fix(ivy): handle overloaded constructors in ngtsc (#34590)

Currently ngtsc looks for the first `ConstructorDeclaration` when figuring out what the parameters are so that it can generate the DI instructions. The problem is that if a constructor has overloads, it'll have several `ConstructorDeclaration` members with a different number of parameters. These changes tweak the logic so it looks for the constructor implementation.

PR Close #34590

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

@@ -35,8 +35,12 @@ export class TypeScriptReflectionHost implements ReflectionHost {
   getConstructorParameters(clazz: ClassDeclaration): CtorParameter[]|null {
     const tsClazz = castDeclarationToClassOrDie(clazz);
 
-    // First, find the constructor.
-    const ctor = tsClazz.members.find(ts.isConstructorDeclaration);
+    // First, find the constructor with a `body`. The constructors without a `body` are overloads
+    // whereas we want the implementation since it's the one that'll be executed and which can
+    // have decorators.
+    const ctor = tsClazz.members.find(
+        (member): member is ts.ConstructorDeclaration =>
+            ts.isConstructorDeclaration(member) && member.body !== undefined);
     if (ctor === undefined) {
       return null;
     }
@@ -564,4 +568,4 @@ function getExportedName(decl: ts.Declaration, originalId: ts.Identifier): strin
   return ts.isImportSpecifier(decl) ?
       (decl.propertyName !== undefined ? decl.propertyName : decl.name).text :
       originalId.text;
-}
+}

packages/compiler-cli/src/ngtsc/reflection/test/ts_host_spec.ts

@@ -211,6 +211,29 @@ runInEachFileSystem(() => {
         expect(args.length).toBe(1);
         expectParameter(args[0], 'bar', {moduleName: './bar', name: 'Bar'});
       });
+
+      it('should reflect the arguments from an overloaded constructor', () => {
+        const {program} = makeProgram([{
+          name: _('/entry.ts'),
+          contents: `
+            class Bar {}
+            class Baz {}
+
+            class Foo {
+              constructor(bar: Bar);
+              constructor(bar: Bar, baz?: Baz) {}
+            }
+        `
+        }]);
+        const clazz = getDeclaration(program, _('/entry.ts'), 'Foo', isNamedClassDeclaration);
+        const checker = program.getTypeChecker();
+        const host = new TypeScriptReflectionHost(checker);
+        const args = host.getConstructorParameters(clazz) !;
+        expect(args.length).toBe(2);
+        expectParameter(args[0], 'bar', 'Bar');
+        expectParameter(args[1], 'baz', 'Baz');
+      });
+
     });