[clang] [CIR] Unblock simple C++ structure support (PR #138368)

[Andy Kaylor via cfe-commits]

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@@ -12,6 +12,17 @@ IncompleteS *p;
 // LLVM: @p = dso_local global ptr null
 // OGCG: @p = global ptr null, align 8
 
+struct CompleteS {
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andykaylor wrote:

Yes, I think unions should work. I'll add a test for that.

https://github.com/llvm/llvm-project/pull/138368