!ASIS Issue #022
!topic Normalize associations list
!reference ASIS95
!from Sergey Rybin and Steve Blake 96-11-06
!keywords association list normalized component parameter
!discussion

There are two queries in ASIS95 for obtaining the association list
from a subprogram or entry call -
Asis.Expressions.Function_Call_Parameters for functions and
Asis.Statements.Call_Statement_Parameters for procedures and
entries. Both these queries have the Normalized parameter.
 
The problem is that a function call may be a call to an
attribute-function (such as P'Pred (X) or T'Max (Y,Z),and a procedure
call may be a call to a attribute-procedure (such as T'Read (Var)),
and the existing documentation of these two queries does not cover
situations, when a call being decomposed is the call to
attribute-subprogram, and the Normalized parameter is set True.
 
Ada does not allow the positional associations for calls to
functions-attributes. I failed to find any place where it is said
explicitly, but function-attributes have no declarations (neither
explicit nor implicit), so there cannot be any visible declarations
for any formal parameter name from such a call.
 
The questions are:
 - should ASIS allow obtaining normalized component list from a call
   to attribute-function?
 
 - if it should, what is a normalized parameter association for a call
   to attribute-function?
 
Our suggestion is:
 
 1. Calls with the Normalized parameter set True should be allowed for
    all function calls and procedure calls, including cases when
    the called entity is an attribute. (It does not make any formal
    contradiction with Ada, because normalized associations are entirely
    ASIS internal notion.) Another solution may be to raise
    Asis_Inappropriate_Element, but it would have at least two
    disadvantagies - first, it would change the existing semantics of
    these queries, second, it would force an application to use additional
    exception handlers to deal with possible exceptions.
 
 2. Normalised associations obtained from calls to attributes-subprograms
    should test Is_Normalized, it could never be Is_Defaulted_Association.
 
 3. When further decomposed, a Normalised association obtained from a call
    to an attributes-subprogram should yield Nil_Element as a formal
    parameter (a result of Asis.Expressions.Formal_Parameter.
 
The corresponding statements should be added to the documentation of
Asis.Expressions.Function_Call_Parameters,
Asis.Statements.Call_Statement_Parameters and
Asis.Expressions.Formal_Parameter.

!resolution  Accepted, with Modification.
!date 96-12-03
!Notes

Additional commentary has been added to some of the interfaces.  Some
clean-up was also performed.  These appeared in ASIS version 2.0.K.