[fedora-java] Regression in libgcj: spurious IncompatibleClassChangeError with BC-compiled code.

[Andrew Haley]

This happens if a class and its superclass are loaded by the boot
classloader.  If one if them is in the precompiled database and one
isn't, we fail this check:

      if (   sub->loader != super->loader
	  || !_Jv_ClassNameSamePackage (sub->name, super->name))
	{
	  throw_incompatible_class_change_error (sub->getName ());
	}

We fail this check becasue of this line in natVMClassLoader.cc

      // Record the defining loader.  For the bootstrap class loader,
      // we record NULL.
      if (loader != bootLoader)
	klass->loader = loader;

So, at the point of this test:

       sub->loader != super->loader

sub->loader == bootLoader, and super->loader == NULL.

All this happens because when a class is loaded by natSharedLibLoader,
we do this:


void
_Jv_sharedlib_register_hook (jclass cls)
{
  cls->protectionDomain = curHelper->domain;
  cls->loader = curLoader;
  if (! cls->engine)
    cls->engine = &_Jv_soleCompiledEngine;
  curHelper->registerClass(cls->getName(), cls);
}

note that we always set the loader; we don't check for it being the
bootLoader.

There are several ways to fix this.  We need it for FC6.

Andrew.


2006-07-25  Andrew Haley  <aph at redhat.com>

	* gnu/gcj/runtime/natSharedLibLoader.cc (init): Don't set
	curLoader to VMClassLoader::bootLoader.

--- natSharedLibLoader.cc~	2006-07-25 16:47:05.000000000 +0100
+++ natSharedLibLoader.cc	2006-07-25 18:11:25.000000000 +0100
@@ -20,6 +20,8 @@
 #include <java/lang/UnsupportedOperationException.h>
 #include <java/lang/UnknownError.h>
 
+#include <java/lang/VMClassLoader.h>
+
 // If we're using the Boehm GC, then we need this include to override dlopen.
 #ifdef HAVE_BOEHM_GC
 // Set GC_DEBUG before including gc.h!
@@ -87,7 +89,8 @@
     flags = RTLD_GLOBAL | RTLD_LAZY;
   JvSynchronize dummy1(&java::lang::Class::class$);
   SharedLibDummy dummy2;
-  curLoader = loader;
+  curLoader = ((void*)loader == java::lang::VMClassLoader::bootLoader
+	       ? NULL : loader);
   curHelper = this;
   _Jv_RegisterClassHook = _Jv_sharedlib_register_hook;
   _Jv_RegisterCoreHook = core_hook;