[clang] [Clang]Throw frontend error for target feature mismatch when using `flatten` attribute (PR #150044)

[Aaron Ballman via cfe-commits]

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@@ -0,0 +1,12 @@
+// RUN: %clang_cc1 %s -triple=x86_64-linux-gnu -S -verify -o -
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AaronBallman wrote:

```suggestion
// RUN: %clang_cc1 %s -triple=x86_64-linux-gnu -emit-llvm -verify -o /dev/null
```

https://github.com/llvm/llvm-project/pull/150044