[clang-tools-extra] [clang-tidy] Make `bugprone-unhandled-self-assignment` check more general (PR #147066)

[Baranov Victor via cfe-commits]

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@@ -540,6 +547,89 @@ class NotACopyAssignmentOperator {
   Uy *getUy() const { return Ptr2; }
 };
 
+// Support "extended" copy/move constructors
+class AllocatorAwareClass {
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vbvictor wrote:

Could you add cases when the check will fire (I suppose it at least):

- when the user did `swap(tmp, *this);`
- when user forgot to place `swap` at all.
- when user created `tmp` variable and did `swap`, but `tmp` variable had a wrong type.

https://github.com/llvm/llvm-project/pull/147066