[flang] Fix bogus errors about CONTIGUOUS attribute

[klausler]

Summary

Incorrect error messages were issuing for symbol table entries
with the CONTIGUOUS attribute that didn't deserve them, like
host association symbols. Put the CONTIGUOUS check into
CheckObjectEntity().

[vzakhari]

LGTM. Thanks!

flang/lib/Semantics/check-declarations.cpp

void CheckHelper::Check(const Symbol &symbol) {
   if (symbol.attrs().test(Attr::BIND_C)) {
     CheckBindC(symbol);
   }
   if (symbol.attrs().test(Attr::SAVE) &&
       !symbol.implicitAttrs().test(Attr::SAVE)) {
     CheckExplicitSave(symbol);
   }
   const auto *object{symbol.detailsIf<ObjectEntityDetails>()};
-  if (symbol.attrs().test(Attr::CONTIGUOUS)) {
-    if ((!object && !symbol.has<UseDetails>()) ||
-        !((IsPointer(symbol) && symbol.Rank() > 0) || IsAssumedShape(symbol) ||
-            evaluate::IsAssumedRank(symbol))) {
-      if (symbol.owner().IsDerivedType()) { // C752
-        messages_.Say(
-            "A CONTIGUOUS component must be an array with the POINTER attribute"_err_en_US);
-      } else { // C830
-        messages_.Say(
-            "CONTIGUOUS entity must be an array pointer, assumed-shape, or assumed-rank"_err_en_US);
-      }
-    }
-  }
   CheckGlobalName(symbol);
   if (isDone) {
     return; // following checks do not apply
   }
 
   if (symbol.attrs().test(Attr::PROTECTED)) {
     if (symbol.owner().kind() != Scope::Kind::Module) { // C854
       messages_.Say(
if (auto whyNot{
       }
     }
   }
   if (symbol.attrs().test(Attr::EXTERNAL)) {
     SayWithDeclaration(symbol,
         "'%s' is a data object and may not be EXTERNAL"_err_en_US,
         symbol.name());
   }
+  if (symbol.attrs().test(Attr::CONTIGUOUS)) {
+    if ((IsPointer(symbol) && symbol.Rank() > 0) || IsAssumedShape(symbol) ||
+        evaluate::IsAssumedRank(symbol)) {
+    } else if (symbol.owner().IsDerivedType()) { // C752
+      messages_.Say(
+          "A CONTIGUOUS component must be an array with the POINTER attribute"_err_en_US);
+    } else { // C830
+      messages_.Say(
+          "CONTIGUOUS entity must be an array pointer, assumed-shape, or assumed-rank"_err_en_US);
+    }
+  }
 }
 
 void CheckHelper::CheckPointerInitialization(const Symbol &symbol) {
   if (IsPointer(symbol) && !context_.HasError(symbol) &&
       !scopeIsUninstantiatedPDT_) {
     if (const auto *object{symbol.detailsIf<ObjectEntityDetails>()}) {
       if (object->init()) { // C764, C765; C808
         if (auto designator{evaluate::AsGenericExpr(symbol)}) {

flang/test/Semantics/resolve14.f90

 program p2
   use m1, xx => x, y => z
   use m2
   volatile w
   !ERROR: Cannot change CONTIGUOUS attribute on use-associated 'w'
   contiguous w
   !ERROR: 'z' is use-associated from module 'm2' and cannot be re-declared
   integer z
+  real, target :: a(10)
+  real, contiguous, pointer :: p(:) => a
   !ERROR: Reference to 'y' is ambiguous
   y = 1
+ contains
+  subroutine inner
+    p(1) = 0. ! ok - check for regression on contiguous host assoc.
+  end subroutine
 end