Argument is read-only when used default parameters.

jsx#327

src/analysis.jsx

@@ -324,8 +324,13 @@ class ArgumentDeclaration extends LocalVariable {
 		this._defaultValue = defaultValue;
 	}
 
+	function constructor (name : Token, type : Type, isConst : boolean, defaultValue : Expression) {
+		super(name, type, isConst);
+		this._defaultValue = defaultValue;
+	}
+
 	function clone () : ArgumentDeclaration {
-		return new ArgumentDeclaration(this._name, this._type, Util.cloneNullable(this._defaultValue));
+		return new ArgumentDeclaration(this._name, this._type, this._isConstant, Util.cloneNullable(this._defaultValue));
 	}
 
 	function getDefaultValue() : Expression {
@@ -334,7 +339,7 @@ class ArgumentDeclaration extends LocalVariable {
 
 	override function _instantiate (instantiationContext : InstantiationContext) : ArgumentDeclaration {
 		var type = this._type != null ? this._type.instantiate(instantiationContext, false) : null;
-		return new ArgumentDeclaration(this._name, type, this._defaultValue);
+		return new ArgumentDeclaration(this._name, type, this._isConstant, this._defaultValue);
 	}
 
 	override function instantiateAndPush (instantiationContext : InstantiationContext) : ArgumentDeclaration {

src/classdef.jsx

@@ -1698,7 +1698,7 @@ class MemberFunctionDefinition extends MemberDefinition implements Block {
 		for (; origArgIndex != this.getArguments().length; ++origArgIndex) {
 			// build list of formal args (of the generated function)
 			var formalArgs = this.getArguments().slice(0, origArgIndex).map.<ArgumentDeclaration>((arg) -> {
-				return new ArgumentDeclaration(arg.getName(), arg.getType());
+				return new ArgumentDeclaration(arg.getName(), arg.getType(), true, null);
 			});
 			// build function body
 			var argExprs = formalArgs.map.<Expression>((arg) -> {

src/parser.jsx

@@ -3409,6 +3409,7 @@ class Parser {
 
 	function _functionArgumentsExpr (allowVarArgs : boolean, requireTypeDeclaration : boolean, allowDefaultValues : boolean) : ArgumentDeclaration[] {
 		var args = new ArgumentDeclaration[];
+		var hasDefaultValue = false;
 		if (this._expectOpt(")") == null) {
 			var token = null : Token;
 			do {
@@ -3438,7 +3439,7 @@ class Parser {
 					// vararg is the last argument
 					if (argType == null && isVarArg)
 						throw new Error("not yet implemented!");
-					args.push(new ArgumentDeclaration(argName, new VariableLengthArgumentType(argType)));
+					args.push(new ArgumentDeclaration(argName, new VariableLengthArgumentType(argType), hasDefaultValue, null));
 					if (this._expect(")") == null)
 						return null;
 					break;
@@ -3447,6 +3448,12 @@ class Parser {
 				var assignToken = this._expectOpt("=");
 				if (assignToken != null)  {
 					var state = this._preserveState();
+					if (!hasDefaultValue) {
+						args = args.map.<ArgumentDeclaration>((arg) -> {
+							return new ArgumentDeclaration(arg.getName(), arg.getType(), true, arg.getDefaultValue());
+						});
+						hasDefaultValue = true;
+					}
 					this._pushScope(null, args);
 					try {
 						if ((defaultValue = this._assignExpr(true)) == null) {
@@ -3469,7 +3476,7 @@ class Parser {
 						return null;
 					}
 				}
-				args.push(new ArgumentDeclaration(argName, argType, defaultValue));
+				args.push(new ArgumentDeclaration(argName, argType, hasDefaultValue, defaultValue));
 				token = this._expect([ ")", "," ]);
 				if (token == null)
 					return null;

t/compile_error/219.constant-param-within-default-parameters.jsx

@@ -0,0 +1,7 @@
+class C {
+
+	function fn(a : number, b : number = 10) {
+		a = 11;
+	}
+
+}