Fwd: java.lang.VerifyError: Bad type on operand stack
Sven Reimers
sven.reimers at gmail.com
Wed Jan 7 21:03:08 UTC 2015
Ah, ok got it..
Indeed changing it to the following line compiles fine.
Point3D<Integer> integerPoint = new
Point3D<>(Integer.valueOf(1),Integer.valueOf(2),Integer.valueOf(3));
Thanks
Sven
On Wed, Jan 7, 2015 at 12:25 PM, Maurizio Cimadamore <
maurizio.cimadamore at oracle.com> wrote:
> I consulted with the inference Gods (they seem to be lurking in Valhalla
> from time to time) and it would seem that this is actually the correct
> behavior.
> The problem is that the constructor is considered perfectly applicable
> during the 'strict' applicability step, which only uses subtyping -
> therefore the only allowed inference result there is 'int' - and the target
> type seems to contradict there. It is possible that we will relax this a
> bit moving forward by introducing some ad hoc rules, but the status quo
> seems to be expressive enough, while avoiding being unnecessarily messy.
>
> At the same time, the Gods pointed out that inference should only be
> allowed to do boxing/unboxing tricks when an inference constraints of the
> kind
>
> alpha :> int
>
> has been derived from a compatibility check (i.e. because we want to pass
> an 'int' where 'alpha' is expected). These tricks should not be allowed in
> the general case - example:
>
> <any T> T[] clone(T[] arg) { return arg; }
>
> int[] arr1 = clone(new int[3]); //ok
> Integer[] arr2 = clone(new int[3]); //fail
>
> Here, the array subtyping rules essentially mean that no boxing can
> occurr, so the only choice for T is 'int' in the second case, which, again,
> is incompatible with the target.
>
> The compiler gets some of this right and some other things only happen to
> be right 'by accident' - I'm working on a patch that will clean this up a
> bit.
>
> Maurizio
>
>
> On 06/01/15 16:27, Sven Reimers wrote:
>
>> @Maurizio: sorry forgot the mailing list...
>>
>>
>> ---------- Forwarded message ----------
>> From: Sven Reimers <sven.reimers at gmail.com>
>> Date: Tue, Jan 6, 2015 at 5:20 PM
>> Subject: Re: java.lang.VerifyError: Bad type on operand stack
>> To: Maurizio Cimadamore <maurizio.cimadamore at oracle.com>
>>
>>
>> Follow-Up:
>>
>> I tried a few different things and got into this:
>>
>> Point3D<Integer> integerPoint = new Point3D<>(1,2,3);
>>
>> compiles only if
>>
>> public static class Point3D<T> {... }
>>
>> not for
>>
>> public static class Point3D<any T> {... }
>>
>> ErrorMessage from the compiler is:
>>
>> incompatible types: cannot infer type arguments for Point3D<>
>> Point3D<Integer> integerPoint = new Point3D<>(1,2,3);
>> ^
>> reason: cannot infer type-variable(s) T
>> (argument mismatch; int cannot be converted to Integer)
>> where T is a type-variable:
>> T extends <any> declared in class Point3D
>>
>> Is this intentional (not sure I found this stated in the draft)?
>>
>> Thanks
>>
>> Sven
>>
>>
>> On Tue, Jan 6, 2015 at 4:10 PM, Maurizio Cimadamore <
>> maurizio.cimadamore at oracle.com> wrote:
>>
>> Whoops :-)
>>>
>>> Thanks for the report
>>>
>>> Maurizio
>>>
>>>
>>> On 06/01/15 15:13, Sven Reimers wrote:
>>>
>>> Hi,
>>>>
>>>> as suggested by Brian I tried to get some sample code written and
>>>> running
>>>> on top of valhalla.
>>>>
>>>> First problem I encountered was that a missing diamond <> on the right
>>>> hand
>>>> side (my bad - seems I am really relying on my IDE) was just a warning
>>>> that
>>>> I was using a raw type.
>>>>
>>>> Running my example I got this:
>>>>
>>>> Specializing Valhalla$Point3D${0=I}; searching for
>>>> Valhalla$Point3D.class
>>>> (not found)
>>>> Specializing Valhalla$Point3D${0=I}; searching for
>>>> Valhalla$Point3D.class
>>>> (found)
>>>> Error: A JNI error has occurred, please check your installation and try
>>>> again
>>>> Exception in thread "main" java.lang.VerifyError: Bad type on operand
>>>> stack
>>>> Exception Details:
>>>> Location:
>>>> Valhalla.main([Ljava/lang/String;)V @36: invokevirtual
>>>> Reason:
>>>> Type 'Valhalla$Point3D' (current frame, stack[2]) is not
>>>> assignable
>>>> to
>>>> 'Valhalla$Point3D${0=I}'
>>>> Current Frame:
>>>> bci: @36
>>>> flags: { }
>>>> locals: { '[Ljava/lang/String;', 'Valhalla$Point3D' }
>>>> stack: { 'java/io/PrintStream', 'java/lang/StringBuilder',
>>>> 'Valhalla$Point3D' }
>>>> Bytecode:
>>>> 0000000: bb00 0259 04b8 0003 05b8 0003 06b8 0003
>>>> 0000010: b700 044c b200 05bb 0006 59b7 0007 1208
>>>> 0000020: b600 092b b600 0ab6 000b b600 0cb6 000d
>>>> 0000030: b1
>>>>
>>>> at java.lang.Class.getDeclaredMethods0(Native Method)
>>>> at java.lang.Class.privateGetDeclaredMethods(Class.java:2704)
>>>> at java.lang.Class.privateGetMethodRecursive(Class.java:3049)
>>>> at java.lang.Class.getMethod0(Class.java:3019)
>>>> at java.lang.Class.getMethod(Class.java:1787)
>>>> at sun.launcher.LauncherHelper.validateMainClass(
>>>> LauncherHelper.java:568)
>>>> at sun.launcher.LauncherHelper.checkAndLoadMain(
>>>> LauncherHelper.java:535)
>>>>
>>>> Example Code (see the missing <> just after Point3D...):
>>>>
>>>> public class Valhalla {
>>>>
>>>>
>>>> public static void main (String[] args) {
>>>>
>>>> Point3D<int> intPoint = new Point3D(1,2,3);
>>>>
>>>> System.out.println("X: " + intPoint.getX());
>>>>
>>>> }
>>>>
>>>> public static class Point3D<any T> {
>>>> private T x;
>>>> private T y;
>>>> private T z;
>>>>
>>>> public Point3D(T x, T y, T z) {
>>>> this.x = x;
>>>> this.y = y;
>>>> this.z = z;
>>>> }
>>>>
>>>> public T getX() {
>>>> return x;
>>>> }
>>>>
>>>> public T getY() {
>>>> return y;
>>>> }
>>>>
>>>> public T getZ() {
>>>> return z;
>>>> }
>>>>
>>>> }
>>>>
>>>> }
>>>>
>>>> Hope to provide more feedback once I got more code running.
>>>>
>>>> Thanks for the impressive work so far.
>>>>
>>>> -Sven
>>>>
>>>>
>>>>
>>
>
--
Sven Reimers
* Senior Expert Software Architect
* NetBeans Dream Team Member: http://dreamteam.netbeans.org
* Community Leader NetBeans: http://community.java.net/netbeans
Desktop Java:
http://community.java.net/javadesktop
* JUG Leader JUG Bodensee: http://www.jug-bodensee.de
* Duke's Choice Award Winner 2009
* Blog: https://www.java.net//blog/sven
* XING: https://www.xing.com/profile/Sven_Reimers8
* LinkedIn: http://www.linkedin.com/in/svenreimers
Join the NetBeans Groups:
* XING: http://www.xing.com/group-20148.82db20
* NUGM: http://haug-server.dyndns.org/display/NUGM/Home
* LinkedIn: http://www.linkedin.com/groups?gid=1860468
http://www.linkedin.com/groups?gid=107402
http://www.linkedin.com/groups?gid=1684717
* Oracle: https://mix.oracle.com/groups/18497
More information about the valhalla-dev
mailing list