[
  structure_item (pr6865.ml[9,153+0]..[9,153+14]) ghost
    Pstr_extension "foo"
    [
      structure_item (pr6865.ml[9,153+0]..[9,153+14])
        Pstr_value Nonrec
        [
          <def>
            pattern (pr6865.ml[9,153+8]..[9,153+9])
              Ppat_var "x" (pr6865.ml[9,153+8]..[9,153+9])
            expression (pr6865.ml[9,153+12]..[9,153+14])
              Pexp_constant
              constant (pr6865.ml[9,153+12]..[9,153+14])
                PConst_int (42,None)
        ]
    ]
  structure_item (pr6865.ml[10,168+0]..[10,168+25]) ghost
    Pstr_extension "foo"
    [
      structure_item (pr6865.ml[10,168+0]..[10,168+25])
        Pstr_value Nonrec
        [
          <def>
            pattern (pr6865.ml[10,168+8]..[10,168+9])
              Ppat_any
            expression (pr6865.ml[10,168+12]..[10,168+14])
              Pexp_construct "()" (pr6865.ml[10,168+12]..[10,168+14])
              None
          <def>
            pattern (pr6865.ml[10,168+19]..[10,168+20])
              Ppat_any
            expression (pr6865.ml[10,168+23]..[10,168+25])
              Pexp_construct "()" (pr6865.ml[10,168+23]..[10,168+25])
              None
        ]
    ]
  structure_item (pr6865.ml[11,194+0]..[11,194+14]) ghost
    Pstr_extension "foo"
    [
      structure_item (pr6865.ml[11,194+0]..[11,194+14])
        Pstr_value Nonrec
        [
          <def>
            pattern (pr6865.ml[11,194+8]..[11,194+9])
              Ppat_any
            expression (pr6865.ml[11,194+12]..[11,194+14])
              Pexp_construct "()" (pr6865.ml[11,194+12]..[11,194+14])
              None
        ]
    ]
]

File "pr6865.ml", line 9, characters 4-7:
9 | let%foo x = 42
        ^^^
Error: Uninterpreted extension 'foo'.