Pragma inside grep block

[rovf]

Why does Perl 5.8.8 complain "no" not allowed in expression in this program:

use strict; use warnings;
grep { no strict 'refs'; }qw(x);

but not in this:

use strict; use warnings;
grep { 0; no strict 'refs'; }qw(x);

?

[moritz]

Because perl mis-parses this for grep HASHREF (but I have no idea why), expects a statement, sees a 'no' and complains.

Yes, this could be done better, but fiddling with the perl 5 lexer is non-trivial and not for the faint of hearted.

[RMGir]

Good question.

5.10.0 has the same problem:

$ perl -e'use strict; use warnings;
grep { no strict "refs"; }qw(x);
'
"no" not allowed in expression at -e line 2, at end of line
BEGIN not safe after errors--compilation aborted at -e line 2.
$ perl -e'use strict; use warnings;
grep { 0; no strict "refs"; }qw(x);
'
$

Of course,

{
    no strict "refs";
    grep {0;} qw(x);
}

would work fine, so at least there's a workaround...

[Anonymous Monk]

Workaround is to add ;

grep { ;no strict 'refs'; } qw(x);

but that confuse Deparse :D

perl -MO=Deparse
use strict;
use warnings;
grep { ;no strict 'refs'; } qw(x);
^D
use warnings;
use strict 'refs';
grep {();} 'x';
- syntax OK

Also works

grep { do{ no strict 'refs'; } } qw(x)