C Semantics in K Framework

[Derek M Jones <derek AT knosof.co.uk>]

Chucky,

> Doesn't being a constraint violation make it undefined?  I can't really

A constraint violation means the that program is erroneous and need not
be translated by a conforming implementation.

Of course a conforming implementation can translation an erroneous
program, but the behavior is undefined (3.4.3p1).  There is nothing
that says a C compiler cannot process Fortran source as if it were
a Fortran compiler.

What is special about your example?

> find what the point of constraints are in the standard, but I've always
> assumed constraint violations were undefined.
>
> All I can find talking around it are
>
> - constraint: "restriction, either syntactic or semantic, by which the
> exposition of language elements is to be interpreted"
> and then this beast
> - If a ‘‘shall’’ or ‘‘shall not’’ requirement that appears outside of a
> constraint or runtime-constraint is violated, the behavior is undefined.
> This seems to leave unexplained what happens if a shall or shall not
> requirement that appears INSIDE a constraint or runtime-constraint is
> violated, but its existence may imply it's not undefined.
>
> At any rate, the behavior certainly doesn't seem DEFINED.
>
> What gives?  And what do you think about how not being able to cast away
> const means we can't keep const pointers we eventually free?  Seems
> limiting to me.
>
> -Chucky
>
> On Thu, Feb 19, 2015 at 9:47 AM, Derek M Jones 
> <derek AT knosof.co.uk>
>  wrote:
>
> > Chucky,
> >
> > Good to hear from you.  Hope you are having fun.
> >
> >   int * p3 = p2; // I think this is undefined, since the case is not listed
> > > in 6.3.2.3 or anywhere else I can tell
> >
> > Its a constraint violation, 6.7.8p11 -> 6.5.16.1p1
> >
> >
> > --
> > Derek M. Jones           Software analysis
> > tel: +44 (0)1252 520667  blog:shape-of-code.coding-guidelines.com

--
Derek M. Jones           Software analysis
tel: +44 (0)1252 520667  blog:shape-of-code.coding-guidelines.com