Fix rust-analyzer's complaint about not finding proc macro library

[vtta]

The generated rust-project.json contains:

      {
            "cfg": [],
            "deps": [],
            "display_name": "macros",
            "edition": "2021",
            "env": {
                "RUST_MODFILE": "This is only for rust-analyzer"
            },
            "is_proc_macro": true,
            "is_workspace_member": true,
            "proc_macro_dylib_path": "rust/libmacros.so",
            "root_module": "***/rust/macros/lib.rs"
        },

If we use this file in an out-of-tree module to let rust-analyzer index symbols it will complain about not finding proc macro library

Make proc_macro_dylib_path absolute fix this issue.

[bjorn3]

Is .resolve() necessary?

[vtta]

Yes, during my testing, objtree sometimes is empty, the reason is unknown.

[bjorn3]

In which case is it empty where you need absolute paths?

[vtta]

as shown here

[vtta]

In which case is it empty where you need absolute paths?

After I copied the generated rust-project.json from build tree to my out-of-tree module directory, the complaint will show up.

[bjorn3]

You did have to run this script for your out of tree module rather than copying the in-tree rust-project.json file anyway to handle the out of tree module itself, right?

[vtta]

In theory yes, but currently the kernel Makefile does not support calling it in module directory with make -C <path-to-build-root> M=<path-to-module> rust-analyzer

Maybe I will add that support later

[bjorn3]

Right, #914 would add support for this AFAICT. Looks like it also fixes proc macros.

[vtta]

Oh, I didn't notice that one. Then I will close this.