Re: Fixed point constants issue

["Vinzent Hoefler" <nntp-2010-09@t-domaingrabbing.de>]

On Tue, 14 Sep 2010 08:54:20 +0200, J-P. Rosen <rosen@adalog.fr> wrote:

> Every language with overloading has to decide whether resolution goes
> from the outside to the inside, or the other way round. In the case of
> Ada, it is the "enclosing context" that determines the type of what's in
> it. If the enclosing context is a type conversion, it tells nothing
> about the expected type of its argument, hence the fall back to
> universal types. If the enclosing context is typed, it determines the
> type of the "*" operator.

I understand that. What I don't understand is that two different compilers  
do
seem to handle it differently. Actually, I just wanted to know which one  
does
it wrong. ;)

Now, to make matters worse:

ARM 3.5(9):
"[...] the evaluation of the range evaluates these simple_expressions
in an arbitrary order, and converts them to the type of the range."

which I read as "_first_ evaluate and _then_ convert". But this only  
applies to
the dynamic case, right?

Then:

ARM 3.5(5):
"For a subtype_indication containing a range_constraint, [...], the type  
of the
range shall resolve to that of the type determined by the subtype_mark of  
the
subtype_indication. For a range of a given type, the simple_expressions of  
the range
(likewise, the simple_expressions of the equivalent range for a
range_attribute_reference) are expected to be of the type of the range."

Which is quite specific and seems to happen here.

Yet, this is not the end:

ARM 3.5.9(3) defines a fixed point definition to have a  
"real_range_specification",
which according to ARM 3.5.7(5) "is expected to be of any real type; the  
types
need not be the same".

Now, I suspect that in

type    Fixed_1 is         delta 0.5 range 0.0 .. 50.0 * 0.1;
subtype Fixed_2 is Fixed_1           range 0.0 .. 50.0 * 0.1;

(where "One_Tenth" shall be a non-static function).

Fixed_1 and Fixed_4 have a range of 0.0 .. 5.0 then, whilst Fixed_2's  
range suddenly
is 0.0 .. 0.0 again, right?


Vinzent.

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