parser bug: print not (1,2,3)[0]

[p5pRT]

Migrated from rt.perl.org#1847 (status was 'resolved')

Searchable as RT1847$

[p5pRT]

From @andk

perl -e 'print not (1,2,3)[0];'
syntax error at -e line 1, near ")["
Execution of -e aborted due to compilation errors.

This was legal up to perl5.005_03.

I found this while trying to compile DBD​::XBase for devel releases.

Perl Info

Site configuration information for perl 5.00562:

Configured by k at Sun Oct 17 08:54:16 CEST 1999.

Summary of my perl5 (revision 5.0 version 5 subversion 62) configuration:
  Platform:
    osname=linux, osvers=2.2.12, archname=i586-linux
    uname='linux hohenstaufen.in-berlin.de 2.2.12 #2 smp sat oct 2 11:10:42 cest 1999 i586 unknown '
    config_args='-Dusemymalloc=y -Doptimize=-g -Dprefix=/usr/local/perl5.005_62-Oct17 -des'
    hint=recommended, useposix=true, d_sigaction=define
    usethreads=undef useperlio=undef d_sfio=undef
    use64bits=undef usemultiplicity=undef
  Compiler:
    cc='cc', optimize='-g', gccversion=2.7.2.3
    cppflags='-Dbool=char -DHAS_BOOL -DDEBUGGING -I/usr/local/include'
    ccflags ='-Dbool=char -DHAS_BOOL -DDEBUGGING -I/usr/local/include'
    stdchar='char', d_stdstdio=define, usevfork=false
    intsize=4, longsize=4, ptrsize=4, doublesize=8
    d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=12
    alignbytes=4, usemymalloc=y, prototype=define
  Linker and Libraries:
    ld='cc', ldflags =' -L/usr/local/lib'
    libpth=/usr/local/lib /lib /usr/lib
    libs=-lnsl -lndbm -lgdbm -ldb -ldl -lm -lc -lposix -lcrypt
    libc=/lib/libc-2.0.7.so, so=so, useshrplib=false, libperl=libperl.a
  Dynamic Linking:
    dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-rdynamic'
    cccdlflags='-fpic', lddlflags='-shared -L/usr/local/lib'

Locally applied patches:
    


@INC for perl 5.00562:
    /usr/local/perl5.005_62-Oct17/lib/5.00562/i586-linux
    /usr/local/perl5.005_62-Oct17/lib/5.00562
    /usr/local/perl5.005_62-Oct17/lib/site_perl/5.00562/i586-linux
    /usr/local/perl5.005_62-Oct17/lib/site_perl
    .


Environment for perl 5.00562:
    HOME=/home/k
    LANG (unset)
    LANGUAGE (unset)
    LD_LIBRARY_PATH (unset)
    LOGDIR (unset)
    PATH=/home/k/bin:/usr/local/bin:/usr/bin:/bin:.:/usr/local/bin:/usr/sbin:/usr/X11R6/bin:/usr/local/perl/bin
    PERL_BADLANG (unset)
    SHELL=/bin/zsh

[p5pRT]

From @gsar

On Fri, 03 Dec 1999 13​:05​:25 +0100, "Andreas J. Koenig" wrote​:

perl -e 'print not (1,2,3)[0];'
syntax error at -e line 1, near ")["
Execution of -e aborted due to compilation errors.

This was legal up to perl5.005_03.

I found this while trying to compile DBD​::XBase for devel releases.

I'm not sure how serious a compatibility issue this will be.
Opinions welcome.

Sarathy
gsar@​ActiveState.com

Inline Patch

-----------------------------------8<-----------------------------------
Change 4673 by gsar@auger on 1999/12/09 04:00:23

	document compatibility issue with literal list slices and NOTOP
	(C<not (1,2,3)[0]> is now a syntax error)

Affected files ...

... //depot/perl/pod/perldelta.pod#118 edit

Differences ...

==== //depot/perl/pod/perldelta.pod#118 (text) ====
Index: perl/pod/perldelta.pod
--- perl/pod/perldelta.pod.~1~	Wed Dec  8 20:00:28 1999
+++ perl/pod/perldelta.pod	Wed Dec  8 20:00:28 1999
@@ -125,6 +125,28 @@
 has been removed, because it could potentially result in memory
 leaks.
 
+=item Parenthesized not() behaves like a list operator
+
+The C<not> operator now falls under the "if it looks like a function,
+it behaves like a function" rule.
+
+As a result, the parenthesized form can be used with C<grep> and C<map>.
+The following construct used to be a syntax error before, but it works
+as expected now:
+
+    grep not($_), @things;
+
+On the other hand, using C<not> with a literal list slice may not
+work.  The following previously allowed construct:
+
+    print not (1,2,3)[0];
+
+needs to written with additional parentheses now:
+
+    print not((1,2,3)[0]);
+
+The behavior remains unaffected when C<not> is not followed by parentheses.
+
 =back
 
 =head2 C Source Incompatibilities
End of Patch.

[p5pRT]

From @andk

On Wed, 08 Dec 1999 20​:04​:58 -0800, Gurusamy Sarathy <gsar@​ActiveState.com> said​:

On Fri, 03 Dec 1999 13​:05​:25 +0100, "Andreas J. Koenig" wrote​:

perl -e 'print not (1,2,3)[0];'
syntax error at -e line 1, near ")["
Execution of -e aborted due to compilation errors.

This was legal up to perl5.005_03.

I found this while trying to compile DBD​::XBase for devel releases.

I'm not sure how serious a compatibility issue this will be.
Opinions welcome.

I have compiled 100s of CPAN modules after that change and so it seems
that only DBD​::XBase uses "not" in such an idiom. I CC the author so
he can reduce the compatibility problem.

Sarathy
gsar@​ActiveState.com
-----------------------------------8<-----------------------------------
Change 4673 by gsar@​auger on 1999/12/09 04​:00​:23

document compatibility issue with literal list slices and NOTOP
\(C\<not \(1\,2\,3\)\[0\]> is now a syntax error\)

Affected files ...

... //depot/perl/pod/perldelta.pod#118 edit

Differences ...

==== //depot/perl/pod/perldelta.pod#118 (text) ====
Index​: perl/pod/perldelta.pod
--- perl/pod/perldelta.pod.1 Wed Dec 8 20​:00​:28 1999
+++ perl/pod/perldelta.pod Wed Dec 8 20​:00​:28 1999
@​@​ -125,6 +125,28 @​@​
has been removed, because it could potentially result in memory
leaks.

+=item Parenthesized not() behaves like a list operator
+
+The C<not> operator now falls under the "if it looks like a function,
+it behaves like a function" rule.
+
+As a result, the parenthesized form can be used with C<grep> and C<map>.
+The following construct used to be a syntax error before, but it works
+as expected now​:
+
+ grep not($_), @​things;
+
+On the other hand, using C<not> with a literal list slice may not
+work. The following previously allowed construct​:
+
+ print not (1,2,3)[0];
+
+needs to written with additional parentheses now​:
+
+ print not((1,2,3)[0]);
+
+The behavior remains unaffected when C<not> is not followed by parentheses.
+
=back

=head2 C Source Incompatibilities
End of Patch.

--
andreas