Fix clippy-wrapper test race condition.

crates/cargo-test-support/src/lib.rs

@@ -523,29 +523,6 @@ pub fn cargo_exe() -> PathBuf {
     snapbox::cmd::cargo_bin("cargo")
 }
 
-/// A wrapper around `rustc` instead of calling `clippy`.
-pub fn wrapped_clippy_driver() -> PathBuf {
-    let clippy_driver = project()
-        .at(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();
-
-    clippy_driver.bin("clippy-driver")
-}
-
 /// This is the raw output from the process.
 ///
 /// This is similar to `std::process::Output`, however the `status` is

crates/cargo-test-support/src/tools.rs

@@ -7,6 +7,7 @@ use std::sync::OnceLock;
 
 static ECHO_WRAPPER: OnceLock<Mutex<Option<PathBuf>>> = OnceLock::new();
 static ECHO: OnceLock<Mutex<Option<PathBuf>>> = OnceLock::new();
+static CLIPPY_DRIVER: OnceLock<Mutex<Option<PathBuf>>> = OnceLock::new();
 
 /// Returns the path to an executable that works as a wrapper around rustc.
 ///
@@ -107,3 +108,34 @@ pub fn echo_subcommand() -> Project {
     p.cargo("build").run();
     p
 }
+
+/// A wrapper around `rustc` instead of calling `clippy`.
+pub fn wrapped_clippy_driver() -> PathBuf {
+    let mut lock = CLIPPY_DRIVER
+        .get_or_init(|| Default::default())
+        .lock()
+        .unwrap();
+    if let Some(path) = &*lock {
+        return path.clone();
+    }
+    let clippy_driver = project()
+        .at(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 path = clippy_driver.bin("clippy-driver");
+    *lock = Some(path.clone());
+    path
+}

tests/testsuite/check.rs

@@ -6,8 +6,8 @@ use crate::messages::raw_rustc_output;
 use cargo_test_support::install::exe;
 use cargo_test_support::paths::CargoPathExt;
 use cargo_test_support::registry::Package;
+use cargo_test_support::tools;
 use cargo_test_support::{basic_bin_manifest, basic_manifest, git, project};
-use cargo_test_support::{tools, wrapped_clippy_driver};
 
 #[cargo_test]
 fn check_success() {
@@ -1432,7 +1432,7 @@ fn check_fixable_warning_for_clippy() {
 
     foo.cargo("check")
         // We can't use `clippy` so we use a `rustc` workspace wrapper instead
-        .env("RUSTC_WORKSPACE_WRAPPER", wrapped_clippy_driver())
+        .env("RUSTC_WORKSPACE_WRAPPER", tools::wrapped_clippy_driver())
         .with_stderr_contains("[..] (run `cargo clippy --fix --lib -p foo` to apply 1 suggestion)")
         .run();
 }

tests/testsuite/fix.rs

@@ -5,8 +5,8 @@ use cargo_test_support::compare::assert_match_exact;
 use cargo_test_support::git::{self, init};
 use cargo_test_support::paths::{self, CargoPathExt};
 use cargo_test_support::registry::{Dependency, Package};
+use cargo_test_support::tools;
 use cargo_test_support::{basic_manifest, is_nightly, project, Project};
-use cargo_test_support::{tools, wrapped_clippy_driver};
 
 #[cargo_test]
 fn do_not_fix_broken_builds() {
@@ -193,7 +193,7 @@ fn broken_clippy_fixes_backed_out() {
         .env("__CARGO_FIX_YOLO", "1")
         .env("RUSTC", p.root().join("foo/target/debug/foo"))
         //  We can't use `clippy` so we use a `rustc` workspace wrapper instead
-        .env("RUSTC_WORKSPACE_WRAPPER", wrapped_clippy_driver())
+        .env("RUSTC_WORKSPACE_WRAPPER", tools::wrapped_clippy_driver())
         .with_stderr_contains(
             "warning: failed to automatically apply fixes suggested by rustc \
              to crate `bar`\n\