Dear Monks,

as some of you have noticed from my grumbling in the ChatterBox, I'm getting weird CPAN Testers' reports. With Tux's help, I was able to identify the trigger: the problem happens in threaded 5.10.0 only.

The minimal example is here: 

eval ' "x" =~ ?x? '

[download]

(in fact, eval '??' is even shorter, but probably harder to decipher, and doesn't show so clearly that it has to match to trigger the exception).

In threaded 5.10.0 (compiled with a few bugs in make test even with the latest Devel::PatchPerl applied), it throws 

Modification of a read-only value attempted at ...

[download]

Interestingly, the exception goes away if I add reset after the match: 

eval ' "x" =~ ?x?; reset '

[download]

It's clearly a Perl bug, and it's been fixed, as later versions don't show the same behaviour. Nevertheless, I'd be interested in any explanation why "match-only-once" in stringy eval caused this particular error (normal match or the same code outside of eval don't fail).

($q=q:Sq=~/;[c](.)(.)/;chr(-||-|5+lengthSq)`"S|oS2"`map{chr |+ord
}map{substrSq`S_+|`|}3E|-|`7**2-3:)=~y+S|`+$1,++print+eval$q,q,a,

[download]

In reply to Threaded 5.10.0 + ?PATTERN? = Modification of a read-only value attempted by choroba

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