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From: Stephen Leake <stephen_leake@stephe-leake.org>
Newsgroups: comp.lang.ada
Subject: 'for cursor in container.first loop' bug?
Date: Thu, 28 Aug 2014 12:56:56 -0500
Message-ID: <85y4u8xztj.fsf@stephe-leake.org>
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Xref: news.eternal-september.org comp.lang.ada:21956
Date: 2014-08-28T12:56:56-05:00
List-Id: <comp.lang.ada>

I'm trying to use the 'for cursor in container.first loop' syntax in Ada
2012 with my own container, and having lots of problems.

So first I tried a simple example using Ada.Containers.Vector, with GNAT
2014:

with Ada.Text_Io; use Ada.Text_Io;
with Ada.Containers.Vectors;
procedure Try_Containers
is
   package Integer_Vectors is new Ada.Containers.Vectors (Natural, Integer);
   use Integer_Vectors;

   A : Vector := To_Vector (1, 10);
begin
   Loop_1 :
   for Element of A loop
      Put_Line ("A (i) => " & Integer'Image (Element));
      -- can't do Element := 2;
   end loop Loop_1;

   Loop_2 :
   for Cursor in First (A) loop
      Put_Line ("A (I) => " & Integer'Image (Element (Cursor)));
      Replace_Element (A, Cursor, 2);
      Reference (A, Cursor) := 2;
   end loop Loop_2;

end Try_Containers;

This gives compilation errors:

gnatmake -k ../try_containers.adb
gcc -c -I../ -I- ../try_containers.adb
try_containers.adb:17:28: invalid prefix in call
try_containers.adb:17:28: invalid prefix in selected component "I572b"
gnatmake: "../try_containers.adb" compilation error

Same error (with a different generated name) with GnatPro 7.2.

Commenting out loop_2 gives the expected results.

Am I missing something simple, or is this a compiler bug? At the very
least, it's not a good error message.

-- 
-- Stephe