From 5708e99ecaba8907642e371efb2d431a982b7242 Mon Sep 17 00:00:00 2001
From: Tim Neutkens <tim@timneutkens.nl>
Date: Tue, 11 Dec 2018 21:46:23 +0100
Subject: [PATCH] Run compilers sequentially when in lambdas mode (#5862)

---
 packages/next/build/compiler.ts |  2 +-
 packages/next/build/index.ts    | 13 +++++++++++--
 2 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/packages/next/build/compiler.ts b/packages/next/build/compiler.ts
index 9b7fd0f1..52fad6a9 100644
--- a/packages/next/build/compiler.ts
+++ b/packages/next/build/compiler.ts
@@ -1,6 +1,6 @@
 import webpack from 'webpack'
 
-type CompilerResult = {
+export type CompilerResult = {
   errors: Error[],
   warnings: Error[]
 }
diff --git a/packages/next/build/index.ts b/packages/next/build/index.ts
index 147c0ba8..721c1666 100644
--- a/packages/next/build/index.ts
+++ b/packages/next/build/index.ts
@@ -6,7 +6,7 @@ import getBaseWebpackConfig from './webpack-config'
 import {generateBuildId} from './generate-build-id'
 import {writeBuildId} from './write-build-id'
 import {isWriteable} from './is-writeable'
-import {runCompiler} from './compiler'
+import {runCompiler, CompilerResult} from './compiler'
 
 export default async function build (dir: string, conf = null, lambdas: boolean = false): Promise<void> {
   if (!await isWriteable(dir)) {
@@ -17,12 +17,21 @@ export default async function build (dir: string, conf = null, lambdas: boolean
   const lambdasOption = config.lambdas ? config.lambdas : lambdas
   const distDir = join(dir, config.distDir)
   const buildId = await generateBuildId(config.generateBuildId, nanoid)
+
   const configs: any = await Promise.all([
     getBaseWebpackConfig(dir, { buildId, isServer: false, config, lambdas: lambdasOption }),
     getBaseWebpackConfig(dir, { buildId, isServer: true, config, lambdas: lambdasOption })
   ])
 
-  const result = await runCompiler(configs)
+  let result: CompilerResult = {warnings: [], errors: []}
+  if (lambdasOption) {
+    const clientResult = await runCompiler([configs[0]])
+    const serverResult = await runCompiler([configs[1]])
+    result = {warnings: [...clientResult.warnings, ...serverResult.warnings], errors: [...clientResult.errors, ...serverResult.errors]}
+  } else {
+    result = await runCompiler(configs)
+  }
+
   if (result.warnings.length > 0) {
     console.warn('> Emitted warnings from webpack')
     console.warn(...result.warnings)