use target compiler for LlvmBitcodeLinker

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

Author: onur-ozkan

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

@@ -1792,7 +1792,7 @@ impl Step for Assemble {
             }
         }
 
-        let maybe_install_llvm_bitcode_linker = |compiler| {
+        let maybe_install_llvm_bitcode_linker = |compiler: Compiler| {
             if builder.config.llvm_bitcode_linker_enabled {
                 let src_path = builder.ensure(crate::core::build_steps::tool::LlvmBitcodeLinker {
                     compiler,
@@ -1974,7 +1974,7 @@ impl Step for Assemble {
             );
         }
 
-        maybe_install_llvm_bitcode_linker(build_compiler);
+        maybe_install_llvm_bitcode_linker(target_compiler);
 
         // Ensure that `libLLVM.so` ends up in the newly build compiler directory,
         // so that it can be found when the newly built `rustc` is run.

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

@@ -73,10 +73,7 @@ impl Step for ToolBuild {
     fn run(mut self, builder: &Builder<'_>) -> PathBuf {
         match self.mode {
             Mode::ToolRustc => {
-                assert!(
-                    self.compiler.stage > 0,
-                    "stage0 isn't supported for `Mode::ToolRustc` programs"
-                );
+                assert!(self.compiler.stage > 0, "stage0 isn't supported for {}", self.path);
                 // Similar to `compile::Assemble`, build with the previous stage's compiler. Otherwise
                 // we'd have stageN/bin/rustc and stageN/bin/$tool_name be effectively different stage
                 // compilers, which isn't what we want.