build: add rust target for macOS cross compiles

When we build the macOS pkg, we build Node.js twice (on arm64):
- Once for arm64 (native)
- Once for x64, using a combination of Rosetta 2 and compiler flags

before combining both into a universal binary.

For the x64 case, pass target flag to `rustc` so that the binary is
built for the correct target architecture.

Signed-off-by: Richard Lau <richard.lau@ibm.com>

Author: richardlau

configure.py

@@ -1725,6 +1725,23 @@ def host_arch_cc():
   return rtn
 
 
+def is_rosetta2():
+  if flavor != 'mac':
+    return False
+  try:
+    proc = subprocess.Popen(['sysctl', '-n', 'sysctl.proc_translated'],
+                            stdin=subprocess.PIPE, stderr=subprocess.PIPE,
+                            stdout=subprocess.PIPE)
+  except OSError:
+    warn('sysctl failed')
+    return False
+  with proc:
+    out = to_utf8(proc.communicate()[0]).strip()
+    warn(f'proc_translated: {out}')
+    # return out == '1'
+    return True
+
+
 def host_arch_win():
   """Host architecture check using environ vars (better way to do this?)"""
 
@@ -1855,6 +1872,8 @@ def configure_node(o):
   if flavor == 'win':
     o['variables']['cargo_rust_target'] = \
       'aarch64-pc-windows-msvc' if target_arch == 'arm64' else 'x86_64-pc-windows-msvc'
+  if target_arch == 'x64' and is_rosetta2():
+    o['variables']['cargo_rust_target'] = 'x86_64-apple-darwin'
 
   # Allow overriding the compiler - needed by embedders.
   if options.use_clang:

deps/crates/crates.gyp

@@ -11,12 +11,17 @@
       },
       'conditions': [
         ['cargo_rust_target!=""', {
+          'variables': {
+            'cargo_build_flags': ['--target', '<(cargo_rust_target)'],
+          }
+        }],
+        ['OS=="win"', {
           'variables': {
             'node_crates_libpath': '<(SHARED_INTERMEDIATE_DIR)/$(Platform)/release/node_crates.lib',
           },
         }, {
           'variables': {
-            'node_crates_libpath': '<(SHARED_INTERMEDIATE_DIR)/release/<(STATIC_LIB_PREFIX)node_crates<(STATIC_LIB_SUFFIX)',
+            'node_crates_libpath': '<(SHARED_INTERMEDIATE_DIR)/<(cargo_rust_target)/release/<(STATIC_LIB_PREFIX)node_crates<(STATIC_LIB_SUFFIX)',
           },
         }],
       ],
@@ -26,12 +31,17 @@
       },
       'conditions': [
         ['cargo_rust_target!=""', {
+          'variables': {
+            'cargo_build_flags': ['--target', '$(cargo_rust_target)'],
+          }
+        }],
+        ['OS=="win"', {
           'variables': {
             'node_crates_libpath': '<(SHARED_INTERMEDIATE_DIR)/$(Platform)/debug/node_crates.lib',
           },
         }, {
           'variables': {
-            'node_crates_libpath': '<(SHARED_INTERMEDIATE_DIR)/debug/<(STATIC_LIB_PREFIX)node_crates<(STATIC_LIB_SUFFIX)',
+            'node_crates_libpath': '<(SHARED_INTERMEDIATE_DIR)/<(cargo_rust_target)/debug/<(STATIC_LIB_PREFIX)node_crates<(STATIC_LIB_SUFFIX)',
           },
         }],
       ],
@@ -62,7 +72,7 @@
         ],
       },
       'conditions': [
-        ['cargo_rust_target!=""', {
+        ['OS=="win"', {
           'actions': [
             {
               'action_name': 'cargo_build',