luajit 2.1.0 testcase

testcase.lua

-- The following code should print "nil" several times,
-- but one of the nils gets replaced with a table somehow.

local function key(expr)
   if type(expr) == 'table' then
      -- Removing the zero removes spurious table
      local res = {0}
      for i=1, #expr do
         res[i] = key(expr[i])
         -- Uncommenting the following line removes spurious table
         -- io.stdout:write()
      end
      -- This unexpectedly prints "table: 0xaddress" once
      print(res[2])
   end

   return
end

-- Turning jit off removes spurious table
-- jit.off()

key { 0,
      { 0,
         { 0,
            { 0, 0, 0 },
            { 0,
               { 0,
                  { 0, 0, 0 },
               0 },
               { 0,
                  { 0, 0, 0 },
                  { 0,
                     { 0, 0 },
                     { 0,
                        { 0, 0, 0 },
                        { 0,
                           { 0, 0, 0 },
                        0 },
                     0 },
                     { 0 }
                  },
               0 },
               { 0 }
            },
         0 },
         { 0 },
         { 0,
            { 0,
               { 0, 0, 0 },
               { 0,
                  { 0,
                     { 0, 0, 0 },
                  0 },
                  { 0,
                     { 0, 0, 0 },
                     { 0,
                        { 0, 0,
                           { 0, 0, 0 }
                        },
                        { 0,
                           { 0, 0, 0 },
                           { 0,
                              { 0, 0, 0 },
                           0 },
                        0 },
                        { 0 }
                     },
                  0 },
                  { 0 }
               },
            0 },
            { 0,
               { 0, 0, 0 },
               { 0,
                  { 0, 0 },
                  { 0,
                     { 0,
                        { 0, 0,
                           { 0, 0, 0 }
                        }
                     }
                  }
               },
            0 }
         }
      },
   { }
}