[perl #36875] [PATCH] scalar reverse undef does not warn (was: Certain string handling functions don't warn on undef)

On Thu Aug 11 23:04:35 2005, tassilo.von.parseval@rwth-aachen.de wrote:
> -----------------------------------------------------------------
> 
> It appears that perl (any perl between 5.5.4 and 5.9.3) wont always
>    warn when
> an undefined value is used as an argument:
> 
>     perl -we 'print lc(undef)'
> 
> There will be no uninitialized-value-warning with (at least)
>    (lc|uc)(_first)?
> and reverse in scalar context.
> 
> -----------------------------------------------------------------

lc, uc, lcfirst and ucfirst already warn in blead.

./perl -wle 'my $v;$_ = lc $v;$_ = uc $v;$_ = lcfirst $v;$_ = ucfirst 
$v;'
Use of uninitialized value $v in lc at -e line 1.
Use of uninitialized value $v in uc at -e line 1.
Use of uninitialized value $v in lcfirst at -e line 1.
Use of uninitialized value $v in ucfirst at -e line 1.


A patch that adds a warnings for reverse:

./perl -wle 'my $r1;$_=undef;$_=reverse;$_=reverse $r1;'
Use of uninitialized value in reverse at -e line 1.
Use of uninitialized value $r1 in reverse at -e line 1


Also in the patch is a test to see that reverse "foo", undef, "bar" warns:
(this warning was already there, becaues it uses do_join which warns on 
undef, but it wasn't being tested (AFAICT))

./perl -wle 'my $r1;$_=reverse "foo", $r1, "bar";'
Use of uninitialized value $r1 in reverse at -e line 1


Doesn't warn on:
./perl -wle 'my $r1;my @a=reverse "foo", $r1, "bar";'

(which is what I expect)


Kind regards,

Bram

• [perl #36875] [PATCH] scalar reverse undef does not warn (was: Certain string handling functions don't warn on undef) by Bram via RT
• Re: [perl #36875] [PATCH] scalar reverse undef does not warn (was: Certain string handling functions don't warn on undef) by Rafael Garcia-Suarez