remove function wrappers for member type declarations

To declare the types of class members, we want to emit e.g.
  /** @type {Foo} */
  MyClass.prototype.foo;

We cannot declare these in the class constructor because sometimes
we don't have a constructor and it's difficult to create our own
(we'd need to match the superclass in that case).

We sometimes cannot declare these at the top level because it's possible
there's a supertype that throws on get, which means the code cannot be
loaded as written without compiling it first.  (We know this actually
can happen because we tried it.)

In the past we declared these in a helper method or bare function,
but it turns out declarations in those are ignored by Closure in
unpredictable circumstances.

So our final approach is:
- for interfaces, declare them at the top level
- for classes, wrap them in an 'if (false)' block.
To do so we must suppress the 'useless code' compiler check, because
putting code in an 'if (false)' is pretty suspicious looking otherwise.

Author: evmar

src/fileoverview_comment_transformer.ts

@@ -60,6 +60,9 @@ function augmentFileoverviewComments(tags: jsdoc.Tag[]) {
   // 2) Suppress extraRequire.  We remove extra requires at the TypeScript level, so any require
   // that gets to the JS level is a load-bearing require.
   suppressions.add('extraRequire');
+  // 3) Suppress uselessCode.  We emit an "if (false)" around type declarations,
+  // which is flagged as unused code unless we suppress it.
+  suppressions.add('uselessCode');
   suppressTag.type = Array.from(suppressions.values()).sort().join(',');
 
   return tags;

src/tsickle.ts

@@ -1288,7 +1288,7 @@ class Annotator extends ClosureRewriter {
     if (docTags.length > 0) this.emit(jsdoc.toString(docTags));
     // this.writeNode(classDecl, true /*skipComments*/);
     this.writeNodeFrom(classDecl, classDecl.getStart(), classDecl.getEnd());
-    this.emitTypeAnnotationsHelper(classDecl);
+    this.emitMemberTypes(classDecl);
     return true;
   }
 
@@ -1312,23 +1312,20 @@ class Annotator extends ClosureRewriter {
     const name = getIdentifierText(iface.name);
     this.emit(`function ${name}() {}\n`);
 
-    this.emit(`\n\nfunction ${name}_tsickle_Closure_declarations() {\n`);
     const memberNamespace = [name, 'prototype'];
     for (const elem of iface.members) {
       const isOptional = elem.questionToken != null;
       this.visitProperty(memberNamespace, elem, isOptional);
     }
-    this.emit(`}\n`);
   }
 
   /**
-   * emitTypeAnnotationsHelper produces a _tsickle_typeAnnotationsHelper() where
-   * none existed in the original source. It's necessary in the case where
-   * TypeScript syntax specifies there are additional properties on the class,
-   * because to declare these in Closure you must declare these in a method
-   * somewhere.
+   * emitMemberTypes emits the type annotations for members of a class.
+   * It's necessary in the case where TypeScript syntax specifies
+   * there are additional properties on the class, because to declare
+   * these in Closure you must declare these separately from the class.
    */
-  private emitTypeAnnotationsHelper(classDecl: ts.ClassDeclaration) {
+  private emitMemberTypes(classDecl: ts.ClassDeclaration) {
     // Gather parameter properties from the constructor, if it exists.
     const ctors: ts.ConstructorDeclaration[] = [];
     let paramProps: ts.ParameterDeclaration[] = [];
@@ -1372,7 +1369,7 @@ class Annotator extends ClosureRewriter {
     const className = getIdentifierText(classDecl.name);
 
     // See test_files/fields/fields.ts:BaseThatThrows for a note on this wrapper.
-    this.emit(`\n\nfunction ${className}_tsickle_Closure_declarations() {\n`);
+    this.emit(`\n\nif (false) {`);
     staticProps.forEach(p => this.visitProperty([className], p));
     const memberNamespace = [className, 'prototype'];
     nonStaticProps.forEach((p) => this.visitProperty(memberNamespace, p));

test_files/abstract/abstract.js

@@ -1,6 +1,6 @@
 /**
  * @fileoverview added by tsickle
- * @suppress {checkTypes,extraRequire} checked by tsc
+ * @suppress {checkTypes,extraRequire,uselessCode} checked by tsc
  */
 goog.module('test_files.abstract.abstract');
 var module = module || { id: 'test_files/abstract/abstract.ts' };
@@ -19,7 +19,7 @@ class Base {
         this.hasReturnType();
     }
 }
-function Base_tsickle_Closure_declarations() {
+if (false) {
     /**
      * @abstract
      * @return {void}

test_files/arrow_fn.es5/arrow_fn_es5.js

@@ -1,6 +1,6 @@
 /**
  * @fileoverview Reproduces an error that caused incorrect Automatic Semicolon Insertion.
- * @suppress {checkTypes,extraRequire} checked by tsc
+ * @suppress {checkTypes,extraRequire,uselessCode} checked by tsc
  */
 goog.module('test_files.arrow_fn.es5.arrow_fn_es5');
 var module = module || { id: 'test_files/arrow_fn.es5/arrow_fn_es5.ts' };

test_files/arrow_fn.untyped/arrow_fn.untyped.js

@@ -1,6 +1,6 @@
 /**
  * @fileoverview added by tsickle
- * @suppress {checkTypes,extraRequire} checked by tsc
+ * @suppress {checkTypes,extraRequire,uselessCode} checked by tsc
  */
 goog.module('test_files.arrow_fn.untyped.arrow_fn.untyped');
 var module = module || { id: 'test_files/arrow_fn.untyped/arrow_fn.untyped.ts' };

test_files/arrow_fn/arrow_fn.js

@@ -1,6 +1,6 @@
 /**
  * @fileoverview added by tsickle
- * @suppress {checkTypes,extraRequire} checked by tsc
+ * @suppress {checkTypes,extraRequire,uselessCode} checked by tsc
  */
 goog.module('test_files.arrow_fn.arrow_fn');
 var module = module || { id: 'test_files/arrow_fn/arrow_fn.ts' };

test_files/basic.untyped/basic.untyped.js

@@ -1,6 +1,6 @@
 /**
  * @fileoverview added by tsickle
- * @suppress {checkTypes,extraRequire} checked by tsc
+ * @suppress {checkTypes,extraRequire,uselessCode} checked by tsc
  */
 goog.module('test_files.basic.untyped.basic.untyped');
 var module = module || { id: 'test_files/basic.untyped/basic.untyped.ts' };
@@ -20,7 +20,7 @@ class Foo {
         this.field = 'hello';
     }
 }
-function Foo_tsickle_Closure_declarations() {
+if (false) {
     /** @type {?} */
     Foo.prototype.field;
     /** @type {?} */

test_files/class.untyped/class.js

@@ -1,17 +1,15 @@
 /**
  * @fileoverview added by tsickle
- * @suppress {checkTypes,extraRequire} checked by tsc
+ * @suppress {checkTypes,extraRequire,uselessCode} checked by tsc
  */
 goog.module('test_files.class.untyped.class');
 var module = module || { id: 'test_files/class.untyped/class.ts' };
 /**
  * @record
  */
 function Interface() { }
-function Interface_tsickle_Closure_declarations() {
-    /** @type {?} */
-    Interface.prototype.interfaceFunc;
-}
+/** @type {?} */
+Interface.prototype.interfaceFunc;
 class Super {
     /**
      * @return {?}
@@ -62,15 +60,15 @@ superVar = new ImplementsTypeAlias();
 function Zone() { }
 class ZoneImplementsInterface {
 }
-function ZoneImplementsInterface_tsickle_Closure_declarations() {
+if (false) {
     /** @type {?} */
     ZoneImplementsInterface.prototype.zone;
 }
 /** @typedef {?} */
 var ZoneAlias;
 class ZoneImplementsAlias {
 }
-function ZoneImplementsAlias_tsickle_Closure_declarations() {
+if (false) {
     /** @type {?} */
     ZoneImplementsAlias.prototype.zone;
 }

test_files/class/class.js

@@ -1,7 +1,7 @@
 // test_files/class/class.ts(129,1): warning TS0: type/symbol conflict for Zone, using {?} for now
 /**
  * @fileoverview added by tsickle
- * @suppress {checkTypes,extraRequire} checked by tsc
+ * @suppress {checkTypes,extraRequire,uselessCode} checked by tsc
  */
 // This test exercises the various ways classes and interfaces can interact.
 // There are three types of classy things:
@@ -17,10 +17,8 @@ var module = module || { id: 'test_files/class/class.ts' };
  * @record
  */
 function Interface() { }
-function Interface_tsickle_Closure_declarations() {
-    /** @type {function(): void} */
-    Interface.prototype.interfaceFunc;
-}
+/** @type {function(): void} */
+Interface.prototype.interfaceFunc;
 class Class {
     /**
      * @return {void}
@@ -36,7 +34,7 @@ class AbstractClass {
      */
     nonAbstractFunc() { }
 }
-function AbstractClass_tsickle_Closure_declarations() {
+if (false) {
     /**
      * @abstract
      * @return {void}
@@ -48,10 +46,8 @@ function AbstractClass_tsickle_Closure_declarations() {
  * @extends {Interface}
  */
 function InterfaceExtendsInterface() { }
-function InterfaceExtendsInterface_tsickle_Closure_declarations() {
-    /** @type {function(): void} */
-    InterfaceExtendsInterface.prototype.interfaceFunc2;
-}
+/** @type {function(): void} */
+InterfaceExtendsInterface.prototype.interfaceFunc2;
 /** @type {!InterfaceExtendsInterface} */
 let interfaceExtendsInterface = {
     /**
@@ -67,10 +63,8 @@ let interfaceExtendsInterface = {
  * @record
  */
 function InterfaceExtendsClass() { }
-function InterfaceExtendsClass_tsickle_Closure_declarations() {
-    /** @type {function(): void} */
-    InterfaceExtendsClass.prototype.interfaceFunc3;
-}
+/** @type {function(): void} */
+InterfaceExtendsClass.prototype.interfaceFunc3;
 /**
  * @implements {Interface}
  */
@@ -198,15 +192,15 @@ abstractClassVar = new ClassExtendsAbstractClass();
 function Zone() { }
 class ZoneImplementsInterface {
 }
-function ZoneImplementsInterface_tsickle_Closure_declarations() {
+if (false) {
     /** @type {string} */
     ZoneImplementsInterface.prototype.zone;
 }
 /** @typedef {?} */
 var ZoneAlias;
 class ZoneImplementsAlias {
 }
-function ZoneImplementsAlias_tsickle_Closure_declarations() {
+if (false) {
     /** @type {string} */
     ZoneImplementsAlias.prototype.zone;
 }

test_files/clutz.no_externs/strip_clutz_type.js

@@ -1,6 +1,6 @@
 /**
  * @fileoverview added by tsickle
- * @suppress {checkTypes,extraRequire} checked by tsc
+ * @suppress {checkTypes,extraRequire,uselessCode} checked by tsc
  */
 goog.module('test_files.clutz.no_externs.strip_clutz_type');
 var module = module || { id: 'test_files/clutz.no_externs/strip_clutz_type.ts' };