Compiling the example: error[E048]: Could not resolve reference to <anything>

[timokroeger]

Hi all,

compiling the simple_program.st works well but prints one warning:

warning[E067]: Implicit downcast from 'REAL' to 'INT'.
  ┌─ /home/user/plc_code/rusty/simple_program.st:8:10
  │
8 │     a := b;
  │          ^ Implicit downcast from 'REAL' to 'INT'

When trying to fix the warning with a := REAL_TO_INT(b); I now get another error:

error[E048]: Could not resolve reference to REAL_TO_INT
  ┌─ /home/user/plc_code/rusty/simple_program.st:8:10
  │
8 │     a := REAL_TO_INT(b);
  │          ^^^^^^^^^^^ Could not resolve reference to REAL_TO_INT

The function is available in the libs/stdlib/iec61131-st/num_conversion.st, thats why I tried to include the whole library (after compiling it with cargo) in my plc.json file which looks like:

{
    "name": "simple-test",
    "files": [
        "simple_program.st"
    ],
    "libraries": [
        {
            "name": "iec61131std",
            "path": "/home/user/rusty/target/release/",
            "package": "Static",
            "include_path": [
                "/home/user/rusty/libs/stdlib/iec61131-st/*.s"
            ]
        }
    ]
}

I get E048 for any function or variable I try to use from the stdlib like PI_REAL or SIN().

Probably I’m missing only a small detail, can you give me a heads up?

[ghaith]

Hello @timokroeger ,

To build the standard library we still depend on some extra liking step to link the rust code, so I would recommend using the build script: ./scripts/build --build --release --package which will place the lib along with all includes into a folder called output in your source location.
IN addition I think you might have a typo in the json file which is causing the Unresolved reference: the source files end with .st not .s

[timokroeger]

Thank you @ghaith, got it working!

For reference, if anybody faces the same issue in the future:

I ran the suggested command (./scripts/build --build --release --package) and moved the files from output to my working directory, which now looks like:

├── include
│   ├── arithmetic_functions.st
│   ├── bistable_functionblocks.st
│   ├── ...
│   ├── timers.st
│   └── validation_functions.st
├── lib
│   ├── libiec61131std.a
│   └── libiec61131std.so
├── plc.json
└── simple_program.st

When updating plc.json, it is important to use an absolute path for the include_path array. When using a relative include path of include/*.st, the E048 error does not go away. Interestingly, relative paths work just fine for the path key.

{
    "name": "simple-test",
    "files": [
        "simple_program.st"
    ],
    "libraries": [
        {
            "name": "iec61131std",
            "path": "lib",
            "package": "Static",
            "include_path": [
                "/home/user/plc_code/rusty/include/*.st"
            ]
        }
    ]
}

[timokroeger]

Ok another update regarding the relative path issue.
After reading the source code I found that include_path must be relative to the specified path directory.
That means the following plc.json also works for the directory structure described in the last reply.

{
    "name": "simple-test",
    "files": [
        "simple_program.st"
    ],
    "libraries": [
        {
            "name": "iec61131std",
            "path": "lib",
            "package": "Static",
            "include_path": [
                "../include/*.st"
            ]
        }
    ]
}

[ghaith]

Yes, I wanted to comment on this. The path is relative to the library, but the library path itself is subject to change. The idea is that library section should eventually be its own file and packaged with the library itself, where the include would then be relative the library file. Also the path currently points tot he so but we want to change it to be the top level and we would search for the so using different means so that we can better support multi arch systems.