Mixing BC and CNI in the same executable

[Andrew Haley]

On 01/25/2010 03:45 PM, Stephen Kell wrote:
>> Thanks.
>>
>> I've seen something like this years ago, but I can't remember what
>> caused it.  I expect it's something quite simple, but I can't tell
>> from what you've posted here.
>>
>> If you can make a self-contained test case theat reproduces the
>> problem I'll debug it.
> 
> Great -- thanks! The following tarball *should* be self-contained...
> "make testcase" should trigger the bug.
> 
> http://www.cl.cam.ac.uk/~srk31/private/testcase-20100125.tar.bz2

It's a combination of bugs.  Firstly, there's a bug in libgcj when a
needed class is not found in an executable: it causes a crash when
trying to report the problem.  Fixed thusly:

Index: java/lang/natClass.cc
===================================================================
--- java/lang/natClass.cc	(revision 156043)
+++ java/lang/natClass.cc	(working copy)
@@ -689,9 +689,12 @@
 _Jv_ClosureList::registerClosure (jclass klass, void *ptr)
 {
   _Jv_ClosureList **closures = klass->engine->get_closure_list (klass);
-  this->ptr = ptr;
-  this->next = *closures;
-  *closures = this;
+  if (closures)
+    {
+      this->ptr = ptr;
+      this->next = *closures;
+      *closures = this;
+    }
 }
 #endif
 
Secondly, you don't catch errors in your main program, just exceptions,
so you won't see Errors.  Do this instead:

		catch (java::lang::Throwable *e)
		{
			java::lang::System::err->print(e->toString());
			return 1;
		}				

Thirdly, you aren't linking in inner classes.  This works for me:

 gcj -fno-eliminate-unused-debug-symbols -fno-eliminate-unused-debug-types -findirect-dispatch -fno-indirect-classes -fpic -g3 --classpath=./java:./antlr-runtime-3.1.3.jar:: -Wall   -Wl,-R.   cake.o main.o  parser/parser.a antlr-runtime.jar.so stringtemplate.jar.so  -lstdc++ -o "cake" -Wl,-Map,map java/cake/TreewalkError.o java/cake/InternalError.o java/cake/CloneableTree.o java/cake/SemanticError.o ./parser/cake/cakeJavaParser\$DFA*.o ./parser/cake/cakeJavaLexer\$DFA*.o ./parser/cake/cakeJavaParser\$*_return.o 

It would be better to compile from .java -> .o, and then you would not
have to worry about all the inner classes.

Andrew.