replace-workspace-values.py

# This script implements the workspace inheritance mechanism described
# here: https://doc.rust-lang.org/cargo/reference/workspaces.html#the-package-table
#
# Please run `mypy --strict`, `black`, and `isort --profile black` on this after editing, thanks!

import sys
from typing import Any

import tomli
import tomli_w


def load_file(path: str) -> dict[str, Any]:
    with open(path, "rb") as f:
        return tomli.load(f)


# This replicates the dependency merging logic from Cargo.
# See `inner_dependency_inherit_with`:
# https://github.com/rust-lang/cargo/blob/4de0094ac78743d2c8ff682489e35c8a7cafe8e4/src/cargo/util/toml/mod.rs#L982
def replace_key(
    workspace_manifest: dict[str, Any], table: dict[str, Any], section: str, key: str
) -> bool:
    if (
        isinstance(table[key], dict)
        and "workspace" in table[key]
        and table[key]["workspace"] is True
    ):
        print("replacing " + key)

        local_dep = table[key]
        del local_dep["workspace"]

        workspace_dep = workspace_manifest[section][key]

        if section == "dependencies":
            if isinstance(workspace_dep, str):
                workspace_dep = {"version": workspace_dep}

            final: dict[str, Any] = workspace_dep.copy()

            merged_features = local_dep.pop("features", []) + workspace_dep.get("features", [])
            if merged_features:
                final["features"] = merged_features

            local_default_features = local_dep.pop("default-features", None)
            workspace_default_features = workspace_dep.get("default-features")

            if not workspace_default_features and local_default_features:
                final["default-features"] = True

            optional = local_dep.pop("optional", False)
            if optional:
                final["optional"] = True

            if local_dep:
                raise Exception(f"Unhandled keys in inherited dependency {key}: {local_dep}")

            table[key] = final
        elif section == "package":
            table[key] = workspace_dep

        return True

    return False


def replace_dependencies(
    workspace_manifest: dict[str, Any], root: dict[str, Any]
) -> bool:
    changed = False

    for key in ["dependencies", "dev-dependencies", "build-dependencies"]:
        if key in root:
            for k in root[key].keys():
                changed |= replace_key(workspace_manifest, root[key], "dependencies", k)

    return changed


def main() -> None:
    top_cargo_toml = load_file(sys.argv[2])

    if "workspace" not in top_cargo_toml:
        # If top_cargo_toml is not a workspace manifest, then this script was probably
        # ran on something that does not actually use workspace dependencies
        print(f"{sys.argv[2]} is not a workspace manifest, doing nothing.")
        return

    crate_manifest = load_file(sys.argv[1])
    workspace_manifest = top_cargo_toml["workspace"]

    if "workspace" in crate_manifest:
        return

    changed = False

    for key in crate_manifest["package"].keys():
        changed |= replace_key(
            workspace_manifest, crate_manifest["package"], "package", key
        )

    changed |= replace_dependencies(workspace_manifest, crate_manifest)

    if "target" in crate_manifest:
        for key in crate_manifest["target"].keys():
            changed |= replace_dependencies(
                workspace_manifest, crate_manifest["target"][key]
            )

    if (
        "lints" in crate_manifest
        and "workspace" in crate_manifest["lints"]
        and crate_manifest["lints"]["workspace"] is True
    ):
        crate_manifest["lints"] = workspace_manifest["lints"]

    if not changed:
        return

    with open(sys.argv[1], "wb") as f:
        tomli_w.dump(crate_manifest, f)


if __name__ == "__main__":
    main()