From b022edce934b2fb939f876ccb78c1fb8b5bd6349 Mon Sep 17 00:00:00 2001
From: Wonko <wonko@hanstool.org>
Date: Fri, 9 Jan 2026 15:17:06 +0100
Subject: [PATCH 1/2] add test for unstacking cognitive_complexity= attribute

---
 tests/ui/cognitive_complexity.rs     | 25 +++++++++++++++++++++++++
 tests/ui/cognitive_complexity.stderr | 18 +++++++++++++++++-
 2 files changed, 42 insertions(+), 1 deletion(-)

diff --git a/tests/ui/cognitive_complexity.rs b/tests/ui/cognitive_complexity.rs
index 8080c6775e0b..3945028f8271 100644
--- a/tests/ui/cognitive_complexity.rs
+++ b/tests/ui/cognitive_complexity.rs
@@ -472,3 +472,28 @@ mod issue14422 {
         return;
     }
 }
+
+#[clippy::cognitive_complexity = "1"]
+mod attribute_stacking {
+    fn bad() {
+        //~^ cognitive_complexity
+        if true {
+            println!("a");
+        }
+    }
+
+    #[clippy::cognitive_complexity = "2"]
+    fn ok() {
+        if true {
+            println!("a");
+        }
+    }
+
+    // should revert to cognitive_complexity = "1"
+    fn bad_again() {
+        //~^ cognitive_complexity
+        if true {
+            println!("a");
+        }
+    }
+}
diff --git a/tests/ui/cognitive_complexity.stderr b/tests/ui/cognitive_complexity.stderr
index 67ef4e5655bd..e5f54a37229d 100644
--- a/tests/ui/cognitive_complexity.stderr
+++ b/tests/ui/cognitive_complexity.stderr
@@ -176,5 +176,21 @@ LL |     fn bar() {
    |
    = help: you could split it up into multiple smaller functions
 
-error: aborting due to 22 previous errors
+error: the function has a cognitive complexity of (2/1)
+  --> tests/ui/cognitive_complexity.rs:478:8
+   |
+LL |     fn bad() {
+   |        ^^^
+   |
+   = help: you could split it up into multiple smaller functions
+
+error: the function has a cognitive complexity of (2/1)
+  --> tests/ui/cognitive_complexity.rs:493:8
+   |
+LL |     fn bad_again() {
+   |        ^^^^^^^^^
+   |
+   = help: you could split it up into multiple smaller functions
+
+error: aborting due to 24 previous errors
 

From 13b82eb615c68c71baf85ea8dcfbcab51a1dce1a Mon Sep 17 00:00:00 2001
From: Wonko <wonko@hanstool.org>
Date: Fri, 9 Jan 2026 13:43:55 +0100
Subject: [PATCH 2/2] Fix LimitStack::pop_attrs in release mode

The `LimitStack::pop_attrs` function used to pop from the stack in
`debug_assert_eq!` and check the value. The `pop` operation was therefore
only executed in debug builds, leading to an unbalanced stack in
release builds when attributes were present.

This change ensures the `pop` operation is always executed, by moving
it out of the debug-only assertion. The assertion is kept for debug
builds.

changelog: fix unbalanced stack in attributes
---
 clippy_utils/src/attrs.rs | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/clippy_utils/src/attrs.rs b/clippy_utils/src/attrs.rs
index 32f6cb4fd5e9..56490cfc8b65 100644
--- a/clippy_utils/src/attrs.rs
+++ b/clippy_utils/src/attrs.rs
@@ -159,7 +159,10 @@ impl LimitStack {
     }
     pub fn pop_attrs(&mut self, sess: &Session, attrs: &[impl AttributeExt], name: Symbol) {
         let stack = &mut self.stack;
-        parse_attrs(sess, attrs, name, |val| debug_assert_eq!(stack.pop(), Some(val)));
+        parse_attrs(sess, attrs, name, |val| {
+            let popped = stack.pop();
+            debug_assert_eq!(popped, Some(val));
+        });
     }
 }