Auto merge of #11399 - Muscraft:autofix-for-clippy, r=weihanglo

fix: Make auto-fix note work with `clippy`

[Someone pointed out](#10976 (comment)) that the suggestion to run `cargo --fix` did not work properly for `cargo clippy`. This makes sure the correct command to run is output when running under `cargo clippy`.

This is done by checking if the `RUSTC_WORKSPACE_WRAPPER` environment variable is set, since `clippy` [sets this every run](https://github.com/rust-lang/rust-clippy/blob/51ec465cc3dfb62a2dad7e808b399fa76a1c9170/src/main.rs#L140). Since other things can use `RUSTC_WORKSPACE_WRAPPER`, we look for a wrapper named [`clippy-driver`](https://github.com/rust-lang/rust-clippy/blob/51ec465cc3dfb62a2dad7e808b399fa76a1c9170/src/main.rs#L120).

Since `clippy` might not be available everywhere `cargo` is tested, this is tested using a `rustc` wrapper.

src/cargo/core/compiler/job_queue.rs

@@ -54,6 +54,7 @@ use std::collections::{BTreeMap, HashMap, HashSet};
 use std::fmt::Write as _;
 use std::io;
 use std::marker;
+use std::path::PathBuf;
 use std::sync::Arc;
 use std::thread::{self, Scope};
 use std::time::Duration;
@@ -799,7 +800,11 @@ impl<'cfg> DrainState<'cfg> {
                             self.tokens.extend(rustc_tokens);
                         }
                         self.to_send_clients.remove(&id);
-                        self.report_warning_count(cx.bcx.config, id);
+                        self.report_warning_count(
+                            cx.bcx.config,
+                            id,
+                            &cx.bcx.rustc().workspace_wrapper,
+                        );
                         self.active.remove(&id).unwrap()
                     }
                     // ... otherwise if it hasn't finished we leave it
@@ -1243,7 +1248,12 @@ impl<'cfg> DrainState<'cfg> {
     }
 
     /// Displays a final report of the warnings emitted by a particular job.
-    fn report_warning_count(&mut self, config: &Config, id: JobId) {
+    fn report_warning_count(
+        &mut self,
+        config: &Config,
+        id: JobId,
+        rustc_workspace_wrapper: &Option<PathBuf>,
+    ) {
         let count = match self.warning_count.remove(&id) {
             // An error could add an entry for a `Unit`
             // with 0 warnings but having fixable
@@ -1276,7 +1286,16 @@ impl<'cfg> DrainState<'cfg> {
             if let FixableWarnings::Positive(fixable) = count.fixable {
                 // `cargo fix` doesnt have an option for custom builds
                 if !unit.target.is_custom_build() {
-                    let mut command = {
+                    // To make sure the correct command is shown for `clippy` we
+                    // check if `RUSTC_WORKSPACE_WRAPPER` is set and pointing towards
+                    // `clippy-driver`.
+                    let clippy = std::ffi::OsStr::new("clippy-driver");
+                    let command = match rustc_workspace_wrapper.as_ref().and_then(|x| x.file_stem())
+                    {
+                        Some(wrapper) if wrapper == clippy => "cargo clippy --fix",
+                        _ => "cargo fix",
+                    };
+                    let mut args = {
                         let named = unit.target.description_named();
                         // if its a lib we need to add the package to fix
                         if unit.target.is_lib() {
@@ -1288,16 +1307,15 @@ impl<'cfg> DrainState<'cfg> {
                     if unit.mode.is_rustc_test()
                         && !(unit.target.is_test() || unit.target.is_bench())
                     {
-                        command.push_str(" --tests");
+                        args.push_str(" --tests");
                     }
                     let mut suggestions = format!("{} suggestion", fixable);
                     if fixable > 1 {
                         suggestions.push_str("s")
                     }
                     drop(write!(
                         message,
-                        " (run `cargo fix --{}` to apply {})",
-                        command, suggestions
+                        " (run `{command} --{args}` to apply {suggestions})"
                     ))
                 }
             }

tests/testsuite/check.rs

@@ -1447,3 +1447,50 @@ fn check_fixable_mixed() {
         .with_stderr_contains("[..] (run `cargo fix --bench \"bench\"` to apply 1 suggestion)")
         .run();
 }
+
+#[cargo_test]
+fn check_fixable_warning_for_clippy() {
+    // A wrapper around `rustc` instead of calling `clippy`
+    let clippy_driver = project()
+        .at(cargo_test_support::paths::global_root().join("clippy-driver"))
+        .file("Cargo.toml", &basic_manifest("clippy-driver", "0.0.1"))
+        .file(
+            "src/main.rs",
+            r#"
+            fn main() {
+                let mut args = std::env::args_os();
+                let _me = args.next().unwrap();
+                let rustc = args.next().unwrap();
+                let status = std::process::Command::new(rustc).args(args).status().unwrap();
+                std::process::exit(status.code().unwrap_or(1));
+            }
+            "#,
+        )
+        .build();
+    clippy_driver.cargo("build").run();
+
+    let foo = project()
+        .file(
+            "Cargo.toml",
+            r#"
+                [package]
+                name = "foo"
+                version = "0.0.1"
+            "#,
+        )
+        // We don't want to show a warning that is `clippy`
+        // specific since we are using a `rustc` wrapper
+        // inplace of `clippy`
+        .file("src/lib.rs", "use std::io;")
+        .build();
+
+    foo.cargo("check")
+        // We can't use `clippy` so we use a `rustc` workspace wrapper instead
+        .env(
+            "RUSTC_WORKSPACE_WRAPPER",
+            clippy_driver.bin("clippy-driver"),
+        )
+        .masquerade_as_nightly_cargo(&["auto-fix note"])
+        .with_stderr_contains("[..] (run `cargo clippy --fix --lib -p foo` to apply 1 suggestion)")
+        .run();
+}