warn $];                               #> 5.024001

$null = 1;
warn 'never' until $null = 666;
warn $null;                             #> 666 

$one = 1;
warn 'never' until my $one = 666;       # my !
warn $one;                              #> Warning: something's wrong at ...

##</code><code>##

D:\tmp>perl -MO=Deparse tst_scope.pl
warn $];
$null = 1;
warn 'never' until $null = 666;
warn $null;
$one = 1;
warn 'never' until my $one = 666;
warn $one;
tst_scope.pl syntax OK

##</code><code>##

D:\tmp>perl -MO=Concise,-src tst_scope.pl
18 <@> leave[1 ref] vKP/REFC ->(end)
1     <0> enter ->2
# 1: warn $];                               # 5.024001
2     <;> nextstate(main 1 tst_scope.pl:1) v:{ ->3
5     <@> warn[t2] vK/1 ->6
3        <0> pushmark s ->4
-        <1> ex-rv2sv sK/1 ->5
4           <#> gvsv[*]] s ->5
# 3: $null = 1;
6     <;> nextstate(main 1 tst_scope.pl:3) v:{ ->7
9     <2> sassign vKS/2 ->a
7        <$> const[IV 1] s ->8
-        <1> ex-rv2sv sKRM*/1 ->9
8           <#> gvsv[*null] s ->9
# 4: warn 'never' until $null = 666;
a     <;> nextstate(main 1 tst_scope.pl:4) v:{ ->b
k     <@> leave vK* ->l
b        <0> enter v ->c
-        <1> null vKP/1 ->k
f           <|> or(other->g) vK/1 ->k
-              <1> ex-not sK*/1 ->f
e                 <2> sassign sKS/2 ->f
c                    <$> const[IV 666] s ->d
-                    <1> ex-rv2sv sKRM*/1 ->e
d                       <#> gvsv[*null] s ->e
-              <@> lineseq vK ->-
i                 <@> warn[t4] vK/1 ->j
g                    <0> pushmark s ->h
h                    <$> const[PV "never"] s ->i
j                 <0> unstack v ->c
# 5: warn $null;                             #> 666 ...
l     <;> nextstate(main 1 tst_scope.pl:5) v:{ ->m
o     <@> warn[t7] vK/1 ->p
m        <0> pushmark s ->n
-        <1> ex-rv2sv sK/1 ->o
n           <#> gvsv[*null] s ->o
# 7: $one = 1;
p     <;> nextstate(main 1 tst_scope.pl:7) v:{ ->q
s     <2> sassign vKS/2 ->t
q        <$> const[IV 1] s ->r
-        <1> ex-rv2sv sKRM*/1 ->s
r           <#> gvsv[*one] s ->s
# 8: warn 'never' until my $one = 666;       # my !
t     <;> nextstate(main 1 tst_scope.pl:8) v:{ ->u
13    <@> leave vK* ->14
u        <0> enter v ->v
-        <1> null vKP/1 ->13
y           <|> or(other->z) vK/1 ->13
-              <1> ex-not sK*/1 ->y
x                 <2> sassign sKS/2 ->y
v                    <$> const[IV 666] s ->w
w                    <0> padsv[$one:1,2] sRM*/LVINTRO ->x
-              <@> lineseq vK ->-
11                <@> warn[t9] vK/1 ->12
z                    <0> pushmark s ->10
10                   <$> const[PV "never"] s ->11
12                <0> unstack v ->v
# 9: warn $one;                              #> Warning: something's wrong at ...
14    <;> nextstate(main 2 tst_scope.pl:9) v:{ ->15
17    <@> warn[t11] vK/1 ->18
15       <0> pushmark s ->16
16       <0> padsv[$one:1,2] s ->17
tst_scope.pl syntax OK

D:\tmp>