build: add gn-check to precommit linting (#19850)

package.json

@@ -79,6 +79,7 @@
     "create-typescript-definitions": "npm run create-api-json && electron-typescript-definitions --api=electron-api.json && node spec/ts-smoke/runner.js",
     "gn-typescript-definitions": "npm run create-typescript-definitions && shx cp electron.d.ts",
     "pre-flight": "pre-flight",
+    "gn-check": "node ./script/gn-check.js",
     "preinstall": "node -e 'process.exit(0)'",
     "prepack": "check-for-leaks",
     "repl": "node ./script/start.js --interactive",
@@ -115,6 +116,7 @@
       "remark -qf"
     ],
     "*.{gn,gni}": [
+      "npm run gn-check",
       "python script/run-gn-format.py",
       "git add"
     ],

script/gn-check.js

@@ -0,0 +1,34 @@
+const cp = require('child_process')
+const path = require('path')
+
+const { getOutDir } = require('./lib/utils')
+
+const SOURCE_ROOT = path.normalize(path.dirname(__dirname))
+const DEPOT_TOOLS = path.resolve(SOURCE_ROOT, '..', 'third_party', 'depot_tools')
+const OUT_DIR = getOutDir()
+
+if (!OUT_DIR) {
+  throw new Error(`No viable out dir: one of Debug, Testing, or Release must exist.`)
+}
+
+const env = Object.assign({
+  CHROMIUM_BUILDTOOLS_PATH: path.resolve(SOURCE_ROOT, '..', 'buildtools'),
+  DEPOT_TOOLS_WIN_TOOLCHAIN: '0'
+}, process.env)
+// Users may not have depot_tools in PATH.
+env.PATH = `${env.PATH}${path.delimiter}${DEPOT_TOOLS}`
+
+const gnCheckDirs = [
+  '//electron:electron_lib',
+  '//electron:electron_app',
+  '//electron:manifests',
+  '//electron/shell/common/api:mojo'
+]
+
+for (const dir of gnCheckDirs) {
+  const args = ['check', `../out/${OUT_DIR}`, dir]
+  const result = cp.spawnSync('gn', args, { env, stdio: 'inherit' })
+  if (result.status !== 0) process.exit(result.status)
+}
+
+process.exit(0)