[clang-tools-extra] [clang-tidy] Unsafe CRTP check (PR #82403)

[via cfe-commits]

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+// 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;
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isuckatcs wrote:

@whisperity I think you meant `struct Derived`, and then you example proves me wrong.

The check should also warn about the accessibility of any function, which can construct the CRTP from anywhere other than the derived class and itself.

https://github.com/llvm/llvm-project/pull/82403