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From "Mark Hindess" <mark.hind...@googlemail.com>
Subject [classlib] [build] Unnecessary linking
Date Wed, 02 Jun 2010 10:12:49 GMT

If you are following the commits, you might have noticed that I am
trying to fix some of the unnecessary linking in our builds.  Most
recently I've been looking at the linking of the static library hypool.

We link against this static library in almost all of the build files
in classlib but only hyzip (both versions) and hythr actually use it.
However, if I remove the unnecessary references to hypool.{a,lib} from
the build then some instrument tests fail.

Running the failing test with ld debug like this:

  cd target/hdk/build/test/instrument
  LD_DEBUG_OUTPUT=ld.log LD_DEBUG=all \
    ../../../jdk/jre/bin/java \
      -cp ../junit.jar:../hamcrest-library.jar:instrument_tests.jar \
        org.junit.runner.JUnitCore \
          org.apache.harmony.tests.java.lang.instrument.HelloWorldTest

reveals the problem[0]:

  target/hdk/jdk/jre/bin/libhyinstrument.so:
    error: symbol lookup error: undefined symbol: pool_removeElement (fatal)

The problem is that while instrument doesn't use hypool.  It does
statically link hyzip which does use hypool but does not include it.
Obviously I could just link hyinstrument with hypool again but fixing
indirect dependencies this way seems kind of ugly.

Fixing it on windows is straightforward as adding a .lib to a .lib
does the right thing.  But on linux you can't just include hypool.a in
hyzip.a because it just creates a nested archive so you have to un/pack
the members.

I'm just running a few more tests before I check in the changes but I
thought I'd mention it here since the reason for the changes wont be
entirely obvious from the diff and because the LD_DEBUG trick is quite
useful for debugging these kind of problems.

Regards,
 Mark.

[0] Find the correct log for the child process, jump to the end and search
    back for "fatal".



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