Function addDep

yarn.config.cjs:94–119

(workspace, seen = new Set())

function enforceNoCircularDependencies({Yarn}) {
  // enforce that there are no circular dependencies between our packages
  function addDep(workspace, seen = new Set()) {
    if (seen.has(workspace.ident)) {
      let arr = [...seen];
      let index = arr.indexOf(workspace.ident);
      // ok for pkg to depend on itself
      if (arr.slice(index).length > 1) {
        // better to error the constraints early for this for a more meaningful error message
        throw new Error(
          `Circular dependency detected: ${arr.slice(index).join(' -> ')} -> ${workspace.ident}`
        );
      } else {
        return;
      }
    }

    seen.add(workspace.ident);

    for (let d of Yarn.dependencies({ident: workspace.ident})) {
      if (d.type === 'peerDependencies') {
        continue;
      }
      addDep(d.workspace, seen);
    }

    seen.delete(workspace.ident);
  }

  for (const workspace of Yarn.workspaces()) {
    addDep(workspace);