From @ShimmerFairy

<TimToady> p​: say «{4 + 2} 4+2»
<camelia> rakudo-parrot 215ba6​: OUTPUT«64+2␤»
<TimToady> so where's the space?
<TimToady> p​: say ((6,),'4+2')
<camelia> rakudo-parrot 215ba6​: OUTPUT«6 4+2␤»
<lue> n​: say «{4 + 2} 4+2»
<camelia> niecza v24-98-g473bd20​: OUTPUT«6 4+2␤»

<lue> p​: say «1 2 3»
<camelia> rakudo-parrot 215ba6​: OUTPUT«1 2 3␤»
<lue> p​: say «1 see{2} 3»
<camelia> rakudo-parrot 215ba6​: OUTPUT«1 see23␤»
<lue> o.o
<lue> p​: say «1 see{2}it 3»
<camelia> rakudo-parrot 215ba6​: OUTPUT«1 see2it 3␤»

In rakudo, if an interpolation occurs at the edge of a «» quoteword item, the space separating the two items at that edge fails to appear.

<TimToady> p​: say «1 {2} 3».perl
<camelia> rakudo-parrot 215ba6​: OUTPUT«("1", ("2",).list, "3")␤»
<TimToady> p​: say ("1", ("2",).list, "3")
<camelia> rakudo-parrot 215ba6​: OUTPUT«1 2 3␤»
<TimToady> p​: say ("1", ("2",).list, "3").gist
<camelia> rakudo-parrot 215ba6​: OUTPUT«1 2 3␤»
<TimToady> p​: say ("1", ("2",).list, "3").Str
<camelia> rakudo-parrot 215ba6​: OUTPUT«1 2 3␤»
<TimToady> p​: say ~("1", ("2",).list, "3")
<camelia> rakudo-parrot 215ba6​: OUTPUT«1 2 3␤»
<TimToady> so, what's eating the space?

<lue> p​: say qqw/1 {2} 3/
<camelia> rakudo-parrot 215ba6​: OUTPUT«1 2 3␤»

As seen here, it's seems to be specific to the «» construct, not the .perl of the quoteword list, nor even the qqw construct. Just the guillemets.

Some non-closure examples​:

<TimToady> n​: my $x = 2; say «1 '$x' 3»
<camelia> niecza v24-98-g473bd20​: OUTPUT«1 '2' 3␤»
* woosley (~woosley@​210.13.87.122) has joined
<TimToady> p​: my $x = 2; say «1 '$x' 3»
<camelia> rakudo-parrot 215ba6​: OUTPUT«1$x3␤»
<TimToady> p​: my $x = 2; say «1 "$x" 3»
<camelia> rakudo-parrot 215ba6​: OUTPUT«123␤»
<lue> p​: my $x = 2; say «1 $x 3»
<camelia> rakudo-parrot 215ba6​: OUTPUT«123␤»

<lue> p​: say «1 '2' 3»
<camelia> rakudo-parrot 215ba6​: OUTPUT«123␤»
<lue> p​: say «1 ''2 3»
<camelia> rakudo-parrot 215ba6​: OUTPUT«12 3␤»

The fun starts here for reference​: http://irclog.perlgeek.de/perl6/2013-11-04#i_7809016

From @usev6

This works now as expected -- e.g.​:

$ perl6 -e 'my $x = 2; say «1 $x 3»'
(1 2 3)

$ perl6 -e 'say «{4 + 2} 4+2»'
(6 4+2)

I added a test to S02-literals/string-interpolation.t with commit Raku/roast@8e47b67

I'm closing this ticket as 'resolved'.

@usev6 - Status changed from 'new' to 'resolved'