[clang-tools-extra] [clang-tidy] Add `bugprone-virtual-arithmetic` check (PR #91951)

[Piotr Zegar via cfe-commits]

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@@ -0,0 +1,59 @@
+// RUN: %check_clang_tidy %s bugprone-virtual-arithmetic %t
+
+class Base {
+public:  
+  virtual ~Base() {}
+};
+
+class Derived : public Base {};
+
+void operators() {
+  Base *b = new Derived[10];
+
+  b += 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: pointer arithmetic on class 'Base' that declares a virtual function, undefined behavior if the pointee is a different class [bugprone-virtual-arithmetic]
+
+  b = b + 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:7: warning: pointer arithmetic on class 'Base' that declares a virtual function, undefined behavior if the pointee is a different class [bugprone-virtual-arithmetic]
+
+  b++;
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: pointer arithmetic on class 'Base' that declares a virtual function, undefined behavior if the pointee is a different class [bugprone-virtual-arithmetic]
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PiotrZSL wrote:

add tests for ++b;

https://github.com/llvm/llvm-project/pull/91951