Auto merge of #10149 - jyn514:duplicate-sysroot, r=flip1995

Don't pass `--sysroot` twice if SYSROOT is set

This is useful for rust-lang/rust to allow setting a sysroot that's *only* for build scripts, different from the regular sysroot passed in RUSTFLAGS (since cargo doesn't apply RUSTFLAGS to build scripts or proc-macros).

That said, the exact motivation is not particularly important: this fixes a regression from
https://github.com/rust-lang/rust-clippy/pull/9881/commits/5907e9155ed7f1312d108aa2110853472da3b029#r1060215684.

Note that only RUSTFLAGS is tested in the new integration test; passing --sysroot through `clippy-driver` never worked as far as I can tell, and no one is using it, so I didn't fix it here.

Helps with https://github.com/rust-lang/rust/pull/106394.

---

changelog: other: `SYSROOT` and `--sysroot` can now be set at the same time
[#10149](https://github.com/rust-lang/rust-clippy/pull/10149)
<!-- changelog_checked -->

3 files changed, 20 insertions, 1 deletions

diff --git a/.github/driver.sh b/.github/driver.sh
index 6ff189fc859..798782340ee 100644
--- a/.github/driver.sh
+++ b/.github/driver.sh
@@ -17,6 +17,13 @@ test "$sysroot" = $desired_sysroot
 sysroot=$(SYSROOT=$desired_sysroot ./target/debug/clippy-driver --print sysroot)
 test "$sysroot" = $desired_sysroot
 
+# Check that the --sysroot argument is only passed once (SYSROOT is ignored)
+(
+    cd rustc_tools_util
+    touch src/lib.rs
+    SYSROOT=/tmp RUSTFLAGS="--sysroot=$(rustc --print sysroot)" ../target/debug/cargo-clippy clippy --verbose
+)
+
 # Make sure this isn't set - clippy-driver should cope without it
 unset CARGO_MANIFEST_DIR
 
diff --git a/src/driver.rs b/src/driver.rs
index bcc096c570e..d521e8d8839 100644
--- a/src/driver.rs
+++ b/src/driver.rs
@@ -256,11 +256,14 @@ pub fn main() {
     LazyLock::force(&ICE_HOOK);
     exit(rustc_driver::catch_with_exit_code(move || {
         let mut orig_args: Vec<String> = env::args().collect();
+        let has_sysroot_arg = arg_value(&orig_args, "--sysroot", |_| true).is_some();
 
         let sys_root_env = std::env::var("SYSROOT").ok();
         let pass_sysroot_env_if_given = |args: &mut Vec<String>, sys_root_env| {
             if let Some(sys_root) = sys_root_env {
-                args.extend(vec!["--sysroot".into(), sys_root]);
+                if !has_sysroot_arg {
+                    args.extend(vec!["--sysroot".into(), sys_root]);
+                }
             };
         };
 
diff --git a/tests/integration.rs b/tests/integration.rs
index 818ff70b33f..a771d8b87c8 100644
--- a/tests/integration.rs
+++ b/tests/integration.rs
@@ -1,3 +1,12 @@
+//! This test is meant to only be run in CI. To run it locally use:
+//!
+//! `env INTEGRATION=rust-lang/log cargo test --test integration --features=integration`
+//!
+//! You can use a different `INTEGRATION` value to test different repositories.
+//!
+//! This test will clone the specified repository and run Clippy on it. The test succeeds, if
+//! Clippy doesn't produce an ICE. Lint warnings are ignored by this test.
+
 #![cfg(feature = "integration")]
 #![cfg_attr(feature = "deny-warnings", deny(warnings))]
 #![warn(rust_2018_idioms, unused_lifetimes)]