fix: override host-specific variables when reading headers config.gypi

lib/create-config-gypi.js

@@ -15,6 +15,40 @@ function parseConfigGypi (config) {
   return JSON.parse(config)
 }
 
+// Variables that describe the build host (the machine running node-gyp), not
+// the target Node binary. The official Node release headers tarball is a
+// single universal artifact whose embedded config.gypi reflects the build
+// farm host (currently Linux x64 / GCC), so when a consumer on a different
+// platform inherits it verbatim via --disturl/--nodedir, these fields end up
+// wrong. The most visible symptom on macOS arm64 is `clang=0` silently
+// dropping the `clang==1` branches in common.gypi (e.g. `-std=gnu++20`),
+// breaking node-addon-api compilation. See PR #2497 for the original code
+// path and electron/rebuild#1209 for the first user report.
+const HOST_SPECIFIC_VARIABLES = [
+  'host_arch',
+  'clang',
+  'llvm_version',
+  'xcode_version',
+  'arm_fpu',
+  'gas_version',
+  'shlib_suffix'
+]
+
+function overrideHostSpecificVariables (config) {
+  if (!config || !config.variables || !process.config || !process.config.variables) {
+    return config
+  }
+  for (const key of HOST_SPECIFIC_VARIABLES) {
+    const value = process.config.variables[key]
+    if (value !== undefined) {
+      config.variables[key] = value
+    } else {
+      delete config.variables[key]
+    }
+  }
+  return config
+}
+
 async function getBaseConfigGypi ({ gyp, nodeDir }) {
   // try reading $nodeDir/include/node/config.gypi first when:
   // 1. --dist-url or --nodedir is specified
@@ -25,7 +59,7 @@ async function getBaseConfigGypi ({ gyp, nodeDir }) {
     try {
       const baseConfigGypiPath = path.resolve(nodeDir, 'include/node/config.gypi')
       const baseConfigGypi = await fs.readFile(baseConfigGypiPath)
-      return parseConfigGypi(baseConfigGypi.toString())
+      return overrideHostSpecificVariables(parseConfigGypi(baseConfigGypi.toString()))
     } catch (err) {
       log.warn('read config.gypi', err.message)
     }

test/fixtures/nodedir-mismatched-host/include/node/config.gypi

@@ -0,0 +1,14 @@
+# Test fixture: mimics the official Node release headers tarball, whose
+# embedded config.gypi is produced on a Linux x64 / GCC build farm and ships
+# unchanged to all platforms. The host-specific fields here MUST be
+# overridden by process.config when running on a different host.
+{
+  'variables': {
+    'host_arch': 'x64',
+    'clang': 0,
+    'llvm_version': '0.0',
+    'gas_version': '2.38',
+    'shlib_suffix': 'so.137',
+    'build_with_electron': true
+  }
+}

test/test-create-config-gypi.js

@@ -52,6 +52,52 @@ describe('create-config-gypi', function () {
     assert.strictEqual(config.variables.build_with_electron, undefined)
   })
 
+  it('config.gypi overrides host-specific vars from process.config when nodedir is set', async function () {
+    // The fixture mimics a Linux x64 / GCC build farm headers tarball. When
+    // running on a different host (e.g. macOS arm64 / clang), the host-specific
+    // fields must come from process.config, not from the headers tarball,
+    // otherwise binding.gyp / common.gypi `if (clang==1)` branches break
+    // (e.g. -std=gnu++20 is silently dropped, breaking node-addon-api).
+    const nodeDir = path.join(__dirname, 'fixtures', 'nodedir-mismatched-host')
+
+    const prog = gyp()
+    prog.parseArgv(['_', '_', `--nodedir=${nodeDir}`])
+
+    const config = await getCurrentConfigGypi({ gyp: prog, nodeDir, vsInfo: {} })
+
+    // target build config from headers is still preserved (PR #2497 intent).
+    assert.strictEqual(config.variables.build_with_electron, true)
+
+    // host-specific fields come from process.config.
+    assert.strictEqual(config.variables.host_arch, process.config.variables.host_arch)
+    assert.strictEqual(config.variables.clang, process.config.variables.clang)
+    assert.strictEqual(config.variables.llvm_version, process.config.variables.llvm_version)
+
+    // fields that are present in headers but absent in process.config must be
+    // deleted (e.g. gas_version is Linux-only and meaningless on macOS).
+    if (process.config.variables.gas_version === undefined) {
+      assert.strictEqual('gas_version' in config.variables, false)
+    }
+    if (process.config.variables.xcode_version === undefined) {
+      assert.strictEqual('xcode_version' in config.variables, false)
+    }
+  })
+
+  it('config.gypi with --force-process-config bypasses host override too (back-compat)', async function () {
+    const nodeDir = path.join(__dirname, 'fixtures', 'nodedir-mismatched-host')
+
+    const prog = gyp()
+    prog.parseArgv(['_', '_', '--force-process-config', `--nodedir=${nodeDir}`])
+
+    const config = await getCurrentConfigGypi({ gyp: prog, nodeDir, vsInfo: {} })
+
+    // --force-process-config still skips reading the headers entirely.
+    assert.strictEqual(config.variables.build_with_electron, undefined)
+    // And of course the host fields are from process.config (always were).
+    assert.strictEqual(config.variables.host_arch, process.config.variables.host_arch)
+    assert.strictEqual(config.variables.clang, process.config.variables.clang)
+  })
+
   it('config.gypi parsing', function () {
     const str = "# Some comments\n{'variables': {'multiline': 'A'\n'B'}}"
     const config = parseConfigGypi(str)