On 2/21/06, Jeffrey A Law <[EMAIL PROTECTED]> wrote:
> On Mon, 2006-02-20 at 22:00 +0100, Richard Guenther wrote:
> > On 2/20/06, Jeffrey A Law <[EMAIL PROTECTED]> wrote:
> > > On Sun, 2006-02-19 at 20:43 +0100, Laurent GUERBY wrote:
> > > > On Sun, 2006-02-19 at 14:23 -0500, Richard Kenner wrote:
> > > > >     "Second, for a given integer type (such as
> > > > >     natural___XDLU_0_2147483647), the type for the nodes in 
> > > > > TYPE_MIN_VALUE
> > > > >     and TYPE_MAX_VALUE really should be a natural___XDLU_0_2147483647.
> > > > >     ie, the type of an integer constant should be the same as the 
> > > > > type of
> > > > >     its min/max values."
> > > > >
> > > > > No, the type of the bounds of a subtype should be the *base type*.  
> > > > > That's
> > > > > how the tree has always looked, as far back as  I can remember.
> > > >
> > > > This is because intermediate computations can produce results
> > > > outside the subtype range but within the base type range (RM 3.5(6)),
> > > > right?
> > > >
> > > >  type T1 is range 0 .. 127;
> > > >  -- Compiler will choose some type for T'Base, likely to be -128..127
> > > >  -- but could be Integer (implementation dependant)
> > > >  subtype T is T1 range 0 .. 100;
> > > >  R : T := 100+X-X;
> > > >  -- guaranteed work as long 100+X<=T'Base'Last and 100-X>=T'Base'First

Is the final "conversion" a checked conversion or an unchecked conversion?  I.e.
are we supposed to check for overflow using 'Valid on the final result?  Or will
the value be truncated or a runtime error raised?

Richard.

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