RFR: Here are some URLClassPath patches

[David Holmes]

Hi Martin,

On 28/02/2018 1:02 PM, Martin Buchholz wrote:
> I should probably do more testing than usual when touching classloading...
> 
> We have a jdi test that does this (hg blame finds duke as only author):
> 
>      public static ClassLoader classLoaderValue;
>      {
>          try {
>              urls[0] = new URL("hi there");
>          } catch (java.net.MalformedURLException ee) {
>          }
>          classLoaderValue = new URLClassLoader(urls);
>      }
> 
> The assignment to urls[0] never succeeds (!), so URLClassLoader(URL[]) 
> is called with an array holding a null.  Which should cause a NPE, but 
> did not prior to JDK-8198484 
> <https://bugs.openjdk.java.net/browse/JDK-8198484>.
> ArrayDeque does not permit null elements!
> 
> Should we accept the NPE as a bug fix and file a retroactive CSR for 
> that, or should we continue to compatibly tolerate null URLs (yuk)?

As I wrote in the bug report the tolerance for nulls is very limited. 
Seems you can have them in the initial URL[] but if you actually try to 
use one you get NPE. So accepting a null entry in the URL[] seems rather 
pointless - and addURL explicitly states that null is ignored. So I'd 
argue for the CSR so we can at least consider whether we need tolerate this.

> Can we get jdi team to fix their dodgy tests?

Yes. Depending on which way we go we may need a new bug, otherwise this 
one can be assigned back to hotspot->svc. I'm also perplexed by the test 
logic.

Thanks,
David