From @masak

<masak> r​: my %l = foo => 1, bar => 2; my %r = bar => 3, baz => 4; say
%l >>+<< %r
<camelia> rakudo 25a0b3​: OUTPUT«use of uninitialized value of type Any
in numeric context in block at /tmp/OI858EugnG​:1␤␤use of
uninitialized value of type Any in numeric context in block at
/tmp/OI858EugnG​:1␤␤("foo" => 1, "bar" => 5, "baz" => 4).hash␤»
<masak> I must say I don't need that one often... but when I do, it's
*very* nice to have.
<masak> what's with all the warnings, though?
<isBEKaml> heh, what does >>+<< on hashes mean? do we take in keys too?
<masak> isBEKaml​: do the operation on the values. >>+<< takes the
union of the keys; <<+>> takes the intersection.
<masak> isBEKaml​: in this case I needed the union.
<masak> which is why I think the undefinedness warnings are unnecessary.
<masak> I *know* some keys/values are missing. that's why I did >>+<<
* masak submits rakudobug

From @MasterDuke17

On Tue May 28 10​:11​:39 2013, masak wrote​:

<masak> r​: my %l = foo => 1, bar => 2; my %r = bar => 3, baz => 4; say
%l >>+<< %r
<camelia> rakudo 25a0b3​: OUTPUT«use of uninitialized value of type Any
in numeric context in block at /tmp/OI858EugnG​:1␤␤use of
uninitialized value of type Any in numeric context in block at
/tmp/OI858EugnG​:1␤␤("foo" => 1, "bar" => 5, "baz" => 4).hash␤»
<masak> I must say I don't need that one often... but when I do, it's
*very* nice to have.
<masak> what's with all the warnings, though?
<isBEKaml> heh, what does >>+<< on hashes mean? do we take in keys too?
<masak> isBEKaml​: do the operation on the values. >>+<< takes the
union of the keys; <<+>> takes the intersection.
<masak> isBEKaml​: in this case I needed the union.
<masak> which is why I think the undefinedness warnings are unnecessary.
<masak> I *know* some keys/values are missing. that's why I did >>+<<
* masak submits rakudobug

<MasterDuke> m​: my %l = foo => 1, bar => 2; my %r = bar => 3, baz => 4; say %l >>+<< %r
<camelia> rakudo-moar d2b115​: OUTPUT«Use of uninitialized value of type Any in numeric context␤ in block <unit> at <tmp> line 1␤Use of uninitialized value of type Any in numeric context␤ in block <unit> at <tmp> line 1␤{bar => 5, baz => 4, foo => 1}␤»
<MasterDuke> m​: my %l = foo => 1, bar => 2; my %r = bar => 3, baz => 4; quietly say %l >>+<< %r
<camelia> rakudo-moar d2b115​: OUTPUT«{bar => 5, baz => 4, foo => 1}␤»
<MasterDuke> so there is a built in way to suppress those warnings
<MasterDuke> it looks like quietly was implemented two years after the RT

Is this (still) a bug?

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

From @masak

Is this (still) a bug?

<masak> MasterDuke​: yes, still a bug.
<masak> MasterDuke​: "you can turn off the warnings" is at most a fine workaround.
<masak> but the spec is clear that there shouldn't be any warnings in the first place.
<masak> quoting myself from that ticket​: ">>+<< takes the union of the keys; <<+>> takes the intersection. I *know* some keys/values are missing. that's why I did >>+<<" (union)
<masak> warnings should give new information, not bug me about things I knew when I wrote the code.
* masak adds this to the ticket
<MasterDuke> cool, i'll keep playing around with it

From @MasterDuke17

On Fri Sep 02 05​:36​:10 2016, masak wrote​:

Is this (still) a bug?

<masak> MasterDuke​: yes, still a bug.
<masak> MasterDuke​: "you can turn off the warnings" is at most a fine
workaround.
<masak> but the spec is clear that there shouldn't be any warnings in
the first place.
<masak> quoting myself from that ticket​: ">>+<< takes the union of the
keys; <<+>> takes the intersection. I *know* some keys/values are
missing. that's why I did >>+<<" (union)
<masak> warnings should give new information, not bug me about things
I knew when I wrote the code.
* masak adds this to the ticket
<MasterDuke> cool, i'll keep playing around with it

Some commentary from jnthn here http://irclog.perlgeek.de/perl6-dev/2016-09-12#i_13194037

Fixed here rakudo/rakudo#859

Test added here Raku/roast@8b2446dc94

@MasterDuke17 - Status changed from 'open' to 'resolved'