[flang] Add some semantic checks for derived type with BIND attribute

[peixin]

Summary

This supports checks in C1801-C1805 for derived type with BIND attribute.
The other compilers such as 'gfortran' and 'ifort' do not report error
for C1802 and C1805, so emit warnings for them.

[klausler]

flang/lib/Semantics/check-declarations.cpp

1920

derived*

1924

derived*

s/from another/another/

1931

derived*

1939

derived*

This should be an error.

1943

derived*

This should probably be a portability warning.

[peixin]

Thanks @klausler for the review. Addressed the comments.

[peixin]

ping

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>()}) {
+    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;
+        }
+      }
+    }
+    if (derived->componentNames().empty()) { // C1805
+      messages_.Say(symbol.name(),
+          "A derived type with the BIND attribute is empty"_port_en_US);
+    }
+  }
 }
 
 bool CheckHelper::CheckDioDummyIsData(
     const Symbol &subp, const Symbol *arg, std::size_t position) {
   if (arg && arg->detailsIf<ObjectEntityDetails>()) {
     return true;
   } else {
     if (arg) {

flang/test/Semantics/bind-c06.f90

+! RUN: %python %S/test_errors.py %s %flang_fc1
+! Check for C1801 - C1805
+
+module m
+  public s
+contains
+  subroutine s
+  end
+end
+
+program main
+  use m
+  type, abstract :: v
+    integer :: i
+  end type
+
+  ! ERROR: A derived type with the BIND attribute cannot have the SEQUENCE attribute
+  type, bind(c) :: t1
+    sequence
+    integer :: x
+  end type
+
+  ! ERROR: A derived type with the BIND attribute has type parameter(s)
+  type, bind(c) :: t2(k)
+    integer, KIND :: k
+    integer :: x
+  end type
+
+  ! ERROR: A derived type with the BIND attribute cannot extend from another derived type
+  type, bind(c), extends(v) :: t3
+    integer :: x
+  end type
+
+  ! ERROR: A derived type with the BIND attribute cannot have a type bound procedure
+  type, bind(c) :: t4
+    integer :: x
+   contains
+    procedure, nopass :: b => s
+  end type
+
+  ! WARNING: A derived type with the BIND attribute is empty
+  type, bind(c) :: t5
+  end type
+
+end

flang/test/Semantics/modfile11.f90

 ! RUN: %python %S/test_modfile.py %s %flang_fc1
 module m
   type t1(a, b, c)
     integer, kind :: a
     integer(8), len :: b, c
     integer :: d
   end type
   type, extends(t1) :: t2(e)
     integer, len :: e
   end type
-  type, extends(t2), bind(c) :: t3
+  type, extends(t2) :: t3
   end type
 end
 
 !Expect: m.mod
 !module m
 !  type::t1(a,b,c)
 !    integer(4),kind::a
 !    integer(8),len::b
 !    integer(8),len::c
 !    integer(4)::d
 !  end type
 !  type,extends(t1)::t2(e)
 !    integer(4),len::e
 !  end type
-!  type,bind(c),extends(t2)::t3
+!  type,extends(t2)::t3
 !  end type
 !end