"???" garbage in compile logs

Some logs contain strings like:

tst_qcontact.cpp:678:25: warning: variable ???ti??? set but not used [-Wunused-but-set-variable]

(from http://testresults.qt-project.org/ci/QtPim_master_Integration/build_00398/linux-arm-gnueabi-g++_Ubuntu_11.10_x86/log.txt.gz )

It seems that quote characters are being munged somewhere.
There may be some layers which disagree about the encoding used for compiler output.