[flang] Add semantic checks for interoperability of derived type (C1806)

[peixin]

Summary

As Fortran 2018 C1806, each component of a derived type with the BIND
attribute shall be a nonpointer, nonallocatable data component with
interoperable type.

flang/lib/Semantics/check-declarations.cpp

void CheckHelper::CheckBindC(const Symbol &symbol) {
   }
   if (const auto *proc{symbol.detailsIf<ProcEntityDetails>()}) {
     if (!proc->interface().symbol() ||
         !proc->interface().symbol()->attrs().test(Attr::BIND_C)) {
       messages_.Say(symbol.name(),
           "An interface name with BIND attribute must be specified if the BIND attribute is specified in a procedure declaration statement"_err_en_US);
       context_.SetError(symbol);
     }
-  }
-  if (const auto *derived{symbol.detailsIf<DerivedTypeDetails>()}) {
+  } else if (const auto *derived{symbol.detailsIf<DerivedTypeDetails>()}) {
     if (derived->sequence()) { // C1801
       messages_.Say(symbol.name(),
           "A derived type with the BIND attribute cannot have the SEQUENCE attribute"_err_en_US);
       context_.SetError(symbol);
     } else if (!derived->paramDecls().empty()) { // C1802
       messages_.Say(symbol.name(),
           "A derived type with the BIND attribute has type parameter(s)"_err_en_US);
       context_.SetError(symbol);
     } else if (symbol.scope()->GetDerivedTypeParent()) { // C1803
       messages_.Say(symbol.name(),
           "A derived type with the BIND attribute cannot extend from another derived type"_err_en_US);
       context_.SetError(symbol);
     } else {
       for (const auto &pair : *symbol.scope()) {
         const Symbol *component{&*pair.second};
         if (IsProcedure(*component)) { // C1804
           messages_.Say(symbol.name(),
               "A derived type with the BIND attribute cannot have a type bound procedure"_err_en_US);
           context_.SetError(symbol);
           break;
+        } else if (IsAllocatableOrPointer(*component)) { // C1806
+          messages_.Say(symbol.name(),
+              "A derived type with the BIND attribute cannot have a pointer or allocatable component"_err_en_US);
+          context_.SetError(symbol);
+          break;
+        } else if (component->GetType() && component->GetType()->AsDerived() &&
+            !component->GetType()->AsDerived()->typeSymbol().attrs().test(
+                Attr::BIND_C)) {
+          messages_.Say(component->GetType()->AsDerived()->typeSymbol().name(),
+              "The component of the interoperable derived type must have the BIND attribute"_err_en_US);
+          context_.SetError(symbol);
+          break;
         }
       }
     }
     if (derived->componentNames().empty()) { // C1805
       messages_.Say(symbol.name(),
           "A derived type with the BIND attribute is empty"_port_en_US);
     }
   }

flang/module/__fortran_builtins.f90

module __Fortran_builtins
   intrinsic :: selected_int_kind
   private :: selected_int_kind
   integer, parameter, private :: int64 = selected_int_kind(18)
 
   type :: __builtin_c_ptr
     integer(kind=int64) :: __address
   end type
 
-  type :: __builtin_c_funptr
+  type, bind(c) :: __builtin_c_funptr
     integer(kind=int64) :: __address
   end type
 
   type :: __builtin_event_type
     integer(kind=int64) :: __count
   end type
 
   type :: __builtin_lock_type

flang/test/Semantics/bind-c06.f90

program main
    contains
     procedure, nopass :: b => s
   end type
 
   ! WARNING: A derived type with the BIND attribute is empty
   type, bind(c) :: t5
   end type
 
+  ! ERROR: A derived type with the BIND attribute cannot have a pointer or allocatable component
+  type, bind(c) :: t6
+    integer, pointer :: x
+  end type
+
+  ! ERROR: A derived type with the BIND attribute cannot have a pointer or allocatable component
+  type, bind(c) :: t7
+    integer, allocatable :: y
+  end type
+
+  ! ERROR: The component of the interoperable derived type must have the BIND attribute
+  type :: t8
+    integer :: x
+  end type
+
+  type, bind(c) :: t9
+    type(t8) :: y
+    integer :: z
+  end type
+
 end