fix(ssm): correctly deduplicate parameter names

packages/@aws-cdk/aws-ssm/lib/parameter.ts

@@ -1,7 +1,7 @@
 import iam = require('@aws-cdk/aws-iam');
 import {
   CfnDynamicReference, CfnDynamicReferenceService, CfnParameter,
-  Construct, ContextProvider, Fn, IConstruct, IResource, Resource, Stack, Token, ConstructNode
+  Construct, ContextProvider, Fn, IConstruct, IResource, Resource, Stack, Token
 } from '@aws-cdk/core';
 import cxapi = require('@aws-cdk/cx-api');
 import ssm = require('./ssm.generated');
@@ -372,7 +372,7 @@ function _assertValidValue(value: string, allowedPattern: string): void {
 }
 
 function makeIdentityForImportedValue(parameterName: string) {
-  return ConstructNode.sanitizeId(`SsmParameterValue:${parameterName}:C96584B6-F00A-464E-AD19-53AFF4B05118`);
+  return `SsmParameterValue:${parameterName}:C96584B6-F00A-464E-AD19-53AFF4B05118`;
 }
 
 function arnForParameterName(scope: IConstruct, parameterName: string): string {

packages/@aws-cdk/core/lib/construct.ts

@@ -27,14 +27,6 @@ export class ConstructNode {
    */
   public static readonly PATH_SEP = '/';
 
-  /**
-   * Return a sanitized version of an arbitrary string, so it can be used as an ID
-   */
-  public static sanitizeId(id: string) {
-    // Cannot have PATH_SEPs in the ID
-    return id.replace(/\//g, '-');
-  }
-
   /**
    * Synthesizes a CloudAssembly from a construct tree.
    * @param root The root of the construct tree.
@@ -137,7 +129,7 @@ export class ConstructNode {
   constructor(private readonly host: Construct, scope: IConstruct, id: string) {
     id = id || ''; // if undefined, convert to empty string
 
-    this.id = id;
+    this.id = sanitizeId(id);
     this.scope = scope;
 
     // We say that scope is required, but root scopes will bypass the type
@@ -147,20 +139,13 @@ export class ConstructNode {
         throw new Error('Only root constructs may have an empty name');
       }
 
-      if (ConstructNode.sanitizeId(id) !== id) {
-        throw new Error('Invalid characters in id, use ConstructNode.sanitizeId(): ' + id);
-      }
-
       // Has side effect so must be very last thing in constructor
       scope.node.addChild(host, this.id);
     } else {
       // This is a root construct.
       this.id = id;
     }
 
-    // escape any path separators so they don't wreck havoc
-    this.id = this._escapePathSeparator(this.id);
-
     if (Token.isUnresolved(id)) {
       throw new Error(`Cannot use tokens in construct ID: ${id}`);
     }
@@ -186,25 +171,13 @@ export class ConstructNode {
   }
 
   /**
-   * Return a descendant by path, or undefined
-   *
-   * Note that if the original ID of the construct you are looking for contained
-   * a '/', then it would have been replaced by '--'.
+   * Return a direct child by id, or undefined
    *
-   * @param path Relative path of a direct or indirect child
-   * @returns a child by path or undefined if not found.
+   * @param id Identifier of direct child
+   * @returns the child if found, or undefined
    */
-  public tryFindChild(path: string): IConstruct | undefined {
-    if (path.startsWith(ConstructNode.PATH_SEP)) {
-      throw new Error('Path must be relative');
-    }
-    const parts = path.split(ConstructNode.PATH_SEP);
-
-    let curr: IConstruct | undefined = this.host;
-    while (curr != null && parts.length > 0) {
-      curr = curr.node._children[parts.shift()!];
-    }
-    return curr;
+  public tryFindChild(id: string): IConstruct | undefined {
+    return this._children[sanitizeId(id)];
   }
 
   /**
@@ -539,14 +512,6 @@ export class ConstructNode {
       this.invokedAspects.push(aspect);
     }
   }
-
-  /**
-   * If the construct ID contains a path separator, it is replaced by double dash (`--`).
-   */
-  private _escapePathSeparator(id: string) {
-    if (!id) { return id; }
-    return id.split(ConstructNode.PATH_SEP).join('--');
-  }
 }
 
 /**
@@ -727,3 +692,11 @@ function ignore(_x: any) {
 // Import this _after_ everything else to help node work the classes out in the correct order...
 
 import { Reference } from './reference';
+
+/**
+ * Return a sanitized version of an arbitrary string, so it can be used as an ID
+ */
+function sanitizeId(id: string) {
+  // Escape path seps as double dashes
+  return id.replace(/\//g, '--');
+}

packages/@aws-cdk/core/test/test.construct.ts

@@ -20,12 +20,6 @@ export = {
     test.done();
   },
 
-  'constructs names cannot have a slash in them'(test: Test) {
-    const root = new Root();
-    test.throws(() => new Construct(root, 'hello/bye'));
-    test.done();
-  },
-
   'construct.name returns the name of the construct'(test: Test) {
     const t = createTree();