[Ada] AI-108

[Arnaud Charlet <charlet at adacore dot com>]

Tested under i686-linux, committed on mainline.

For a reference to a stream attribute whose prefix denotes a limited type,
the attribute reference is legal if the attribute has been specified by an
attribute definition clause for the type. Per AI-108 (LRM 13.13.2(9/1)),
the reference is also legal if the attribute has been specified for any
ancestor of the type.
This change implements this new case, and allows the corresponding new
ACATS test (CDD2A03) to be compiled and executed properly.

2005-03-17  Thomas Quinot  <quinot@adacore.com>

	* exp_ch3.adb (Check_Attr): New subprogram.
	(Check_Stream_Attribute): Move the code for 13.13.2(9/1) enforcement
	into a new Check_Attr subprogram, in order to provide a more
	explanatory error message (including the name of the missing attribute).
	(Stream_Operation_OK): Renamed from Stream_Operations_OK. This
	subprogram determines whether a default implementation exists for a
	given stream attribute.
	(Make_Predefined_Primitive_Specs, Predefined_Primitive_Bodies):
	Determine whether to generate a default implementation for each stream
	attribute separately, as this depends on the specific attribute.

	* exp_strm.adb (Make_Field_Attribute): For the case of an illegal
	limited extension where a stream attribute is missing for a limited
	component (which will have been flagged in Exp_Ch3.Sem_Attr), do not
	generate a bogus reference to the missing attribute to prevent
	cascaded errors. Instead, generate a null statement.

	* sem_attr.adb (Check_Stream_Attribute): A stream attribute is
	available for a limited type if it has been specified for an ancestor
	of the type.

Attachment: difs.7
Description: Text document