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From: Victor Porton <porton@narod.ru>
Newsgroups: comp.lang.ada
Subject: Interfacing enums with C
Date: Sun, 17 Aug 2014 22:02:45 +0300
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Xref: news.eternal-september.org comp.lang.ada:21795
Date: 2014-08-17T22:02:45+03:00
List-Id: <comp.lang.ada>

Let in C code are defined:

typedef enum { A=1, B=2 } option_type;

void f(option_type option);

Let we also have

type Option_Type is (A, B);
for Option_Type'Size use Interfaces.C.unsigned'Size;
for Option_Type use (A=>1, B=>2);

X: Option_Type := A;

Which of the following code is correct (accordingly RM)?

-- First code
declare
   procedure F (Option: Option_Type)
      with Import, Convention=>C, External_Name=>"f";
begin
   F(X);
end;

or

-- Second code
declare
   procedure F (Option: Interfaces.C.unsigned)
      with Import, Convention=>C, External_Name=>"f";
   function Conv is new Ada.Unchecked_Conversion(Option_Type, Interfaces.C.unsigned);
begin
   F(Conv(X));
end;

I think both first and second Ada fragments are correct but am not sure.

-- 
Victor Porton - http://portonvictor.org