fix(cloudfront): EdgeFunction fails with newStyleStackSynthesis

The EdgeFunction construct copied some patterns from CodePipelines to enable
cross-environment interaction. One key difference is that for Lambda@Edge,
CDK assets are created in the cross-environment support stack. This isn't
supported by the BootstraplessSynthesizer, so this custom logic (copied from
CodePipelines) needs to be removed.

The EdgeFunction support stack will now use whatever synthesizer is default for
the current stack.

fixes #12172

packages/@aws-cdk/aws-cloudfront/lib/experimental/edge-function.ts

@@ -6,9 +6,9 @@ import * as iam from '@aws-cdk/aws-iam';
 import * as lambda from '@aws-cdk/aws-lambda';
 import * as ssm from '@aws-cdk/aws-ssm';
 import {
-  BootstraplessSynthesizer, CfnResource, ConstructNode,
+  CfnResource, ConstructNode,
   CustomResource, CustomResourceProvider, CustomResourceProviderRuntime,
-  DefaultStackSynthesizer, IStackSynthesizer, Resource, Stack, Stage, Token,
+  Resource, Stack, Stage, Token,
 } from '@aws-cdk/core';
 import { Construct } from 'constructs';
 
@@ -214,7 +214,6 @@ export class EdgeFunction extends Resource implements lambda.IVersion {
     let edgeStack = stage.node.tryFindChild(edgeStackId) as Stack;
     if (!edgeStack) {
       edgeStack = new Stack(stage, edgeStackId, {
-        synthesizer: crossRegionSupportSynthesizer(this.stack),
         env: { region: EdgeFunction.EDGE_REGION },
       });
     }
@@ -230,21 +229,6 @@ interface FunctionConfig {
   readonly functionStack: Stack;
 }
 
-// Stolen (and modified) from `@aws-cdk/aws-codepipeline`'s `Pipeline`.
-function crossRegionSupportSynthesizer(stack: Stack): IStackSynthesizer | undefined {
-  // If we have the new synthesizer we need a bootstrapless copy of it,
-  // because we don't want to require bootstrapping the environment
-  // of the account in this replication region.
-  // Otherwise, return undefined to use the default.
-  const scopeStackSynthesizer = stack.synthesizer;
-  return (scopeStackSynthesizer instanceof DefaultStackSynthesizer)
-    ? new BootstraplessSynthesizer({
-      deployRoleArn: scopeStackSynthesizer.deployRoleArn,
-      cloudFormationExecutionRoleArn: scopeStackSynthesizer.cloudFormationExecutionRoleArn,
-    })
-    : undefined;
-}
-
 function addEdgeLambdaToRoleTrustStatement(role: iam.IRole) {
   if (role instanceof iam.Role && role.assumeRolePolicy) {
     const statement = new iam.PolicyStatement();

packages/@aws-cdk/aws-cloudfront/test/experimental/edge-function.test.ts

@@ -1,3 +1,4 @@
+import * as path from 'path';
 import '@aws-cdk/assert/jest';
 import * as cloudwatch from '@aws-cdk/aws-cloudwatch';
 import * as iam from '@aws-cdk/aws-iam';
@@ -227,6 +228,23 @@ test('metric methods', () => {
   }
 });
 
+test('cross-region stack supports new-style synthesis with assets', () => {
+  app = new cdk.App({
+    context: { '@aws-cdk/core:newStyleStackSynthesis': true },
+  });
+  stack = new cdk.Stack(app, 'Stack', {
+    env: { account: '111111111111', region: 'testregion' },
+  });
+
+  new cloudfront.experimental.EdgeFunction(stack, 'MyFn', {
+    code: lambda.Code.fromAsset(path.join(__dirname, 'my-lambda-handler')),
+    handler: 'index.handler',
+    runtime: lambda.Runtime.PYTHON_3_8,
+  });
+
+  expect(() => app.synth()).not.toThrow();
+});
+
 function defaultEdgeFunctionProps(stackId?: string) {
   return {
     code: lambda.Code.fromInline('foo'),

packages/@aws-cdk/aws-cloudfront/test/experimental/my-lambda-handler/index.py

@@ -0,0 +1,4 @@
+def main(event, context):
+    return {
+        'message': 'Hello, world!'
+    }