STable conflict with .^add_method

[p6rt]

Migrated from rt.perl.org#126341 (status was 'open')

Searchable as RT126341$

[p6rt]

From tokuhirom@gmail.com

Here is a code that throws exception.
```
#!/bin/bash

mkdir lib/

cat > lib/Child.pm6 <<EOF;
use v6;
use Parent;

unit class Child is Parent;
EOF

cat > lib/Parent.pm6 <<EOF;
use v6;
unit class Parent;

:​:?CLASS.^add_method​: 'x', method () { };
EOF

perl6-m -Ilib --target=mbc --output=lib/Parent.pm6.moarvm lib/Parent.pm6
perl6-m -Ilib --target=mbc --output=lib/Child.pm6.moarvm lib/Child.pm6

perl6-m -Ilib -e 'use Child'
```

Output is​:
```
===SORRY!===
STable conflict detected during deserialization.
(Probable attempt to load two modules that cannot be loaded together).
```

I guess this code should work(I know it works if i enclose MOP methods by BEGIN block).
If it isn't, perl6-m should show more human readable message.

[p6rt]

From @jnthn

On Mon Oct 12 21​:21​:48 2015, tokuhirom wrote​:

Here is a code that throws exception.
```
#!/bin/bash

mkdir lib/

cat > lib/Child.pm6 <<EOF;
use v6;
use Parent;

unit class Child is Parent;
EOF

cat > lib/Parent.pm6 <<EOF;
use v6;
unit class Parent;

:​:?CLASS.^add_method​: 'x', method () { };
EOF

perl6-m -Ilib --target=mbc --output=lib/Parent.pm6.moarvm
lib/Parent.pm6
perl6-m -Ilib --target=mbc --output=lib/Child.pm6.moarvm lib/Child.pm6

perl6-m -Ilib -e 'use Child'
```

Output is​:
```
===SORRY!===
STable conflict detected during deserialization.
(Probable attempt to load two modules that cannot be loaded together).
```

I guess this code should work(I know it works if i enclose MOP methods
by BEGIN block).

If you want to pre-compile such code, you must put the MOP method call inside of a BEGIN block. Otherwise, it performs the change on each module load, causing the updated class to be serialized into the two downstream modules, and then you get a conflict when trying to load the two versions.

If it isn't, perl6-m should show more human readable message.

Yes, we can de-jargon the message somewhat; we'll keep this ticket around for that purpose.

Thanks,

Jonathan

[p6rt]

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