Rollup merge of rust-lang#129152 - onur-ozkan:custom-clippy, r=Kobzol

custom/external clippy support for bootstrapping

Similar to cargo, rustc, and rustfmt, this adds the support of using custom clippy on bootstrap. It’s designed for those who want to test their own clippy builds or avoid downloading the stage0 clippy.

Closes rust-lang#121518

config.example.toml

@@ -230,6 +230,13 @@
 # use this rustfmt binary instead as the stage0 snapshot rustfmt.
 #rustfmt = "/path/to/rustfmt"
 
+# Instead of downloading the src/stage0 version of cargo-clippy specified,
+# use this cargo-clippy binary instead as the stage0 snapshot cargo-clippy.
+#
+# Note that this option should be used with the same toolchain as the `rustc` option above. 
+# Otherwise, clippy is likely to fail due to a toolchain conflict.
+#cargo-clippy = "/path/to/cargo-clippy"
+
 # Whether to build documentation by default. If false, rustdoc and
 # friends will still be compiled but they will not be used to generate any
 # documentation.

src/bootstrap/src/core/builder.rs

@@ -1298,8 +1298,12 @@ impl<'a> Builder<'a> {
 
     pub fn cargo_clippy_cmd(&self, run_compiler: Compiler) -> BootstrapCommand {
         if run_compiler.stage == 0 {
-            // `ensure(Clippy { stage: 0 })` *builds* clippy with stage0, it doesn't use the beta clippy.
-            let cargo_clippy = self.build.config.download_clippy();
+            let cargo_clippy = self
+                .config
+                .initial_cargo_clippy
+                .clone()
+                .unwrap_or_else(|| self.build.config.download_clippy());
+
             let mut cmd = command(cargo_clippy);
             cmd.env("CARGO", &self.initial_cargo);
             return cmd;

src/bootstrap/src/core/config/config.rs

@@ -344,6 +344,7 @@ pub struct Config {
     // These are either the stage0 downloaded binaries or the locally installed ones.
     pub initial_cargo: PathBuf,
     pub initial_rustc: PathBuf,
+    pub initial_cargo_clippy: Option<PathBuf>,
 
     #[cfg(not(test))]
     initial_rustfmt: RefCell<RustfmtState>,
@@ -834,6 +835,7 @@ define_config! {
         cargo: Option<PathBuf> = "cargo",
         rustc: Option<PathBuf> = "rustc",
         rustfmt: Option<PathBuf> = "rustfmt",
+        cargo_clippy: Option<PathBuf> = "cargo-clippy",
         docs: Option<bool> = "docs",
         compiler_docs: Option<bool> = "compiler-docs",
         library_docs_private_items: Option<bool> = "library-docs-private-items",
@@ -1439,6 +1441,7 @@ impl Config {
             cargo,
             rustc,
             rustfmt,
+            cargo_clippy,
             docs,
             compiler_docs,
             library_docs_private_items,
@@ -1491,6 +1494,14 @@ impl Config {
             config.out = absolute(&config.out).expect("can't make empty path absolute");
         }
 
+        if cargo_clippy.is_some() && rustc.is_none() {
+            println!(
+                "WARNING: Using `build.cargo-clippy` without `build.rustc` usually fails due to toolchain conflict."
+            );
+        }
+
+        config.initial_cargo_clippy = cargo_clippy;
+
         config.initial_rustc = if let Some(rustc) = rustc {
             if !flags.skip_stage0_validation {
                 config.check_stage0_version(&rustc, "rustc");

src/bootstrap/src/utils/change_tracker.rs

@@ -235,4 +235,9 @@ pub const CONFIG_CHANGE_HISTORY: &[ChangeInfo] = &[
         severity: ChangeSeverity::Info,
         summary: "The `build.profiler` option now tries to use source code from `download-ci-llvm` if possible, instead of checking out the `src/llvm-project` submodule.",
     },
+    ChangeInfo {
+        change_id: 129152,
+        severity: ChangeSeverity::Info,
+        summary: "New option `build.cargo-clippy` added for supporting the use of custom/external clippy.",
+    },
 ];