fix CI-rustc bugs

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

Author: onur-ozkan

src/bootstrap/src/core/build_steps/clippy.rs

@@ -207,16 +207,18 @@ impl Step for Rustc {
         let compiler = builder.compiler(builder.top_stage, builder.config.build);
         let target = self.target;
 
-        if compiler.stage != 0 {
-            // If we're not in stage 0, then we won't have a std from the beta
-            // compiler around. That means we need to make sure there's one in
-            // the sysroot for the compiler to find. Otherwise, we're going to
-            // fail when building crates that need to generate code (e.g., build
-            // scripts and their dependencies).
-            builder.ensure(compile::Std::new(compiler, compiler.host));
-            builder.ensure(compile::Std::new(compiler, target));
-        } else {
-            builder.ensure(check::Std::new(target).build_kind(Some(Kind::Check)));
+        if !builder.download_rustc() {
+            if compiler.stage != 0 {
+                // If we're not in stage 0, then we won't have a std from the beta
+                // compiler around. That means we need to make sure there's one in
+                // the sysroot for the compiler to find. Otherwise, we're going to
+                // fail when building crates that need to generate code (e.g., build
+                // scripts and their dependencies).
+                builder.ensure(compile::Std::new(compiler, compiler.host));
+                builder.ensure(compile::Std::new(compiler, target));
+            } else {
+                builder.ensure(check::Std::new(target).build_kind(Some(Kind::Check)));
+            }
         }
 
         let mut cargo = builder::Cargo::new(
@@ -286,7 +288,9 @@ macro_rules! lint_any {
                 let compiler = builder.compiler(builder.top_stage, builder.config.build);
                 let target = self.target;
 
-                builder.ensure(check::Rustc::new(target, builder).build_kind(Some(Kind::Check)));
+                if !builder.download_rustc() {
+                    builder.ensure(check::Rustc::new(target, builder).build_kind(Some(Kind::Check)));
+                };
 
                 let cargo = prepare_tool_cargo(
                     builder,

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

@@ -772,6 +772,7 @@ impl Step for StdLink {
             builder.cp_link_r(&stage0_bin_dir, &sysroot_bin_dir);
 
             let stage0_lib_dir = builder.out.join(host).join("stage0/lib");
+            t!(fs::create_dir_all(sysroot.join("lib")));
             builder.cp_link_r(&stage0_lib_dir, &sysroot.join("lib"));
 
             // Copy codegen-backends from stage0
@@ -790,6 +791,12 @@ impl Step for StdLink {
             let sysroot = builder.out.join(compiler.host.triple).join("stage0-sysroot");
             builder.cp_link_r(&builder.initial_sysroot.join("lib"), &sysroot.join("lib"));
         } else {
+            if builder.download_rustc() {
+                // Ensure there are no CI-rustc std artifacts.
+                let _ = fs::remove_dir_all(&libdir);
+                let _ = fs::remove_dir_all(&hostdir);
+            }
+
             add_to_sysroot(
                 builder,
                 &libdir,

src/bootstrap/src/core/build_steps/tool.rs

@@ -330,6 +330,11 @@ pub(crate) fn get_tool_rustc_compiler(
         return target_compiler;
     }
 
+    if builder.download_rustc() && target_compiler.stage == 1 {
+        // We shouldn't drop to stage0 compiler when using CI rustc.
+        return builder.compiler(1, builder.config.build);
+    }
+
     // Similar to `compile::Assemble`, build with the previous stage's compiler. Otherwise
     // we'd have stageN/bin/rustc and stageN/bin/$rustc_tool be effectively different stage
     // compilers, which isn't what we want. Rustc tools should be linked in the same way as the
@@ -809,7 +814,6 @@ impl Step for LldWrapper {
             fields(build_compiler = ?self.build_compiler, target_compiler = ?self.target_compiler),
         ),
     )]
-
     fn run(self, builder: &Builder<'_>) -> ToolBuildResult {
         if builder.config.dry_run() {
             return ToolBuildResult {

src/bootstrap/src/core/builder/mod.rs

@@ -1276,7 +1276,6 @@ impl<'a> Builder<'a> {
             ),
         ),
     )]
-
     /// FIXME: This function is unnecessary (and dangerous, see <https://github.com/rust-lang/rust/issues/137469>).
     /// We already have uplifting logic for the compiler, so remove this.
     pub fn compiler_for(