# New Ticket Created by "Carl Mäsak" # Please include the string: [perl #56640] # in the subject line of all future correspondence about this issue. # <URL: http://rt.perl.org/rt3/Ticket/Display.html?id=56640 >
A "Null PMC access" is produced when evaluating the return value from
an empty block. The attached patch fixes the problem.
$ cat undef.pl
sub f { undef }
say f
$ ./perl6 undef.pl
$ cat nothing.pl
sub f { }
say f
$ ./perl6 nothing.pl
Null PMC access in get_string()
current instr.: 'print' pc 11069 (src/gen_builtins.pir:7223)
called from Sub 'say' pc 11091 (src/gen_builtins.pir:7233)
called from Sub '_block11' pc 28 (EVAL_13:11)
called from Sub 'parrot;PCT::HLLCompiler;eval' pc 806
(src/PCT/HLLCompiler.pir:481)
called from Sub 'parrot;PCT::HLLCompiler;evalfiles' pc 1088
(src/PCT/HLLCompiler.pir:610)
called from Sub 'parrot;PCT::HLLCompiler;command_line' pc 1267
(src/PCT/HLLCompiler.pir:699)
called from Sub 'parrot;Perl6::Compiler;main' pc 13257 (perl6.pir:172)
perl6(73490) malloc: *** error for object 0x28909d0: double free
*** set a breakpoint in malloc_error_break to debug
Segmentation fault
$ patch -p0 < empty-block.patch ; make perl6
[...]
$ ./perl6 nothing.pl
$
empty-block.patch
Description: Binary data
