The Solution

Hmmm, perlver?

$ perlver funk


   ------------------------------------
 | file | explicit | syntax  | external |
 | ------------------------------------ |
 | funk | ~        | v5.10.0 | n/a      |
 | ------------------------------------ |
 | Minimum explicit version : ~                             |
 | Minimum syntax version   : v5.10.0                       |
 | Minimum version of perl  : v5.10.0                       |
   ------------------------------------


$ cat funk
$funk //= @ARGV;
[download]

so enhance perlver to be more verbose/explicit?