[flang-commits] [flang] [flang][OpenMP] Detect DSA conflicts in nested loop constructs (PR #195323)

[Leandro Lupori via flang-commits]

================
@@ -498,15 +502,19 @@ void OmpStructureChecker::CheckIterationVariables(
           "The DO loop iteration variable must be of integer type"_err_en_US,
           iv.ToString());
     }
-    const Symbol *host{GetHostSymbol(*iv.symbol)};
-    if (!host) {
-      continue;
-    }
-    if (host->test(Symbol::Flag::OmpThreadprivate)) {
+    if (iv.symbol->GetUltimate().test(Symbol::Flag::OmpThreadprivate)) {
       context_.Say(iv.source,
           "Loop iteration variable of an affected loop cannot be THREADPRIVATE"_err_en_US,
           iv.ToString());
     }
+    // Get the symbol from the variable that was listed in a DSA clause.
+    const Symbol *host{iv.symbol};
+    while (host && !dsa.count(host)) {
+      host = GetHostSymbol(*host);
+    }
----------------
luporl wrote:

In the PR's example, why was a single `GetHostSymbol()` not enough to detect `k`'s DSA in the nested loop?
Was it returning a symbol with no DSA in DO's scope, representing a use from the symbol in the enclosing PARALLEL scope?

https://github.com/llvm/llvm-project/pull/195323