Re: Reördering SVt_* constants; "internal" SV type

On 6/18/26 06:07, Richard Leach wrote:
> On Thu, 18 Jun 2026 at 12:45, Paul "LeoNerd" Evans
> <[email protected]> wrote:
>>    An SV should be treated as a Perl-visible scalar
>>      if SvTYPE(sv) <= SVt_PVXX
> 
> Yeah, this would be nice to have.
> 
>>    SVt_INVLIST   is not a perl-visible scalar, in fact should not be
>>                  visible to any perl code anywhere for any reason, but
>>                  it sorts right after SVt_PV and before SVt_PVIV and is
>>                  thus accidentally included in the above scalar test
> 
> I think it's located there because it's sort of a PV under the hood.
> Not sure offhand if moving it out of the "Perl-visible scalar"
> grouping would break anything.

I searched for the best place to insert it, and came up with that.  I 
believe that there were pre-existing  conditionals that used a < 
comparison that putting it further down would break.
> 
>> I know there are some ordering constraints involved in the SvTYPE
>> values, but I don't believe it would be too problematic to move
>> SVt_PVLV to just after SVt_PVMG (and thus allow a contiguous range for
>> scalars).
> 
> Might need to adjust the handful of places that do "type <= SVt_PVLV"
> and similar.
> 
> Are there some code paths in which SVt_PVGV is also treated like a
> "Perl-visible scalar" or at least would be nice to have it covered by
> a "SvTYPE(sv) <= some-other-value" check?