hmm me too.

My theory is that the scalar aassign in the concise output returns a modifiable value, but that the compiler "forgot" to moan here.

That's probably an implementation detail that might change in the future and break this code.

C:\>perl -e "@a=1..5; print 0+( @a );"
5
C:\>perl -e "@a=1..5; print --( @a);"
Can't modify array dereference in predecrement (--) at -e line 1, near
+ ");"
Execution of -e aborted due to compilation errors.

C:\>perl -MO=Concise -e "print --( () = /;/g );"
a  <@> leave[1 ref] vKP/REFC ->(end)
1     <0> enter ->2
2     <;> nextstate(main 1 -e:1) v:{ ->3
9     <@> print vK ->a
3        <0> pushmark s ->4
8        <1> predec sK/1 ->9
7           <2> aassign[t1] sKPRMS ->8
-              <1> ex-list lK ->6
4                 <0> pushmark s ->5
5                 </> match(/";"/) l/RTIME ->6
-              <1> ex-list lK ->7
6                 <0> pushmark s ->7
-                 <0> stub lPRM* ->-
-e syntax OK
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