Library "ppx_dhall_type" not found

[GavinXu520]

When I executed a dune build in the root directory of mina, I reported an error: Library "ppx_dhall_type" not found. I found out that this is a local library, but how can I obtain this local library?
The error is as follows:

Through a global search for 'ppx_dhall_type', it was found that the dune file in the directory 'mini/src/app/hall_types' has a reference to' ppx_dhall_type 'and is declared as a' local library ':

And used in 'mini/src/app/hall_types/dump_dhall_types. ml':

So how can I obtain this' local library '?
Is there any expert who knows and can provide guidance? Thank you very much!

[shimkiv]

Hey @GavinXu520 can you describe your build procedure in more details please?

https://github.com/MinaProtocol/mina/blob/develop/README-dev.md#building

Some dependencies that are not taken from opam or integrated with dune must be added manually. Run the scripts/pin-external-packages.sh script.