Currently, this is only relevant when using LevelDB, and a newer version
of libstdc++, which uses a different C++ ABI which clang does not yet support.
A symptom of the problem are unexpected linking failures, caused by undefined
symbols, while other symbols from the same library do not cause errors.
The solution is a workaround, that avoids using the offending symbols, at the
cost of reduced functionality. As this currently only affects the text of an
error message, the impact is minor.
Previously, the HTML documentation would be generated even if there were
warnings, and a subsequent build would consider the documentation
up-to-date.
It seems like CMake has no option to remove a (possibly partially generated!)
target if the command exits with a non-zero status...
Unknown
Rogier