tst_QStringConverter: compare pointer distances, not pointersHEADdev

Strictly speaking, we did want to compare pointers, but char* are
special with QCOMPARE in that the pointed-to strings are compared, not
the pointers. So this wasn't doing what we wanted it to do.

We could static_cast to void* to do it, but subtracting one from the
other also gets us what we want, with simpler code. The drawback is that
if appendToBuffer() ever returns nullptr, we'll print a huge number as
the offset.

Found by Valgrind:
==3769588== Conditional jump or move depends on uninitialised value(s)
==3769588==    at 0x483FEDC: strcmp (in /usr/lib/x86_64-linux-gnu/valgrind/vgpreload_memcheck-amd64-linux.so)
==3769588==    by 0x4C41EB6: qstrcmp(char const*, char const*) (in lib/libQt6Core.so.6.9.0)
==3769588==    by 0x48975D8: QTest::compare_string_helper(char const*, char const*, char const*, char const*, char const*, int) (in lib/libQt6Test.so.6.9.0)
==3769588==    by 0x12B12A: QTest::qCompare(char*, char*, char const*, char const*, char const*, int) (in tests/auto/corelib/text/qstringconverter/tst_qstringconverter)
==3769588==    by 0x10EE94: tst_QStringConverter::invalidConverter() (in tests/auto/corelib/text/qstringconverter/tst_qstringconverter)

Amends c46ee7df57c30c94107df8506d30d8872ffa3baa.

Pick-to: 6.2 6.5 6.7 6.8
Fixes: QTBUG-126107
Change-Id: I44265a5eb67e47a59fc8fffd17d64051657af529
Reviewed-by: Marc Mutz <marc.mutz@qt.io>
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

0 files changed, 0 insertions, 0 deletions