[flang] Accept BIND(C) derived type for Cray pointees (llvm#76538)

The compiler requires that a Cray pointee have a SEQUENCE type, but a
recent bug report points out that a BIND(C) type should also be
accepted.

Fixes llvm#76529.

Author: klausler

flang/include/flang/Evaluate/tools.h

@@ -1227,6 +1227,7 @@ bool IsFunctionResult(const Symbol &);
 bool IsKindTypeParameter(const Symbol &);
 bool IsLenTypeParameter(const Symbol &);
 bool IsExtensibleType(const DerivedTypeSpec *);
+bool IsSequenceOrBindCType(const DerivedTypeSpec *);
 bool IsBuiltinDerivedType(const DerivedTypeSpec *derived, const char *name);
 bool IsBuiltinCPtr(const Symbol &);
 bool IsEventType(const DerivedTypeSpec *);

flang/lib/Evaluate/tools.cpp

@@ -1724,9 +1724,13 @@ bool IsLenTypeParameter(const Symbol &symbol) {
 }
 
 bool IsExtensibleType(const DerivedTypeSpec *derived) {
-  return derived && !IsIsoCType(derived) &&
-      !derived->typeSymbol().attrs().test(Attr::BIND_C) &&
-      !derived->typeSymbol().get<DerivedTypeDetails>().sequence();
+  return !IsSequenceOrBindCType(derived) && !IsIsoCType(derived);
+}
+
+bool IsSequenceOrBindCType(const DerivedTypeSpec *derived) {
+  return derived &&
+      (derived->typeSymbol().attrs().test(Attr::BIND_C) ||
+          derived->typeSymbol().get<DerivedTypeDetails>().sequence());
 }
 
 bool IsBuiltinDerivedType(const DerivedTypeSpec *derived, const char *name) {

flang/lib/Semantics/resolve-names.cpp

@@ -5940,9 +5940,9 @@ void DeclarationVisitor::Post(const parser::BasedPointer &bp) {
     }
     if (const auto *pointeeType{pointee->GetType()}) {
       if (const auto *derived{pointeeType->AsDerived()}) {
-        if (!derived->typeSymbol().get<DerivedTypeDetails>().sequence()) {
+        if (!IsSequenceOrBindCType(derived)) {
           Say(pointeeName,
-              "Type of Cray pointee '%s' is a non-sequence derived type"_err_en_US);
+              "Type of Cray pointee '%s' is a derived type that is neither SEQUENCE nor BIND(C)"_err_en_US);
         }
       }
     }
@@ -6177,15 +6177,13 @@ void DeclarationVisitor::CheckCommonBlocks() {
         Say(name,
             "Unlimited polymorphic pointer '%s' may not appear in a COMMON block"_err_en_US);
       } else if (const auto *derived{type->AsDerived()}) {
-        auto &typeSymbol{derived->typeSymbol()};
-        if (!typeSymbol.attrs().test(Attr::BIND_C) &&
-            !typeSymbol.get<DerivedTypeDetails>().sequence()) {
+        if (!IsSequenceOrBindCType(derived)) {
           Say(name,
               "Derived type '%s' in COMMON block must have the BIND or"
               " SEQUENCE attribute"_err_en_US);
         }
         UnorderedSymbolSet typeSet;
-        CheckCommonBlockDerivedType(name, typeSymbol, typeSet);
+        CheckCommonBlockDerivedType(name, derived->typeSymbol(), typeSet);
       }
     }
   }

flang/test/Semantics/resolve61.f90

@@ -107,11 +107,16 @@ subroutine p12
   type t2
     integer c2
   end type
+  type, bind(c) :: t3
+    integer c3
+  end type
   type(t1) :: x1
   type(t2) :: x2
+  type(t3) :: x3
   pointer(a, x1)
-  !ERROR: Type of Cray pointee 'x2' is a non-sequence derived type
+  !ERROR: Type of Cray pointee 'x2' is a derived type that is neither SEQUENCE nor BIND(C)
   pointer(b, x2)
+  pointer(c, x3)
 end
 
 subroutine p13