[flang] ERROR STOP is not an image control statement

[klausler]

Summary

The predicate that determines image control statements needs
to distinguish STOP (which is) from ERROR STOP (which isn't).

[clementval]

LGTM

flang/lib/Semantics/tools.cpp

return parser::Message{
         at, "'%s' is not a variable"_en_US, expr.AsFortran()};
   } else {
     // reference to function returning POINTER
   }
   return std::nullopt;
 }
 
 class ImageControlStmtHelper {
-  using ImageControlStmts = std::variant<parser::ChangeTeamConstruct,
-      parser::CriticalConstruct, parser::EventPostStmt, parser::EventWaitStmt,
-      parser::FormTeamStmt, parser::LockStmt, parser::StopStmt,
-      parser::SyncAllStmt, parser::SyncImagesStmt, parser::SyncMemoryStmt,
-      parser::SyncTeamStmt, parser::UnlockStmt>;
+  using ImageControlStmts =
+      std::variant<parser::ChangeTeamConstruct, parser::CriticalConstruct,
+          parser::EventPostStmt, parser::EventWaitStmt, parser::FormTeamStmt,
+          parser::LockStmt, parser::SyncAllStmt, parser::SyncImagesStmt,
+          parser::SyncMemoryStmt, parser::SyncTeamStmt, parser::UnlockStmt>;
 
 public:
   template <typename T> bool operator()(const T &) {
     return common::HasMember<T, ImageControlStmts>;
   }
   template <typename T> bool operator()(const common::Indirection<T> &x) {
     return (*this)(x.value());
   }
if (auto *name{std::get_if<parser::Name>(&procedureDesignator.u)}) {
                       &actualArg.u)}) {
             return HasCoarray(argExpr->value());
           }
         }
       }
     }
     return false;
   }
+  bool operator()(const parser::StopStmt &stmt) {
+    // STOP is an image control statement; ERROR STOP is not
+    return std::get<parser::StopStmt::Kind>(stmt.t) ==
+        parser::StopStmt::Kind::Stop;
+  }
   bool operator()(const parser::Statement<parser::ActionStmt> &stmt) {
     return common::visit(*this, stmt.statement.u);
   }
 
 private:
   bool IsCoarrayObject(const parser::AllocateObject &allocateObject) {
     const parser::Name &name{GetLastName(allocateObject)};
     return name.symbol && evaluate::IsCoarray(*name.symbol);