lib/B/Deparse.t: many "Variable not imported"-related failures

[jkeenan]

Consider this program, which will be run from the root directory of a git checkout of the Perl core distribution. The program is adapted from lib/B/Deparse.t.

# $ cat ~/tmp/deparse-problem.pl 
my @INC = ("./lib");
my $path = join " ", map { qq["-I$_"] } @INC;
my $alpha = qq|$^X $path "-MO=Deparse" -anl -e 1 2>&1|;
print "XXX: $alpha\n";

my $output = `$alpha`;
print "YYY: $output\n";

We first run it from Perl 5.

$ ./perl -Ilib ~/tmp/deparse-problem.pl 
XXX: /home/jkeenan/gitwork/perl/perl "-I./lib" "-MO=Deparse" -anl -e 1 2>&1
YYY: -e syntax OK
BEGIN { $/ = "\n"; $\ = "\n"; }
LINE: while (defined($_ = readline ARGV)) {
    chomp $_;
    our @F = split(' ', $_, 0);
    '???';
}

We run it again from Perl 5, but this time imposing strictures.

$ ./perl -Ilib -Mstrict ~/tmp/deparse-problem.pl 
XXX: /home/jkeenan/gitwork/perl/perl "-I./lib" "-MO=Deparse" -anl -e 1 2>&1
YYY: -e syntax OK
BEGIN { $/ = "\n"; $\ = "\n"; }
LINE: while (defined($_ = readline ARGV)) {
    chomp $_;
    our @F = split(' ', $_, 0);
    '???';
}

No change in output. Next, we run it against a Perl 7 executable where we have strict-by-default.

$ ./perl -Ilib ~/tmp/deparse-problem.pl 
XXX: /home/jkeenan/gitwork/perl-atoomic-2/perl "-I./lib" "-MO=Deparse" -anl -e 1 2>&1
YYY: Variable "$savebackslash" is not imported at (eval 1) line 25.
Loading compiler backend 'B::Deparse' failed: Global symbol "$savebackslash" requires explicit package name (did you forget to declare "my $savebackslash"?) at (eval 1) line 25.
 at -e line 0.
BEGIN failed--compilation aborted.

It fails. Now, as I've been working my way through hundreds of test files in the core distribution, "Variable $___ is not imported" failures can usually be resolved by fully qualifying the variable -- something like $main::savebackslash -- or making the variable a package-scoped global variable -- our $savebackslash.

However, I have had no luck with that approach in this point. That's probably because, in lib/B/Deparse.pm, this variable already is fully qualified.

 851 sub compile {
 852     my(@args) = @_;
...
 862     if ($/ ne "\n" or defined $O::savebackslash) { # deparse -l and -0
 863         my $fs = perlstring($/) || 'undef';
 864         my $bs = perlstring($O::savebackslash) || 'undef';
 865         print qq(BEGIN { \$/ = $fs; \$\\ = $bs; }\n);
 866     }

There are many unit tests within lib/B/Deparse.t which fail with this kind of problem. I don't understand B::Deparse well enough to know how to fix them. @atoomic

Thank you very much.
Jim Keenan

[atoomic]

I think the error comes from O.pm and the patch should be something like this

diff --git a/ext/B/O.pm b/ext/B/O.pm
index 81c879835b..1388f21822 100644
--- a/ext/B/O.pm
+++ b/ext/B/O.pm
@@ -27,7 +27,8 @@ sub import {
            B::save_BEGINs;
        }

+    our $savebackslash;
      CHECK {
            if ($quiet) {
                close STDOUT;
                open (STDOUT, ">&", $saveout_fh);

note: when running ./perl -Ilib -Mstrict ~/tmp/deparse-problem.pl you are not enforcing strict to the perl command you are running later in the script

[jkeenan]

On 8/13/20 11:28 AM, ℕicolas ℝ. wrote: I think the error comes from O.pm and the patch should be something like this diff --git a/ext/B/O.pm b/ext/B/O.pm index 81c879835b..1388f21822 100644 --- a/ext/B/O.pm +++ b/ext/B/O.pm @@ -27,7 +27,8 @@ sub import { B::save_BEGINs; } + our $savebackslash; CHECK { if ($quiet) { close STDOUT; open (STDOUT, ">&", $saveout_fh); note: when running |./perl -Ilib -Mstrict ~/tmp/deparse-problem.pl | you are not enforcing strict to the perl command you are running later in the script

The existence of the `O` module completely escaped me. I'll take a look at that later today. Thank you very much. Jim Keenan