Error in Principal.mo

Developers Motoko
1

I have the following error:

$ dfx build
Building canisters...
Error: Failed while trying to build all canisters.
Caused by: Failed while trying to build all canisters.
  The build step failed for canister 'aovwi-4maaa-aaaaa-qaagq-cai' (test) with an embedded error: Failed to build Motoko canister 'test'.: Failed to compile Motoko.: Failed to run 'moc'.: The command '"/home/porton/.cache/dfinity/versions/0.14.0/moc" "/home/porton/Projects/NacDB/src/test/main.mo" "-o" "/home/porton/Projects/NacDB/.dfx/local/canisters/test/test.wasm" "-c" "--debug" "--idl" "--stable-types" "--public-metadata" "candid:service" "--actor-idl" "/home/porton/Projects/NacDB/.dfx/local/canisters/idl/" "--actor-alias" "test" "aovwi-4maaa-aaaaa-qaagq-cai" "--package" "base" ".vessel/base/f26c8064c70af292a4bf20bdea6225b9223ab0fe/src" "--package" "btree" ".vessel/btree/v0.3.1/src" "--package" "stable-rbtree" ".vessel/stable-rbtree/v0.6.1/src"' failed with exit status 'exit status: 1'.
Stdout:

Stderr:
.vessel/base/f26c8064c70af292a4bf20bdea6225b9223ab0fe/src/Principal.mo:101.52-101.56: type error [M0072], field isController does not exist in type
...

$ dfx --version
dfx 0.14.0
$ vessel --version
vessel 0.6.5
2

Isn’t isController brand new? As of moc 0.9.1?

Dfx 0.14.0 bundles with an older moc. You might need to install the latest moc binary and set the DFX_MOC_PATH environment variable when calling dfx build.

3

An alternative solution is to edit package-set.dhall:

  overrides =
    [
      { name = "base"
      , repo = "https://github.com/dfinity/motoko-base"
      , version = "moc-0.9.0"
      , dependencies = [] : List Text
      },
    ] : List Package
4

But is that enough? In package-set.dhall you specify the version of motoko-base, not of the compiler. I thought that you probably need compiler support for isController to work because it uses a new syscall ic0.is_controller. But maybe I’m wrong. Just guessing, I haven’t tried any of this myself.

5

Yes, @timo is correct, support for ic0.is_controller was only added in moc v0.9.1.

@qwertytrewq you would need at least version 0.9.1 of both the compiler and the base package.
The DFX_MOC_PATH env variable allows you to do this, so you do not need to wait on a DFX release.

DFX v0.14.0 only comes with Motoko compiler 0.8.7.