keep Rustc private and use Assemble instead

Signed-off-by: onur-ozkan <work@onurozkan.dev>

Author: onur-ozkan

src/bootstrap/src/core/build_steps/compile.rs

@@ -839,9 +839,9 @@ fn cp_rustc_component_to_ci_sysroot(builder: &Builder<'_>, sysroot: &Path, conte
 
 #[derive(Debug, PartialOrd, Ord, Clone, PartialEq, Eq, Hash)]
 pub struct Rustc {
-    pub target: TargetSelection,
+    target: TargetSelection,
     /// The **previous** compiler used to compile this compiler.
-    pub compiler: Compiler,
+    compiler: Compiler,
     /// Whether to build a subset of crates, rather than the whole compiler.
     ///
     /// This should only be requested by the user, not used within bootstrap itself.
@@ -851,6 +851,7 @@ pub struct Rustc {
 }
 
 impl Rustc {
+    #[cfg(test)]
     pub fn new(compiler: Compiler, target: TargetSelection) -> Self {
         Self { target, compiler, crates: Default::default() }
     }
@@ -923,7 +924,8 @@ impl Step for Rustc {
 
         let compiler_to_use = builder.compiler_for(compiler.stage, compiler.host, target);
         if compiler_to_use != compiler {
-            builder.ensure(Rustc::new(compiler_to_use, target));
+            let _ = builder.compiler(compiler_to_use.stage, target);
+
             let msg = if compiler_to_use.host == target {
                 format!(
                     "Uplifting rustc (stage{} -> stage{})",
@@ -1424,7 +1426,7 @@ impl Step for CodegenBackend {
         let target = self.target;
         let backend = self.backend;
 
-        builder.ensure(Rustc::new(compiler, target));
+        let _ = builder.compiler(compiler.stage, target);
 
         if builder.config.keep_stage.contains(&compiler.stage) {
             builder.info(
@@ -1861,7 +1863,11 @@ impl Step for Assemble {
         // link to these. (FIXME: Is that correct? It seems to be correct most
         // of the time but I think we do link to these for stage2/bin compilers
         // when not performing a full bootstrap).
-        let actual_stage = builder.ensure(Rustc::new(build_compiler, target_compiler.host));
+        let actual_stage = builder.ensure(Rustc {
+            compiler: build_compiler,
+            target: target_compiler.host,
+            crates: vec![],
+        });
         // Current build_compiler.stage might be uplifted instead of being built; so update it
         // to not fail while linking the artifacts.
         build_compiler.stage = actual_stage;

src/bootstrap/src/core/build_steps/dist.rs

@@ -727,7 +727,7 @@ impl Step for RustcDev {
             return None;
         }
 
-        builder.ensure(compile::Rustc::new(compiler, target));
+        let _ = builder.compiler(compiler.stage, target);
 
         let tarball = Tarball::new(builder, "rustc-dev", &target.triple);
 

src/bootstrap/src/core/build_steps/doc.rs

@@ -953,7 +953,7 @@ macro_rules! tool_doc {
                     // Rustdoc needs the rustc sysroot available to build.
                     // FIXME: is there a way to only ensure `check::Rustc` here? Last time I tried it failed
                     // with strange errors, but only on a full bors test ...
-                    builder.ensure(compile::Rustc::new(compiler, target));
+                    let _ = builder.compiler(compiler.stage, target);
                 }
 
                 // Build cargo command.

src/bootstrap/src/core/build_steps/test.rs

@@ -251,7 +251,6 @@ impl Step for Cargotest {
     /// test` to ensure that we don't regress the test suites there.
     fn run(self, builder: &Builder<'_>) {
         let compiler = builder.compiler(self.stage, self.host);
-        builder.ensure(compile::Rustc::new(compiler, compiler.host));
         let cargo = builder.ensure(tool::Cargo { compiler, target: compiler.host });
 
         // Note that this is a short, cryptic, and not scoped directory name. This
@@ -369,7 +368,7 @@ impl Step for RustAnalyzer {
 
         // We don't need to build the whole Rust Analyzer for the proc-macro-srv test suite,
         // but we do need the standard library to be present.
-        builder.ensure(compile::Rustc::new(compiler, host));
+        let _ = builder.compiler(compiler.stage, host);
 
         let workspace_path = "src/tools/rust-analyzer";
         // until the whole RA test suite runs on `i686`, we only run
@@ -1662,7 +1661,7 @@ NOTE: if you're sure you want to do this, please open an issue as to why. In the
         };
 
         if suite.ends_with("fulldeps") {
-            builder.ensure(compile::Rustc::new(compiler, target));
+            let _ = builder.compiler(compiler.stage, target);
         }
 
         if suite == "debuginfo" {
@@ -2813,7 +2812,7 @@ impl Step for CrateRustdoc {
         // the target rustdoc (`ci-rustc-sysroot` vs `stage2`). In that case, we need to ensure this
         // explicitly to make sure it ends up in the stage2 sysroot.
         builder.ensure(compile::Std::new(compiler, target));
-        builder.ensure(compile::Rustc::new(compiler, target));
+        let _ = builder.compiler(compiler.stage, target);
 
         let mut cargo = tool::prepare_tool_cargo(
             builder,
@@ -2904,7 +2903,7 @@ impl Step for CrateRustdocJsonTypes {
         // `compiler`, then it would cause rustdoc to be built *again*, which
         // isn't really necessary.
         let compiler = builder.compiler_for(builder.top_stage, target, target);
-        builder.ensure(compile::Rustc::new(compiler, target));
+        let _ = builder.compiler(compiler.stage, target);
 
         let cargo = tool::prepare_tool_cargo(
             builder,