From shoichikaji@gmail.com

The following script exits with segmentation fault.
(code is also available at
https://gist.github.com/shoichikaji/42f03675cec2d6b4a489)

```
#!/bin/bash

set -xu

rm -rf lib
mkdir lib

cat >lib/A.pm6 <<'EOF';
class B {}
class A {
  sub foo($b, *@​) {}
  BEGIN {
  B.^add_method​: 'bar', method () { foo(self) };
  }
}
EOF

perl6-m --target=mbc --output=lib/A.pm6.moarvm lib/A.pm6
perl6-m -Ilib -MA -e 'B.bar'
```

```
$ bash test.sh
+ rm -rf lib
+ mkdir lib
+ cat
+ perl6-m --target=mbc --output=lib/A.pm6.moarvm lib/A.pm6
+ perl6-m -Ilib -MA -e B.bar
test.sh​: line 19​: 31493 Segmentation fault perl6-m -Ilib -MA -e 'B.bar'
```

My perl version is​:
$ perl6-m -v
This is perl6 version 2015.09-360-g154f44b built on MoarVM version
2015.09-79-gee9fc2b

From @FROGGS

It seems to segfault in the op getlex when trying to locate &foo.

Moving sub foo to within the BEGIN block helps and moving it outside of A gives​:
Cannot invoke this object
  in method <anon> at lib/A.pm6​:5

Neither the rakudo optimizer nor spesh seem to be to blame.

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

From @FROGGS

To clarify​: f in getlex after the while loop is null.

From @nwc10

On Tue, Oct 13, 2015 at 09​:20​:54AM -0700, Shoichi Kaji wrote​:

+ perl6-m -Ilib -MA -e B.bar
test.sh​: line 19​: 31493 Segmentation fault perl6-m -Ilib -MA -e 'B.bar'
```

$ ./perl6-m -Ilib -MA -e 'B.bar'
ASAN​:SIGSEGV

==27416==ERROR​: AddressSanitizer​: SEGV on unknown address 0x000000000008 (pc 0x7f78d5719316 sp 0x7fffff5a7640 bp 0x7fffff5a8ff0 T0)
  #​0 0x7f78d5719315 in MVM_interp_run src/core/interp.c​:196
  #​1 0x7f78d59e757e in MVM_vm_run_file src/moar.c​:243
  #​2 0x401a4f in main src/main.c​:191
  #​3 0x7f78d4f7ad5c in __libc_start_main (/lib64/libc.so.6+0x1ed5c)
  #​4 0x401058 (/home/nicholas/Sandpit/moar-san/bin/moar+0x401058)

AddressSanitizer can not provide additional info.
SUMMARY​: AddressSanitizer​: SEGV src/core/interp.c​:196 MVM_interp_run
==27416==ABORTING

So there's nothing wrong happening before a NULL pointer dereference.

Nicholas Clark