Bug#432541: eclipse-cdt FTBFS with gcj-4.2

[Andrew Haley]

Michael Koch wrote:
> On Sun, Mar 02, 2008 at 12:01:03PM +0000, Andrew Haley wrote:
>> Michael Koch wrote:
>>> On Sun, Mar 02, 2008 at 10:35:28AM +0000, Andrew Haley wrote:
>>>> And what was the reason?  I need to know.
>>> !ENTRY org.eclipse.osgi 4 0 2008-03-02 12:38:50.196
>>> !MESSAGE Application error
>>> !STACK 1
>>> java.lang.ClassNotFoundException: org.eclipse.core.runtime.Plugin
>>>    at org.eclipse.osgi.framework.internal.core.BundleLoader.findClass(BundleLoader.java:402)
>>>    at org.eclipse.osgi.framework.internal.core.BundleLoader.findClass(BundleLoader.java:347)
>>> make: *** [build-stamp] Fehler 13
>>>
>>> The only small strange thing is that org.eclipse.core.runtime.Plugin and
>>> org.eclipse.core.runtime.Platform are in the same Jar. This must be some
>>> OSGi issue. At least I know now where to start debugging.
>> Oh, right, so you *don't* actually know what the cause of this is.  Me either, but
>> I'm debugging it at the moment.
> 
> Yeah, yesterday I thought it was just a missing jar file. Today I took a
> closer look at at it...
> 
>> gcj should not distinguish between natively compiled code and bytecode.
>> The fact that it makes a difference must be a bug.
> 
> Sounds like it. Can I somehow help? I know this is a hard case and
> currently cant think of a simpler testcase.

OK, I've found it.  The ClassNotFoundException is thrown from a security check
in libgcj.  We are calling Method m1 from method m0, and m1's class loader
is different from m0's class loader.  We have to check that for every arg
in m1, the actual type is the same in both m1.loader and m0.loader.

The method in question is org.eclipse.core.runtime.Platform.getPlugin(String), 
which returns an instance of org.eclipse.core.runtime.Plugin.  It gets this
by calling org.eclipse.core.internal.plugins.PluginDescriptor.getPlugin().

When we do the security check, we call Platform's class loader to ask it to 
loadClass("org.eclipse.core.runtime.Plugin") and it throws a
ClassNotFoundException.

Tom Tromey: opinion, please.

Andrew.




public final class Platform {

...
       public static Plugin getPlugin(String id) {
               try {
                       IPluginRegistry registry = getPluginRegistry();
                       if (registry == null)
                               throw new IllegalStateException();
                       IPluginDescriptor pd = registry.getPluginDescriptor(id);
                       if (pd == null)
                               return null;
                       return pd.getPlugin();   // <== This is where the ClassNotFoundException is thrown
               } catch (CoreException e) {
                       // TODO log the exception                                                                                                                                                                                  
               }
               return null;
       }