Add support for collapsing parameter properties with default values.

src/main/java/com/google/javascript/gents/GentsCodeGenerator.java

@@ -122,6 +122,7 @@ boolean maybeOverrideCodeGen(Node n) {
         add(n.getDeclaredTypeExpression());
         add(")");
         return true;
+      case DEFAULT_VALUE:
       case NAME:
         // Prepend access modifiers on constructor params
         if (n.getParent().isParamList()) {

src/main/java/com/google/javascript/gents/TypeAnnotationPass.java

@@ -162,6 +162,19 @@ public void visit(NodeTraversal t, Node n, Node parent) {
             maybeSetInlineTypeExpression(parent, n, bestJSDocInfo, true);
           }
           break;
+          // If a DEVAULE_VALUE is in a PARAM_LIST we type annotate its first child which is the
+          // actual parameter.
+        case DEFAULT_VALUE:
+          Node paramNode = n.getFirstChild();
+          if (parent != null && parent.isParamList() && paramNode != null && paramNode.isName()) {
+            boolean wasSetFromFunctionDoc = setParameterTypeFromFunctionDoc(paramNode, parent);
+            if (!wasSetFromFunctionDoc) {
+              // If we didn't set the parameter type from the functions's JsDoc, then maybe the type
+              // is inlined just before the parameter?
+              maybeSetInlineTypeExpression(paramNode, paramNode, bestJSDocInfo, false);
+            }
+          }
+          break;
         case CAST:
           setTypeExpression(n, n.getJSDocInfo().getType(), false);
           break;
@@ -257,7 +270,9 @@ private boolean setParameterTypeFromFunctionDoc(Node node, Node parent) {
       // Modify the AST to represent an optional parameter
       if (parameterType.getRoot().getToken() == Token.EQUALS) {
         attachTypeExpr = IR.name(node.getString());
-        attachTypeExpr.putBooleanProp(Node.OPT_ES6_TYPED, true);
+        if (!node.getParent().isDefaultValue()) {
+          attachTypeExpr.putBooleanProp(Node.OPT_ES6_TYPED, true);
+        }
         nodeComments.replaceWithComment(node, attachTypeExpr);
       }
       setTypeExpression(attachTypeExpr, parameterType, false);

src/main/java/com/google/javascript/gents/TypeConversionPass.java

@@ -309,16 +309,18 @@ public void visit(NodeTraversal t, Node n, Node parent) {
             if (!nodeAfterDefault.isName()) {
               continue;
             }
-            // It appears that adding ACCESS_MODIFIERs to Default params do not come out though
-            // the CodeGenerator, thus not safe to remove the declaration.
-            // TODO(rado): fix in emitting code and remove this line.
-            if (param.isDefaultValue()) {
-              continue;
-            }
             String paramName = nodeAfterDefault.getString();
             @Nullable
             JSTypeExpression paramType =
                 constructorJsDoc == null ? null : constructorJsDoc.getParameterType(paramName);
+            // The class member declaration on "this" will not have "=" in the JSDoc most of the
+            // time. Therefore we need to remove the "=" from the JSDoc of the parameter
+            // declaration so we can compare the types and collapse the parameter property.
+            if (param.isDefaultValue() && Token.EQUALS.equals(paramType.getRoot().getToken())) {
+              paramType =
+                  new JSTypeExpression(
+                      paramType.getRoot().getFirstChild(), paramType.getSourceName());
+            }
             // Names must be equal. Types must be equal, or if the declaration has no type it is
             // assumed to be the type of the parameter.
             if (declaration.memberName.equals(paramName)

src/test/java/com/google/javascript/gents/singleTests/destr.js

@@ -18,4 +18,6 @@ class C {
     /** @private {number} */
     this.d = d;
   }
-}
+}
+
+let {x = 0} = {};

src/test/java/com/google/javascript/gents/singleTests/destr.ts

@@ -2,17 +2,13 @@
 class C {
   private a: number;
   private b: number;
-  private c: number;
 
   /**
    * @param c with default
    */
-  constructor({a}, {b} = {b: 1}, c = 0, private d: number) {
+  constructor({a}, {b} = {b: 1}, private c: number = 0, private d: number) {
     this.a = a;
     this.b = b;
-    //!! Due to a closure bug this one stays behind even though it is possible
-    //!! to write it in shorthand form.
-    //!! Note: Tslint fix pass will pick it up.
-    this.c = c;
   }
 }
+let {x = 0} = {};

src/test/java/com/google/javascript/gents/singleTests/functions.ts

@@ -5,7 +5,7 @@ let oneParam = function(n: number) {};
 
 function twoParams(b: boolean, s: string) {}
 
-function withDefaultValue(list = []) {}
+function withDefaultValue(list: any[] = []) {}
 
 // Function returns
 let anyReturn = function(): any {

src/test/java/com/google/javascript/gents/singleTests/module_class3.ts

@@ -2,12 +2,10 @@
 /** Possibly outdated information about Klass. */
 export class Klass {
   n: any;
-  list: any[];
   x: any = 4;
 
-  constructor(n: number, list = []) {
+  constructor(n: number, public readonly list: any[] = []) {
     this.n = n;
-    this.list = list;
   }
 
   foo(): boolean {

src/test/java/com/google/javascript/gents/singleTests/parameter_prop.js

@@ -37,4 +37,12 @@ function B(a, b, c, d, e) {
   this.d = d;
   /** @const {number} */
   this.e = e;
+}
+
+class C {
+  /** @param {string} a */
+  constructor(a = 'default value') {
+    /** @const */
+    this.a = a;
+  }
 }

src/test/java/com/google/javascript/gents/singleTests/parameter_prop.ts

@@ -17,3 +17,7 @@ class B {
       public a: number, public b: number, protected c: number,
       private d: number, public readonly e: number) {}
 }
+
+class C {
+  constructor(public readonly a: string = 'default value') {}
+}