::of(&booleans::NONMINIMAL_BOOL),
         LintId::of(&bytecount::NAIVE_BYTECOUNT),
-        LintId::of(&cognitive_complexity::COGNITIVE_COMPLEXITY),
         LintId::of(&collapsible_if::COLLAPSIBLE_IF),
         LintId::of(&comparison_chain::COMPARISON_CHAIN),
         LintId::of(&copies::IFS_SAME_COND),
@@ -1509,7 +1508,6 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         LintId::of(&assign_ops::MISREFACTORED_ASSIGN_OP),
         LintId::of(&attrs::DEPRECATED_CFG_ATTR),
         LintId::of(&booleans::NONMINIMAL_BOOL),
-        LintId::of(&cognitive_complexity::COGNITIVE_COMPLEXITY),
         LintId::of(&double_comparison::DOUBLE_COMPARISONS),
         LintId::of(&double_parens::DOUBLE_PARENS),
         LintId::of(&duration_subsec::DURATION_SUBSEC),
@@ -1678,6 +1676,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
 
     store.register_group(true, "clippy::nursery", Some("clippy_nursery"), vec![
         LintId::of(&attrs::EMPTY_LINE_AFTER_OUTER_ATTR),
+        LintId::of(&cognitive_complexity::COGNITIVE_COMPLEXITY),
         LintId::of(&fallible_impl_from::FALLIBLE_IMPL_FROM),
         LintId::of(&floating_point_arithmetic::IMPRECISE_FLOPS),
         LintId::of(&floating_point_arithmetic::SUBOPTIMAL_FLOPS),

clippy_lints/src/methods/mod.rs

@@ -1317,7 +1317,7 @@ declare_lint_pass!(Methods => [
 ]);
 
 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Methods {
-    #[allow(clippy::cognitive_complexity, clippy::too_many_lines)]
+    #[allow(clippy::too_many_lines)]
     fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx hir::Expr<'_>) {
         if in_macro(expr.span) {
             return;

clippy_lints/src/mutable_debug_assertion.rs

@@ -53,7 +53,6 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for DebugAssertWithMutCall {
 }
 
 //HACK(hellow554): remove this when #4694 is implemented
-#[allow(clippy::cognitive_complexity)]
 fn extract_call<'a, 'tcx>(cx: &'a LateContext<'a, 'tcx>, e: &'tcx Expr<'_>) -> Option<Span> {
     if_chain! {
         if let ExprKind::Block(ref block, _) = e.kind;

clippy_lints/src/types.rs

@@ -315,7 +315,6 @@ impl Types {
     /// The parameter `is_local` distinguishes the context of the type; types from
     /// local bindings should only be checked for the `BORROWED_BOX` lint.
     #[allow(clippy::too_many_lines)]
-    #[allow(clippy::cognitive_complexity)]
     fn check_ty(&mut self, cx: &LateContext<'_, '_>, hir_ty: &hir::Ty<'_>, is_local: bool) {
         if hir_ty.span.from_expansion() {
             return;

src/lintlist/mod.rs

@@ -250,7 +250,7 @@ pub static ref ALL_LINTS: Vec<Lint> = vec![
     },
     Lint {
         name: "cognitive_complexity",
-        group: "complexity",
+        group: "nursery",
         desc: "functions that should be split up into multiple functions",
         deprecation: None,
         module: "cognitive_complexity",

tests/ui/collapsible_else_if.fixed

@@ -1,5 +1,5 @@
 // run-rustfix
-#![allow(clippy::cognitive_complexity, clippy::assertions_on_constants)]
+#![allow(clippy::assertions_on_constants)]
 
 #[rustfmt::skip]
 #[warn(clippy::collapsible_if)]

tests/ui/collapsible_else_if.rs

@@ -1,5 +1,5 @@
 // run-rustfix
-#![allow(clippy::cognitive_complexity, clippy::assertions_on_constants)]
+#![allow(clippy::assertions_on_constants)]
 
 #[rustfmt::skip]
 #[warn(clippy::collapsible_if)]

tests/ui/collapsible_if.fixed

@@ -1,5 +1,5 @@
 // run-rustfix
-#![allow(clippy::cognitive_complexity, clippy::assertions_on_constants)]
+#![allow(clippy::assertions_on_constants)]
 
 #[rustfmt::skip]
 #[warn(clippy::collapsible_if)]