================
@@ -0,0 +1,232 @@
+// RUN: %check_clang_tidy %s bugprone-unsafe-crtp %t
+
+namespace class_implicit_ctor {
+template <typename T>
+class CRTP {};
+// CHECK-MESSAGES: :[[@LINE-1]]:7: warning: the implicit default constructor
of the CRTP is publicly accessible [bugprone-unsafe-crtp]
+// CHECK-MESSAGES: :[[@LINE-2]]:7: note: consider making it private
+// CHECK-FIXES: CRTP() = default;
+
+class A : CRTP<A> {};
+} // namespace class_implicit_ctor
+
+namespace class_uncostructible {
+template <typename T>
+class CRTP {
+// CHECK-MESSAGES: :[[@LINE-1]]:7: warning: the CRTP cannot be constructed
from the derived class [bugprone-unsafe-crtp]
+// CHECK-MESSAGES: :[[@LINE-2]]:7: note: consider declaring the derived class
as friend
+// CHECK-FIXES: friend T;
----------------
isuckatcs wrote:
If you want to use `boost::noncopyable` as a CRPT, then it is an interesting
question.
The idea that the checker is built around is that we want to help the user
ensuring, that their CRTP class won't be instantiated accidentally. This could
be achieved by making the constructor accessible only to the derived class.
`boost::noncopyable` uses a protected constructor and makes the
copy-constructor private, which if used as a CRTP would automatically trigger
the other issue, when a protected constructor allows any template parameter to
be passed. E.g.: `class Derived : Noncopyable<Foo> {};`
As a result I think a functionality such as `boost::noncopyable` is not
suitable for a CRTP, but if the user insists on creating it `//
NOLINT(bugprone-unsafe-crtp)` could be applied.
https://github.com/llvm/llvm-project/pull/82403
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