Destructuring parameters with defaults. function x({ foo, bar } = {}) { }

lib/ast.js

@@ -384,7 +384,7 @@ var AST_ArrowParametersOrSeq = DEFNODE("ArrowParametersOrSeq", "expressions", {
     as_params: function (croak) {
         // We don't want anything which doesn't belong in a destructuring
         var root = this;
-        return this.expressions.map(function to_fun_args(ex) {
+        return this.expressions.map(function to_fun_args(ex, _, __, default_seen_above) {
             if (ex instanceof AST_Object) {
                 if (ex.properties.length == 0)
                     croak("Invalid destructuring function parameter", ex.start.line, ex.start.col);
@@ -392,6 +392,7 @@ var AST_ArrowParametersOrSeq = DEFNODE("ArrowParametersOrSeq", "expressions", {
                     start: ex.start,
                     end: ex.end,
                     is_array: false,
+                    default: default_seen_above,
                     names: ex.properties.map(to_fun_args)
                 });
             } else if (ex instanceof AST_ObjectSymbol) {
@@ -408,6 +409,7 @@ var AST_ArrowParametersOrSeq = DEFNODE("ArrowParametersOrSeq", "expressions", {
             } else if (ex instanceof AST_SymbolRef) {
                 return new AST_SymbolFunarg({
                     name: ex.name,
+                    default: default_seen_above,
                     start: ex.start,
                     end: ex.end
                 });
@@ -420,15 +422,11 @@ var AST_ArrowParametersOrSeq = DEFNODE("ArrowParametersOrSeq", "expressions", {
                     start: ex.start,
                     end: ex.end,
                     is_array: true,
+                    default: default_seen_above,
                     names: ex.elements.map(to_fun_args)
                 });
-            } else if (ex instanceof AST_Assign && ex.left instanceof AST_Symbol) {
-                return new AST_SymbolFunarg({
-                    name: ex.left.name,
-                    default: ex.right,
-                    start: ex.start,
-                    end: ex.end
-                });
+            } else if (ex instanceof AST_Assign) {
+                return to_fun_args(ex.left, undefined, undefined, ex.right);
             } else {
                 croak("Invalid function parameter", ex.start.line, ex.start.col);
             }
@@ -492,7 +490,7 @@ var AST_Defun = DEFNODE("Defun", null, {
 }, AST_Lambda);
 
 /* -----[ DESTRUCTURING ]----- */
-var AST_Destructuring = DEFNODE("Destructuring", "names is_array", {
+var AST_Destructuring = DEFNODE("Destructuring", "names is_array default", {
     $documentation: "A destructuring of several names. Used in destructuring assignment and with destructuring function argument names",
     _walk: function(visitor) {
         return visitor._visit(this, function(){

lib/output.js

@@ -639,6 +639,12 @@ function OutputStream(options) {
             name.print(output);
         })
         output.print(self.is_array ? "]" : "}");
+        if (self.default) {
+            output.space();
+            output.print('=');
+            output.space();
+            self.default.print(output)
+        }
     })
 
     DEFPRINT(AST_Debugger, function(self, output){

test/compress/harmony.js

@@ -136,8 +136,9 @@ default_arguments: {
     input: {
         function x(a = 6) { }
         function x(a = (6 + 5)) { }
+        function x({ foo } = {}, [ bar ] = [ 1 ]) { }
     }
-    expect_exact: "function x(a=6){}function x(a=6+5){}"
+    expect_exact: "function x(a=6){}function x(a=6+5){}function x({foo}={},[bar]=[1]){}"
 }
 
 concise_methods: {