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Re^2: How does 'goto LABEL' search for its label? (do-blocks)

by LanX (Bishop)
on Jan 17, 2013 at 18:50 UTC ( #1013854=note: print w/replies, xml ) Need Help??

in reply to Re: How does 'goto LABEL' search for its label? (call stack)
in thread How does 'goto LABEL' search for its label?

> As for there being a new warning for if(1){X:...} goto X:, I lack the details for why this got deprecated.

It's analogous to if(0) the constant block is optimized to a do-block╣ ...

> perl -MO=Deparse -E'if (1) { label: say 1;}; goto label' BEGIN { $^H{'feature_say'} = q(1); $^H{'feature_state'} = q(1); $^H{'feature_switch'} = q(1); } do { label: say 1 }; goto label;

... which seems to fall into the same category like other loop-like-blocks:

ATM I have only 5.10 available. Could someone please test this with >= 5.12?

perl -wE'do { label: say 1;}; goto label'

EDIT: removed exit


here test code w/o endless looping.

perl -wE'my $x=0;do { label: say $x++; die if $x>1}; goto label' 0 1 Died at -e line 1.


Thanks to davido for testing

[davido]: LanX: perl -E 'goto IN; do{ IN: say "Hello world\n";};' does + produce the warning on 5.16.2.

Cheers Rolf

╣) which is somehow strange, I expected a simple bare block.

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