[ub] Remove undefined behavior from the preprocessor

Lawrence Crowl Lawrence at Crowl.org
Thu Oct 17 01:49:23 CEST 2013


On 10/14/13, Gabriel Dos Reis <gdr at microsoft.com> wrote:
> > On 10/14/2013 03:18 PM, Gabriel Dos Reis wrote:
> > > Revision based on feedback attached.
> > >   - UCN token splicing is made conditionally supported with
> > >     implementation defined semantics, instead of just ill-formed
> > >     as proposed earlier.
> >
> > Aren't there just two options:  Either this becomes a UCN by token
> > splicing, or it stays a sequence of individual characters?  Can't
> > we just say that?
>
> A third option is "ill-formed".  I don't think we should get down to
> that level of detail here.  I would rather leave it to implementations
> and tools whether they want to support clean mode (diagnose), garbage
> mode (individual characters), or make sense of it
> (implementation-defined semantics.)

For the preprocessor, I would rather not see undiagnosed differences in
behavior.  Wouldn't it be best to simply poll the vendors and see if
they are okay with standardizing on "UCN from splicing"?

-- 
Lawrence Crowl


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