fix(arborist): don't checkEngine/checkPlatform for extraneous deps

workspaces/arborist/lib/arborist/build-ideal-tree.js

@@ -194,7 +194,7 @@ module.exports = cls => class IdealTreeBuilder extends cls {
   async #checkEngineAndPlatform () {
     const { engineStrict, npmVersion, nodeVersion } = this.options
     for (const node of this.idealTree.inventory.values()) {
-      if (!node.optional) {
+      if (!node.optional && !node.extraneous) {
         try {
           // if devEngines is present in the root node we ignore the engines check
           if (!(node.isRoot && node.package.devEngines)) {

workspaces/arborist/test/arborist/build-ideal-tree.js

@@ -4091,3 +4091,67 @@ t.test('should take devEngines in account', async t => {
   const tree = await buildIdeal(path)
   t.matchSnapshot(String(tree.meta))
 })
+
+t.test(
+  'extraneous dependency not buildable on current platform does not throw',
+  async (t) => {
+    const isLinux = process.platform === 'linux'
+    const incompatibleOS = isLinux ? 'darwin' : 'linux'
+
+    const path = t.testdir({
+      'package.json': JSON.stringify({
+        name: 'extraneous-test',
+        version: '1.0.0',
+        dependencies: {
+          'dependency-with-shrinkwrap': '1.0.0',
+        },
+      }),
+      'package-lock.json': JSON.stringify({
+        name: 'extraneous-test',
+        version: '1.0.0',
+        lockfileVersion: 3,
+        requires: true,
+        packages: {
+          '': {
+            name: 'extraneous-test',
+            version: '1.0.0',
+            dependencies: {
+              'dependency-with-shrinkwrap': '^1.0.0',
+            },
+          },
+          'node_modules/dependency-with-shrinkwrap': {
+            version: '1.0.0',
+            hasShrinkwrap: true,
+            dependencies: {},
+          },
+          'node_modules/dependency-with-shrinkwrap/node_modules/dev-dependency':
+            {
+              version: '1.0.0',
+              extraneous: true,
+              optionalDependencies: {
+                'optional-dependancy': '1.0.0',
+              },
+            },
+          'node_modules/dependency-with-shrinkwrap/node_modules/optional-dependancy':
+            {
+              version: '1.0.0',
+              cpu: ['x64'],
+              extraneous: true,
+              os: [incompatibleOS],
+            },
+        },
+      }),
+    })
+
+    createRegistry(t, false)
+    const arb = newArb(path)
+
+    try {
+      await arb.buildIdealTree({ prune: false })
+    } catch (e) {
+      t.fail(
+        'should not throw for extraneous dependency not buildable on this platform'
+      )
+    }
+  }
+)