clippy-driver: pass all args to rustc if --rustc is present

[matthiaskrgr]

changelog: clippy-driver: pass all args to rustc if --rustc is present

[jsgf]

No, this doesn't help. rustc isn't necessarily in the path, and even if it were, doesn't necessarily have anything to do with the version of rustc clippy-driver was built against. If I wanted to know the version of the rustc executable, I could just run rustc --version.

[flip1995]

What we could test for starters, is if the first argument is rustc, that we immediately return rustc_driver::run_compiler(&args, DefaultCallbacks, None, None), where args is orig_args without clippy_driver. This should implement clippy_driver rustc ... = rustc ...-linked-with-clippy. If that works, we can carefully go through the args modifications in this closure and determine what should be kept when rustc is passed.

[flip1995]

I just realized, that the clippy-driver rustc idea doesn't work:

rust-clippy/src/driver.rs

Lines 353 to 355 in 06f0ab0

	// Setting RUSTC_WRAPPER causes Cargo to pass 'rustc' as the first argument.
	// We're invoking the compiler programmatically, so we ignore this/
	let wrapper_mode = orig_args.get(1).map(Path::new).and_then(Path::file_stem) == Some("rustc".as_ref());

clippy-driver rustc is run, when running cargo clippy...

[flip1995]

What do you think about clippy-driver --rustc?

[flip1995]

This would be the patch for adding this #5178 (comment):

diff --git a/src/driver.rs b/src/driver.rs
index 097b796e..b280169d 100644
--- a/src/driver.rs
+++ b/src/driver.rs
@@ -299,6 +299,12 @@ pub fn main() {
         rustc_driver::catch_fatal_errors(move || {
             let mut orig_args: Vec<String> = env::args().collect();
 
+            if let Some(pos) = orig_args.iter().position(|arg| arg == "--rustc") {
+                orig_args.remove(pos);
+                orig_args[0] = "rustc".to_string();
+                return rustc_driver::run_compiler(&orig_args, &mut DefaultCallbacks, None, None);
+            }
+
             if orig_args.iter().any(|a| a == "--version" || a == "-V") {
                 let version_info = rustc_tools_util::get_version_info!();
                 println!("{}", version_info);

[matthiaskrgr]

I just realized, that the clippy-driver rustc idea doesn't work

Urgh that sucks...
Imo the intuition with --arguments is that the order does not really matter, so clippy-driver --rustc --version should behave like clippy-driver --version --rustc which is not the case here :(
But I don't have any better ideas right now..

[flip1995]

The patch I posted in #5178 (comment) takes care of this and everything will be passed to rustc, when --rustc is passed, no matter in which position. The only thing, that didn't work as expected is clippy-driver --rustc some_file.rs, which should be rustc some_file.rs, but threw error: counldn't find crate for std.

[bors]

☔ The latest upstream changes (presumably #5608) made this pull request unmergeable. Please resolve the merge conflicts.

[flip1995]

Friendly ping @matthiaskrgr. Do you think we can/should move forward with this?

[matthiaskrgr]

looks like the error: counldn't find crate for std. problem is caused by missing --sysroot arg when calling rustc, this is actually injected a little bit later in the code: https://github.com/rust-lang/rust-clippy/blob/master/src/driver.rs#L386

[flip1995]

Can you add a test script, that compares output of some clippy-driver --rustc [some_args] commands with rustc [some_args]? Similar to the .github/driver.sh script. (Or you can just add tests for this there)

[matthiaskrgr]

Added test for clippy-driver --rustc --version --verbose vs rustc --version --verbose to driver.sh

[flip1995]

This test would also be nice to have:

echo "fn main() {}" > tmp.rs
clippy-driver --rustc tmp.rs

and maybe a test where --rustc is not the first argument.

[matthiaskrgr]

Hmm, clippy-driver --version --rustc prints rustc --version, this is a bug, right?

[flip1995]

Hmm, clippy-driver --version --rustc prints rustc --version, this is a bug, right?

Nope that is the expected behavior. When the --rustc arg is passed to the clippy-driver everything should be forwarded to the rustc used by Clippy. This is consistent behavior.

Can you add the --rustc arg to the Clippy help:

rust-clippy/src/driver.rs

Lines 200 to 210 in 67ec96c

	fn display_help() {
	println!(
	"\
	Checks a package to catch common mistakes and improve your Rust code.
	Usage:
	cargo clippy [options] [--] [<opts>...]
	Common options:
	-h, --help Print this message
	-V, --version Print version info and exit

[matthiaskrgr]

CI was failing because I was testing against a file that I forgot to git-commit... 😆

[flip1995]

@bors r+ rollup

[bors]

📌 Commit 7a62380 has been approved by flip1995

[bors]

🌲 The tree is currently closed for pull requests below priority 10, this pull request will be tested once the tree is reopened