Promote the `wasm32-wasip2` target to Tier 2

This commit promotes the `wasm32-wasip2` Rust target to tier 2 as
proposed in rust-lang/compiler-team#760. There are two major changes in
this PR:

1. The `dist-various-2` container, which already produces the other WASI
   targets, now has an extra target added for `wasm32-wasip2`.
2. A new `wasm-component-ld` binary is added to all host toolchains when
   LLD is enabled. This is the linker used for the `wasm32-wasip2` target.

This new linker is added for all host toolchains to ensure that all host
toolchains can produce the `wasm32-wasip2` target. This is similar to
how `rust-lld` was originally included for all host toolchains to be
able to produce WebAssembly output when the targets were first added.
The new linker is developed [here][wasm-component-ld] and is pulled in
via a crates.io-based dependency to the tree here.

[wasm-component-ld]: https://github.com/bytecodealliance/wasm-component-ld

2 files changed, 43 insertions, 0 deletions

diff --git a/src/bootstrap/src/core/build_steps/compile.rs b/src/bootstrap/src/core/build_steps/compile.rs
index 11a7a404535..175ef52b33f 100644
--- a/src/bootstrap/src/core/build_steps/compile.rs
+++ b/src/bootstrap/src/core/build_steps/compile.rs
@@ -1829,6 +1829,21 @@ impl Step for Assemble {
                     &self_contained_lld_dir.join(exe(name, target_compiler.host)),
                 );
             }
+
+            // In addition to `rust-lld` also install `wasm-component-ld` when
+            // LLD is enabled. This is a relatively small binary that primarily
+            // delegates to the `rust-lld` binary for linking and then runs
+            // logic to create the final binary. This is used by the
+            // `wasm32-wasip2` target of Rust.
+            let wasm_component_ld_exe =
+                builder.ensure(crate::core::build_steps::tool::WasmComponentLd {
+                    compiler: build_compiler,
+                    target: target_compiler.host,
+                });
+            builder.copy_link(
+                &wasm_component_ld_exe,
+                &libdir_bin.join(wasm_component_ld_exe.file_name().unwrap()),
+            );
         }
 
         if builder.config.llvm_enabled(target_compiler.host) {
diff --git a/src/bootstrap/src/core/build_steps/tool.rs b/src/bootstrap/src/core/build_steps/tool.rs
index ad92a01bce7..e19a05371a7 100644
--- a/src/bootstrap/src/core/build_steps/tool.rs
+++ b/src/bootstrap/src/core/build_steps/tool.rs
@@ -702,6 +702,34 @@ impl Step for LldWrapper {
 }
 
 #[derive(Debug, Clone, Hash, PartialEq, Eq)]
+pub struct WasmComponentLd {
+    pub compiler: Compiler,
+    pub target: TargetSelection,
+}
+
+impl Step for WasmComponentLd {
+    type Output = PathBuf;
+
+    fn should_run(run: ShouldRun<'_>) -> ShouldRun<'_> {
+        run.never()
+    }
+
+    fn run(self, builder: &Builder<'_>) -> PathBuf {
+        builder.ensure(ToolBuild {
+            compiler: self.compiler,
+            target: self.target,
+            tool: "wasm-component-ld",
+            mode: Mode::ToolStd,
+            path: "src/tools/wasm-component-ld",
+            source_type: SourceType::InTree,
+            extra_features: Vec::new(),
+            allow_features: "",
+            cargo_args: Vec::new(),
+        })
+    }
+}
+
+#[derive(Debug, Clone, Hash, PartialEq, Eq)]
 pub struct RustAnalyzer {
     pub compiler: Compiler,
     pub target: TargetSelection,