Link errors: Confused about calling C code from GCJ via jni

[Barnet Wagman <wagman at enteract dot com>]

Please excuse the elementary nature of this question: I've searched the
archives, FAQ, etc. and not found the answer to my problem.

I'm trying to call  C (not C++) functions from GCJ compiled Java via jni (these are functions I'm currently using with regular interpreted Java, which is why I'd prefer not to switch to CNI).  I ran gcjh and recompiled the C functions (with the -D_REENTRANT option) and put the binaries into a library ('ld -shared ...')

The header generated by gcjh looks like C to me, but when I try to link this library against gcj compiled java, it looks as if gcj is looking for C++.

I.e. from my class Locfit.java, gcjh generates names for two functions,
 

extern void Java_locfit_Locfit_jniLocfit (
                JNIEnv *env, jobject, jint,
                jdoubleArray,,jdoubleArray, jdouble, jint, jint, jint, jdoubleArray);

extern void Java_locfit_Locfit_jniSetup (JNIEnv *env, jclass);

They refer to two C functions in one file, which gets compiled and put
into library liblocfit.so

Then  after compiling the calling java classes

> gcj -c --no-bounds-check -O3 -g0 SimRunner.java
> gcj -c --no-bounds-check -O3 -g0 Locfit.java
linking
> gcj --main=liveT.SimRunner -o SimRunner SimRunner.o Locfit.o
> liblocfit.so
>  
yields the error messages
 
> /home/moi/JavaTree/locfit/Locfit.o: In function `locfit::Locfit::_003cclinit_003e(unsigned)':
> /home/moi/JavaTree/locfit/Locfit.o(.text+0x383): undefined reference
> to `locfit::Locfit::jniSetup(void)'
> /home/moi/JavaTree/locfit/Locfit.o(.data+0x20c): undefined reference
> to `locfit::Locfit::jniLocfit(int, JArray<double> *, JArray<double>
> *, double, int, int, int, JArray<double> *)'
> /home/moi/JavaTree/locfit/Locfit.o(.data+0x21c): undefined reference
> to `locfit::Locfit::jniSetup(void)'
> /home/moi/JavaTree/locfit/Locfit.o(.data+0x29c): undefined reference
> to `locfit::Locfit::jniLocfit(int, JArray<double> *, JArray<double>
> *, double, int, int, int, JArray<double> *)'
> collect2: ld returned 1 exit status
> make: *** [SimRunner] Error 1
>  
It looks like the linker is looking for C++ references.   Of
course in the library, the names are
> 00057380 T Java_locfit_Locfit_jniLocfit
> 000576b0 T Java_locfit_Locfit_jniSetup
>  
I'd greatly appreciate any suggestions about how to get this working.

Thanks,

Barnet Wagman