Revert "Revert "Automatically defines the clippy feature""

This reverts commit e4dceef.

Author: mcarton

CHANGELOG.md

@@ -1,6 +1,12 @@
 # Change Log
 All notable changes to this project will be documented in this file.
 
+## 0.0.97 — 2016-10-24
+* For convenience, `cargo clippy` defines a `cargo-clippy` feature. This was
+  previously added for a short time under the name `clippy` but removed for
+  compatibility.
+* `cargo clippy --help` is more helping (and less helpful :smile:)
+
 ## 0.0.96 — 2016-10-22
 * Rustup to *rustc 1.14.0-nightly (f09420685 2016-10-20)*
 * New lint: [`iter_skip_next`]

README.md

@@ -163,6 +163,14 @@ You can add options  to `allow`/`warn`/`deny`:
 
 Note: `deny` produces errors instead of warnings.
 
+For convenience, `cargo clippy` automatically defines a `cargo-clippy`
+features. This lets you set lints level and compile with or without clippy
+transparently:
+
+```rust
+#[cfg_attr(feature = "cargo-clippy", allow(needless_lifetimes))]
+```
+
 ## Link with clippy service
 
 `clippy-service` is a rust web initiative providing `rust-clippy` as a web service.

src/main.rs

@@ -111,8 +111,7 @@ impl<'a> CompilerCalls<'a> for ClippyCompilerCalls {
 
 use std::path::Path;
 
-const CARGO_CLIPPY_HELP: &str = "\
-Checks a package to catch common mistakes and improve your Rust code.
+const CARGO_CLIPPY_HELP: &str = r#"Checks a package to catch common mistakes and improve your Rust code.
 
 Usage:
     cargo clippy [options] [--] [<opts>...]
@@ -129,8 +128,13 @@ one of:
     -W --warn OPT       Set lint warnings
     -A --allow OPT      Set lint allowed
     -D --deny OPT       Set lint denied
-    -F --forbid OPT     Set lint forbidden\
-";
+    -F --forbid OPT     Set lint forbidden
+
+The feature `cargo-clippy` is automatically defined for convinence. You can use
+it to allow or deny lints, eg.:
+
+    #[cfg_attr(feature = "cargo-clippy", allow(needless_lifetimes))]
+"#;
 
 pub fn main() {
     use std::env;
@@ -213,13 +217,16 @@ pub fn main() {
 
         // this conditional check for the --sysroot flag is there so users can call `cargo-clippy` directly
         // without having to pass --sysroot or anything
-        let args: Vec<String> = if env::args().any(|s| s == "--sysroot") {
+        let mut args: Vec<String> = if env::args().any(|s| s == "--sysroot") {
             env::args().collect()
         } else {
             env::args().chain(Some("--sysroot".to_owned())).chain(Some(sys_root)).collect()
         };
+
         // this check ensures that dependencies are built but not linted and the final crate is
         // linted but not built
+        args.extend_from_slice(&["--cfg".to_owned(), r#"feature="cargo-clippy""#.to_owned()]);
+
         let mut ccc = ClippyCompilerCalls::new(env::args().any(|s| s == "-Zno-trans"));
         let (result, _) = rustc_driver::run_compiler(&args, &mut ccc, None, None);
 
@@ -251,6 +258,8 @@ fn process<P, I>(old_args: I, dep_path: P, sysroot: &str) -> Result<(), i32>
     args.push(String::from("--sysroot"));
     args.push(sysroot.to_owned());
     args.push("-Zno-trans".to_owned());
+    args.push("--cfg".to_owned());
+    args.push(r#"feature="cargo-clippy""#.to_owned());
 
     let path = std::env::current_exe().expect("current executable path invalid");
     let exit_status = std::process::Command::new("cargo")