GH-121634: have `wasi.py` accept the host target triple as an argument (GH-123030)

Misc/NEWS.d/next/Build/2024-08-14-19-17-34.gh-issue-121634.eOMfHG.rst

@@ -0,0 +1 @@
+Allow for specifying the target compile triple for WASI.

Tools/wasm/wasi.py

@@ -20,8 +20,6 @@
 
 CROSS_BUILD_DIR = CHECKOUT / "cross-build"
 BUILD_DIR = CROSS_BUILD_DIR / "build"
-HOST_TRIPLE = "wasm32-wasi"
-HOST_DIR = CROSS_BUILD_DIR / HOST_TRIPLE
 
 LOCAL_SETUP = CHECKOUT / "Modules" / "Setup.local"
 LOCAL_SETUP_MARKER = "# Generated by Tools/wasm/wasi.py\n".encode("utf-8")
@@ -63,12 +61,17 @@ def subdir(working_dir, *, clean_ok=False):
     def decorator(func):
         @functools.wraps(func)
         def wrapper(context):
+            nonlocal working_dir
+
+            if callable(working_dir):
+                working_dir = working_dir(context)
             try:
                 tput_output = subprocess.check_output(["tput", "cols"],
                                                       encoding="utf-8")
-                terminal_width = int(tput_output.strip())
             except subprocess.CalledProcessError:
                 terminal_width = 80
+            else:
+                terminal_width = int(tput_output.strip())
             print("⎯" * terminal_width)
             print("📁", working_dir)
             if (clean_ok and getattr(context, "clean", False) and
@@ -193,7 +196,7 @@ def wasi_sdk_env(context):
     return env
 
 
-@subdir(HOST_DIR, clean_ok=True)
+@subdir(lambda context: CROSS_BUILD_DIR / context.host_triple, clean_ok=True)
 def configure_wasi_python(context, working_dir):
     """Configure the WASI/host build."""
     if not context.wasi_sdk_path or not context.wasi_sdk_path.exists():
@@ -238,7 +241,7 @@ def configure_wasi_python(context, working_dir):
     # to find the stdlib due to Python not recognizing that it's being
     # executed from within a checkout.
     configure = [os.path.relpath(CHECKOUT / 'configure', working_dir),
-                    f"--host={HOST_TRIPLE}",
+                    f"--host={context.host_triple}",
                     f"--build={build_platform()}",
                     f"--with-build-python={build_python}"]
     if pydebug:
@@ -258,7 +261,7 @@ def configure_wasi_python(context, working_dir):
     sys.stdout.flush()
 
 
-@subdir(HOST_DIR)
+@subdir(lambda context: CROSS_BUILD_DIR / context.host_triple)
 def make_wasi_python(context, working_dir):
     """Run `make` for the WASI/host build."""
     call(["make", "--jobs", str(cpu_count()), "all"],
@@ -342,6 +345,9 @@ def main():
                         help="Command template for running the WASI host "
                              "(default designed for wasmtime 14 or newer: "
                                 f"`{default_host_runner}`)")
+    for subcommand in build, configure_host, make_host:
+        subcommand.add_argument("--host-triple", action="store", default="wasm32-wasi",
+                        help="The target triple for the WASI host build")
 
     context = parser.parse_args()