oil AST

(command.CommandList
  children: [
    (command.ShAssignment
      pairs: [
        (assign_pair
          lhs: (sh_lhs_expr.Name name:ld)
          op: assign_op.Equal
          rhs: 
            {
              (DQ 
                (command_sub
                  left_token: <Id.Left_Backtick '`'>
                  command_list: (command.CommandList children:[(C {<head>} {<-1>} {<conf-ld>})])
                )
              )
            }
          spids: [0]
        )
      ]
    )
    (command.ShAssignment
      pairs: [
        (assign_pair
          lhs: (sh_lhs_expr.Name name:systype)
          op: assign_op.Equal
          rhs: 
            {
              (DQ 
                (command_sub
                  left_token: <Id.Left_Backtick '`'>
                  command_list: (command.CommandList children:[(C {<cat>} {<systype>})])
                )
              )
            }
          spids: [13]
        )
      ]
    )
    (C {<cat>} {<warn-auto.sh>})
    (C {<echo>} {(SQ <'main="$1"; shift'>)})
    (C {<echo>} {<exec>} {(DQ ($ Id.VSub_DollarName '$ld'))} {(SQ <'-o "$main" "$main".o ${1+"$@"}'>)})
  ]
)