[clang] [llvm] [SPIRV][HLSL] Add DXC compatibility option for extension (PR #151554)

[Nathan Gauër via llvm-commits]

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@@ -14,6 +14,14 @@
 // RUN: %clang_dxc -spirv -Tlib_6_7 -### %s -fspv-extension=SPV_TEST1 -fspv-extension=KHR -fspv-extension=SPV_TEST2 2>&1 | FileCheck %s -check-prefix=TEST3
 // TEST3: "-spirv-ext=+SPV_TEST1,KHR,+SPV_TEST2"
 
+// Merge KHR with other extensions.
+// RUN: %clang_dxc -spirv -Tlib_6_7 -### %s -fspv-extension=KHR -fspv-extension=SPV_TEST2 2>&1 | FileCheck %s -check-prefix=TEST4
+// TEST4: "-spirv-ext=KHR,+SPV_TEST2"
+
+// Merge KHR with other extensions.
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Keenuts wrote:

nit: comment seems wrong
```suggestion
```

https://github.com/llvm/llvm-project/pull/151554