Auto merge of #6884 - matthiaskrgr:lintcheck_crate, r=Manishearth

move lintcheck into its own crate

This pr:
* moves lintcheck out of `clippy dev` and into its own crate (`lintcheck`)  (I should have done this earlier :D)
* makes lintcheck terminate if it is not launched from the repo root (to prevent problems with wrong paths when using `cargo run` in the crate root)
* fixes json lint messages leaking the runners `$HOME` when a lint messages comes from a proc macro that originates from a crate inside the `$CARGO_CACHE`
* adds more documentation to lintchecks `README.md` and mentions lintcheck in `docs/basics.md`

changelog: none

Author: bors

.cargo/config

@@ -1,7 +1,7 @@
 [alias]
 uitest = "test --test compile-test"
 dev = "run --target-dir clippy_dev/target --package clippy_dev --bin clippy_dev --manifest-path clippy_dev/Cargo.toml --"
-dev-lintcheck = "run --target-dir clippy_dev/target --package clippy_dev --bin clippy_dev --manifest-path clippy_dev/Cargo.toml --features lintcheck -- lintcheck"
+lintcheck = "run --target-dir lintcheck/target --package lintcheck --bin lintcheck --manifest-path lintcheck/Cargo.toml  -- "
 
 [build]
 rustflags = ["-Zunstable-options"]

.gitignore

@@ -21,6 +21,7 @@ out
 /clippy_utils/target
 /clippy_workspace_tests/target
 /clippy_dev/target
+/lintcheck/target
 /rustc_tools_util/target
 
 # Generated by dogfood

clippy_dev/Cargo.toml

@@ -7,20 +7,11 @@ edition = "2018"
 [dependencies]
 bytecount = "0.6"
 clap = "2.33"
-flate2 = { version = "1.0.19", optional = true }
-fs_extra = { version = "1.2.0", optional = true }
 itertools = "0.9"
 opener = "0.4"
 regex = "1"
-serde = { version = "1.0", features = ["derive"], optional = true }
-serde_json = { version = "1.0", optional = true }
 shell-escape = "0.1"
-tar = { version = "0.4.30", optional = true }
-toml = { version = "0.5", optional = true }
-ureq = { version = "2.0.0-rc3", optional = true }
-rayon = { version = "1.5.0", optional = true }
 walkdir = "2"
 
 [features]
-lintcheck = ["flate2", "serde_json", "tar", "toml", "ureq", "serde", "fs_extra", "rayon"]
 deny-warnings = []

clippy_dev/src/fmt.rs

@@ -54,6 +54,7 @@ pub fn run(check: bool, verbose: bool) {
         success &= cargo_fmt(context, project_root.as_path())?;
         success &= cargo_fmt(context, &project_root.join("clippy_dev"))?;
         success &= cargo_fmt(context, &project_root.join("rustc_tools_util"))?;
+        success &= cargo_fmt(context, &project_root.join("lintcheck"))?;
 
         for entry in WalkDir::new(project_root.join("tests")) {
             let entry = entry?;

clippy_dev/src/lib.rs

@@ -12,7 +12,6 @@ use walkdir::WalkDir;
 
 pub mod bless;
 pub mod fmt;
-pub mod lintcheck;
 pub mod new_lint;
 pub mod ra_setup;
 pub mod serve;

clippy_dev/src/main.rs

@@ -2,21 +2,13 @@
 
 use clap::{App, Arg, ArgMatches, SubCommand};
 use clippy_dev::{bless, fmt, new_lint, ra_setup, serve, stderr_length_check, update_lints};
-
-#[cfg(feature = "lintcheck")]
-use clippy_dev::lintcheck;
-
 fn main() {
     let matches = get_clap_config();
 
     match matches.subcommand() {
         ("bless", Some(matches)) => {
             bless::bless(matches.is_present("ignore-timestamp"));
         },
-        #[cfg(feature = "lintcheck")]
-        ("lintcheck", Some(matches)) => {
-            lintcheck::run(&matches);
-        },
         ("fmt", Some(matches)) => {
             fmt::run(matches.is_present("check"), matches.is_present("verbose"));
         },
@@ -53,34 +45,7 @@ fn main() {
 }
 
 fn get_clap_config<'a>() -> ArgMatches<'a> {
-    #[cfg(feature = "lintcheck")]
-    let lintcheck_sbcmd = SubCommand::with_name("lintcheck")
-        .about("run clippy on a set of crates and check output")
-        .arg(
-            Arg::with_name("only")
-                .takes_value(true)
-                .value_name("CRATE")
-                .long("only")
-                .help("only process a single crate of the list"),
-        )
-        .arg(
-            Arg::with_name("crates-toml")
-                .takes_value(true)
-                .value_name("CRATES-SOURCES-TOML-PATH")
-                .long("crates-toml")
-                .help("set the path for a crates.toml where lintcheck should read the sources from"),
-        )
-        .arg(
-            Arg::with_name("threads")
-                .takes_value(true)
-                .value_name("N")
-                .short("j")
-                .long("jobs")
-                .help("number of threads to use, 0 automatic choice"),
-        )
-        .arg(Arg::with_name("fix").help("runs cargo clippy --fix and checks if all suggestions apply"));
-
-    let app = App::new("Clippy developer tooling")
+    App::new("Clippy developer tooling")
         .subcommand(
             SubCommand::with_name("bless")
                 .about("bless the test output changes")
@@ -197,10 +162,6 @@ fn get_clap_config<'a>() -> ArgMatches<'a> {
                         .validator_os(serve::validate_port),
                 )
                 .arg(Arg::with_name("lint").help("Which lint's page to load initially (optional)")),
-        );
-
-    #[cfg(feature = "lintcheck")]
-    let app = app.subcommand(lintcheck_sbcmd);
-
-    app.get_matches()
+        )
+        .get_matches()
 }

doc/basics.md

@@ -11,8 +11,9 @@ the codebase take a look at [Adding Lints] or [Common Tools].
   - [Get the Code](#get-the-code)
   - [Building and Testing](#building-and-testing)
   - [`cargo dev`](#cargo-dev)
-  - [Common Abbreviations](#common-abbreviations)
+  - [lintcheck](#lintcheck)
   - [PR](#pr)
+  - [Common Abbreviations](#common-abbreviations)
 
 ## Get the Code
 
@@ -91,6 +92,16 @@ cargo dev new_lint
 cargo dev ra_setup
 ```
 
+## lintcheck
+`cargo lintcheck` will build and run clippy on a fixed set of crates and generate a log of the results.  
+You can `git diff` the updated log against its previous version and 
+see what impact your lint made on a small set of crates.  
+If you add a new lint, please audit the resulting warnings and make sure 
+there are no false positives and that the suggestions are valid.
+
+Refer to the tools [README] for more details.
+
+[README]: https://github.com/rust-lang/rust-clippy/blob/master/lintcheck/README.md
 ## PR
 
 We follow a rustc no merge-commit policy.