Proposal for referring to values at labels

[MartinClochardPro]

No description provided.

[ronan-d]

Can you give an example to illustrate this?

[jklmnn]

To my understanding this means that something like

X := 1;
<<My_Label>>
X := 2;
declare
   Y : Integer := 0;
begin
   pragma Assert ((X-1)'At (My_Label) = Y);
end;

is not allowed.

[sttaft]

A label is declared in the innermost declare block enclosing the label. So this would be legal.

[denismazzucato]

A few lines below: "Furthermore, the statement_identifier referenced by an 'At attribute and the attribute itself shall have the same innermost enclosing body."

To my understanding, this would make it illegal as <<My_Label>> and (X-1)'At (My_Label) do not have the same innermost enclosing body.

[sttaft]

Enclosing body is not the same as enclosing declare block. A "body" refers to a function, procedure, task, or package body.

[MartinClochardPro]

Can you give an example to illustrate this?

Something like

declare
  X : Integer := 0;
begin
  X := 1;
  if Condition then
     <<L>>
     X := 2;
  end if;
  pragma Assert ((X-1)'At (L) = 1);
end;

must not be allowed. However Ada language rules states that the label L is declared in the innermost enclosing declare block, which makes it visible at the assertion.

[ronan-d]

I see, thanks.

[sttaft]

The "goto" statement legality rule is similar, and perhaps you should copy as nearly as possible the wording of 5.8(4):

The innermost sequence_of_statements that encloses the target statement shall also enclose the goto_statement. Furthermore, if a goto_statement is enclosed by an accept_statement or a body, then the target statement shall not be outside this enclosing construct.

So, perhaps:

The innermost sequence_of_statements that encloses the target statement shall also enclose the At reference. Furthermore, if an At reference is enclosed by an accept_statement or a body, then the target statement shall not be outside this enclosing construct.

[MartinClochardPro]

I incorporated the change, modulo using "statement_identifier" instead of the "target statement".