[flang][semantics][OpenMP] store DSA using ultimate sym (llvm#107002)

Previously we tracked data sharing attributes by the symbol itself not
by the ultimate symbol. When the private clause came first, subsequent
uses of the symbol found a host-associated version instead of the
ultimate symbol and so the check didn't consider them to be the same
symbol. Always adding and checking for the ultimate symbol ensures that
we have the same behaviour no matter the order of clauses.

The modified list is only used for this multiple clause check.

Closes llvm#78235

Author: tblah

flang/lib/Semantics/resolve-directives.cpp

@@ -2514,14 +2514,14 @@ void OmpAttributeVisitor::CheckMultipleAppearances(
       target = &details->symbol();
     }
   }
-  if (HasDataSharingAttributeObject(*target) &&
+  if (HasDataSharingAttributeObject(target->GetUltimate()) &&
       !WithMultipleAppearancesOmpException(symbol, ompFlag)) {
     context_.Say(name.source,
         "'%s' appears in more than one data-sharing clause "
         "on the same OpenMP directive"_err_en_US,
         name.ToString());
   } else {
-    AddDataSharingAttributeObject(*target);
+    AddDataSharingAttributeObject(target->GetUltimate());
     if (privateDataSharingAttributeFlags.test(ompFlag)) {
       AddPrivateDataSharingAttributeObjects(*target);
     }

flang/test/Semantics/OpenMP/clause-order.f90

@@ -0,0 +1,19 @@
+! RUN: %python %S/../test_errors.py %s %flang -fopenmp
+! Ensure that checks on more than one data-sharing clause do not depend upon
+! the clause order
+
+PROGRAM main
+  INTEGER:: I, N1, N2
+
+  !ERROR: 'n1' appears in more than one data-sharing clause on the same OpenMP directive
+  !$OMP PARALLEL DO PRIVATE(N1) SHARED(N1)
+  DO I=1, 4
+  ENDDO
+  !$OMP END PARALLEL DO
+
+  !ERROR: 'n2' appears in more than one data-sharing clause on the same OpenMP directive
+  !$OMP PARALLEL DO SHARED(N2) PRIVATE(N2)
+  DO I=1, 4
+  ENDDO
+  !$OMP END PARALLEL DO
+END PROGRAM