Using the `cargo metadata` command (with examples)

1: Print the workspace members and resolved dependencies of the current package

cargo metadata

Motivation:

This command is useful when you want to obtain information about the current package’s dependencies and workspace members.

Explanation:

Executing cargo metadata without any arguments will print the workspace members and the resolved dependencies of the current package.

Example Output:

{
  "workspace_members": [
    "/path/to/my_package"
  ],
  "packages": [
    {
      "name": "my_package",
      "version": "0.1.0",
      "id": "my_package 0.1.0 (path+file:///path/to/my_package)",
      // More package information ...
    },
    // More packages ...
  ]
}

2: Print only the workspace members and do not fetch dependencies

cargo metadata --no-deps

Motivation:

In some cases, you may just need information about the workspace members without their resolved dependencies. This can be useful when you only want to inspect the structure of the workspace or process the members separately.

Explanation:

By adding the --no-deps flag to the cargo metadata command, the resolved dependencies will not be fetched or included in the output. Only the workspace members will be printed.

Example Output:

{
  "workspace_members": [
    "/path/to/my_package"
  ],
  "packages": [
    {
      "name": "my_package",
      "version": "0.1.0",
      "id": "my_package 0.1.0 (path+file:///path/to/my_package)",
      // More package information ...
    },
    // More packages ...
  ]
}

3: Print metadata in a specific format based on the specified version

cargo metadata --format-version version

Motivation:

Sometimes, you may need the metadata in a specific format that is compatible with a particular version of Cargo. This can be useful when you are working with older tools or scripts that rely on specific metadata formats.

Explanation:

To specify a specific format version for the metadata output, replace version in the command with the desired format version number. For example, 1 for the initial format version.

Example Output:

{
  "version": 1,
  "workspace_members": [
    // Workspace members ...
  ],
  "packages": [
    // Packages ...
  ]
}

4: Print metadata with the resolve field including dependencies only for the given target triple

cargo metadata --filter-platform target_triple

Motivation:

In certain scenarios, you may want to filter the metadata output to include only dependencies specific to a particular target triple. This can be useful when you are building for a specific platform and need to analyze the dependencies for that platform.

Explanation:

To obtain metadata with the resolve field including dependencies only for the given target triple, replace target_triple in the command with the appropriate target triple. The packages array will still include the dependencies for all targets.

Example Output:

{
  "resolve": {
    "nodes": [
      // Nodes specific to the target triple ...
    ],
    "root": {
      "id": "my_package 0.1.0 (path+file:///path/to/my_package)",
      "dependencies": [
        // Dependencies specific to the target triple ...
      ]
    }
  },
  "workspace_members": [
    "/path/to/my_package"
  ],
  "packages": [
    // All packages including dependencies for other targets ...
  ]
}

By utilizing the cargo metadata command with its various options, you can obtain workspace members and resolved dependencies information, format the metadata output, filter it based on target triples, and fetch or omit dependencies as per your requirements.