[clang-tools-extra] [clang-tidy] Add check bugprone-misleading-setter-of-reference (PR #132242)

[Donát Nagy via cfe-commits]

================
@@ -0,0 +1,47 @@
+.. title:: clang-tidy - bugprone-misleading-setter-of-reference
+
+bugprone-misleading-setter-of-reference
+=======================================
+
+Finds setter-like member functions that take a pointer parameter and set a
+(non-const) reference member of the same class with the pointed value.
+
+The checker detects public member functions that have a single parameter (which
+is a pointer) and contain a single (maybe overloaded) assignment operator call.
+The assignment should set a member variable with the dereference of the
+parameter pointer. The member variable can have any visibility.
+
+The fact that a setter function takes a pointer might cause the belief that an
+internal reference (if it would be a pointer) is changed instead of the
+pointed-to (or referenced) value.
+
+Example:
+
+.. code-block:: c++
+
+  class MyClass {
+    int &InternalRef;  // non-const reference member
+  public:
+    MyClass(int &Value) : InternalRef(Value) {}
+
+    // Warning: This setter could lead to unintended behaviour.
+    void setRef(int *Value) {
+      InternalRef = *Value;  // This assigns to the referenced value, not changing what ref_ references.
+    }
+  };
+
+  int main() {
+    int Value1 = 42;
+    int Value2 = 100;
+    MyClass X(Value1);
+    
+    // This might look like it changes what InternalRef references to,
+    // but it actually modifies Value1 to be 100.
+    X.setRef(&Value2);
+  }
+
+Possible fixes:
+  - Change the parameter type of the "set" function to non-pointer or const reference
+    type.
----------------
NagyDonat wrote:

```suggestion
  - Change the parameter type of the "set" function to a non-pointer type (for
    example, a const reference).
```
"non-pointer or const reference type" was strange, because const references are a subset of non-pointer types.

https://github.com/llvm/llvm-project/pull/132242