feat(ivy): resolve forwardRef() for queries (#25080)

@ContentChild[ren] and @ViewChild[ren] can contain a forwardRef() to a
type. This commit allows ngtsc to unwrap the forward reference and
deal with the node inside.

It includes two modes of support for forward reference resolution -
a foreign function resolver which understands deeply nested forward
references in expressions that are being statically evaluated, and
an unwrapForwardRef() function which deals only with top-level nodes.

Both will be useful in the future, but for now only unwrapForwardRef()
is used.

PR Close #25080

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

@@ -14,7 +14,7 @@ import {Reference, filterToMembersWithDecorator, reflectObjectLiteral, staticall
 import {AnalysisOutput, CompileResult, DecoratorHandler} from '../../transform';
 
 import {SelectorScopeRegistry} from './selector_scope';
-import {getConstructorDependencies, isAngularCore, unwrapExpression} from './util';
+import {getConstructorDependencies, isAngularCore, unwrapExpression, unwrapForwardRef} from './util';
 
 const EMPTY_OBJECT: {[key: string]: string} = {};
 
@@ -156,12 +156,13 @@ export function extractQueryMetadata(
     throw new Error(`@${name} must have arguments`);
   }
   const first = name === 'ViewChild' || name === 'ContentChild';
-  const arg = staticallyResolve(args[0], reflector, checker);
+  const node = unwrapForwardRef(args[0], reflector);
+  const arg = staticallyResolve(node, reflector, checker);
 
   // Extract the predicate
   let predicate: Expression|string[]|null = null;
   if (arg instanceof Reference) {
-    predicate = new WrappedNodeExpr(args[0]);
+    predicate = new WrappedNodeExpr(node);
   } else if (typeof arg === 'string') {
     predicate = [arg];
   } else if (isStringArrayOrDie(arg, '@' + name)) {

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

@@ -67,14 +67,14 @@ export class NgModuleDecoratorHandler implements DecoratorHandler<NgModuleAnalys
     if (ngModule.has('imports')) {
       const importsMeta = staticallyResolve(
           ngModule.get('imports') !, this.reflector, this.checker,
-          node => this._extractModuleFromModuleWithProvidersFn(node));
+          ref => this._extractModuleFromModuleWithProvidersFn(ref.node));
       imports = resolveTypeList(importsMeta, 'imports');
     }
     let exports: Reference[] = [];
     if (ngModule.has('exports')) {
       const exportsMeta = staticallyResolve(
           ngModule.get('exports') !, this.reflector, this.checker,
-          node => this._extractModuleFromModuleWithProvidersFn(node));
+          ref => this._extractModuleFromModuleWithProvidersFn(ref.node));
       exports = resolveTypeList(exportsMeta, 'exports');
     }
 

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

@@ -10,7 +10,7 @@ import {Expression, R3DependencyMetadata, R3ResolvedDependencyType, WrappedNodeE
 import * as ts from 'typescript';
 
 import {Decorator, ReflectionHost} from '../../host';
-import {Reference} from '../../metadata';
+import {AbsoluteReference, Reference} from '../../metadata';
 
 export function getConstructorDependencies(
     clazz: ts.ClassDeclaration, reflector: ReflectionHost,
@@ -103,3 +103,69 @@ export function unwrapExpression(node: ts.Expression): ts.Expression {
   }
   return node;
 }
+
+function expandForwardRef(arg: ts.Expression): ts.Expression|null {
+  if (!ts.isArrowFunction(arg) && !ts.isFunctionExpression(arg)) {
+    return null;
+  }
+
+  const body = arg.body;
+  // Either the body is a ts.Expression directly, or a block with a single return statement.
+  if (ts.isBlock(body)) {
+    // Block body - look for a single return statement.
+    if (body.statements.length !== 1) {
+      return null;
+    }
+    const stmt = body.statements[0];
+    if (!ts.isReturnStatement(stmt) || stmt.expression === undefined) {
+      return null;
+    }
+    return stmt.expression;
+  } else {
+    // Shorthand body - return as an expression.
+    return body;
+  }
+}
+
+/**
+ * Possibly resolve a forwardRef() expression into the inner value.
+ *
+ * @param node the forwardRef() expression to resolve
+ * @param reflector a ReflectionHost
+ * @returns the resolved expression, if the original expression was a forwardRef(), or the original
+ * expression otherwise
+ */
+export function unwrapForwardRef(node: ts.Expression, reflector: ReflectionHost): ts.Expression {
+  if (!ts.isCallExpression(node) || !ts.isIdentifier(node.expression) ||
+      node.arguments.length !== 1) {
+    return node;
+  }
+  const expr = expandForwardRef(node.arguments[0]);
+  if (expr === null) {
+    return node;
+  }
+  const imp = reflector.getImportOfIdentifier(node.expression);
+  if (imp === null || imp.from !== '@angular/core' || imp.name !== 'forwardRef') {
+    return node;
+  } else {
+    return expr;
+  }
+}
+
+/**
+ * A foreign function resolver for `staticallyResolve` which unwraps forwardRef() expressions.
+ *
+ * @param ref a Reference to the declaration of the function being called (which might be
+ * forwardRef)
+ * @param args the arguments to the invocation of the forwardRef expression
+ * @returns an unwrapped argument if `ref` pointed to forwardRef, or null otherwise
+ */
+export function forwardRefResolver(
+    ref: Reference<ts.FunctionDeclaration|ts.MethodDeclaration>,
+    args: ts.Expression[]): ts.Expression|null {
+  if (!(ref instanceof AbsoluteReference) || ref.moduleName !== '@angular/core' ||
+      ref.symbolName !== 'forwardRef' || args.length !== 1) {
+    return null;
+  }
+  return expandForwardRef(args[0]);
+}