RFR: JDK-8211071: unpack.cpp fails to compile with statement has no effect [-Werror=unused-value]

[Roman Kennke]

Not sure this is the correct list. Please redirect as appropriate.

Please review the following proposed change:


There are 3 asserts in unpack.cpp which check only constants, and which
the compiler rejects as 'has no effect' (in fastdebug builds). This
seems to be caused by:

https://bugs.openjdk.java.net/browse/JDK-8211029

I propose to fix this by defining a STATIC_ASSERT which can evaluate and
reject this at compile time:

Webrev:
http://cr.openjdk.java.net/~rkennke/JDK-8211071/webrev.00/
Bug:
https://bugs.openjdk.java.net/browse/JDK-8211071

It might be useful to define the STATIC_ASSERT in a more central place
to be used elsewhere too. For example, there is a similar #define in
Hotspot's debug.hpp

Thanks, Roman