fix(ngcc): handle new __spreadArrays tslib helper (#33617)

We already have special cases for the `__spread` helper function and with this change we handle the new tslib helper introduced in version 1.10 `__spreadArrays`.

For more context see: https://github.com/microsoft/tslib/releases/tag/1.10.0

Fixes: #33614

PR Close #33617

packages/compiler-cli/ngcc/src/host/esm5_host.ts

@@ -627,10 +627,13 @@ function getTsHelperFn(node: ts.NamedDeclaration): TsHelperFn|null {
       stripDollarSuffix(node.name.text) :
       null;
 
-  if (name === '__spread') {
+  switch (name) {
-    return TsHelperFn.Spread;
+    case '__spread':
-  } else {
+      return TsHelperFn.Spread;
-    return null;
+    case '__spreadArrays':
+      return TsHelperFn.SpreadArrays;
+    default:
+      return null;
   }
 }
 

packages/compiler-cli/ngcc/test/host/esm5_host_spec.ts

@@ -1651,7 +1651,7 @@ runInEachFileSystem(() => {
       it('should recognize TypeScript __spread helper function declaration', () => {
         const file: TestFile = {
           name: _('/declaration.d.ts'),
-          contents: `export declare function __spread(...args: any[]): any[];`,
+          contents: `export declare function __spread(...args: any[][]): any[];`,
         };
         loadTestFiles([file]);
         const {program} = makeTestBundleProgram(file.name);
@@ -1711,6 +1711,78 @@ runInEachFileSystem(() => {
            expect(definition.helper).toBe(TsHelperFn.Spread);
            expect(definition.parameters.length).toEqual(0);
          });
+
+      it('should recognize TypeScript __spreadArrays helper function declaration', () => {
+        const file: TestFile = {
+          name: _('/declaration.d.ts'),
+          contents: `export declare function __spreadArrays(...args: any[][]): any[];`,
+        };
+        loadTestFiles([file]);
+        const {program} = makeTestBundleProgram(file.name);
+        const host = new Esm5ReflectionHost(new MockLogger(), false, program.getTypeChecker());
+
+        const node =
+            getDeclaration(program, file.name, '__spreadArrays', isNamedFunctionDeclaration) !;
+
+        const definition = host.getDefinitionOfFunction(node) !;
+        expect(definition.node).toBe(node);
+        expect(definition.body).toBeNull();
+        expect(definition.helper).toBe(TsHelperFn.SpreadArrays);
+        expect(definition.parameters.length).toEqual(0);
+      });
+
+      it('should recognize TypeScript __spreadArrays helper function implementation', () => {
+        const file: TestFile = {
+          name: _('/implementation.js'),
+          contents: `
+                var __spreadArrays = (this && this.__spreadArrays) || function () {
+                  for (var s = 0, i = 0, il = arguments.length; i < il; i++) s += arguments[i].length;
+                  for (var r = Array(s), k = 0, i = 0; i < il; i++)
+                      for (var a = arguments[i], j = 0, jl = a.length; j < jl; j++, k++)
+                          r[k] = a[j];
+                  return r;
+                };`,
+        };
+        loadTestFiles([file]);
+        const {program} = makeTestBundleProgram(file.name);
+        const host = new Esm5ReflectionHost(new MockLogger(), false, program.getTypeChecker());
+
+        const node =
+            getDeclaration(program, file.name, '__spreadArrays', ts.isVariableDeclaration) !;
+
+        const definition = host.getDefinitionOfFunction(node) !;
+        expect(definition.node).toBe(node);
+        expect(definition.body).toBeNull();
+        expect(definition.helper).toBe(TsHelperFn.SpreadArrays);
+        expect(definition.parameters.length).toEqual(0);
+      });
+
+      it('should recognize TypeScript __spreadArrays helper function implementation when suffixed',
+         () => {
+           const file: TestFile = {
+             name: _('/implementation.js'),
+             contents: `
+                var __spreadArrays$2 = (this && this.__spreadArrays$2) || function () {
+                  for (var s = 0, i = 0, il = arguments.length; i < il; i++) s += arguments[i].length;
+                  for (var r = Array(s), k = 0, i = 0; i < il; i++)
+                      for (var a = arguments[i], j = 0, jl = a.length; j < jl; j++, k++)
+                          r[k] = a[j];
+                  return r;
+                };`,
+           };
+           loadTestFiles([file]);
+           const {program} = makeTestBundleProgram(file.name);
+           const host = new Esm5ReflectionHost(new MockLogger(), false, program.getTypeChecker());
+
+           const node =
+               getDeclaration(program, file.name, '__spreadArrays$2', ts.isVariableDeclaration) !;
+
+           const definition = host.getDefinitionOfFunction(node) !;
+           expect(definition.node).toBe(node);
+           expect(definition.body).toBeNull();
+           expect(definition.helper).toBe(TsHelperFn.SpreadArrays);
+           expect(definition.parameters.length).toEqual(0);
+         });
     });
 
     describe('getImportOfIdentifier()', () => {

packages/compiler-cli/src/ngtsc/partial_evaluator/src/ts_helpers.ts

@@ -15,10 +15,12 @@ import {ResolvedValue, ResolvedValueArray} from './result';
 
 export function evaluateTsHelperInline(
     helper: TsHelperFn, node: ts.Node, args: ResolvedValueArray): ResolvedValue {
-  if (helper === TsHelperFn.Spread) {
+  switch (helper) {
-    return evaluateTsSpreadHelper(node, args);
+    case TsHelperFn.Spread:
-  } else {
+    case TsHelperFn.SpreadArrays:
-    throw new Error(`Cannot evaluate unknown helper ${helper} inline`);
+      return evaluateTsSpreadHelper(node, args);
+    default:
+      throw new Error(`Cannot evaluate unknown helper ${helper} inline`);
   }
 }
 

packages/compiler-cli/src/ngtsc/partial_evaluator/test/evaluator_spec.ts

@@ -514,7 +514,28 @@ runInEachFileSystem(() => {
             {
               name: _('/node_modules/tslib/index.d.ts'),
               contents: `
-          export declare function __spread(...args: any[]): any[];
+          export declare function __spread(...args: any[][]): any[];
+        `
+            },
+          ]);
+      const reflectionHost = new TsLibAwareReflectionHost(checker);
+      const evaluator = new PartialEvaluator(reflectionHost, checker);
+      const value = evaluator.evaluate(expression);
+      expect(value).toEqual([1, 2, 3]);
+    });
+
+    it('should evaluate TypeScript __spreadArrays helper', () => {
+      const {checker, expression} = makeExpression(
+          `
+        import * as tslib from 'tslib';
+        const a = [1];
+        const b = [2, 3];
+      `,
+          'tslib.__spreadArrays(a, b)', [
+            {
+              name: _('/node_modules/tslib/index.d.ts'),
+              contents: `
+          export declare function __spreadArrays(...args: any[][]): any[];
         `
             },
           ]);
@@ -612,10 +633,13 @@ runInEachFileSystem(() => {
   function getTsHelperFn(node: ts.FunctionDeclaration): TsHelperFn|null {
     const name = node.name !== undefined && ts.isIdentifier(node.name) && node.name.text;
 
-    if (name === '__spread') {
+    switch (name) {
-      return TsHelperFn.Spread;
+      case '__spread':
-    } else {
+        return TsHelperFn.Spread;
-      return null;
+      case '__spreadArrays':
+        return TsHelperFn.SpreadArrays;
+      default:
+        return null;
     }
   }
 });

packages/compiler-cli/src/ngtsc/reflection/src/host.ts

@@ -336,6 +336,10 @@ export enum TsHelperFn {
    * Indicates the `__spread` function.
    */
   Spread,
+  /**
+   * Indicates the `__spreadArrays` function.
+   */
+  SpreadArrays,
 }
 
 /**