From @masak

<masak> rakudo​: say "oh hai" .= uc
<p6eval> rakudo 2953ac​: OUTPUT«OH HAI␤»
<masak> rakudo​: say "oh hai"."uc"
<p6eval> rakudo 2953ac​: OUTPUT«OH HAI␤»
<masak> rakudo​: my $a = "oh hai"; say $a.="uc"
<p6eval> rakudo 2953ac​: OUTPUT«OH HAI␤»
<masak> rakudo​: my $a = "oh hai"; say $a .= "uc"
<sjohnson> heh
<p6eval> rakudo 2953ac​: OUTPUT«.= must have a call on the right hand side [...]
* masak submits rakudobug

From @bbkr

[18​:14] <bbkr> rakudo​: my $a = "oh hai"; say $a .= "uc"
[18​:14] <p6eval> rakudo bb6df2​: OUTPUT«===SORRY!===␤Quoted method name
requires parenthesized arguments at line 20, near ""␤»

[18​:14] <bbkr> std​: my $a = "oh hai"; say $a .= "uc"
[18​:14] <p6eval> std 31643​:
OUTPUT«�[31m===�[0mSORRY!�[31m===�[0m␤Unsupported use of . to
concatenate strings or to call a quoted method; in Perl 6 please use ~
to concatenate, or if you meant to call a quoted method, please supply
the required parentheses at /tmp/HDXgt_YnN3 line 1​:␤------> �[32mmy $a =
"oh hai";

String methodrefs are not valid without parentheses.

But example that was causing trouble works now​:

[18​:16] <bbkr> rakudo​: my $a = "oh hai"; say $a .= "uc"()
[18​:16] <p6eval> rakudo bb6df2​: OUTPUT«OH HAI␤»

Taken for tests.

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

From @bbkr

well, but STD disagrees

[18​:22] <bbkr> std​: my $a = "oh hai"; say $a .= "uc"()
[18​:22] <p6eval> std 31643​: OUTPUT«Potential difficulties​:␤ Useless use
of quotes at /tmp/OiJYK6kYDj line 1​:␤------> �[32mmy $a = "oh hai"; say
$a .= "uc"�[33m⏏�[31m()�[0m␤ Unsupported use of .= as append operator;
in Perl 6 please use ~= at /tmp/OiJYK6kYDj line 1​:␤------> �[32mmy $a =
"oh hai"; say $a
[18​:22] <p6eval> ...=�[33m⏏�[3…

From @bbkr

rechecked on * release, same result

Note​:
STD warns that .= is an P5 concat. In this case such warning should be
also displayed by Rakudo.

From @diakopter

On Mon Jul 12 09​:18​:47 2010, bbkr wrote​:

[18​:14] <bbkr> rakudo​: my $a = "oh hai"; say $a .= "uc"
[18​:14] <p6eval> rakudo bb6df2​: OUTPUT«===SORRY!===␤Quoted method
name
requires parenthesized arguments at line 20, near ""␤»

[18​:14] <bbkr> std​: my $a = "oh hai"; say $a .= "uc"
[18​:14] <p6eval> std 31643​:
OUTPUT«�[31m===�[0mSORRY!�[31m===�[0m␤Unsupported use of . to
concatenate strings or to call a quoted method; in Perl 6 please use ~
to concatenate, or if you meant to call a quoted method, please supply
the required parentheses at /tmp/HDXgt_YnN3 line 1​:␤------> �[32mmy $a
=
"oh hai";

String methodrefs are not valid without parentheses.

But example that was causing trouble works now​:

[18​:16] <bbkr> rakudo​: my $a = "oh hai"; say $a .= "uc"()
[18​:16] <p6eval> rakudo bb6df2​: OUTPUT«OH HAI␤»

Taken for tests.

new failure mode​:

16​:11 <diakopter> rakudo​: my $a = "oh hai"; say $a .= "uc"()
16​:11 <p6eval> rakudo 3b1596​: OUTPUT«No such method 'Capture[0xa7f4a80]'
for invocant of
  type 'Str'␤ in method dispatch​:<.=> at
src/gen/CORE.setting​:824␤ in block
  <anon> at /tmp/dVBS2sG7ir​:1␤␤»

From @Mouq

Behavior is now​:

$ perl6 -e'my $a = "oh hai"; say $a .= "uc"()'
No such method '' for invocant of type 'Str'
  in method dispatch​:<.=> at src/gen/m-CORE.setting​:1330
  in block <unit> at -e​:1

$ perl6 -e'my $a = "oh hai"; say $a.="uc"()'
OH HAI
$ perl6 -v
This is perl6 version 2015.01-114-g9db8b8d built on MoarVM version 2015.01-28-ga910556

On Tue May 29 14​:13​:51 2012, diakopter wrote​:

On Mon Jul 12 09​:18​:47 2010, bbkr wrote​:

[18​:14] <bbkr> rakudo​: my $a = "oh hai"; say $a .= "uc"
[18​:14] <p6eval> rakudo bb6df2​: OUTPUT«===SORRY!===␤Quoted method
name
requires parenthesized arguments at line 20, near ""␤»

[18​:14] <bbkr> std​: my $a = "oh hai"; say $a .= "uc"
[18​:14] <p6eval> std 31643​:
OUTPUT«�[31m===�[0mSORRY!�[31m===�[0m␤Unsupported use of . to
concatenate strings or to call a quoted method; in Perl 6 please use ~
to concatenate, or if you meant to call a quoted method, please supply
the required parentheses at /tmp/HDXgt_YnN3 line 1​:␤------> �[32mmy $a
=
"oh hai";

String methodrefs are not valid without parentheses.

But example that was causing trouble works now​:

[18​:16] <bbkr> rakudo​: my $a = "oh hai"; say $a .= "uc"()
[18​:16] <p6eval> rakudo bb6df2​: OUTPUT«OH HAI␤»

Taken for tests.

new failure mode​:

16​:11 <diakopter> rakudo​: my $a = "oh hai"; say $a .= "uc"()
16​:11 <p6eval> rakudo 3b1596​: OUTPUT«No such method 'Capture[0xa7f4a80]'
for invocant of
type 'Str'␤ in method dispatch​:<.=> at
src/gen/CORE.setting​:824␤ in block
<anon> at /tmp/dVBS2sG7ir​:1␤␤»

From @FROGGS

I come to the conclusion that making $foo.="bar"() work is more useful than complaining about a potential P5ism.

So, patch and tests are here​:
rakudo/rakudo@98d9b87aaa
Raku/roast@5f82bde7e0

Closing ticket.

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