refactor(compiler-cli): use ngDevMode guard for setClassMetadata …

…call (angular#39987)

Prior to this change, the `setClassMetadata` call would be invoked
inside of an IIFE that was marked as pure. This allows the call to be
tree-shaken away in production builds, as the `setClassMetadata` call
is only present to make the original class metadata available to the
testing infrastructure. The pure marker is problematic, though, as the
`setClassMetadata` call does in fact have the side-effect of assigning
the metadata into class properties. This has worked under the assumption
that only build optimization tools perform tree-shaking, however modern
bundlers are also able to elide calls that have been marked pure so this
assumption does no longer hold. Instead, an `ngDevMode` guard is used
which still allows the call to be elided but only by tooling that is
configured to consider `ngDevMode` as constant `false` value.

PR Close angular#39987

packages/compiler-cli/ngcc/test/integration/ngcc_spec.ts

@@ -181,7 +181,8 @@ runInEachFileSystem(() => {
       const jsContents = fs.readFile(_(`/node_modules/test-package/index.js`)).replace(/\s+/g, ' ');
       expect(jsContents)
           .toContain(
-              '/*@__PURE__*/ (function () { ɵngcc0.ɵsetClassMetadata(FooDirective, ' +
+              '(function () { (typeof ngDevMode === "undefined" || ngDevMode) && ' +
+              'ɵngcc0.ɵsetClassMetadata(FooDirective, ' +
               '[{ type: Directive, args: [{ selector: \'[foo]\' }] }], ' +
               'function () { return []; }, ' +
               '{ bar: [{ type: Input }] }); })();');

packages/compiler-cli/ngcc/test/rendering/renderer_spec.ts

@@ -254,7 +254,7 @@ A.ɵcmp = ɵngcc0.ɵɵdefineComponent({ type: A, selectors: [["a"]], decls: 1, v
 
         const addAdjacentStatementsSpy = testFormatter.addAdjacentStatements as jasmine.Spy;
         expect(addAdjacentStatementsSpy.calls.first().args[2]).toEqual(`// TRANSPILED
-/*@__PURE__*/ (function () { ɵngcc0.ɵsetClassMetadata(A, [{
+(function () { (typeof ngDevMode === "undefined" || ngDevMode) && ɵngcc0.ɵsetClassMetadata(A, [{
         type: Component,
         args: [{ selector: 'a', template: '{{ person!.name }}' }]
     }], null, null); })();`);
@@ -321,7 +321,7 @@ A.ɵdir = ɵngcc0.ɵɵdefineDirective({ type: A, selectors: [["", "a", ""]] });`
                  .toEqual(jasmine.objectContaining(
                      {name: 'A', decorators: [jasmine.objectContaining({name: 'Directive'})]}));
              expect(addAdjacentStatementsSpy.calls.first().args[2]).toEqual(`// TRANSPILED
-/*@__PURE__*/ (function () { ɵngcc0.ɵsetClassMetadata(A, [{
+(function () { (typeof ngDevMode === "undefined" || ngDevMode) && ɵngcc0.ɵsetClassMetadata(A, [{
         type: Directive,
         args: [{ selector: '[a]' }]
     }], null, null); })();`);
@@ -688,7 +688,8 @@ UndecoratedBase.ɵdir = ɵngcc0.ɵɵdefineDirective({ type: UndecoratedBase, vie
               decorationAnalyses, switchMarkerAnalyses, privateDeclarationsAnalyses);
           const addAdjacentStatementsSpy = testFormatter.addAdjacentStatements as jasmine.Spy;
           expect(addAdjacentStatementsSpy.calls.first().args[2])
-              .toContain(`/*@__PURE__*/ (function () { ɵngcc0.setClassMetadata(`);
+              .toContain(
+                  `function () { (typeof ngDevMode === "undefined" || ngDevMode) && ɵngcc0.setClassMetadata(`);
           const addImportsSpy = testFormatter.addImports as jasmine.Spy;
           expect(addImportsSpy.calls.first().args[1]).toEqual([
             {specifier: './r3_symbols', qualifier: 'ɵngcc0'}
@@ -713,7 +714,8 @@ UndecoratedBase.ɵdir = ɵngcc0.ɵɵdefineDirective({ type: UndecoratedBase, vie
               decorationAnalyses, switchMarkerAnalyses, privateDeclarationsAnalyses);
           const addAdjacentStatementsSpy = testFormatter.addAdjacentStatements as jasmine.Spy;
           expect(addAdjacentStatementsSpy.calls.first().args[2])
-              .toContain(`/*@__PURE__*/ (function () { setClassMetadata(`);
+              .toContain(
+                  `function () { (typeof ngDevMode === "undefined" || ngDevMode) && setClassMetadata(`);
           const addImportsSpy = testFormatter.addImports as jasmine.Spy;
           expect(addImportsSpy.calls.first().args[1]).toEqual([]);
         });

packages/compiler-cli/src/ngtsc/annotations/src/metadata.ts

@@ -6,7 +6,7 @@
  * found in the LICENSE file at https://angular.io/license
  */
 
-import {Expression, ExternalExpr, FunctionExpr, Identifiers, InvokeFunctionExpr, LiteralArrayExpr, LiteralExpr, literalMap, NONE_TYPE, ReturnStatement, Statement, WrappedNodeExpr} from '@angular/compiler';
+import {devOnlyGuardedExpression, Expression, ExternalExpr, FunctionExpr, Identifiers, InvokeFunctionExpr, LiteralArrayExpr, LiteralExpr, literalMap, NONE_TYPE, ReturnStatement, Statement, WrappedNodeExpr} from '@angular/compiler';
 import * as ts from 'typescript';
 
 import {DefaultImportRecorder} from '../../imports';
@@ -17,7 +17,8 @@ import {valueReferenceToExpression, wrapFunctionExpressionsInParens} from './uti
 
 /**
  * Given a class declaration, generate a call to `setClassMetadata` with the Angular metadata
- * present on the class or its member fields.
+ * present on the class or its member fields. An ngDevMode guard is used to allow the call to be
+ * tree-shaken away, as the `setClassMetadata` invocation is only needed for testing purposes.
  *
  * If no such metadata is present, this function returns `null`. Otherwise, the call is returned
  * as a `Statement` for inclusion along with the class.
@@ -93,14 +94,8 @@ export function generateSetClassMetadataCall(
         metaCtorParameters,
         new WrappedNodeExpr(metaPropDecorators),
       ]);
-  const iifeFn = new FunctionExpr([], [fnCall.toStmt()], NONE_TYPE);
-  const iife = new InvokeFunctionExpr(
-      /* fn */ iifeFn,
-      /* args */[],
-      /* type */ undefined,
-      /* sourceSpan */ undefined,
-      /* pure */ true);
-  return iife.toStmt();
+  const iife = new FunctionExpr([], [devOnlyGuardedExpression(fnCall).toStmt()]);
+  return iife.callFn([]).toStmt();
 }
 
 /**

packages/compiler-cli/src/ngtsc/annotations/test/metadata_spec.ts

@@ -24,7 +24,7 @@ runInEachFileSystem(() => {
     @Component('metadata') class Target {}
     `);
       expect(res).toEqual(
-          `/*@__PURE__*/ (function () { i0.ɵsetClassMetadata(Target, [{ type: Component, args: ['metadata'] }], null, null); })();`);
+          `(function () { (typeof ngDevMode === "undefined" || ngDevMode) && i0.ɵsetClassMetadata(Target, [{ type: Component, args: ['metadata'] }], null, null); })();`);
     });
 
     it('should convert namespaced decorated class metadata', () => {
@@ -34,7 +34,7 @@ runInEachFileSystem(() => {
     @core.Component('metadata') class Target {}
     `);
       expect(res).toEqual(
-          `/*@__PURE__*/ (function () { i0.ɵsetClassMetadata(Target, [{ type: core.Component, args: ['metadata'] }], null, null); })();`);
+          `(function () { (typeof ngDevMode === "undefined" || ngDevMode) && i0.ɵsetClassMetadata(Target, [{ type: core.Component, args: ['metadata'] }], null, null); })();`);
     });
 
     it('should convert decorated class constructor parameter metadata', () => {