hg: valhalla/valhalla/langtools: BytecodeMapping generation fixes:

[Maurizio Cimadamore]

As you found out, layering support is still missing from the prototype; 
you have ability to declare RefOnly/ValOnly members but that's pretty 
much about it. It's still quite powerful though, albeit some things 
don't work automagically as you'd expect. What you are looking for is a 
way to write implementation by parts - and that's the bit that's missing 
from the current implementation (we have a rough proof of concept that 
does that, but it's not very polished, and the syntax that it supports 
is very different from the one described in the document).

Maurizio

On 06/01/15 17:27, Peter Levart wrote:
> On 01/06/2015 02:00 PM, maurizio.cimadamore at oracle.com wrote:
>> Changeset: 8331682af2ed
>> Author:    mcimadamore
>> Date:      2015-01-06 12:54 +0000
>> URL:http://hg.openjdk.java.net/valhalla/valhalla/langtools/rev/8331682af2ed
>>
>> BytecodeMapping generation fixes:
>> * missing BMA for eq/ne any comparisons nested within logic operators &&/||
>> * missing BMA for field/method access immediately following a constructor call
>> * refactor Items code in order to avoid cast to AnyItem in order to access type info associated with a given item
>> * added tests
>>
>> ! src/jdk.compiler/share/classes/com/sun/tools/javac/jvm/Gen.java
>> ! src/jdk.compiler/share/classes/com/sun/tools/javac/jvm/Items.java
>> + test/tools/javac/valhalla/typespec/items/tests/TestBinary.java
>> ! test/tools/javac/valhalla/typespec/items/tests/TestInstanceof.java
>> ! test/tools/javac/valhalla/typespec/items/tests/TestNew.java
>>
>
> Thanks Maurizio,
>
> It works now. But I have another (seems like javac) problem. Since 
> layers are not yet implemented (or I just can't seem to figure out how 
> to use them), I tried to use __WhereRef(T) and __WhereVal(T) with 
> inheritance to simulate them. My 1st goal was to create a Box<any T> 
> class that would implement Object.equals() in a way that would use 
> Objects.equals() for reference T and '==' for value T. Here's what I 
> came up with:
>
> // the Ref "layer"
>
> abstract class RefBoxBase<any T> {
>
>     public abstract T get();
>
>     public __WhereRef(T) int hashCode() {
>         return Objects.hashCode(get());
>     }
>
>     public __WhereRef(T) boolean equals(Object obj) {
>         return (this == obj) ||
>             (obj != null &&
>                 this.getClass() == obj.getClass() &&
>                 Objects.equals(this.get(), ((RefBoxBase<T>) obj).get())
>             );
>     }
> }
>
> // the Val "overlay"
>
> public final class Box<any T> extends RefBoxBase<T> {
>
>     private T value;
>
>     public Box(T value) {
>         this.value = value;
>     }
>
>     public Box() {
>         // leave default value
>     }
>
>     public T get() {
>         return value;
>     }
>
>     public __WhereVal(T) int hashCode() {
>         return 0; // don't know yet how to do something meaningful here
>     }
>
>     public __WhereVal(T) boolean equals(Object obj) {
>         return (this == obj) ||
>             (obj != null &&
>                 this.getClass() == obj.getClass() &&
>                 this.get() == ((Box<T>)obj).get());
>     }
> }
>
>
> And the test:
>
> public class Test {
>     public static void main(String[] args) {
>         System.out.println(new Box<int>(1).equals(new Box<int>(1))); 
> // this compiles fine
>
>         System.out.println(new Box<String>("a").equals(new 
> Box<String>("a"))); // compilation error
>     }
> }
>
> src/util/Test.java:6: error: bad receiver type Box<String> in 
> restricted method call
>         System.out.println(new Box<String>("a").equals(new 
> Box<String>("a")));
>                                                       ^
> Note: src/util/RefBoxBase.java uses unchecked or unsafe operations.
> Note: Recompile with -Xlint:unchecked for details.
> 1 error
>
>
> It's true that Box.equals() is restricted for Val receiver, but I 
> thought that RefBoxBase.equals() would be "uncovered" in this case an 
> inherited in Ref specialization.
>
>
>
> Regards, Peter
>
>