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Date: Sat, 7 Apr 2018 11:35:00 -0700 (PDT)
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Subject: Linking Ada to C++ Overloaded Functions and Methods
From: Ron Wills <ron.rwsoft@gmail.com>
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Xref: reader02.eternal-september.org comp.lang.ada:51386
Date: 2018-04-07T11:35:00-07:00
List-Id: <comp.lang.ada>

I know that both Ada and C++ can overload functions and methods. The proble=
m I'm having is when I'm trying to link Ada to overload C++ functions. I kn=
ow I could use different Ada names, but if it's possible to keep the same n=
ames in Ada it would save a lot of re-coding.

An example is from the FLTK library. The "draw_box" method from the Fl_Widg=
et class is overloaded and I get the following from g++ -fdump-ada-spec.

procedure draw_box (this : access constant Fl_Widget'Class);
pragma Import (CPP, draw_box, "_ZNK9Fl_Widget8draw_boxEv");

procedure draw_box
  (this : access constant Fl_Widget'Class;
   t : Fl_Enumerations_H.Fl_Boxtype;
   c : Fl_Enumerations_H.Fl_Color);  -- /usr/include/Fl/Fl_Widget.H:181
pragma Import (CPP, draw_box, "_ZNK9Fl_Widget8draw_boxE10Fl_Boxtypej");

The C++ name mangling works to uniquely identify the C++ methods, but the c=
ompiler is choking on the Ada names as already being declared.

fl_fl_widget_h.ads:171:07: entity "draw_box" was previously imported
fl_fl_widget_h.ads:171:07: (pragma "Import" applies to all previous entitie=
s)
fl_fl_widget_h.ads:171:07: import not allowed for "draw_box" declared at li=
ne 164
fl_fl_widget_h.ads:181:07: entity "draw_box" was previously imported
fl_fl_widget_h.ads:181:07: (pragma "Import" applies to all previous entitie=
s)
fl_fl_widget_h.ads:181:07: import not allowed for "draw_box" declared at li=
ne 167

Is there a way to use overloaded Ada names with C++ or do I need to find a =
unique Ada name for every C++ overload method?