changed Std.instance definition (close #2534)

std/Std.hx

@@ -38,7 +38,7 @@ extern class Std {
 		Returns null if the object is not an instance of the class.
 		Is not guaranteed to work with interfaces or core types such as String, Array and Date.
 	**/
-	public static function instance<T>( v : {}, c : Class<T> ) : T;
+	public static function instance<T:{},S:T>( value : T, c : Class<S> ) : S;
 
 	/**
 		Converts any value to a String.

std/cpp/_std/Std.hx

@@ -24,8 +24,8 @@
 		return untyped __global__.__instanceof(v,t);
 	}
 
-	@:keep public static function instance<T>( v : { }, c : Class<T> ) : T {
-		return Std.is(v, c) ? cast v : null;
+	@:keep public static function instance<T:{},S:T>( value : T, c : Class<S> ) : S {
+		return Std.is(value, c) ? cast value : null;
 	}
 
 	@:keep public static function string( s : Dynamic ) : String {

std/cs/_std/Std.hx

@@ -234,8 +234,8 @@ import cs.internal.Exceptions;
 		}
 	}
 
-	public static function instance<T>( v : { }, c : Class<T> ) : T {
-		return Std.is(v, c) ? cast v : null;
+	public static function instance<T:{},S:T>( value : T, c : Class<S> ) : S {
+		return Std.is(value, c) ? cast value : null;
 	}
 
 	public static function random( x : Int ) : Int {

std/flash/_std/Std.hx

@@ -27,8 +27,8 @@ import flash.Boot;
 		return untyped flash.Boot.__instanceof(v,t);
 	}
 
-	public inline static function instance<T>( v : { }, c : Class<T> ) : T {
-		return flash.Lib.as(v, c);
+	public static inline function instance<T:{},S:T>( value : T, c : Class<S> ) : S {
+		return flash.Lib.as(value, c);
 	}
 
 	public static function string( s : Dynamic ) : String {

std/flash8/_std/Std.hx

@@ -26,8 +26,8 @@
 		return untyped flash.Boot.__instanceof(v,t);
 	}
 
-	public static function instance<T>( v : { }, c : Class<T> ) : T {
-		return Std.is(v, c) ? cast v : null;
+	public static function instance<T:{},S:T>( value : T, c : Class<S> ) : S {
+		return Std.is(value, c) ? cast value : null;
 	}
 	
 	public static function string( s : Dynamic ) : String {

std/java/_std/Std.hx

@@ -240,8 +240,8 @@ import java.internal.Exceptions;
 		return 0.0;
 	}
 
-	public static function instance<T>( v : { }, c : Class<T> ) : T {
-		return Std.is(v, c) ? cast v : null;
+	public static function instance<T:{},S:T>( value : T, c : Class<S> ) : S {
+		return Std.is(value, c) ? cast value : null;
 	}
 
 	public static function random( x : Int ) : Int {

std/js/_std/Std.hx

@@ -28,7 +28,7 @@ import js.Boot;
 		return untyped js.Boot.__instanceof(v,t);
 	}
 	
-	public static inline function instance<T>( v : { }, c : Class<T> ) : T {
+	public static inline function instance<T:{},S:T>( value : T, c : Class<S> ) : S {
 		return untyped __instanceof__(v, c) ? cast v : null;
 	}
 

std/neko/_std/Std.hx

@@ -26,8 +26,8 @@
 		return untyped neko.Boot.__instanceof(v,t);
 	}
 	
-	public static function instance<T>( v : { }, c : Class<T> ) : T {
-		return Std.is(v, c) ? cast v : null;
+	public static function instance<T:{},S:T>( value : T, c : Class<S> ) : S {
+		return Std.is(value, c) ? cast value : null;
 	}
 
 	public static function string( s : Dynamic ) : String {

std/php/_std/Std.hx

@@ -25,8 +25,8 @@
 		return untyped untyped __call__("_hx_instanceof", v,t);
 	}
 	
-	public static function instance<T>( v : { }, c : Class<T> ) : T {
-		return Std.is(v, c) ? cast v : null;
+	public static function instance<T:{},S:T>( value : T, c : Class<S> ) : S {
+		return Std.is(value, c) ? cast value : null;
 	}
 
 	public static function string( s : Dynamic ) : String {