From @softmoth

Rakudo behaves differently to Niecza and Pugs here​:

14​:30 <thou> nrp​: class A { method foo() { say "Foo!"; return self; };
method bar() { say "Bar." }}; my A $a .= new.foo; $a.bar;
14​:30 <p6eval> rakudo e20252​: OUTPUT«===SORRY!===␤Confused␤at
/tmp/TKFTMXpqZJ​:1␤»
14​:30 <p6eval> ..niecza v19-20-g07dcc9e, pugs​: OUTPUT«Foo!␤Bar.␤»

I expected it to behave the same as​:

14​:30 <thou> nrp​: class A { method foo() { say "Foo!"; return self; };
method bar() { say "Bar." }}; my A $a = A.new.foo; $a.bar;
14​:30 <p6eval> rakudo e20252, niecza v19-20-g07dcc9e, pugs​: OUTPUT«Foo!␤Bar.␤»

jnthn seems to disagree​:

14​:20 <thou> prn​: class A { method foo() { say "Foo!"; }}; my A $a .= new.foo;
14​:20 <p6eval> niecza v19-20-g07dcc9e​: OUTPUT«Potential difficulties​:␤
$a is declared but not used at /tmp/J0sWSYjJij line 1​:␤------> [32mA
{ method foo() { say "Foo!"; }}; my A [33m⏏ [31m$a .=
new.foo; [0m␤␤Foo!␤»
14​:20 <p6eval> ..rakudo e20252​: OUTPUT«===SORRY!===␤Confused␤at
/tmp/7x7OEuUesF​:1␤»
14​:20 <p6eval> ..pugs​: OUTPUT«Foo!␤»
14​:20 <thou> ^ rakudobug?
14​:21 <jnthn> On on earth is that parsed?
14​:21 <jnthn> std​: class A { method foo() { say "Foo!"; }}; my A $a .= new.foo;
14​:21 <p6eval> std d96f25c​: OUTPUT«ok 00​:00 43m␤»
14​:22 <jnthn> I'm wondering if it parses as
14​:22 <jnthn> (class A { method foo() { say "Foo!"; }}; my A $a .= new).foo
14​:22 <jnthn> n​: class A { method foo() { say "Foo!"; }}; say (my A $a
.= new.foo);
14​:22 <p6eval> niecza v19-20-g07dcc9e​: OUTPUT«Potential difficulties​:␤
$a is declared but not used at /tmp/NsCAi8hNTx line 1​:␤------>
[32method foo() { say "Foo!"; }}; say (my A [33m⏏ [31m$a .=
new.foo); [0m␤␤Foo!␤True␤»
14​:22 <jnthn> n​: class A { method foo() { say "Foo!"; }}; my A $a .=
new.foo; say $a
14​:22 <p6eval> niecza v19-20-g07dcc9e​: OUTPUT«Foo!␤A.new(...)␤»
14​:23 <jnthn> Yeah
14​:23 <thou> prn​: class A { method foo() { say "Foo!"; }}; my A $a .= new().foo;
14​:23 <p6eval> rakudo e20252​: OUTPUT«===SORRY!===␤Confused␤at
/tmp/fc3hH_uQrn​:1␤»
14​:23 <p6eval> ..pugs​: OUTPUT«Foo!␤»
14​:23 <p6eval> ..niecza v19-20-g07dcc9e​: OUTPUT«Potential
difficulties​:␤ $a is declared but not used at /tmp/V6GAlCpxVn line
1​:␤------> [32mA { method foo() { say "Foo!"; }}; my A [33m⏏ [31m$a
.= new().foo; [0m␤␤Foo!␤»
14​:23 <masak> std​: class A { method foo() { say "Foo!"; }}; my A $a .= new.foo
14​:23 <p6eval> std d96f25c​: OUTPUT«ok 00​:00 43m␤»
14​:23 <jnthn> or...something else...huh :)
14​:25 <thou> jnthn, i was looking for a way to avoid writing​: my A $a
= A.new.foo;
14​:26 <jnthn> thou​: That isn't what the code you wrote is doing.
14​:26 <masak> thou​: I think the '.= new.foo' syntax should either be
disallowed, or mean 'A $a = A.new.foo'.

From @TimToady

This works now, due to the precedence changes associated with adding the dot infix operator.

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