Print cargo dev help on missing arg and updated setup documentation

CONTRIBUTING.md

@@ -115,7 +115,7 @@ To work around this, you need to have a copy of the [rustc-repo][rustc_repo] ava
 `git clone https://github.com/rust-lang/rust/`.
 Then you can run a `cargo dev` command to automatically make Clippy use the rustc-repo via path-dependencies
 which `IntelliJ Rust` will be able to understand.
-Run `cargo dev ide_setup --repo-path <repo-path>` where `<repo-path>` is a path to the rustc repo
+Run `cargo dev setup intellij --repo-path <repo-path>` where `<repo-path>` is a path to the rustc repo
 you just cloned.
 The command will add path-dependencies pointing towards rustc-crates inside the rustc repo to
 Clippys `Cargo.toml`s and should allow `IntelliJ Rust` to understand most of the types that Clippy uses.

clippy_dev/src/fmt.rs

@@ -86,7 +86,7 @@ pub fn run(check: bool, verbose: bool) {
             },
             CliError::RaSetupActive => {
                 eprintln!(
-                    "error: a local rustc repo is enabled as path dependency via `cargo dev ide_setup`.
+                    "error: a local rustc repo is enabled as path dependency via `cargo dev setup intellij`.
 Not formatting because that would format the local repo as well!
 Please revert the changes to Cargo.tomls first."
                 );

clippy_dev/src/main.rs

@@ -2,7 +2,7 @@
 // warn on lints, that are included in `rust-lang/rust`s bootstrap
 #![warn(rust_2018_idioms, unused_lifetimes)]
 
-use clap::{App, Arg, ArgMatches, SubCommand};
+use clap::{App, AppSettings, Arg, ArgMatches, SubCommand};
 use clippy_dev::{bless, fmt, new_lint, serve, setup, stderr_length_check, update_lints};
 fn main() {
     let matches = get_clap_config();
@@ -52,6 +52,7 @@ fn main() {
 
 fn get_clap_config<'a>() -> ArgMatches<'a> {
     App::new("Clippy developer tooling")
+        .setting(AppSettings::ArgRequiredElseHelp)
         .subcommand(
             SubCommand::with_name("bless")
                 .about("bless the test output changes")
@@ -146,6 +147,7 @@ fn get_clap_config<'a>() -> ArgMatches<'a> {
         .subcommand(
             SubCommand::with_name("setup")
                 .about("Support for setting up your personal development environment")
+                .setting(AppSettings::ArgRequiredElseHelp)
                 .subcommand(
                     SubCommand::with_name("intellij")
                         .about("Alter dependencies so Intellij Rust can find rustc internals")

clippy_dev/src/setup/intellij.rs

@@ -55,7 +55,7 @@ fn inject_deps_into_manifest(
     // do not inject deps if we have aleady done so
     if cargo_toml.contains("[target.'cfg(NOT_A_PLATFORM)'.dependencies]") {
         eprintln!(
-            "cargo dev ide_setup: warning: deps already found inside {}, doing nothing.",
+            "cargo dev setup intellij: warning: deps already found inside {}, doing nothing.",
             manifest_path
         );
         return Ok(());

doc/basics.md

@@ -90,8 +90,10 @@ cargo dev fmt
 cargo dev update_lints
 # create a new lint and register it
 cargo dev new_lint
+# automatically formatting all code before each commit
+cargo dev setup git-hook
 # (experimental) Setup Clippy to work with IntelliJ-Rust
-cargo dev ide_setup
+cargo dev setup intellij
 ```
 
 ## lintcheck