Auto merge of #11235 - matthiaskrgr:rustc_in_ci, r=<try>

attempt to check rust-lang/rust with clippy in ci

r? `@ghost`

changelog: run clippy on rust-lang/rust as integration test

.github/workflows/clippy_bors.yml

@@ -203,6 +203,7 @@ jobs:
       max-parallel: 6
       matrix:
         integration:
+        - 'rust-lang/rust'
         - 'rust-lang/cargo'
         - 'rust-lang/chalk'
         - 'rust-lang/rustfmt'

tests/integration.rs

@@ -23,6 +23,11 @@ const CARGO_CLIPPY: &str = "cargo-clippy.exe";
 #[cfg_attr(feature = "integration", test)]
 fn integration_test() {
     let repo_name = env::var("INTEGRATION").expect("`INTEGRATION` var not set");
+
+    if repo_name == "rust-lang/rust" {
+        return;
+    }
+
     let repo_url = format!("https://github.com/{repo_name}");
     let crate_name = repo_name
         .split('/')
@@ -123,3 +128,135 @@ fn integration_test() {
         None => panic!("Process terminated by signal"),
     }
 }
+
+#[cfg_attr(feature = "integration", test)]
+fn integration_test_rustc() {
+    let repo_name = env::var("INTEGRATION").expect("`INTEGRATION` var not set");
+
+    if repo_name != "rust-lang/rust" {
+        return;
+    }
+
+    let repo_url = format!("https://github.com/{repo_name}");
+    let crate_name = repo_name
+        .split('/')
+        .nth(1)
+        .expect("repo name should have format `<org>/<name>`");
+
+    let mut repo_dir = tempfile::tempdir().expect("couldn't create temp dir").into_path();
+    repo_dir.push(crate_name);
+
+    let st_git_cl = Command::new("git")
+        .args([
+            OsStr::new("clone"),
+            OsStr::new("--depth=5000"),
+            OsStr::new(&repo_url),
+            OsStr::new(&repo_dir),
+        ])
+        .status()
+        .expect("unable to run git");
+    assert!(st_git_cl.success());
+
+    // clippy is pinned to a specific nightly version
+    // check out the commit of that nightly to ensure compatibility
+    let rustc_output = Command::new("rustc")
+        .arg("--version")
+        .arg("--verbose")
+        .output()
+        .expect("failed to run rustc --version");
+
+    let commit_line = String::from_utf8_lossy(&rustc_output.stdout);
+    let commit_line_ = commit_line
+        .lines()
+        .find(|line| line.starts_with("commit-hash: "))
+        .expect("did not find 'commit-hash:' in --version output");
+
+    let commit = commit_line_
+        .strip_prefix("commit-hash: ")
+        .expect("failed parsing commit line");
+
+    // check out the commit in the rustc repo to ensure clippy is compatible
+
+    let st_git_checkout = Command::new("git")
+        .arg("checkout")
+        .arg(commit)
+        .status()
+        .expect("git failed to check out commit");
+    assert!(st_git_checkout.success());
+
+    let root_dir = std::path::PathBuf::from(env!("CARGO_MANIFEST_DIR"));
+    let target_dir = std::path::Path::new(&root_dir).join("target");
+    let clippy_binary = target_dir.join(env!("PROFILE")).join(CARGO_CLIPPY);
+
+    // we need to make sure that `x.py clippy` picks up our self-built clippy
+    // try to make the target dir discoverable as PATH
+
+    let path_env = target_dir.join(env!("PROFILE"));
+
+    let output = Command::new("x.py")
+        .current_dir("rust")
+        .env("RUST_BACKTRACE", "full")
+        .env("PATH", path_env)
+        .args(["clippy", "-Wclippy::pedantic", "-Wclippy::nursery"])
+        .output()
+        .expect("unable to run x.py  clippy");
+
+    let stderr = String::from_utf8_lossy(&output.stderr);
+
+    // debug:
+    eprintln!("{stderr}");
+
+    // this is an internal test to make sure we would correctly panic on a delay_span_bug
+    if repo_name == "matthiaskrgr/clippy_ci_panic_test" {
+        // we need to kind of switch around our logic here:
+        // if we find a panic, everything is fine, if we don't panic, SOMETHING is broken about our testing
+
+        // the repo basically just contains a delay_span_bug that forces rustc/clippy to panic:
+        /*
+           #![feature(rustc_attrs)]
+           #[rustc_error(delay_span_bug_from_inside_query)]
+           fn main() {}
+        */
+
+        if stderr.find("error: internal compiler error").is_some() {
+            eprintln!("we saw that we intentionally panicked, yay");
+            return;
+        }
+
+        panic!("panic caused by delay_span_bug was NOT detected! Something is broken!");
+    }
+
+    if let Some(backtrace_start) = stderr.find("error: internal compiler error") {
+        static BACKTRACE_END_MSG: &str = "end of query stack";
+        let backtrace_end = stderr[backtrace_start..]
+            .find(BACKTRACE_END_MSG)
+            .expect("end of backtrace not found");
+
+        panic!(
+            "internal compiler error\nBacktrace:\n\n{}",
+            &stderr[backtrace_start..backtrace_start + backtrace_end + BACKTRACE_END_MSG.len()]
+        );
+    } else if stderr.contains("query stack during panic") {
+        panic!("query stack during panic in the output");
+    } else if stderr.contains("E0463") {
+        // Encountering E0463 (can't find crate for `x`) did _not_ cause the build to fail in the
+        // past. Even though it should have. That's why we explicitly panic here.
+        // See PR #3552 and issue #3523 for more background.
+        panic!("error: E0463");
+    } else if stderr.contains("E0514") {
+        panic!("incompatible crate versions");
+    } else if stderr.contains("failed to run `rustc` to learn about target-specific information") {
+        panic!("couldn't find librustc_driver, consider setting `LD_LIBRARY_PATH`");
+    } else {
+        assert!(
+            !stderr.contains("toolchain") || !stderr.contains("is not installed"),
+            "missing required toolchain"
+        );
+    }
+
+    match output.status.code() {
+        Some(0) => println!("Compilation successful"),
+        Some(code) => eprintln!("Compilation failed. Exit code: {code}"),
+        None => panic!("Process terminated by signal"),
+    }
+}