bootstrap: copy self-contained linking components to stage0-sysroot

otherwise bootstrap will fail to link the stdlib on a target using the
self-contained linker: rust-lld will not be found since it's currently
not in the stage0-sysroot.

src/bootstrap/compile.rs

@@ -158,6 +158,25 @@ impl Step for Std {
  target_deps.extend(copy_third_party_objects(builder, &compiler, target));
  target_deps.extend(copy_self_contained_objects(builder, &compiler, target));
 
+ // The LLD wrappers and `rust-lld` are self-contained linking components that can be
+ // necessary to link the stdlib on some targets. We'll also need to copy these binaries to
+ // the `stage0-sysroot` to ensure the linker is found when bootstrapping on such a target.
+ if compiler.stage == 0
+ && compiler.host == builder.config.build
+ && builder.config.lld_enabled
+ {
+ // We want to copy the `bin` folder next to the sysroot libdir.
+ let src_sysroot_bin = builder
+ .rustc_snapshot_libdir()
+ .join("rustlib")
+ .join(&compiler.host.triple)
+ .join("bin");
+ let target_sysroot_bin =
+ builder.sysroot_libdir(compiler, target).parent().unwrap().join("bin");
+ t!(fs::create_dir_all(&target_sysroot_bin));
+ builder.cp_r(&src_sysroot_bin, &target_sysroot_bin);
+ }
+
  let mut cargo = builder.cargo(compiler, Mode::Std, SourceType::InTree, target, "build");
  std_cargo(builder, target, compiler.stage, &mut cargo);
  for krate in &*self.crates {