fix(ivy): in ngcc, handle inline exports in commonjs code (#32129)

One of the compiler's tasks is to enumerate the exports of a given ES
module. This can happen for example to resolve `foo.bar` where `foo` is a
namespace import:

```typescript
import * as foo from './foo';

@NgModule({
  directives: [foo.DIRECTIVES],
})
```

In this case, the compiler must enumerate the exports of `foo.ts` in order
to evaluate the expression `foo.DIRECTIVES`.

When this operation occurs under ngcc, it must deal with the different
module formats and types of exports that occur. In commonjs code, a problem
arises when certain exports are downleveled.

```typescript
export const DIRECTIVES = [
  FooDir,
  BarDir,
];
```

can be downleveled to:

```javascript
exports.DIRECTIVES = [
  FooDir,
  BarDir,
```

Previously, ngtsc and ngcc expected that any export would have an associated
`ts.Declaration` node. `export class`, `export function`, etc. all retain
`ts.Declaration`s even when downleveled. But the `export const` construct
above does not. Therefore, ngcc would not detect `DIRECTIVES` as an export
of `foo.ts`, and the evaluation of `foo.DIRECTIVES` would therefore fail.

To solve this problem, the core concept of an exported `Declaration`
according to the `ReflectionHost` API is split into a `ConcreteDeclaration`
which has a `ts.Declaration`, and an `InlineDeclaration` which instead has
a `ts.Expression`. Differentiating between these allows ngcc to return an
`InlineDeclaration` for `DIRECTIVES` and correctly keep track of this
export.

PR Close #32129

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

@@ -92,9 +92,7 @@ export class CommonJsReflectionHost extends Esm5ReflectionHost {
     for (const statement of this.getModuleStatements(sourceFile)) {
       if (isCommonJsExportStatement(statement)) {
         const exportDeclaration = this.extractCommonJsExportDeclaration(statement);
-        if (exportDeclaration !== null) {
-          moduleMap.set(exportDeclaration.name, exportDeclaration.declaration);
-        }
+        moduleMap.set(exportDeclaration.name, exportDeclaration.declaration);
       } else if (isReexportStatement(statement)) {
         const reexports = this.extractCommonJsReexports(statement, sourceFile);
         for (const reexport of reexports) {
@@ -106,14 +104,22 @@ export class CommonJsReflectionHost extends Esm5ReflectionHost {
   }
 
   private extractCommonJsExportDeclaration(statement: CommonJsExportStatement):
-      CommonJsExportDeclaration|null {
+      CommonJsExportDeclaration {
     const exportExpression = statement.expression.right;
     const declaration = this.getDeclarationOfExpression(exportExpression);
-    if (declaration === null) {
-      return null;
-    }
     const name = statement.expression.left.name.text;
-    return {name, declaration};
+    if (declaration !== null) {
+      return {name, declaration};
+    } else {
+      return {
+        name,
+        declaration: {
+          node: null,
+          expression: exportExpression,
+          viaModule: null,
+        },
+      };
+    }
   }
 
   private extractCommonJsReexports(statement: ReexportStatement, containingFile: ts.SourceFile):
@@ -126,8 +132,14 @@ export class CommonJsReflectionHost extends Esm5ReflectionHost {
       const viaModule = stripExtension(importedFile.fileName);
       const importedExports = this.getExportsOfModule(importedFile);
       if (importedExports !== null) {
-        importedExports.forEach(
-            (decl, name) => reexports.push({name, declaration: {node: decl.node, viaModule}}));
+        importedExports.forEach((decl, name) => {
+          if (decl.node !== null) {
+            reexports.push({name, declaration: {node: decl.node, viaModule}});
+          } else {
+            reexports.push(
+                {name, declaration: {node: null, expression: decl.expression, viaModule}});
+          }
+        });
       }
     }
     return reexports;

packages/compiler-cli/ngcc/src/host/esm2015_host.ts

@@ -9,7 +9,7 @@
 import * as ts from 'typescript';
 
 import {AbsoluteFsPath} from '../../../src/ngtsc/file_system';
-import {ClassDeclaration, ClassMember, ClassMemberKind, ClassSymbol, CtorParameter, Declaration, Decorator, TypeScriptReflectionHost, isDecoratorIdentifier, reflectObjectLiteral} from '../../../src/ngtsc/reflection';
+import {ClassDeclaration, ClassMember, ClassMemberKind, ClassSymbol, ConcreteDeclaration, CtorParameter, Declaration, Decorator, TypeScriptReflectionHost, isDecoratorIdentifier, reflectObjectLiteral} from '../../../src/ngtsc/reflection';
 import {Logger} from '../logging/logger';
 import {BundleProgram} from '../packages/bundle_program';
 import {findAll, getNameText, hasNameIdentifier, isDefined, stripDollarSuffix} from '../utils';
@@ -243,7 +243,7 @@ export class Esm2015ReflectionHost extends TypeScriptReflectionHost implements N
 
     // The identifier may have been of an additional class assignment such as `MyClass_1` that was
     // present as alias for `MyClass`. If so, resolve such aliases to their original declaration.
-    if (superDeclaration !== null) {
+    if (superDeclaration !== null && superDeclaration.node !== null) {
       const aliasedIdentifier = this.resolveAliasedClassIdentifier(superDeclaration.node);
       if (aliasedIdentifier !== null) {
         return this.getDeclarationOfIdentifier(aliasedIdentifier);
@@ -409,6 +409,9 @@ export class Esm2015ReflectionHost extends TypeScriptReflectionHost implements N
     if (!exports) return [];
     const infos: ModuleWithProvidersFunction[] = [];
     exports.forEach((declaration, name) => {
+      if (declaration.node === null) {
+        return;
+      }
       if (this.isClass(declaration.node)) {
         this.getMembersOfClass(declaration.node).forEach(member => {
           if (member.isStatic) {
@@ -497,7 +500,7 @@ export class Esm2015ReflectionHost extends TypeScriptReflectionHost implements N
     const aliasedIdentifier = initializer.left;
 
     const aliasedDeclaration = this.getDeclarationOfIdentifier(aliasedIdentifier);
-    if (aliasedDeclaration === null) {
+    if (aliasedDeclaration === null || aliasedDeclaration.node === null) {
       throw new Error(
           `Unable to locate declaration of ${aliasedIdentifier.text} in "${statement.getText()}"`);
     }
@@ -1407,7 +1410,7 @@ export class Esm2015ReflectionHost extends TypeScriptReflectionHost implements N
     }
 
     const ngModuleDeclaration = this.getDeclarationOfExpression(ngModuleValue);
-    if (!ngModuleDeclaration) {
+    if (!ngModuleDeclaration || ngModuleDeclaration.node === null) {
       throw new Error(
           `Cannot find a declaration for NgModule ${ngModuleValue.getText()} referenced in "${declaration!.getText()}"`);
     }
@@ -1416,7 +1419,7 @@ export class Esm2015ReflectionHost extends TypeScriptReflectionHost implements N
     }
     return {
       name,
-      ngModule: ngModuleDeclaration as Declaration<ClassDeclaration>, declaration, container
+      ngModule: ngModuleDeclaration as ConcreteDeclaration<ClassDeclaration>, declaration, container
     };
   }
 
@@ -1430,7 +1433,7 @@ export class Esm2015ReflectionHost extends TypeScriptReflectionHost implements N
     }
 
     const namespaceDecl = this.getDeclarationOfIdentifier(expression.expression);
-    if (!namespaceDecl || !ts.isSourceFile(namespaceDecl.node)) {
+    if (!namespaceDecl || namespaceDecl.node === null || !ts.isSourceFile(namespaceDecl.node)) {
       return null;
     }
 

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

@@ -140,7 +140,7 @@ export class Esm5ReflectionHost extends Esm2015ReflectionHost {
     const outerClassNode = getClassDeclarationFromInnerFunctionDeclaration(id.parent);
     const declaration = super.getDeclarationOfIdentifier(outerClassNode ? outerClassNode.name : id);
 
-    if (!declaration || !ts.isVariableDeclaration(declaration.node) ||
+    if (!declaration || declaration.node === null || !ts.isVariableDeclaration(declaration.node) ||
         declaration.node.initializer !== undefined ||
         // VariableDeclaration => VariableDeclarationList => VariableStatement => IIFE Block
         !ts.isBlock(declaration.node.parent.parent.parent)) {

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

@@ -6,7 +6,8 @@
  * found in the LICENSE file at https://angular.io/license
  */
 import * as ts from 'typescript';
-import {ClassDeclaration, ClassSymbol, Declaration, Decorator, ReflectionHost} from '../../../src/ngtsc/reflection';
+
+import {ClassDeclaration, ClassSymbol, ConcreteDeclaration, Decorator, ReflectionHost} from '../../../src/ngtsc/reflection';
 
 export const PRE_R3_MARKER = '__PRE_R3__';
 export const POST_R3_MARKER = '__POST_R3__';
@@ -39,7 +40,7 @@ export interface ModuleWithProvidersFunction {
    * The declaration of the class that the `ngModule` property on the `ModuleWithProviders` object
    * refers to.
    */
-  ngModule: Declaration<ClassDeclaration>;
+  ngModule: ConcreteDeclaration<ClassDeclaration>;
 }
 
 /**