[clang] [OpenACC] Implement `self` clause for compute constructs (PR #88760)

[Erich Keane via cfe-commits]

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@@ -160,12 +169,58 @@ SemaOpenACC::ActOnClause(ArrayRef<const OpenACCClause *> ExistingClauses,
     // The parser has ensured that we have a proper condition expr, so there
     // isn't really much to do here.
 
-    // TODO OpenACC: When we implement 'self', this clauses causes us to
-    // 'ignore' the self clause, so we should implement a warning here.
+    // If the 'if' clause is true, it makes the 'self' clause have no effect,
+    // diagnose that here.
+    // TODO OpenACC: When we add these two to other constructs, we might not
+    // want to warn on this (for example, 'update').
+    const auto *Itr =
+        llvm::find_if(ExistingClauses, [](const OpenACCClause *C) {
+          return C->getClauseKind() == OpenACCClauseKind::Self;
+        });
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erichkeane wrote:

Cool!  TIL!

https://github.com/llvm/llvm-project/pull/88760