[flang][openacc] Disallow the zero modifier on the copyout clause wit…

…h the declare directive

The OpenACC 3.3 specification does not allow the `zero` modifier
on the `copyout` clause used with the declare directive.

This is similar to D156703 for the create clause.

This might be missing piece in the spec but we disallow it until proven otherwise.

Reviewed By: razvanlupusoru

Differential Revision: https://reviews.llvm.org/D156825

flang/lib/Semantics/check-acc-structure.cpp

@@ -438,6 +438,15 @@ void AccStructureChecker::Enter(const parser::AccClause::Copyout &c) {
                   .str()),
           ContextDirectiveAsFortran());
     }
+    if (GetContext().directive == llvm::acc::Directive::ACCD_declare) {
+      context_.Say(GetContext().clauseSource,
+          "The ZERO modifier is not allowed for the %s clause "
+          "on the %s directive"_err_en_US,
+          parser::ToUpperCaseLetters(
+              llvm::acc::getOpenACCClauseName(llvm::acc::Clause::ACCC_copyout)
+                  .str()),
+          ContextDirectiveAsFortran());
+    }
   }
 }
 

flang/test/Semantics/OpenACC/acc-declare-validity.f90

@@ -57,4 +57,10 @@ subroutine sub2(cc)
     !$acc declare present(cc)
   end subroutine sub2
 
+  subroutine sub3()
+    real :: aa(100)
+    !ERROR: The ZERO modifier is not allowed for the COPYOUT clause on the DECLARE directive
+    !$acc declare copyout(zero: aa)
+  end subroutine
+
 end module openacc_declare_validity