Add a WebAssembly toolchain to tests/WORKSPACE

Author: jmillikin

tests/WORKSPACE

@@ -156,6 +156,38 @@ llvm_toolchain(
     urls = {"": ["https://github.com/llvm/llvm-project/releases/download/llvmorg-17.0.6/clang+llvm-17.0.6-x86_64-linux-gnu-ubuntu-22.04.tar.xz"]},
 )
 
+# Toolchain example for WebAssembly.
+llvm_toolchain(
+    name = "llvm_toolchain_wasm",
+    # WebAssembly tests use a separate (newer) version of LLVM to exercise
+    # support for experimental features such as wasm64.
+    llvm_versions = {
+        # The most recent LLVM as of 2024-10-17
+        "": "19.1.0",
+    },
+    sysroot = {
+        "wasm32": "@wasi_sdk_sysroots//wasm32-wasip2",
+        "wasm64": "@wasi_sdk_sysroots//empty",
+    },
+    stdlib = {
+        "wasm32": "libc",
+        "wasm64": "none",
+    },
+    libclang_rt = {
+        "@libclang_rt_wasm32//:libclang_rt.builtins-wasm32.a": "wasm32-unknown-unknown/libclang_rt.builtins.a",
+    },
+)
+
+load(
+    "@llvm_toolchain_wasm//:toolchains.bzl",
+    llvm_register_toolchains_wasm = "llvm_register_toolchains",
+)
+llvm_register_toolchains_wasm()
+
+load("//wasm:wasi_sdk.bzl", "libclang_rt_wasm32", "wasi_sdk_sysroots")
+libclang_rt_wasm32(name = "libclang_rt_wasm32")
+wasi_sdk_sysroots(name = "wasi_sdk_sysroots")
+
 ## Test dependencies.
 
 # Well known repos; present here only for testing.