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Re: [perl #130497] Revert "Unescaped left brace in regex" fatality

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From:
Karl Williamson
Date:
April 9, 2017 02:51
Subject:
Re: [perl #130497] Revert "Unescaped left brace in regex" fatality
Message ID:
c928add5-f9bd-dc13-fd11-e76ed986ea63@khwilliamson.com
On 04/07/2017 12:21 PM, Kent Fredric wrote:
> On 8 April 2017 at 06:07, Sawyer X <xsawyerx@gmail.com> wrote:
>> Not a bad idea, but we're pretty far in the cycle to test this change
>> out, I think.
>
>
> Yeah, the cleverer the solution, the more time we need to make sure we
> didn't introduce additional bugs in the cleverness.
>
> Which in practice means this late, without additional test cycles,
> this change would be worse than either choice of "leave it in" or
> "take it out".
>

I think people should be aware of the full consequences of this.

It is not just a simple matter of reverting this patch.  Code has 
marched on.  In particular, you may recall that I missed some cases 
where the deprecation should have been output, and code to output these 
was added after this patch, and so presumes that these cases are fatal.

If I change the patch to just silently continue, the other code fails to 
output a warning on some of the cases covered by this.  If I instead 
change it to output a warning, some cases will have 2 warnings output. 
And cleverness is required to fix that.  We could say that at this stage 
in development, that we can live with 2 warnings. But the other warning 
explicitly says it will be made fatal in 5.30.  Part of the reason to 
make these cases fatal now, was so that in 5.28, we could implement some 
of the extensions made feasible by this.  Having 2 warnings closes the 
door on that possibility.

The solution that requires the least cleverness is my original kludge, 
to simply make

  /\${[^\}]*}/

non-fatal.  It's trivial to do this, and keep it to a single warning

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