[Ada] Fix allocation of constrained discriminant object

[Arnaud Charlet <charlet at adacore dot com>]

Tested on i686-linux, committed on trunk.

For "new T", if the object is constrained by discriminant defaults, allocate
the right amount of memory, rather than the maximum for type T.
gnat.dg/test_bounded.adb should execute silently.

This patch also stops Expand_N_Unchecked_Type_Conversion from doing the
optimization of integer literals when biased types are involved.
That is necessary, because unchecked type conversion preserves the
bit pattern (including the bias), and not necessarily the integer
value.

gnat.dg/biased_uc.adb should compile and execute quietly

Implement also part of AI-402 and AI-416 (access discriminants of anonymous
access types.

2006-10-31  Javier Miranda  <miranda@adacore.com>
	    Ed Schonberg  <schonberg@adacore.com>
	    Bob Duff  <duff@adacore.com>
	    Gary Dismukes  <dismukes@adacore.com>
	    Robert Dewar  <dewar@adacore.com>
        
        * exp_ch4.adb (Expand_N_Type_Conversion): Handle missing interface type
	conversion.
        (Expand_N_In): Do validity checks on range
	(Expand_Selected_Component): Use updated for of Denotes_Discriminant.
	(Expand_N_Allocator): For "new T", if the object is constrained by
	discriminant defaults, allocate the right amount of memory, rather than
	the maximum for type T.
	(Expand_Allocator_Expression): Suppress the call to Remove_Side_Effects
	when the allocator is initialized by a build-in-place call, since the
	allocator is already rewritten as a reference to the function result,
	and this prevents an unwanted duplication of the function call.
	Add with and use of Exp_Ch6.
	(Expand_Allocator_Expresssion): Check for an allocator whose expression
	is a call to build-in-place function and apply
	Make_Build_In_Place_Call_In_Allocator to the call (for both tagged and
	untagged designated types).
	(Expand_N_Unchecked_Type_Conversion): Do not do integer literal
	optimization if source or target is biased.
	(Expand_N_Allocator): Add comments for case of an allocator within a
	function that returns an anonymous access type designating tasks.
	(Expand_N_Allocator): apply discriminant checks for access
	discriminants of anonymous access types (AI-402, AI-416)

Attachment: difs
Description: Text document