Regression in libgcj: spurious IncompatibleClassChangeError with BC-compiled code.

Tue Jul 25 17:14:00 GMT 2006

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年07月25日 Andrew Haley <aph@redhat.com>
	* gnu/gcj/runtime/natSharedLibLoader.cc (init): Don't set
	curLoader to VMClassLoader::bootLoader.

--- natSharedLibLoader.cc~	2006年07月25日 16:47:05.000000000 +0100
+++ natSharedLibLoader.cc	2006年07月25日 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;
