find_metadata_big_maps can't handle contracts declaring storage type using shortened pair syntax

[lierdakil]

The culprit:

tezos-contract-metadata/src/lib/micheline_helpers.ml

Line 57 in 4c1f5dc

| Prim (_, "Pair", [l; r], _), Prim (_, "pair", [lt; rt], _) ->

Case in point: KT1VvnQFn9v3oHA7JLTdDZD6hdAx3T4TnUA2 on Hangzhou-net fails with Contract has no valid %metadata big-map! despite containing (big_map %metadata string bytes) within the top-level tree of nested pairs (as per spec). storage is declared as

  storage
   (pair (pair <...>)
          (pair <...>)
          (big_map <...>)
          (big_map %metadata string bytes)) ;

the corresponding Micheline representation is

{
  "code": [
    {...}
    {
      "prim": "storage",
      "args": [
        {
          "prim": "pair",
          "args": [
            {...},
            {...},
            {...},
            {
              "prim": "big_map",
              "args": [
                {
                  "prim": "string"
                },
                {
                  "prim": "bytes"
                }
              ],
              "annots": [
                "%metadata"
              ]
            }
          ]
        }
      ]
    },
    {...}
  ]
}

Notice the pair constructor here has 4 arguments in the Micheline representation, while the code only looks for cases where there are exactly 2.

[smondet]

Yes, for now that piece of code expects normalized michelson.

Cf. the POST RPC /chains/main/blocks/head/context/contracts/<KT1>/storage/normalized