[Ada] Missing Constraint_Error in illegal conversion to C type

[Arnaud Charlet <charlet at adacore dot com>]

This patch removes an old range check optimization which incorrectly assumes
that the type of an arbitrary expression can always fit in the target type of a
conversion.

------------
-- Source --
------------

--  main.adb

with Interfaces; use Interfaces;

procedure Main is
   subtype Small_Positive is Integer_16 range 1 .. Integer_16'Last;

   type Target_Typ is array (Small_Positive range <>) of Boolean;
   pragma Convention (C, Target_Typ);

   subtype Large_Positive is Integer_32 range 1 .. 60_000;

   type Expr_Typ is array (Large_Positive range <>) of Boolean;
   type Expr_Typ_Ptr is access Expr_Typ;

   Expr     : constant Expr_Typ     := (1 .. 60_000 => True);
   Expr_Ptr : constant Expr_Typ_Ptr := new Expr_Typ'(Expr);
   Target   : constant Target_Typ   := Target_Typ (Expr_Ptr.all);
begin
   null;
end Main;

----------------------------
-- Compilation and output --
----------------------------

$ gnatmake -q main.adb
$ ./main.adb

raised CONSTRAINT_ERROR : main.adb:16 range check failed

Tested on x86_64-pc-linux-gnu, committed on trunk

2012-08-06  Hristian Kirtchev  <kirtchev@adacore.com>

	* checks.adb (Discrete_Range_Cond): Do not try to optimize on
	the assumption that the type of an expression can always fit in
	the target type of a conversion.

Attachment: difs
Description: Text document