[clang] [CIR] Add support for derived class declarations (PR #142823)

[Andy Kaylor via cfe-commits]

================
@@ -32,3 +38,16 @@ CompleteC cc;
 // CIR:       cir.global external @cc = #cir.zero : !rec_CompleteC
 // LLVM:  @cc = global %class.CompleteC zeroinitializer
 // OGCG:  @cc = global %class.CompleteC zeroinitializer
+
+class Base {
+public:
+  int a;
+};
+
+class Derived : public Base {
+public:
+  int b;
+};
+
+int use(Derived *d) { return d->b; }
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andykaylor wrote:

We can't handle this yet because it requires an implicit DerivedToBase cast, which will be in an upcoming patch.

https://github.com/llvm/llvm-project/pull/142823