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"splice() offset past end of array" warning doesn't always appear #12927

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p5pRT opened this issue Apr 23, 2013 · 9 comments

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commented Apr 23, 2013

Migrated from rt.perl.org#117729 (status was 'resolved')

Searchable as RT117729$

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commented Apr 23, 2013

From @karenetheridge

According to the splice documentation in perlfunc​:

  splice ARRAY or EXPR,OFFSET

  If OFFSET is past the end of the array, Perl issues a warning, and
  splices at the end of the array.

Consider​:
  perl -wle'use warnings FATAL => "all"; my @​arr = qw(0 .. 10); splice(@​arr, 20); print "ar is @​arr"'

This generates a warning on some versions/architectures and not others.
Based on the versions tested, this appears to have regressed between 5.14.3
and 5.16.0.

warning​:
5.8.9 darwin OSX 10.6.8
5.14.2 darwin OSX 10.6.8
5.14.3 darwin OSX 10.6.8
5.14.3 linux CentOS

no warning​:
5.16.0 linux ubuntu
5.16.0 darwin OSX 10.6.8
5.16.1 darwin OSX 10.6.8
5.16.3 darwin OSX 10.6.8
5.17.11 darwin OSX 10.6.8

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commented Apr 24, 2013

From @jkeenan

On Tue Apr 23 13​:14​:02 2013, perl@​froods.org wrote​:

According to the splice documentation in perlfunc​:

splice ARRAY or EXPR,OFFSET

If OFFSET is past the end of the array, Perl issues a warning, and
splices at the end of the array.

Consider​:
perl -wle'use warnings FATAL => "all"; my @​arr = qw(0 .. 10);
splice(@​arr, 20); print "ar is @​arr"'

This generates a warning on some versions/architectures and not
others.
Based on the versions tested, this appears to have regressed between
5.14.3
and 5.16.0.

warning​:
5.8.9 darwin OSX 10.6.8
5.14.2 darwin OSX 10.6.8
5.14.3 darwin OSX 10.6.8
5.14.3 linux CentOS

no warning​:
5.16.0 linux ubuntu
5.16.0 darwin OSX 10.6.8
5.16.1 darwin OSX 10.6.8
5.16.3 darwin OSX 10.6.8
5.17.11 darwin OSX 10.6.8

Confirmed to occur in blead as well.

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commented Apr 24, 2013

The RT System itself - Status changed from 'new' to 'open'

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commented Apr 24, 2013

From @ikegami

It's not a regression; it's an intentional change.

C<< splice(@​a, $n) >> is commonly used to truncate an array if it's too
large, so C<< splice(@​a, $n) >> (with no further args) does not warn even
if @​a<$n.

See
https://rt-archive.perl.org/perl5/Public/Bug/Display.html?id=78462
http​://perl5.git.perl.org/perl.git/commitdiff/5cd408a276e19848774860967c3ec06b67b863ee?hp=0890f1a536cff0aff68038cae78e02c9d9b6a2b2

So, this is merely a documentation bug for which I'll submit a patch
tomorrow.

- Eric

On Tue, Apr 23, 2013 at 8​:34 PM, James E Keenan via RT <
perlbug-followup@​perl.org> wrote​:

On Tue Apr 23 13​:14​:02 2013, perl@​froods.org wrote​:

According to the splice documentation in perlfunc​:

splice ARRAY or EXPR,OFFSET

If OFFSET is past the end of the array, Perl issues a warning, and
splices at the end of the array.

Consider​:
perl -wle'use warnings FATAL => "all"; my @​arr = qw(0 .. 10);
splice(@​arr, 20); print "ar is @​arr"'

This generates a warning on some versions/architectures and not
others.
Based on the versions tested, this appears to have regressed between
5.14.3
and 5.16.0.

warning​:
5.8.9 darwin OSX 10.6.8
5.14.2 darwin OSX 10.6.8
5.14.3 darwin OSX 10.6.8
5.14.3 linux CentOS

no warning​:
5.16.0 linux ubuntu
5.16.0 darwin OSX 10.6.8
5.16.1 darwin OSX 10.6.8
5.16.3 darwin OSX 10.6.8
5.17.11 darwin OSX 10.6.8

Confirmed to occur in blead as well.

---
via perlbug​: queue​: perl5 status​: new
https://rt-archive.perl.org/perl5/Ticket/Display.html?id=117729

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commented Apr 24, 2013

From @karenetheridge

On Tue, Apr 23, 2013 at 09​:52​:07PM -0700, Eric Brine via RT wrote​:

It's not a regression; it's an intentional change.

C<< splice(@​a, $n) >> is commonly used to truncate an array if it's too
large, so C<< splice(@​a, $n) >> (with no further args) does not warn even
if @​a<$n.

This is quite reasonable (and indeed, this is the exact usecase where I
discovered that there was a warning on my not-quite-as-current production
system). :)

So, this is merely a documentation bug for which I'll submit a patch
tomorrow.

Thanks! (Was there also a perldelta entry for this? it's not too late to
put one in perldelta5160.)

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commented Jun 3, 2013

From @ikegami

On Wed, Apr 24, 2013 at 10​:47 AM, Karen Etheridge <perl@​froods.org> wrote​:

On Tue, Apr 23, 2013 at 09​:52​:07PM -0700, Eric Brine via RT wrote​:

So, this is merely a documentation bug for which I'll submit a patch

tomorrow.

Thanks! (Was there also a perldelta entry for this? it's not too late to

put one in perldelta5160.)

Patched attached. Ok, it's not "tomorrow", but I figured I'd wait til 5.18
was out.

It actually is too late to add to perldelta5160, but it was actually
mentioned.

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commented Jun 3, 2013

From @ikegami

0001-Adjust-documentation-for-removal-of-splice-warning.patch
From b4f8845653bc5261c5f8827c3edad6747396b651 Mon Sep 17 00:00:00 2001
From: Eric Brine <ikegami@adaelis.com>
Date: Sun, 2 Jun 2013 21:46:07 -0700
Subject: [PATCH] Adjust documentation for removal of splice warning

---
 pod/perlfunc.pod |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/pod/perlfunc.pod b/pod/perlfunc.pod
index 5c6b4f8..3b36873 100644
--- a/pod/perlfunc.pod
+++ b/pod/perlfunc.pod
@@ -6766,8 +6766,8 @@ If LENGTH is omitted, removes everything from OFFSET onward.
 If LENGTH is negative, removes the elements from OFFSET onward
 except for -LENGTH elements at the end of the array.
 If both OFFSET and LENGTH are omitted, removes everything.  If OFFSET is
-past the end of the array, Perl issues a warning, and splices at the
-end of the array.
+past the end of the array and a LENGTH was provided, Perl issues a warning,
+and splices at the end of the array.
 
 The following equivalences hold (assuming C<< $#a >= $i >> )
 
-- 
1.7.2.5

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commented Jun 3, 2013

From @cpansprout

On Sun Jun 02 21​:44​:25 2013, ikegami@​adaelis.com wrote​:

On Wed, Apr 24, 2013 at 10​:47 AM, Karen Etheridge <perl@​froods.org> wrote​:

On Tue, Apr 23, 2013 at 09​:52​:07PM -0700, Eric Brine via RT wrote​:

So, this is merely a documentation bug for which I'll submit a patch

tomorrow.

Thanks! (Was there also a perldelta entry for this? it's not too
late to

put one in perldelta5160.)

Patched attached. Ok, it's not "tomorrow", but I figured I'd wait til 5.18
was out.

Thank you. Applied as 8e602cc.

--

Father Chrysostomos

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commented Jun 3, 2013

@cpansprout - Status changed from 'open' to 'resolved'

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