remove rustc-serialize dependency and factor util::cargo out into a crate

clippy_lints/src/utils/cargo.rs

@@ -1,77 +0,0 @@
-use std::collections::HashMap;
-use std::process::Command;
-use std::str::{from_utf8, Utf8Error};
-use std::io;
-use rustc_serialize::json;
-
-#[derive(RustcDecodable, Debug)]
-pub struct Metadata {
-    pub packages: Vec<Package>,
-    resolve: Option<()>,
-    pub version: usize,
-}
-
-#[derive(RustcDecodable, Debug)]
-pub struct Package {
-    pub name: String,
-    pub version: String,
-    id: String,
-    source: Option<String>,
-    pub dependencies: Vec<Dependency>,
-    pub targets: Vec<Target>,
-    features: HashMap<String, Vec<String>>,
-    pub manifest_path: String,
-}
-
-#[derive(RustcDecodable, Debug)]
-pub struct Dependency {
-    pub name: String,
-    source: Option<String>,
-    pub req: String,
-    kind: Option<String>,
-    optional: bool,
-    uses_default_features: bool,
-    features: Vec<String>,
-    target: Option<String>,
-}
-
-#[derive(RustcDecodable, Debug)]
-pub struct Target {
-    pub name: String,
-    pub kind: Vec<String>,
-    src_path: String,
-}
-
-#[derive(Debug)]
-pub enum Error {
-    Io(io::Error),
-    Utf8(Utf8Error),
-    Json(json::DecoderError),
-}
-
-impl From<io::Error> for Error {
-    fn from(err: io::Error) -> Self {
-        Error::Io(err)
-    }
-}
-impl From<Utf8Error> for Error {
-    fn from(err: Utf8Error) -> Self {
-        Error::Utf8(err)
-    }
-}
-impl From<json::DecoderError> for Error {
-    fn from(err: json::DecoderError) -> Self {
-        Error::Json(err)
-    }
-}
-
-pub fn metadata(manifest_path_arg: Option<&str>) -> Result<Metadata, Error> {
-    let mut cmd = Command::new("cargo");
-    cmd.arg("metadata").arg("--no-deps");
-    if let Some(mani) = manifest_path_arg {
-        cmd.arg(mani);
-    }
-    let output = cmd.output()?;
-    let stdout = from_utf8(&output.stdout)?;
-    Ok(json::decode(stdout)?)
-}

clippy_lints/src/utils/mod.rs

@@ -21,7 +21,6 @@ use syntax::errors::DiagnosticBuilder;
 use syntax::ptr::P;
 use syntax::symbol::keywords;
 
-pub mod cargo;
 pub mod comparisons;
 pub mod conf;
 pub mod constants;