[clang] [OpenACC] Implement Default clause for Compute Constructs (PR #88135)

[via cfe-commits]

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@@ -12254,6 +12254,10 @@ def err_acc_construct_appertainment
             "be used in a statement context">;
 def err_acc_clause_appertainment
     : Error<"OpenACC '%1' clause is not valid on '%0' directive">;
+def err_acc_duplicate_clause_diallowed
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Sirraide wrote:

```suggestion
def err_acc_duplicate_clause_disallowed
```

https://github.com/llvm/llvm-project/pull/88135