Build portability: enable or disable warnings

[Alan Bateman]

David Holmes wrote:
> :
>
>> In contrast, there are basically two Java compilers in general use 
>> (javac and ecj)
>> and one is part of OpenJDK.  Yet, the Java code does not have -Werror 
>> enabled by default and there
>> are a mass of warnings there as a result.
>
> I don't understand the point you are making here. Does javac even have 
> a -Werror? The bulk of javac warnings stem from legacy code being 
> compiled under newer compilers with new language features - the 
> resulting code is not erroneous hence only a warning is issued.
>
> I think comparing C/C++ compiler warnings with javac compiler warnings 
> is like comparing apples and elephants.
Yes, javac has -Werror and the build has JAVAC_WARNINGS_FATAL to turn it 
on. I just checked my recent build of the jdk7/jdk7 forest and javac 
emits a total of 9 warnings (7 are unsafe usages of varargs methods and 
the other two are unreachable catch clauses). That isn't a lot but javac 
doesn't have many warnings enabled by default. A nice project for 
someone would be to change the build to -Werror by default and gradually 
crank up the warnings listed by -Xlint.

-Alan.