[flang] Add Symbol::IsArray()

Add and use IsArray for symbols, meaning: it is an object entity
with shape.

Original-commit: flang-compiler/f18@31c1a37f03
Reviewed-on: https://github.com/flang-compiler/f18/pull/277
Tree-same-pre-rewrite: false

flang/lib/semantics/resolve-names.cc

@@ -2358,11 +2358,9 @@ void DeclarationVisitor::CheckAccessibility(
 void DeclarationVisitor::CheckScalarIntegerType(const parser::Name &name) {
   if (name.symbol != nullptr) {
     const Symbol &symbol{*name.symbol};
-    if (const auto *details{symbol.detailsIf<ObjectEntityDetails>()}) {
-      if (details->IsArray()) {
-        Say(name, "Variable '%s' is not scalar"_err_en_US);
-        return;
-      }
+    if (symbol.IsArray()) {
+      Say(name, "Variable '%s' is not scalar"_err_en_US);
+      return;
     }
     if (auto *type{symbol.GetType()}) {
       if (!type->IsNumeric(TypeCategory::Integer)) {
@@ -2536,7 +2534,7 @@ Symbol &DeclarationVisitor::DeclareObjectEntity(
       SetType(name, *type);
     }
     if (!arraySpec().empty()) {
-      if (!details->shape().empty()) {
+      if (details->IsArray()) {
         Say(name,
             "The dimensions of '%s' have already been declared"_err_en_US);
       } else {
@@ -3372,11 +3370,9 @@ void ConstructVisitor::Post(const parser::ConcurrentControl &x) {
     if (auto *type{prev->GetType()}) {
       symbol.SetType(*type);
     }
-    if (const auto *details{prev->detailsIf<ObjectEntityDetails>()}) {
-      if (details->IsArray()) {
-        SayWithDecl(name, *prev, "Index variable '%s' is not scalar"_err_en_US);
-        return;
-      }
+    if (prev->IsArray()) {
+      SayWithDecl(name, *prev, "Index variable '%s' is not scalar"_err_en_US);
+      return;
     }
   }
   CheckScalarIntegerType(name);

flang/lib/semantics/symbol.cc

@@ -214,6 +214,11 @@ void Symbol::SetType(const DeclTypeSpec &type) {
       details_);
 }
 
+bool Symbol::IsArray() const {
+  const auto *details{std::get_if<ObjectEntityDetails>(&details_)};
+  return details && details->IsArray();
+}
+
 bool Symbol::IsSubprogram() const {
   return std::visit(
       common::visitors{

flang/lib/semantics/symbol.h

@@ -452,6 +452,7 @@ public:
 
   void SetType(const DeclTypeSpec &);
 
+  bool IsArray() const;
   bool IsSubprogram() const;
   bool IsSeparateModuleProc() const;
   bool HasExplicitInterface() const {