Add klint-rustdoc command as a helper to invoke rustdoc

Author: nbdd0121

Cargo.toml

@@ -7,6 +7,7 @@ name = "klint"
 version = "0.1.0"
 edition = "2024"
 license = "MIT OR Apache-2.0"
+default-run = "klint"
 
 [dependencies]
 rusqlite = "0.37"
@@ -18,6 +19,14 @@ iced-x86 = { version = "1.21.0", default-features = false, features = ["std", "d
 [dev-dependencies]
 compiletest_rs = { version = "0.11", features = [ "tmp" ] }
 
+[[bin]]
+name = "klint"
+path = "src/main.rs"
+
+[[bin]]
+name = "klint-rustdoc"
+path = "src/rustdoc.rs"
+
 [package.metadata.rust-analyzer]
 # This crate uses #![feature(rustc_private)]
 rustc_private = true

README.md

@@ -41,7 +41,8 @@ This patch can be used even if plain rustc or clippy is used for kernel build.
 To run this tool for Linux kernel build, use `make RUSTC=<path to klint>` to use klint in place of a Rust compiler.
 
 If you compile kernel with rustdoc tests as kunit tests, you also need a matching version of `rustdoc`.
-For Nix users, this is available as symlink `klint-rustdoc`, you can use add `RUSTDOC=klint-rustdoc` to make command line.
+As it can be tricky to get the versions to match, `klint` provides a `klint-rustdoc` binary will execute the correct rustdoc.
+You can add `RUSTDOC="<path to klint>-rustdoc"` to the make command.
 
 `klint`'s atomic context checker is not lint-clean on Linux kernel tree.
 If you want to check it out, you can opt into it with `-Dklint::atomic_context`.

build.rs

@@ -17,4 +17,16 @@ fn main() {
     // binary would be missing the necessary RPATH so it cannot run without using Cargo.
     let sysroot = probe_sysroot();
     println!("cargo::rustc-link-arg=-Wl,-rpath={sysroot}/lib");
+
+    // If the RUSTDOC environment variable is just a plain "rustdoc", we want to discover the full path.
+    // NB: this is the case when built from nix.
+    let mut rustdoc = std::env::var("RUSTDOC").unwrap_or_default();
+    if rustdoc.is_empty() || rustdoc == "rustdoc" {
+        rustdoc = format!("{sysroot}/bin/rustdoc");
+        assert!(
+            std::fs::exists(&rustdoc).unwrap_or_default(),
+            "Cannot find RUSTDOC. This is an unknown environment, please file a bug report."
+        );
+    }
+    println!("cargo::rustc-env=RUSTDOC={rustdoc}");
 }

flake.nix

@@ -64,8 +64,10 @@
               doCheck = false;
 
               # If kernel rustdoc tests are enabled, user would need a matching version of rustdoc.
+              # klint provides a klint-rustdoc binary to ease the process. However, for nix, we already
+              # know the path to the rustdoc binary, so just symlink and replace the wrapper.
               postInstall = ''
-                ln -s "${lib.getExe' rustc "rustdoc"}" $out/bin/klint-rustdoc
+                ln -sf "${lib.getExe' rustc "rustdoc"}" $out/bin/klint-rustdoc
               '';
 
               passthru.rustc = rustc;

src/rustdoc.rs

@@ -0,0 +1,8 @@
+use std::io::Result;
+use std::os::unix::process::CommandExt;
+
+fn main() -> Result<()> {
+    Err(std::process::Command::new(env!("RUSTDOC"))
+        .args(std::env::args().skip(1))
+        .exec())
+}