cargo metadataでプロジェクトの情報を取得する ref: http://qiita.com/kmtr/items/21fe9fd6c25f55169e61

file0.txt

$ cargo init --bin ferris
$ cd ferris
$ ls
Cargo.lock Cargo.toml src
$ cargo metadata --format-version=1
{"packages":[{"name":"ferris","version":"0.1.0","id":"ferris 0.1.0 (path+file:///path/to/ferris)","license":null,"license_file":null,"description":null,"source":null,"dependencies":[],"targets":[{"kind":["bin"],"crate_types":["bin"],"name":"ferris","src_path":"/path/to/ferris/src/main.rs"}],"features":{},"manifest_path":"/path/to/ferris/Cargo.toml"}],"workspace_members":["ferris 0.1.0 (path+file:///path/to/ferris)"],"resolve":{"nodes":[{"id":"ferris 0.1.0 (path+file:///path/to/ferris)","dependencies":[]}],"root":"ferris 0.1.0 (path+file:///path/to/ferris)"},"target_directory":"/path/to/ferris/target","version":1}
$ cargo metadata --format-version=1 | jq .packages[0].name
"ferris"

file1.txt

$ cargo metadata --format-version=1 | jq '.packages | map(select( .name == "ferris" )) | .[0].dependencies'
[]
$ echo 'regex = "0.2.2"' >> Cargo.toml
$ cargo metadata --format-version=1 | jq '.packages | map(select( .name == "ferris" )) | .[0].dependencies'
    Updating registry `https://github.com/rust-lang/crates.io-index`
[
  {
    "name": "regex",
    "source": "registry+https://github.com/rust-lang/crates.io-index",
    "req": "^0.2.2",
    "kind": null,
    "optional": false,
    "uses_default_features": true,
    "features": [],
    "target": null
  }
]

file2.txt

$ cargo metadata --format-version=1 --no-deps | jq .packages[0].dependencies
[
  {
    "name": "regex",
    "source": "registry+https://github.com/rust-lang/crates.io-index",
    "req": "^0.2.2",
    "kind": null,
    "optional": false,
    "uses_default_features": true,
    "features": [],
    "target": null
  }
]

file3.txt

.PHONY: version
version:
    @echo $(shell cargo metadata --format-version=1 --no-deps \
        | jq .packages[0].version)

file4.txt

$ make version
0.1.0