[flang] Add one semantic check for procedure bind(C) interface-name

[peixin]

Summary

As Fortran 2018 C1521, in procedure declaration statement, if
proc-language-binding-spec (bind(c)) is specified, the proc-interface
shall appear, it shall be an interface-name, and interface-name shall
be declared with a proc-language-binding-spec.

[klausler]

flang/lib/Semantics/check-declarations.cpp

1904

If this is an error, the text should read "must be specified". Use "should" for warnings.

[peixin]

flang/lib/Semantics/check-declarations.cpp

1904

Thanks. Fixed. Will also pay attention to this for future patch.

[jeanPerier]

LGTM, thanks

flang/lib/Semantics/check-declarations.cpp

if (!pair.second) {
                 *name)}) {
           msg->Attach(other.name(), "Conflicting symbol"_en_US);
         }
         context_.SetError(symbol);
         context_.SetError(other);
       }
     }
   }
+  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);
+    }
+  }
 }
 
 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-c03.f90

+! RUN: %python %S/test_errors.py %s %flang_fc1
+! Check for C1521
+! If proc-language-binding-spec (bind(c)) is specified, the proc-interface
+! shall appear, it shall be an interface-name, and interface-name shall be
+! declared with a proc-language-binding-spec.
+
+module m
+
+  interface
+    subroutine proc1() bind(c)
+    end
+    subroutine proc2()
+    end
+  end interface
+
+  procedure(proc1), bind(c) :: pc1 ! no error
+
+  !ERROR: An interface name with BIND attribute must be specified if the BIND attribute is specified in a procedure declaration statement
+  procedure(proc2), bind(c) :: pc2
+
+  !ERROR: An interface name with BIND attribute must be specified if the BIND attribute is specified in a procedure declaration statement
+  procedure(integer), bind(c) :: pc3
+
+end

flang/test/Semantics/modfile16.f90

 ! RUN: %python %S/test_modfile.py %s %flang_fc1
 module m
   character(2), parameter :: prefix = 'c_'
   integer, bind(c, name='c_a') :: a
   procedure(sub), bind(c, name=prefix//'b'), pointer :: b
   type, bind(c) :: t
     real :: c
   end type
-  real :: d
-  external :: d
-  bind(c, name='dd') :: d
-  real :: e
-  bind(c, name='ee') :: e
-  external :: e
-  bind(c, name='ff') :: f
-  real :: f
-  external :: f
 contains
   subroutine sub() bind(c, name='sub')
   end
 end
 
 !Expect: m.mod
 !module m
 !  character(2_4,1),parameter::prefix="c_"
 !  integer(4),bind(c, name="c_a")::a
 !  procedure(sub),bind(c, name="c_b"),pointer::b
 !  type,bind(c)::t
 !    real(4)::c
 !  end type
-!  procedure(real(4)),bind(c, name="dd")::d
-!  procedure(real(4)),bind(c, name="ee")::e
-!  procedure(real(4)),bind(c, name="ff")::f
 !contains
 !  subroutine sub() bind(c, name="sub")
 !  end
 !end

flang/test/Semantics/resolve82.f90

abstract interface
     end function procFunc
   end interface
 
   !WARNING: Attribute 'PUBLIC' cannot be used more than once
   procedure(procFunc), public, pointer, public :: proc1
   !WARNING: Attribute 'PRIVATE' cannot be used more than once
   procedure(procFunc), private, pointer, private :: proc2
   !WARNING: Attribute 'BIND(C)' cannot be used more than once
+  !ERROR: An interface name with BIND attribute must be specified if the BIND attribute is specified in a procedure declaration statement
   procedure(procFunc), bind(c), pointer, bind(c) :: proc3
   !WARNING: Attribute 'PROTECTED' cannot be used more than once
   procedure(procFunc), protected, pointer, protected :: proc4
 
 contains
 
     subroutine testProcDecl(arg4, arg5, arg6, arg7, arg8, arg9, arg10, arg11)
       !WARNING: Attribute 'INTENT(IN)' cannot be used more than once