utf8 whacks Carp in 5.12.1

daxim has asked for the wisdom of the Perl Monks concerning the following question:

Is the misbehaviour shown in program "bar" below a known bug? What's the work-around?

I am not able to step through with the debugger, alas demoting the statements to run-time loading/importing makes the bug disappear.

$ cat foo
#!/usr/bin/env perl5.10.1
use utf8;
use strict;
use CGI::Carp qw(fatalsToBrowser);
$c;


$ ./foo   # ok
Status: 500
Content-type: text/html

<h1>Software error:</h1>
<pre>Global symbol &quot;$c&quot; requires explicit package name at ./
+foo line 5.
Execution of ./foo aborted due to compilation errors.
</pre>
<p>
For help, please send mail to this site's webmaster, giving this error
+ message 
and the time and date of the error.

</p>
[Mon Jan 24 xx:xx:xx 2011] foo: Global symbol "$c" requires explicit p
+ackage name at ./foo line 5.
[Mon Jan 24 xx:xx:xx 2011] foo: Execution of ./foo aborted due to comp
+ilation errors.


$ cat bar
#!/usr/bin/env perl5.12.1
use utf8;
use strict;
use CGI::Carp qw(fatalsToBrowser);
$c;


$ ./bar   # nok
BEGIN not safe after errors--compilation aborted at /usr/lib/perl5/5.1
+2.1/Carp.pm line 104.


$ cat quux
#!/usr/bin/env perl5.12.1
# use utf8;
use strict;
use CGI::Carp qw(fatalsToBrowser);
$c;


$ ./quux  # ok
Status: 500
Content-type: text/html

<h1>Software error:</h1>
<pre>Global symbol &quot;$c&quot; requires explicit package name at ./
+quux line 5.
Execution of ./quux aborted due to compilation errors.
</pre>
<p>
For help, please send mail to this site's webmaster, giving this error
+ message 
and the time and date of the error.

</p>
[Mon Jan 24 xx:xx:xx 2011] quux: Global symbol "$c" requires explicit 
+package name at ./quux line 5.
[Mon Jan 24 xx:xx:xx 2011] quux: Execution of ./quux aborted due to co
+mpilation errors.
[download]

Comment on utf8 whacks Carp in 5.12.1 Download Code

Replies are listed 'Best First'.
Re: utf8 whacks Carp in 5.12.1 by Anonyrnous Monk (Hermit) on Jan 25, 2011 at 05:22 UTC
I can reproduce it with 5.12.2, too. Definitely a bug, I'd say. FWIW, the same problem exists with `#!/usr/local/bin/perl5.12.2 use strict; use diagnostics; use utf8; $c;` [download] As soon as `"use utf8"` is in the game, the output is `BEGIN not safe after errors--compilation aborted at /usr/local/lib/per +l5/5.12.2/diagnostics.pm line 569.` [download] while if you comment it out, you get the expected `"Global symbol "$c" requires explicit package name"`, followed by the corresponding diagnostic message. The order of the use statements doesn't seem to matter, and `use utf8` without `use diagnostics` doesn't produce the error. The code works fine with 5.10.1.	[reply] [d/l] [select]
Re^2: utf8 whacks Carp in 5.12.1 by andal (Hermit) on Jan 25, 2011 at 13:34 UTC
Yep, the problem is with the matching done inside of diagnostics.pm at the reported line. If before this line one adds `utf8::encode($_) if utf8::is_utf8($_);` [download] on line 552 of the diagnostics.pm then the problem goes away. Well, actually this problem goes away, instead the Carp.pm fails, again with regex matching. `Global symbol "$c" requires explicit package name at test.pl line 8. Execution of test.pl aborted due to compilation errors (#1) (F) You've said "use strict" or "use strict vars", which indicates + that all variables must either be lexically scoped (using "my" or +"state"), declared beforehand using "our", or explicitly qualified to say which package the global variable is in (using "::"). BEGIN not safe after errors--compilation aborted at /usr/lib64/perl5/5 +.12.2/Carp.pm line 113.` [download] Really weird problem. Things work fine for substitute but fail for regular matching. Looks like this bug happens to be only in $SIG{__DIE__} handler. At least I could reproduce it in `use strict; use utf8; BEGIN { $SIG{__DIE__} = \&report; sub report { my $arg = shift; $arg = "'$arg'" unless $arg =~ /^-?[\d.]+\z/; warn("Done\n"); } } $c;` [download]	[reply] [d/l] [select]