From @masak

<masak> rakudo​: grammar G { regex foo { } }; say "alive"
<p6eval> rakudo 064702​: OUTPUT«alive␤»
* masak submits rakudobug
<masak> std​: grammar G { regex foo { } }
<p6eval> std 263c207​: OUTPUT«�[31m===�[0mSORRY!�[31m===�[0m␤Null
pattern not allowed [...] FAILED 00​:01 116m␤»
<masak> rakudo​: / /
<p6eval> rakudo 064702​: OUTPUT«===SORRY!===␤Null regex not allowed [...]

From @coke

On Sat Oct 16 11​:33​:21 2010, masak wrote​:

<masak> rakudo​: grammar G { regex foo { } }; say "alive"
<p6eval> rakudo 064702​: OUTPUT«alive␤»
* masak submits rakudobug
<masak> std​: grammar G { regex foo { } }
<p6eval> std 263c207​: OUTPUT«�[31m===�[0mSORRY!�[31m===�[0m␤Null
pattern not allowed [...] FAILED 00​:01 116m␤»
<masak> rakudo​: / /
<p6eval> rakudo 064702​: OUTPUT«===SORRY!===␤Null regex not allowed [...]

Fixed​:
16​:35 < [Coke]> r​: grammar G { regex foo { } }; say "alive" ; RT #​78404
16​:35 < synopsebot> Link​:
  https://rt-archive.perl.org/perl6//Public/Bug/Display.html?id=78404
16​:35 <+camelia> rakudo-jvm 4f66ce​: OUTPUT«===SORRY!===␤Null regex not
  allowed␤at /tmp/hdgrwlkAZv​:1␤------> grammar G { regex foo {
  ⏏} }; say "alive" ; RT #​78404␤Undeclared name​:␤ RT used at
  line 1␤␤␤»
16​:35 <+camelia> ..rakudo-parrot 4f66ce​: OUTPUT«===SORRY!===␤Null regex not
  allowed␤at /tmp/ucxkXZy_Y7​:1␤------> grammar G { regex foo {
  ⏏} }; say "alive" ; RT #​78404␤Undeclared name​:␤ RT used at
  line 1␤␤␤»
16​:35 < synopsebot> Link​:
  https://rt-archive.perl.org/perl6//Public/Bug/Display.html?id=78404
16​:35 < synopsebot> Link​:
  https://rt-archive.perl.org/perl6//Public/Bug/Display.html?id=78404

Closable with tests.

--
Will "Coke" Coleda

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

From @moritz

On Tue Jan 14 13​:35​:37 2014, coke wrote​:

On Sat Oct 16 11​:33​:21 2010, masak wrote​:

<masak> rakudo​: grammar G { regex foo { } }; say "alive"
<p6eval> rakudo 064702​: OUTPUT«alive␤»
* masak submits rakudobug
<masak> std​: grammar G { regex foo { } }
<p6eval> std 263c207​: OUTPUT«�[31m===�[0mSORRY!�[31m===�[0m␤Null
pattern not allowed [...] FAILED 00​:01 116m␤»
<masak> rakudo​: / /
<p6eval> rakudo 064702​: OUTPUT«===SORRY!===␤Null regex not allowed
[...]

Fixed​:
16​:35 < [Coke]> r​: grammar G { regex foo { } }; say "alive" ; RT
#​78404
16​:35 < synopsebot> Link​:
https://rt-archive.perl.org/perl6//Public/Bug/Display.html?id=78404
16​:35 <+camelia> rakudo-jvm 4f66ce​: OUTPUT«===SORRY!===␤Null regex not
allowed␤at /tmp/hdgrwlkAZv​:1␤------> grammar G {
regex foo {
⏏} }; say "alive" ; RT #​78404␤Undeclared name​:␤ RT
used at
line 1␤␤␤»
16​:35 <+camelia> ..rakudo-parrot 4f66ce​: OUTPUT«===SORRY!===␤Null
regex not
allowed␤at /tmp/ucxkXZy_Y7​:1␤------> grammar G {
regex foo {
⏏} }; say "alive" ; RT #​78404␤Undeclared name​:␤ RT
used at
line 1␤␤␤»
16​:35 < synopsebot> Link​:
https://rt-archive.perl.org/perl6//Public/Bug/Display.html?id=78404
16​:35 < synopsebot> Link​:
https://rt-archive.perl.org/perl6//Public/Bug/Display.html?id=78404

Closable with tests.

Tested here​:
commit 73208bff83283e4eb1b994bfcd5ef6fd885a00ec
Author​: Moritz Lenz <mlenz@​noris.net>
Date​: Wed Jan 15 10​:58​:54 2014 +0100

  RT #​78404​: Error reporting on Null regexes

diff --git a/S32-exceptions/misc.t b/S32-exceptions/misc.t
index 0d4b9ed..d361f9c 100644
--- a/S32-exceptions/misc.t
+++ b/S32-exceptions/misc.t
@@ -133,6 +133,17 @@ throws_like 'my role R { has $.x; has $.y }; 99 does R("wrong");', X::R
 # RT #73806
 throws_like q[if() {}], X::Comp::Group, sorrows => sub (@s) { @s[0] ~~ X::Syntax::KeywordAs
 
+# RT #78404
+throws_like q[my grammar G { regex foo { } }], X::Syntax::Regex::NullRegex;
+throws_like q[/ /], X::Syntax::Regex::NullRegex;
+# just an empty branch, still same error, please
+#?rakudo skip "LTA error"
+throws_like q[/ a | /], X::Syntax::Regex::NullRegex;
+#?rakudo skip "LTA error"
+throws_like q[/ a || /], X::Syntax::Regex::NullRegex;
+#?rakudo skip "LTA error"
+throws_like q[/ a & /], X::Syntax::Regex::NullRegex;
+
 
 throws_like 'sub f($a?, $b) { }', X::Parameter::WrongOrder,
     misplaced   => 'required',

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