From @nothingmuch

Created by @nothingmuch

Though reported under 5.8.1, this bug was tested for in 5.8.3. I
promise ;-).

When using the fields pragma, in something like

<<EOF;

package Foo;

use fields qw/foo/;

sub new {
  my $pkg = shift;
  my $self = $pkg->fields​::new();
 
  $self->{foo} = 'ding';
}

package Bar;

use base qw/Foo/;

package main;

new Foo; # will not generate an error
new Bar; # will generate an error.

EOF

In 5.8.1 the blessing of \%FIELDS into the 'pseudohash' class was
introduced, to suppress errors.

&fields​::inherit doesn't bless that referant though, so errors for a
derived class are not suppressed.

A solution could be to do

  my $derived_fields = \%{"$derived\​::FIELDS"};
  bless $derived_fields, 'pseudohash';

which resolves the issue.

  if (ref $derived_fields !~ /^pseudohash/){
  bless $derived_fields, 'pseudohash';
  }

can also be done, to supress reblessing (why?).

This should be wrapped in

  if ($] < 5.0009){

  }

as 5.9 changes %FIELDS to be a has locked with &Hash​::Utils​::lock_keys.

Here is a patch to base.pm, which now handles fields​::inherit, and the
test suite. It is against the 5.8.3 tree.

EOF

diff -ru perl-5.8.3/lib/base/t/fields-base.t perl-5.8.3-inherit-has-no-fields-phash-warning/lib/base/t/fields-base.t
--- perl-5.8.3/lib/base/t/fields-base.t	Tue Sep 16 08:28:46 2003
+++ perl-5.8.3-inherit-has-no-fields-phash-warning/lib/base/t/fields-base.t	Sun Jan 18 16:47:02 2004
@@ -20,7 +20,7 @@
 }
 
 use strict;
-use Test::More tests => 25;
+use Test::More tests => 26;
 
 BEGIN { use_ok('base'); }
 
@@ -194,3 +194,23 @@
 ::like( $@, qr/Can't multiply inherit %FIELDS/i, 'Again, no multi inherit' );
 
 
+# Test that a package with no fields can inherit from a package with fields, and that pseudohash messages don't show up
+package B9;
+use fields qw(b1);
+
+sub _mk_obj { fields::new($_[0])->{'b1'} };
+
+package D9;
+use base qw(B9);
+
+package main;
+
+{
+	my $w = 0;
+	local $SIG{__WARN__} = sub { $w++ };
+	
+	B9->_mk_obj();
+	D9->_mk_obj(); # used tp emit a warning that pseudohashes are deprecated, because %FIELDS wasn't blessed.
+	
+	is ($w, 0, "pseudohash warnings in derived class with no fields of it's own");	
+}
diff -ru perl-5.8.3/lib/base.pm perl-5.8.3-inherit-has-no-fields-phash-warning/lib/base.pm
--- perl-5.8.3/lib/base.pm	Fri Dec 19 10:13:27 2003
+++ perl-5.8.3-inherit-has-no-fields-phash-warning/lib/base.pm	Sun Jan 18 16:10:31 2004
@@ -42,7 +42,11 @@
     # Shut up a possible typo warning.
     () = \%{$_[0].'::FIELDS'};
 
-    return \%{$_[0].'::FIELDS'};
+    my $f = \%{$_[0].'::FIELDS'};
+
+    bless $f, 'pseudohash' if ($] < 5.009 and ref($f) ne 'pseudohash'); # should be centrallized in fields? perhaps fields::mk_FIELDS_be_OK. Peh. As long as %{ $package . '::FIELDS' } is used here anyway, it doesn't matter.
+
+    return $f;
 }
 
 sub import {

The test classes could also be B8 and D8, with only

  package B8

  sub _mk_obj { $_[0]->fields​::new()->{'_b1'} };

  package main;

  B8->_mk_obj();
  D8->_mk_obj();

but the naming scheme was not so coherent to me. Plus, being hermetic
is more important than being efficient, in test suites.

Flags:
    category=library
    severity=medium

Site configuration information for perl v5.8.1:

Configured by root at Fri Sep 12 19:46:46 PDT 2003.

Summary of my perl5 (revision 5.0 version 8 subversion 1 RC3) configuration:
  Platform:
    osname=darwin, osvers=7.0, archname=darwin-thread-multi-2level
    uname='darwin hampsten 7.0 darwin kernel version 6.0: fri jul 25 16:58:41 pdt 2003; root:xnu-344.frankd.rootsxnu-344.frankd~objrelease_ppc power macintosh powerpc '
    config_args='-ds -e -Dprefix=/usr -Dccflags=-g  -pipe  -Dldflags=-Dman3ext=3pm -Duseithreads -Duseshrplib'
    hint=recommended, useposix=true, d_sigaction=define
    usethreads=define use5005threads=undef useithreads=define usemultiplicity=define
    useperlio=define d_sfio=undef uselargefiles=define usesocks=undef
    use64bitint=undef use64bitall=undef uselongdouble=undef
    usemymalloc=n, bincompat5005=undef
  Compiler:
    cc='cc', ccflags ='-g -pipe -pipe -fno-common -DPERL_DARWIN -no-cpp-precomp -fno-strict-aliasing -I/usr/local/include',
    optimize='-Os',
    cppflags='-no-cpp-precomp -g -pipe -pipe -fno-common -DPERL_DARWIN -no-cpp-precomp -fno-strict-aliasing -I/usr/local/include'
    ccversion='', gccversion='3.3 20030304 (Apple Computer, Inc. build 1495)', gccosandvers=''
    intsize=4, longsize=4, ptrsize=4, doublesize=8, byteorder=4321
    d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=8
    ivtype='long', ivsize=4, nvtype='double', nvsize=8, Off_t='off_t', lseeksize=8
    alignbytes=8, prototype=define
  Linker and Libraries:
    ld='MACOSX_DEPLOYMENT_TARGET=10.3 cc', ldflags ='-L/usr/local/lib'
    libpth=/usr/local/lib /usr/lib
    libs=-ldbm -ldl -lm -lc
    perllibs=-ldl -lm -lc
    libc=/usr/lib/libc.dylib, so=dylib, useshrplib=true, libperl=libperl.dylib
    gnulibc_version=''
  Dynamic Linking:
    dlsrc=dl_dyld.xs, dlext=bundle, d_dlsymun=undef, ccdlflags=' '
    cccdlflags=' ', lddlflags='-bundle -undefined dynamic_lookup -L/usr/local/lib'

Locally applied patches:
    RC3


@INC for perl v5.8.1:
    /System/Library/Perl/5.8.1/darwin-thread-multi-2level
    /System/Library/Perl/5.8.1
    /Library/Perl/5.8.1/darwin-thread-multi-2level
    /Library/Perl/5.8.1
    /Library/Perl
    /Network/Library/Perl/5.8.1/darwin-thread-multi-2level
    /Network/Library/Perl/5.8.1
    /Network/Library/Perl
    .


Environment for perl v5.8.1:
    DYLD_LIBRARY_PATH (unset)
    HOME=/Users/nothingmuch
    LANG (unset)
    LANGUAGE (unset)
    LD_LIBRARY_PATH (unset)
    LOGDIR (unset)
    PATH=/usr/local/bin:/usr/local/sbin:/bin:/sbin:/usr/bin:/usr/sbin:/usr/X11R6/bin/:/usr/local/bin:/usr/local/teTeX/bin/powerpc-apple-darwin-current
    PERL_BADLANG (unset)
    SHELL=/bin/bash

From @iabyn

On Sun, Jan 18, 2004 at 03​:15​:46PM -0000, nothingmuch@​woobling.org (via RT) wrote​:

When using the fields pragma, in something like

<<EOF;

package Foo;

use fields qw/foo/;

sub new {
my $pkg = shift;
my $self = $pkg->fields​::new();

$self\->\{foo\} = 'ding';

}

package Bar;

use base qw/Foo/;

package main;

new Foo; # will not generate an error
new Bar; # will generate an error.

EOF
[snip]
Here is a patch to base.pm, which now handles fields​::inherit, and the
test suite. It is against the 5.8.3 tree.

Thanks, applied to bleedperl as change #22208. I took the liberty in your
patched code of wrapping lines > 80 chars and changing the indentation
form 8 to 4 to match the surrounding code. I also turned $] < 5.009
from a run-time to compile-time test.

Dave.

--
"You're so sadly neglected, and often ignored.
A poor second to Belgium, When going abroad."
  -- Monty Python - "Finland"

Change 22208 by davem@​davem-percy on 2004/01/24 16​:13​:17

  Subject​: [perl #24942] fields​::inherit doesn't bless derived
  package's \%FIELDS, results in phash deprecation errors.
  From​: "nothingmuch@​woobling.org (via RT)" <perlbug-followup@​perl.org>
  Date​: 18 Jan 2004 15​:15​:46 -0000
  Message-Id​: <rt-3.0.8-24942-70144.16.7177902690315@​perl.org>

Affected files ...

... //depot/perl/lib/base.pm#26 edit
... //depot/perl/lib/base/t/fields-base.t#2 edit

Differences ...

==== //depot/perl/lib/base.pm#26 (text) ====

@​@​ -38,11 +38,26 @​@​
  return $Fattr->{$_[0]};
}

-sub get_fields {
- # Shut up a possible typo warning.
- () = \%{$_[0].'​::FIELDS'};
+if ($] < 5.009) {
+ *get_fields = sub {
+ # Shut up a possible typo warning.
+ () = \%{$_[0].'​::FIELDS'};
+ my $f = \%{$_[0].'​::FIELDS'};
+
+ # should be centralized in fields? perhaps
+ # fields​::mk_FIELDS_be_OK. Peh. As long as %{ $package . '​::FIELDS' }
+ # is used here anyway, it doesn't matter.
+ bless $f, 'pseudohash' if (ref($f) ne 'pseudohash');

- return \%{$_[0].'​::FIELDS'};
+ return $f;
+ }
+}
+else {
+ *get_fields = sub {
+ # Shut up a possible typo warning.
+ () = \%{$_[0].'​::FIELDS'};
+ return \%{$_[0].'​::FIELDS'};
+ }
}

sub import {

==== //depot/perl/lib/base/t/fields-base.t#2 (text) ====

@​@​ -20,7 +20,7 @​@​
}

use strict;
-use Test​::More tests => 25;
+use Test​::More tests => 26;

BEGIN { use_ok('base'); }

@​@​ -194,3 +194,27 @​@​
:​:like( $@​, qr/Can't multiply inherit %FIELDS/i, 'Again, no multi inherit' );

+# Test that a package with no fields can inherit from a package with
+# fields, and that pseudohash messages don't show up
+
+package B9;
+use fields qw(b1);
+
+sub _mk_obj { fields​::new($_[0])->{'b1'} };
+
+package D9;
+use base qw(B9);
+
+package main;
+
+{
+ my $w = 0;
+ local $SIG{__WARN__} = sub { $w++ };
+
+ B9->_mk_obj();
+ # used tp emit a warning that pseudohashes are deprecated, because
+ # %FIELDS wasn't blessed.
+ D9->_mk_obj();
+
+ is ($w, 0, "pseudohash warnings in derived class with no fields of it's own");
+}

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

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