feat(build): Added a version stamp in .metadata.json files.

Also modified StaticReflector to handle multiple versions in a
single .metadata.json file.

Fixes #8974
Closes #8981

modules/@angular/compiler-cli/src/static_reflector.ts

@@ -22,6 +22,8 @@ import {
   InjectMetadata,
 } from "@angular/core";
 import {ReflectorReader} from "./core_private";
+ 
+const SUPPORTED_SCHEMA_VERSION = 1;
 
 /**
  * The host of the static resolver is expected to be able to provide module metadata in the form of
@@ -379,8 +381,14 @@ export class StaticReflector implements ReflectorReader {
     let moduleMetadata = this.metadataCache.get(module);
     if (!moduleMetadata) {
       moduleMetadata = this.host.getMetadataFor(module);
+      if (Array.isArray(moduleMetadata)) {
+        moduleMetadata = (<Array<any>>moduleMetadata).find(element => element.version === SUPPORTED_SCHEMA_VERSION) || moduleMetadata[0];
+      }
       if (!moduleMetadata) {
-        moduleMetadata = {__symbolic: "module", module: module, metadata: {}};
+        moduleMetadata = {__symbolic: "module", version: SUPPORTED_SCHEMA_VERSION, module: module, metadata: {}};
+      }
+      if (moduleMetadata['version'] != SUPPORTED_SCHEMA_VERSION) {
+        throw new Error(`Metadata version mismatch for module ${module}, found version ${moduleMetadata['version']}, expected ${SUPPORTED_SCHEMA_VERSION}`);
       }
       this.metadataCache.set(module, moduleMetadata);
     }

modules/@angular/compiler-cli/test/static_reflector_spec.ts

@@ -64,6 +64,11 @@ describe('StaticReflector', () => {
         .toEqual([[host.findDeclaration('angular2/src/common/directives/ng_for', 'NgFor')]]);
   });
 
+  it('should throw and exception for unsupported metadata versions', () => {
+    let e = host.findDeclaration('src/version-error', 'e');
+    expect(() => reflector.annotations(e)).toThrow(new Error('Metadata version mismatch for module /tmp/src/version-error.d.ts, found version 100, expected 1'));
+  });
+
   it('should get and empty annotation list for an unknown class', () => {
     let UnknownClass = host.findDeclaration('src/app/app.component', 'UnknownClass');
     let annotations = reflector.annotations(UnknownClass);
@@ -300,8 +305,9 @@ class MockReflectorHost implements StaticReflectorHost {
 
   getMetadataFor(moduleId: string): any {
     let data: {[key: string]: any} = {
-      '/tmp/angular2/src/common/forms/directives.d.ts': {
+      '/tmp/angular2/src/common/forms/directives.d.ts': [{
         "__symbolic": "module",
+        "version": 1,
         "metadata": {
           "FORM_DIRECTIVES": [
             {
@@ -311,9 +317,10 @@ class MockReflectorHost implements StaticReflectorHost {
             }
           ]
         }
-      },
+      }],
       '/tmp/angular2/src/common/directives/ng_for.d.ts': {
         "__symbolic": "module",
+        "version": 1,
         "metadata": {
           "NgFor": {
             "__symbolic": "class",
@@ -366,15 +373,16 @@ class MockReflectorHost implements StaticReflectorHost {
         }
       },
       '/tmp/angular2/src/core/linker/view_container_ref.d.ts':
-          {"metadata": {"ViewContainerRef": {"__symbolic": "class"}}},
+          {version: 1, "metadata": {"ViewContainerRef": {"__symbolic": "class"}}},
       '/tmp/angular2/src/core/linker/template_ref.d.ts':
-          {"module": "./template_ref", "metadata": {"TemplateRef": {"__symbolic": "class"}}},
+          {version: 1, "module": "./template_ref", "metadata": {"TemplateRef": {"__symbolic": "class"}}},
       '/tmp/angular2/src/core/change_detection/differs/iterable_differs.d.ts':
-          {"metadata": {"IterableDiffers": {"__symbolic": "class"}}},
+          {version: 1, "metadata": {"IterableDiffers": {"__symbolic": "class"}}},
       '/tmp/angular2/src/core/change_detection/change_detector_ref.d.ts':
-          {"metadata": {"ChangeDetectorRef": {"__symbolic": "class"}}},
+          {version: 1, "metadata": {"ChangeDetectorRef": {"__symbolic": "class"}}},
       '/tmp/src/app/hero-detail.component.d.ts': {
         "__symbolic": "module",
+        "version": 1,
         "metadata": {
           "HeroDetailComponent": {
             "__symbolic": "class",
@@ -422,7 +430,8 @@ class MockReflectorHost implements StaticReflectorHost {
           }
         }
       },
-      '/src/extern.d.ts': {"__symbolic": "module", metadata: {s: "s"}}
+      '/src/extern.d.ts': {"__symbolic": "module", "version": 1, metadata: {s: "s"}},
+      '/tmp/src/version-error.d.ts': {"__symbolic": "module", "version": 100, metadata: {e: "s"}},
     };
     return data[moduleId];
   }

tools/@angular/tsc-wrapped/src/collector.ts

@@ -1,7 +1,7 @@
 import * as ts from 'typescript';
 
 import {Evaluator, ImportMetadata, ImportSpecifierMetadata, isPrimitive} from './evaluator';
-import {ClassMetadata, ConstructorMetadata, ModuleMetadata, MemberMetadata, MetadataError, MetadataMap, MetadataSymbolicExpression, MetadataSymbolicReferenceExpression, MetadataValue, MethodMetadata, isMetadataError, isMetadataSymbolicReferenceExpression,} from './schema';
+import {ClassMetadata, ConstructorMetadata, ModuleMetadata, MemberMetadata, MetadataError, MetadataMap, MetadataSymbolicExpression, MetadataSymbolicReferenceExpression, MetadataValue, MethodMetadata, isMetadataError, isMetadataSymbolicReferenceExpression, VERSION} from './schema';
 import {Symbols} from './symbols';
 
 /**
@@ -207,6 +207,6 @@ export class MetadataCollector {
       }
     });
 
-    return metadata && {__symbolic: 'module', metadata};
+    return metadata && {__symbolic: 'module', version: VERSION, metadata};
   }
 }

tools/@angular/tsc-wrapped/src/schema.ts

@@ -1,5 +1,17 @@
+// Metadata Schema
+
+// If you make a backwards incompatible change to the schema, increment the VERSION number.
+
+// If you make a backwards compatible change to the metadata (such as adding an option field) then
+// leave VERSION the same. If possible, as many versions of the metadata that can represent the
+// semantics of the file in an array. For example, when generating a version 2 file, if version 1
+// can accurately represent the metadata, generate both version 1 and version 2 in an array.
+
+export const VERSION = 1;
+
 export interface ModuleMetadata {
   __symbolic: 'module';
+  version: number;
   metadata: {[name: string]: (ClassMetadata | MetadataValue)};
 }
 export function isModuleMetadata(value: any): value is ModuleMetadata {